Biomedical subjects

Fang Jin

Publications and source records attributed to Fang Jin.

10 recordsLinked to original sources

PubMed2006

[Tooth movement in tissue-engineered bone].

OBJECTIVE: To explore the effect and practical value of repairing the alveolar defects with tissue engineering technique and investigate the influence of the generated new bone on the orthodontic tooth movement. METHODS: The marrow stromal cells of rats were separated, cultured in vitro and induced to osteoblast-like cells. The osteoblast-like cells were implanted onto the ceramic bovine bone. Then the complex was implanted into the alveolar defect in one side of the rat's mandible. The other side of the mandible served as control. Eight weeks later, the orthodontic appliances were placed between the first molar and incisors of SD rats to move the first molar forward. The tooth movement and root resorption of the molar were observed. RESULTS: We found that the tooth movement in the experimental area was faster than that in the normal alveolar bone (P < 0.05). The root resorption and the alveolar bone height loss were less than that in the control area (P < 0.05). CONCLUSIONS: The tissue-engineered bone did not have negative influences on tooth movement. The repair of alveolar bone defect by tissue engineering approach may be used in craniofacial surgery and orthodontics.

Animals↗

PubMed2005

Identification of novel insertion sites in the Ad5 genome that utilize the Ad splicing machinery for therapeutic gene expression.

Therapeutic transgene expression from oncolytic viruses represents one approach to increasing the effectiveness of these agents as cancer therapeutics. In the case of the oncolytic adenovirus (Ad), however, the genomic packaging capacity is constrained. To address this, we explored whether a transposon-based system could identify sites in the viral genome where endogenous Ad promoters could drive transgene expression via splicing and still maintain the replication capacity of the virus. Using GFP as a reporter gene and an E3-deleted Ad genome as a target, we tested three splicing signals. RACE analysis confirmed that gene expression from the GFP-expressing Ads occurs via splicing and traced expression to the Ad major late promoter (MLP). Replacement of the GFP transposon by an equivalent splice acceptor-luciferase expression cassette in the same orientation confirmed that substitute transgenes are also expressed via splicing from the MLP. Interestingly, insertion of the substitute transgene in the opposite orientation also resulted in expression that, in some cases, originated from within the ITR region of the viral genome. In summary, splice acceptor sequences can be used to control transgene expression from endogenous Ad promoters and this represents a genomically economical approach to arming oncolytic Ads.

Adenoviridae↗

PubMed2005

Enhanced efficacy of gemcitabine in combination with anti-CD20 monoclonal antibody against CD20+ non-Hodgkin's lymphoma cell lines in vitro and in scid mice.

BACKGROUND: Despite exciting new targeted therapeutics against non-Hodgkin's lymphoma (NHL), chemotherapy remains a cornerstone of therapy. While purine nucleoside analogs have significant activity in low grade NHL, the pyrimidine nucleoside analog gemcitabine has been less extensively studied, but has important activity. Use of the anti-CD20 monoclonal antibody rituximab in combination with chemotherapy for B-NHL is becoming prevalent in clinical practice, but has not been extensively studied in pre-clinical models. METHODS: We have tested the activity of gemcitabine +/- rituximab in vitro and in scid/human NHL xenograft models. We used two t(14;18)+, CD20+ follicular B cell NHL cell lines, DoHH2 a transformed NHL line and WSU-FSCCL isolated from pleural fluid of a patient with indolent NHL. RESULTS: Gemcitabine is cytotoxic to DoHH2 and WSU-FSCCL cells in vitro, and the IC50 is 2-3 fold lower in the presence of rituximab. Apoptosis is also enhanced in the presence of rituximab. Clearance of NHL cells from ascites in scid mice is prolonged by the combination, as compared with either agent alone. Most importantly, survival of scid mice bearing human NHL cells is significantly prolonged by the combination of gemcitabine + rituximab. CONCLUSION: Based on our pre-clinical data showing prolonged survival of mice bearing human lymphoma cell line xenografts after treatment with gemcitabine + anti-CD20 antibody, this combination, expected to have non-overlapping toxicity profiles, should be explored in clinical trials.

Animals↗

PubMed2005

Wetting of a particle in a thin film.

When a particle is placed in a thin liquid film on a planar substrate, the liquid either climbs or descends the particle surface to satisfy its wetting boundary condition. Analytical solutions for the film shape, the degree of particle immersion, and the downward force exerted by the wetting meniscus on the particle are presented in the limit of small Bond number. When line tension is significant, multiple solutions for the equilibrium meniscus position emerge. When the substrate is unyielding, a dewetting transition is predicted; that is, it is energetically favorable for the particle to rest on top of the film rather than remain immersed in it. If the substrate can bend, the energy to drive this bending is found in the limits of slow or rapid solid deflection. These results are significant in a wide array of disciplines, including controlled delivery of drugs to pulmonary airways, the probing of liquid film/particle interface properties using particles affixed to AFM tips and the positioning of small particles in thin films to create patterned media.

Models, Theoretical↗

PubMed2005

Development of a transposon-based approach for identifying novel transgene insertion sites within the replicating adenovirus.

Therapeutic gene delivery from an oncolytic adenovirus (Ad) is one approach to enhancing the potency of Ad-based virotherapies for cancer. To identify therapeutic transgene insertion sites compatible with the replicating virus, a methodology that broadly scans the viral genome is needed. To address this we modified a transposon (Tn7)-based in vitro transposition system to take advantage of its nonprejudiced scanning ability to identify insertion sites compatible with viral replication. Using this system with a plasmid containing an E3-deleted Ad5, we identified several unique sites for promoter-based expression cassette insertions within the Ad genome. The transposon-based expression cassette is bounded by PmeI restriction endonuclease sites unique to the transposon, making expression cassette substitutions easy to perform. Additional expression cassettes containing different promoters and reporter genes were substituted into two of the newly identified transgene insertion sites. The results suggest that the ease and orientation of expression cassette substitution depend on both the insertion site location and the promoter and gene of the replacement expression cassette. These studies establish the transposon-based system as an efficient approach to scanning the Ad genome and identifying insertion sites compatible with viral replication and represents a powerful tool for the development of armed therapeutic viruses for cancer.

Adenoviridae↗

PubMed2005

Vitrification of mouse embryos at various stages by open-pulled straw (OPS) method.

This study was performed to pursue the optimal condition for the cryopreservation of mouse morulae by a two-step OPS method and to investigate the feasibility of the optimal condition for vitrification of embryos at other developmental stages. First, the mouse morulae were vitrified in OPS using one-step procedure-that is, embryos were vitrified after direct exposure to EDFS30 (15% ethylene glycol (EG), 15% dimethyl sulfoxide (DMSO), Ficoll and sucrose), or two-step method-that is, embryos were first pretreated in 10%E + 10%D (10% EG and 10% DMSO in mPBS) for 30 sec, then exposed to EDFS30 for 15 to 60 sec, respectively. After vitrification and warming, the embryos were morphologically evaluated and assessed by their development to blastocysts, expanded/hatched blastocysts, or to term after transfer. The result showed that all the vitrified-warmed morulae had similar blastocyst rate compared to that of control (91.7% vs. 100%), and the highest developmental rate to expanded blastocysts (100%) or hatched blastocysts (62.3%) was observed when the morulae were pretreated with 10%E + 10%D for 0.5 min, exposed to EDFS30for 25 sec before vitrification and warming in 0.5 M sucrose for 5 min. After transfer, the survival rate (33.1%) in vivo of the vitrified morulae was higher (P > 0.05) than that of the fresh embryos (24.6%). Secondly, embryos at different stages were cryopreserved and thawed following the above program. Most (93.4 to 100%) of the embryos recovered after vitrification were morphologically normal at all the developmental stages. The blastocyst rates of the vitrified one-cell (52.5 to 66.7%) and the two-cell (63.3 to 68.9%) embryos were lower (P < 0.05) than those of the vitrified four-cell embryos (81.7 to 86.4%), the eight-cell embryos (90.0 to 93.3%), morulae (96.7 to 100%), and the expanded blastocysts rate (98.3 to 100.0%) of the vitrified early blastocysts. The highest survival rate in vivo of vitrified embryos were from the early blastocysts (40.4%), which was similar to that of fresh embryos (48.6%). The data demonstrate that the optimal protocol for the cryopreservation of morulae was suitable for the four-cell embryos to early blastocyst stages and that the early blastocyst stage is the most feasible stage for mouse embryo cryopreservation under our experimental conditions.

Animals↗

PubMed2005

Effect of halothane on galphai-3 and its coupling to the M2 muscarinic receptor.

BACKGROUND: Halothane is an effective bronchodilator and inhibits airway smooth muscle contraction in part by inhibiting intracellular signaling pathways activated by the M2 muscarinic receptor and its cognate inhibitory heterotrimeric guanosine-5'-triphosphate (GTP)-binding protein (G protein), Gi. This study hypothesized that halothane inhibits nucleotide exchange at the alpha isoform-3 subunit of Gi (Galphai-3), but only when regulated by the M2 muscarinic receptor. METHODS: GTP hydrolysis by Galphai-3 and the Galphai-3beta1gamma2HF heterotrimer expressed in Spodoptera frugiperda cells was measured using a phosphohydrolase assay with [gammaPi]-labeled GTP. Anesthetic binding to Galphai-3 was measured by saturation transfer difference nuclear magnetic resonance spectroscopy. Galphai-3 nucleotide exchange was measured in crude membranes prepared from COS-7 cells transiently coexpressing the M2 muscarinic receptor and Galphai-3. A radioactive analog of GTP, [S]GTPgammaS, was used as a reporter for Galphai-3 nucleotide exchange. RESULTS: Although spectroscopy demonstrated halothane binding to Galphai-3, this binding had no effect on [gammaPi]-labeled GTP hydrolysis by the Galphai-3beta1gamma2HF heterotrimer expressed in Spodoptera frugiperda cells, nor basal Galphai-3 nucleotide exchange measured in crude membranes when the muscarinic receptor agonist acetylcholine was omitted from the assay. Conversely, halothane caused a concentration-dependent inhibition of Galphai-3 nucleotide exchange with acetylcholine included in the assay. CONCLUSION: These data indicate that despite halothane binding to Galphai-3, halothane has no direct inhibitory effect on the intrinsic activity of the Galphai-3beta1gamma2HF heterotrimer but inhibits M2 muscarinic receptor regulation of the heterotrimer. This novel effect is consistent with the ability of halothane to inhibit airway smooth muscle contraction and bronchoconstriction induced by acetylcholine.

Acetylcholine↗

PubMed2004

Enhanced efficacy of therapy with antisense BCL-2 oligonucleotides plus anti-CD20 monoclonal antibody in scid mouse/human lymphoma xenografts.

Monoclonal anti-CD20 antibody (rituximab) is active, but not curative, therapy for B-cell non-Hodgkin's lymphoma. BCL-2 is an antiapoptotic protein whose expression is dysregulated in most indolent B-cell malignancies. Antisense oligonucleotides (AS-ODNs) that down-regulate BCL-2 expression induce apoptosis and chemosensitize B-cell lymphoma cells. We hypothesized that BCL-2 down-regulation by AS-ODNs would sensitize cells to rituximab and improve therapeutic results. There is enhanced apoptosis and reduction in cell numbers when DoHH2 cells are treated in vitro with rituximab plus BCL-2 AS-ODNs, compared with either agent alone. There is little in vitro effect on WSU-FSCCL cells by rituximab, AS-ODNs that down-regulate BCL-2 by targeting the immunoglobulin portions of the BCL-2-immunoglobulin fusion molecule, or a combination of the two. The combination is more effective than either agent alone in clearing DoHH2 cells from ascites in scid mice. Combination therapy with AS-BCL-2-ODNs and rituximab significantly prolongs survival in both the DoHH2 and WSU-FSCCL models. With higher and repeated doses, this combination could be curative. We conclude that the combination of rituximab and antisense-mediated down-regulation of BCL-2 has enhanced activity against human lymphoma, prolongs survival, and could cure mice bearing human lymphoma. This merits investigation in clinical trials.

Animals↗

PubMed2003

Focal adhesion kinase is required for blood vessel morphogenesis.

The nonreceptor tyrosine kinase focal adhesion kinase (FAK) is a point of convergence for signals from extracellular matrix, soluble factors, and mechanical stimuli. Targeted disruption of the fak gene in mice leads to death at embryonic day 8.5 (E8.5). FAK-/- embryos have severely impaired blood vessel development. Gene expression and in vitro differentiation studies revealed that endothelial cell differentiation was comparable in FAK-/- and wild-type E8.5 embryos. We examined the role of FAK in blood vessel morphogenesis using an in vitro tubulogenesis assay and three different culture systems: FAK+/+ and FAK-/- embryoid bodies, FAK+/+ and FAK-/- endothelial cells, and human umbilical vein endothelial cells expressing antisense FAK, a dominant-negative fragment of FAK, or wild-type FAK. In all of these systems, endothelial cells deficient in FAK expression or function displayed a severely reduced ability to form tubules in Matrigel. These studies demonstrate clearly that the vascular defects in FAK-/- mice result from the inability of FAK-deficient endothelial cells to organize themselves into vascular networks, rather than from defects in tissue-specific differentiation.

Animals↗

PubMed2003

[Orthodontic treatment of malocclusion with mandibular congenital missing teeth guided by Bolton index].

OBJECTIVE: To evaluate the outcome of the treatment of malocclusion with mandibular congenital missing teeth guided by Bolton index. METHODS: 26 class I and II cases (males 10, females 16) were chosen in this study. Guided by Bolton index, enamel stripping, denture and two types of tooth extraction were used in the treatment. RESULTS: Normal Bolton index was achieved and the results of treatment were satisfactory. CONCLUSIONS: Malocclusion with mandibular congenital missing teeth can be treated successfully guided by Bolton index.

Adolescent↗