Biomedical subjects

Jing Yang

Publications and source records attributed to Jing Yang.

At least 73 records · Page 4Linked to original sources

PubMed2006

[A study on expression of caspase-8 in organs of rats after electrical injury at antemortem or postmortem].

OBJECTIVE: This study was conducted to detect the expression of caspase-8 in organs of rats after The electrical injury so as to elucidate whether caspase-8 is useful in identifying electrical lesion. METHODS: experiment included two parts. In the first part (the antemortem electrical injury part), thirty-five healthy male SD rats were randomly divided into seven groups (n = 5 per group), i. e. the group of rats subjected to instantaneous electrothanasia; the groups of rats subjected to cervical dislocation at 1 h, 2 h, 4 h, 8 h after electrical injury; the sham group and the normal control group. In the second part (the postmortem electrical injury part), twenty-five healthy male SD rats wererandomly divided into five groups (n=5 per group), i. e. the groups of rats electrically injured just after death, and at 15 min, 30 min, 60 min after death; and the postmortem sham group. All experimental rats were given respectively an electric shock with two metal clamps that were connected with two poles of 220 V alternating current by clamping the rats' left hind limbs and right forelimbs. The rats of sham group after death were clamped but not electrified. The brain, lung, heart, liver, spleen, kidney, the muscle of electrified limb, the cutis of electrified limb of all experimental rats and those organs of control groups were dissected to detect the expression of caspase-8 by immunohistochemistry staining, and the staining intensities were assessed by image analysis system. RESULTS: In the antemortem electrical injury groups, the expression of caspase-8 was positive in brain, heart, liver and kidney; the strongest staining intensity appeard at 4 h after electrical injury and decreased at 8 h after electrical injury. In the group of rats electrically injuryed just after death, the expression of caspase-8 was faint, and the expression of caspase-8 in spleen, lung, muscle and cutis was negative in the other groups. The expression of caspase-8 in all detected organs was negative in the other rats that were electrified after death. CONCLUSION: Caspase-8 can be regarded as an index in identifying electrical injury and distinguishing between antemortem and postmortem electrical injuryies.

Animals↗

PubMed2006

[Isolation, culture and identification of rat retinal progenitor cells in vitro].

OBJECTIVE: To characterize embryonic rat retinal progenitor cells (RPCs) by flow cytometry (FACS), immunofluorescence and (3)H-Thymidine assay in vitro. METHODS: RPCs were prepared from the retina of embryonic day 19 Sprague Dawley rats and were cultured in DMEM: F12 medium with N2-supplement, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and leukemia inhibitory factor (LIF) for 0 to 4 days. Cell proliferation and cluster formation were quantified by (3)H-Thymidine assay and morphometric analysis, respectively. Antibodies used to characterize the RPCs included markers for neural progenitors (Nestin and Sox-2), astrocytes (glial fibrillary acidic protein [GFAP]), horizontal cells (Calretinin), ganglion cells (CD90), rods (Rhodopsin), biopolar cells (PKC) and amacrine cells (Syntaxin) by the use of FACS. RESULTS: In primary cells, 22.23%, 16.04% and 19.66% of cells were found to express Nestin, Sox-2 and Calretinin, respectively. GFAP, CD90, Rhodopsin, PKC, Syntaxin were not detected or trail. Meanwhile, more than 90% cells were Nestin positive by immunofluorescence. After 6 days culture in vitro, 43.36% cells express Nestin by FACS. Nestin and GFAP were expressed by use of immunofluorescence. There was significant proliferation of RPCs within the first 4 days as evaluated by (3)H-Thymidine assay. CONCLUSIONS: The results demonstrate that combine FACS, immunofluorescence and (3)H-Thymidine assay together could characterize RPCs. RPCs proliferate well at the early period of cell culture.

Animals↗

PubMed2006

[Analysis of protein expression feature and construction of procaryotic expression system for human papillomavirus type 16 (HPV-16) E4 gene].

OBJECTIVE: To clone the E4 gene (E4) from human papillomavirus type 16(HPV-16), construct the engineering bacteria of prokaryotic expression, and explore the expression conditions and the characters of expression product. METHODS: The complete E4 gene was cloned by PCR from the sample cell extract of clinical cervical disease that was the positive HPV-16 confirmed by Real-PCR. The E4 DNA fragment was inserted into the pET32a(+) to construct a prokaryotic expression plasmid, called as pET32/E4. Then the expression plasmids were transferred into competent E. coli BL21 (DE3). Recombinant DNA was identified by Bgl II and Hind III digestion, and then sequencing. The recombine bacterium, BL21/E4, was induced with different IPTG concentrations at different temperatures. The expressed proteins were checked and analyzed by SDS-PAGE and Gel-Pro Analyzer 4. His-tag of BL21/E4 expression protein was hybridized to McAb. RESULTS: The E4 gene cloned by PCR was about 342 bp. The blasted result showed that the E4 gene had 99% homology of HVP-16 DNA sequence, the cloned E4 gene expression frame was the same as HVP-16 East Asia strain's. Compared with other HPV-16 strains in GenBank, the homology of E4 gene was above 97%. pET32/E4 could express recombinant E4 (rE4) in BL21. The highest expression, which was 12.2% or 12.8% of total bacterial proteins respectively, was gotten when BL21/E4 was induced by 0.1 mmol/L IPTG at 28 degrees C or 37 degrees C for 18 hours. The results of SDS-PAGE and Western blot showed the rE4 was expressed mainly to form the inclusion body, and to fuse with his-tag (rE4/His), that was soluble and had a molecular weight as about 34 KDa. CONCLUSION: We cloned successfully the E4 gene from HPV-16 and constructed the prokaryotic expression E. coli BL21/E4, which could expression rE4 protein fused with his-tag (rE4/His), effectively. The fused protein could react to McAb recognizing His-tag, which was convenience purified by affinity chromatography. The above research results built a good foundation for preparing the high grade of purity E4 protein and developing the relative study.

Antibodies, Monoclonal↗

PubMed2006

[Expression of c-fos protein after muscle contusion in experimental rats].

OBJECTIVE: To study the relationship between the expression of c-Fos protooncogene and skeleton muscle contusion of rats, and to search for a sensitive marker of timing for skeleton muscle contusion. METHODS: Fifty Sprague-Dawley rats were randomly distributed into control group and experimental groups. The expression of c-fos was microscopically observed by immunohistochemical method. RESULTS: With the time prolonged the c-fos positive intensity and area were increased. Positive expression of c-fos protein appeared at 15 min after skeleton muscle contusion, and reached to the peak at 1h after skeleton muscle contusion, then decreased gradually and returned to the normal level on 1d after skeleton muscle contusion. CONCLUSION: The detection of the expression of c-fos protein could be a sensitive marker for timing skeleton muscle contusion.

Animals↗

PubMed2006

[Application of monoclonal antibody immobilized polyurethane film for site-specific gene therapy].

OBJECTIVE: To study the feasibility of delivering viral gene vector from a collagen-coated polyurethane (PU) film through a mechanism involving monoclonal antiviral antibody tethering. METHODS: Anti-adenoviral monoclonal antibodies were covalently bound to the collagen-coated PU surface. These antibodies enabled tethering of replication defective adenoviruses through highly specific antigen-antibody affinity. The PU film-based gene delivery using antibody-tethered adenovirus encoding green fluorescent protein (GEP) was tested in rat arterial smooth muscle cell (A10 cell) culture in vitro. The virus binding stability was studied by incubating the collagen-coated PU film in PBS solution at 37 degrees C for 20 days, followed with A10 cell cultures with the incubated films and the corresponding buffer solution. RESULTS: PU films with antibody-tethered adenovirus encoding GFP demonstrated efficient and highly localized gene delivery to A10 cells. Virus binding was stable for at least 10 days at physiological conditions, more than 77% of the originally bound virus remained in the film after 15 day's incubation. CONCLUSION: Gene delivery using PU film-based anti-viral antibody tethering of vectors exhibited potentials of applications in a wide array of single or multiple therapeutic gene strategies, and in further stent-based gene delivery therapeutic strategies.

Adenoviridae↗

PubMed2006

[Biological stability analysis of QY1 pluripotential mesenchymal stem cell line from Sprague Dawley rat bone marrow].

OBJECTIVE: To explore the optimal culture conditions in vitro and the biological characterizations of the QY1 pluripotential mesenchymal stem cell (MSC) line from Sprague-Dawley rat bone marrow and to analyze the biological stability of this MSC line so as to provide an ideal cell model for the further differentiation and actual application. METHODS: The methods and technologies of cell biology and stem cell tissue engineering were used to purify MSCs. We determined the effects of morphology of cell proliferation, the time of change medium, growth curves, doubling time, adhesive rates, chromosome, culture conditions, and repeated frost on the biological characterizations of MSCs. RESULTS: The cells had a fibroblastic-like morphology and were well spread out; 80% - 90% cells became confluent between 10 and 12 days in primary culture. The growth curves of Passage 1, 3, 10, and 20 were quite similar (P>0.05). The doubling time of passage 1, 3, 10, and 20 were 34.2, 33.9, 31.8, and 30.6 hours, respectively. The adhesive rates of Passage 1, 3, 10, and 20 were very much similar (P>0.05) and about 89% subcultured cells adhered to the wall in 10 hours. The most appropriate concentration of serum was 20% and the most appropriate concentration of cell number was 8 x 10(4)/mL. The cells of Passage 8 showed light red cytoplasm and heavy blue nuclear stained by Giemsa staining. The chromosomes of Passage 8 and 20 were normal in appearance and their karyotypes were 42, XY. The cells were resuscitable after repeated frozen, and more than 85% cells were alive. The cells had been continuously cultured for more than 10 months so far. CONCLUSION: The QY1 MSCs line from Sprague-Dawley rat bone marrow is a purified cell line, which can maintain its undifferentiation and the stable biological characterizations for the long term.

Animals↗

PubMed2006

[Effect of gene transfer using nanoparticles as gene vector in different animal models].

OBJECTIVE: To evaluate the effect of antisense monocyte chemotactic protein-1 (A-MCP-1) nanoparticles (NPs) as gene carrier on gene transfer in two kinds of animal models. METHODS: Poly (lactic acid-co-glycolic acid) (PLGA) was used to make the NPs loaded with A-MCP-1 through a double-emulsion/solvent evaporation technique. NPs size was assessed by dynamic laser defractometer. The particle morphology was observed by scanning electron microscopy. DNA content in the NPs was measured by dissolving known amounts of NPs in chloroform and extracting DNA with water. In vitro release was performed in tris-EDTA buffer at 37 degrees C using double-chamber diffusion cells. The receiver buffer was replaced daily. The A-MCP-1 NPs was transfected into the cultured smooth muscle cells. PCR was used to evaluate the transfection of A-MCP-1. Cationic lipid (Lipofectamine) was used to transfect A-MCP-1 as control. After 48 hours incubation, cells were digested and examined by polymerase chain reaction. Twenty New Zealand white rabbits under jugular vein to artery bypass grafting procedure were divided into four groups: the first group received grafts treated with A-MCP-1 NPs, the second group received grafts treated with cationic liposome (dioleoyl trimethyl ammonium propane)-A-MCP-1, the third group received grafts treated with plasmid DNA, and the fourth group received grafts without transfection as control. Fourteen days after surgery the grafts were harvested. The expression of A-MCP-1 and its effect on MCP-1 in vein grafts were detected by dot blotting. The morphology of the grafts was investigated. To establish abdominal aortic aneurysms rats model, rats were randomly divided into three groups: A-MCP-1 NPs injection group, shame NPs injection group and control groups (without injection). Two weeks after surgery, diameter of abdominal aorta was measured and aortic tissue was obtained for PCR analysis to evaluate the A-MCP-1 expression. Western blot were applied to detect the inhibitory effect to the expression of MCP-1 mRNA and CD68 protein by A-MCP-1 NPs. RESULTS: NPs size ranged 198nm to 205nm with average around 201.4 nm. DNA content in the NPs was 4.14%. NPs showed steady release rate in vitro in Tris-EDTA solution. It released faster in the first week then maintained a slowly sustained release up to 16 days. In cell culture A-MCP-1 gene successfully transfected into smooth muscle cells by NPs vector. In vein grafting animal model, A-MCP-1 expression was detected in the vascular walls of NPs and cationic lipid treated groups. The degree of vascular hyperplasia in the gene NPs treated group was significantly lower than that in control group. There was no significant difference in the inhibition of intimal hyperplasia between NPs and cationic lipid treated groups. Two weeks after transfection in abdominal aortic aneurysm rats models, the abdominal aortic diameter of A-MCP-1 NPs injection group was (1.79 +/- 0.12) mm, significantly smaller than that of control groups [shame NPs group was (2.58 +/- 0.21) mm, and saline group was (2.63 +/- 0.29) mm] (P < 0.01). The expressions of MCP-1 mRNA and CD68 protein in A-MCP-1 NPs injection group were 12.5 +/- 1.5 and 17.6 +/- 2.1, which were much lower than those in control group [in shame NPs group, which were 35.7 +/- 4.5, 42.3 +/- 5.7 (P < 0.01), and saline group which is 32.4 +/- 3.9, 39.8 +/- 4.8 (P < 0.01)]. Specific band of A-MCP-1 was detected only in the A-MCP-1 NPs injection group by PCR. CONCLUSION: A-MCP-1 gene NPs can be successfully used in rabbit vein grafting model and abdominal aortic aneurysm rats models, and may be potentially applied in clinical practice.

Animals↗

PubMed2006

[Relationship between laryngeal morphology and voice changes in old people].

OBJECTIVE: To investigate the relationship between laryngeal morphologic changes and voice changes in old people. METHODS: Fifty four healthy people older than 60 years were studied. Laryngeal morphologic changes and vocal acoustics features were observed and analyzed. Forty six college students aged between 21-22 years were included as the young control group, and 23 of them are males and 23 females. RESULTS: Sixteen cases with vocal fold atrophy (55.2%), 18 cases with glottis incompetence (62.1%), 16 cases with hypoglottic mucosal edema (55.2%), 12 cases with surpassing ventricular fold (refers to the phenomenon that the ventricular fold covers part or all of the vocal cord during phonation) (41.4%) were observed in the old male; 15 cases with edema of interarytenoid fold (60.0%), 14 cases with glottis incompetence (56.0%), 12 cases with vocal fold atrophy (48.0%), 8 cases with vocal fold edema (32.0%) were observed in the old female. Fundamental frequency (F 0) ascended in the male while declined in the female; jitter, shimmer and noise to harmonic ratio enlarged, and vocal tremor intensity index increased too. Soft phonation was noticed especially in the voices of the old male. Compared with the control group, there was statistic significance (each p value is less than 0.05 or 0.01) except for the increasing of jitter, shimmer and soft phonation index in the old female. CONCLUSIONS: Significant changes were found in the old when the morphology of larynx and features of vocal acoustics were studied, hypoglottic edema and interarytenoid edema are common in the old.

Aged↗

PubMed2006

[Comparative study of the clinical effects of salvia miltiorrhiza injection and shengmai injection on chronic hepatitis B].

OBJECTIVE: To observe the effect of Salvia miltiorrhiza Injection (SMI) and Shengmai Injection (SI) on liver function and fibrosis related indexes in patients with chronic hepatitis B. METHODS: Seventy-nine chronic hepatitis B patients were randomly divided into the SMI group (n=47) and the SI group (n=32), they were treated with SMI and SI respectively on the basis of conventional treatment. The therapeutic course was 35 days for both groups. The changes of main symptoms and physical signs were observed, and indexes of liver function and fibrosis including serum hyaluronidase, laminin, III type precollagen (PC-III) and IV type collagen (IV-C) were investigated before and after treatment. RESULTS: Symptoms, physical signs and liver functions were improved obviously in both SMI and SI groups, SI showed better effect than SMI (P < 0.05). The four liver fibrosis indexes declined significantly in the SMI group after treatment (P < 0.05), but no obvious change of those was found in the SI group (P > 0.05), showing significant difference between the two groups (P < 0.05). Conclusion SMI is effective in improving liver function and inhibiting liver fibrosis, and SI has even better effect in improving liver function than SMI, though it shows no anti-liver fibrosis effect.

Adult↗

PubMed2005

Targeting heat shock proteins for immunotherapy in multiple myeloma: generation of myeloma-specific CTLs using dendritic cells pulsed with tumor-derived gp96.

PURPOSE: To develop effective immunotherapies for patients with multiple myeloma, it is important to use novel tumor antigens. Recent studies in solid tumors show that tumor-derived heat shock proteins (Hsp) can be used as immunogen; however, no such study has yet been reported in multiple myeloma. EXPERIMENTAL DESIGN: We examined whether myeloma-derived Hsp gp96 can be used as a myeloma antigen. Specific CTL lines were obtained after repeatedly stimulating T cells with autologous, HLA-A*0201+ dendritic cells pulsed with gp96 derived from HLA-A*0201+ human myeloma cell line (HMCL) U266 or primary myeloma cells. RESULTS: These T cells lysed not only gp96-pulsed dendritic cells, U266, and other HLA-A*0201+ HMCLs IM-9 and XG1 but also effectively killed HLA-A*0201+ primary myeloma cells from patients. No killing was observed against unpulsed dendritic cells, dendritic cells pulsed with control gp96, HLA-A*0201- HMCLs, and primary myeloma cells, or HLA-A*0201+ nonmyeloma cells. Cytotoxicity was mainly MHC class I/HLA-A*0201 restricted, suggesting that the CTLs recognized gp96-chaperoned peptides on HLA-A*0201 that were derived from shared myeloma antigens and that myeloma cells naturally present these peptides in the context of their surface MHC molecules. Upon antigen stimulation, these T cells secreted IFN-gamma and tumor necrosis factor-alpha, indicating that they belong to type 1 T-cell subsets. CONCLUSION: These results show that these T cells are potent CTLs that are able to effectively lyse myeloma cells but not normal blood cells and also suggest that Hsps from allogeneic tumor cells may be used as vaccines to immunize patients.

Antigens, Neoplasm↗

PubMed2005

Polymorphisms of IL-13 and IL-4-IL-13-SNPs in patients with penicillin allergies.

OBJECTIVE: Although IL-4 and IL-13 share many biologic activities, some are unique to IL-13. We genotype the IL-13 and IL-4-IL-13-SNPs genes for polymorphisms that could then be used to determine associations with IgE regulation as well as levels of IL-4 and IL-13. METHODS: Eight kinds of IgE specific to penicillins were determined with radioallergosorbent test (RAST) in the sera of 158 patients with penicillin allergies and 89 healthy subjects. Serum levels of IL-4 and IL-13 were measured by using enzyme-linked immunosorbent assay (ELISA). The genotyping of IL-13Arg130Gln, IL-4-IL-13-SNP3 and IL-4-IL13-SNP4 was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS: Among patients with positive specific IgE, significant differences between the IL-4-IL-13-SNP3 and IL-4-IL-13-SNP4 genotypes were observed between patients with positive BPA and the control group (P<0.05, P<0.05). Additionally, we also found significant differences in the IL-4-IL-13-SNP4 genotype between positive and negative BPA-IgE patients (P<0.05). However, we found no significant differences in the prevalence of these polymorphisms between any of the symptomatic groups studied and the control group. Nor were there any significant differences between levels of IL-4 and IL-13 and any of genotypes. CONCLUSION: The data suggest that IL-4-IL-13-SNP genes between IL-4 and IL-13 play a role in regulation of specific IgE levels in patients with penicillin allergies.

Adult↗

PubMed2005

Tumor evasion of the immune system: inhibiting p38 MAPK signaling restores the function of dendritic cells in multiple myeloma.

Dendritic cells (DCs) from patients with cancer are functionally defective, but the molecular mechanisms underlying these defects are poorly understood. In this study, we used the murine 5TGM1 myeloma model to examine the effects and mechanisms of tumor-derived factors on the differentiation and function of DCs. Myeloma cells or tumor culture conditioning medium (TCCM) were shown to inhibit the differentiation and function of BM-derived DCs (BMDCs), as evidenced by the down-regulated expression of DC-related surface molecules, decreased IL-12, and compromised capacity of the cells to activate allospecific T cells. Moreover, TCCM-treated BMDCs were inferior to normal BMDCs at priming tumor-specific immune responses in vivo. Neutralizing antibodies against IL-6, IL-10, and TGF-beta partially abrogated the effects. TCCM treatment activated p38 mitogen-activated protein kinase (MAPK) and Janus kinase (JNK) but inhibited extracellular regulated kinase (ERK). Inhibiting p38 MAPK restored the phenotype, cytokine secretion, and function of TCCM-treated BMDCs. BMDCs from cultures with TCCM and p38 inhibitor was as efficacious as normal BMDCs at inducing tumor-specific antibody, type 1 T cell, and cytotoxic T lymphocyte (CTL) responses and at prolonging mouse survival. Thus, our results suggested that tumor-induced p38 MAPK activation and ERK inhibition in DCs may be a new mechanism for tumor evasion and that regulating these pathways during DC differentiation provides new strategies for generating potent DC vaccines for immunotherapy in patients with cancer.

Animals↗

PubMed2005

Mechanisms of difluoroethylene ozonolysis: a density functional theory study.

We present a density functional theory (DFT) study on the mechanisms of gas-phase ozonolysis of three isomers of difluoroethylene, namely, cis-1,2-difluoroethylene, trans-1,2-difluoroethylene, and 1,1-difluoroethylene. MPW1K/cc-pVDZ and BHandHLYP/cc-pVDZ methods are employed to optimize the geometries of stationary points as well as the points on the minimum energy path (MEP). The energies of all the points were further refined at the QCISD(T)/cc-pVDZ and QCISD(T)/6-31+G(df,p) levels of theory with zero-point energy (ZPE) corrections. The ozone-cis-1,2-difluoroethylene reaction is predicted to be slower than the ozone-trans-1,2-difluoroethylene reaction. The enhanced reactivity of trans-1,2-difluoroethylene relative to the cis isomer is similar to the reactions of ozone with cis- and trans-dichloroethylene. The ozone-1,1-difluoroethylene reaction is predicted to be slower than the ozone-trans-1,2-difluoroethylene reaction. These results are in agreement with experimental studies. The calculated mechanisms indicate that in ozone-difluoroethylene reactions the yields of OH might be trivial, which is different from the reactions of ozone with unsaturated hydrocarbons.

Journal Article↗

PubMed2005

Responsiveness of a neural pacemaker near the bifurcation point.

We compared the responsiveness of a neural firing pacemaker in different dynamic states during the process of period-adding bifurcation to excitatory and inhibitory electrical field stimulus. In the region far from the bifurcation point, with the increase of the intensity of excitatory stimulus, the firing rate increased in an approximately linear manner and no firing pattern transition was observed. While in the region near the bifurcation point, the firing rate increased markedly higher accompanied with the transition of firing pattern when the intensity of excitatory stimulus remained the same. The stimulus-response of the region near the bifurcation point shifted upward significantly compared to that of the region far from the bifurcation point. Inhibitory stimulus with the same intensity, however, decreased the firing rate slightly without the transition of firing pattern in the region near the bifurcation point. These results suggest that the responsiveness in the region near the bifurcation point is more sensitive than that in the region far from the bifurcation point, which we named "critical sensitivity", and this has directional selectivity.

Action Potentials↗

PubMed2005

Taxonomy and molecular phylogeny of Myxobolus bilobus n. sp. (Myxozoa) parasitizing Notemigonus crysoleucas (Cyprinidae) in Algonquin Park, Ontario, Canada.

Myxobolus bilobus n. sp. (Myxozoa) is described from golden shiner Notemigonus crysoleucas in Algonquin Park, Ontario, Canada. Plasmodia develop at the distal end of gill filaments, where they form a novel-shaped plasmodium made up of 2 side-by-side hemispheres joined at a central pore. Surrounding gill tissue is vacuolated, necrotic, and hemorrhagic. Spores of M. bilobus n. sp. resemble those of M. aureatus Ward, 1919, M. angustus Kudo, 1934, M. spalli Landsberg & Lom, 1991, and M. pseudokoi Li & Desser, 1985 in parasitizing cyprinids and in their pyriform shape. Spores of M. bilobus n. sp., however, are much larger (20 to 22.1 microm long, 7.5 to 9.3 microm wide, and 6 microm thick) than those of these other species, and the plasmodium is bi-lobed rather than the typical hollow sphere. A phylogenetic analysis of the 18S rDNA (2014 bp) reveals that M. bilobus n. sp. is a member of a clade that includes 11 species of Myxobolus, all of which are parasites of cyprinid fishes in North America or Eurasia. The study concludes that M. bilobus n. sp. is a member of a clade that has undergone radiation within cyprinid fishes of the 2 continents and that this evolution has involved both host and site switching.

Animals↗

PubMed2005

New biodegradable amphiphilic block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by novel aluminum metal complexes. II. Micellization and solution to gel transition.

In our previous study [J. Yang, L. Jia, L. Yin, J. Yu, Z. Shi, Q. Fang, A. Cao, Macromol. Biosci. 2004, 4, 1092.], new biodegradable copolymers of diblock methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) and methoxy poly(ethylene glycol)-block-poly(delta-valerolactone), and triblock poly(epsilon-caprolactone)-block-poly(ethylene glycol)-block-poly(epsilon-caprolactone) and poly(delta-valerolactone)-block-poly(ethylene glycol)-block-poly(delta-valero-lactone) bearing narrow molecular weight distributions and well-defined block architectures were reported to be prepared with our original aluminum metal complex templates. This work will continue to report new investigations on their water solubility, and reversible thermal responsive micellization and solution to gel transition in distilled water. Among the new synthesized copolymers (P1-P23), seven diblock or triblock samples (P3, P6, P7, P11, P12, P19, and P21) with higher hydrophilic building block populations were revealed to be water soluble under ambient temperature. By means of UV spectrophotometer attached with a thermostat, important parameters as critical micellization mass concentrations (CMCs) and critical micellization temperatures (CMTs) were characterized for these new amphiphile dilute aqueous solution with the aid of an lipophilic organic dye probe of 1,6-diphenyl-1,3,5-hexatriene (DPH). Furthermore, the critical gelation temperatures (CGTs) were simultaneously investigated for these water-soluble block copolymers via a tube tilting method. It was found that the CMC, CMT, and CGT were strongly affected by the population and nature of the hydrophobic building blocks, and a higher hydrophobicity of the new amphiphilic block copolymer finally led to lower CMC and CMT, and higher CGT. In addition, the salts of KBr and NaCl were found to play as a salt-out effect on the solution to gel transition for the diblock P6 and triblock P11, exhibiting an interesting tunable gelation temperature close to 35-42 degrees C. These results will pave new possibility for the synthesized block structural amphiphiles as potential biomaterials to be applied in vivo.

Alum Compounds↗

PubMed2005

Expression divergence between duplicate genes.

A general picture of the role of expression divergence in the evolution of duplicate genes is emerging, thanks to the availability of completely sequenced genomes and functional genomic data, such as microarray data. It is now clear that expression divergence, regulatory-motif divergence and coding-sequence divergence all increase with the age of duplicate genes, although their exact interrelationships remain to be determined. It is also clear that gene duplication increases expression diversity and enables tissue or developmental specialization to evolve. However, the relative roles of subfunctionalization and neofunctionalization in the retention of duplicate genes remain to be clarified, especially for higher eukaryotes. In addition, the relationship between gene duplication and evolution of transcriptional regulatory networks is largely unexplored.

Evolution, Molecular↗

PubMed2005

[Construction and expression of the Ts87 gene of Trichinella spiralis in Pichia pastoris].

OBJECTIVE: To construct the recombinant plasmid P(PICZ) alphaA-Ts87 and obtain secretive protein in Pichia pastoris. METHODS: Ts87 was amplified by PCR and cloned into the expression vector P(PICZ) alphaA of P. pastoris to form P(PICZ) alphaA-Ts87. After the recombinant was isolated and linearized, it was transformed into P. pastoris GS115 by EasyComp kit and screened for zeocin resistant with different conditions and Mut phenotype. The high resistant Mut+ clones were cloned and the product induced by methanol was tested by dot hybridization. The expression product was further identified by SDS-PAGE and Western blotting. RESULTS AND CONCLUSION: The recombinant plasmid P(PiCZ) alphaA-Ts87 has been constructed. Ts87 gene has been expressed and secreted in Pichia pastoris GS115 strain.

Animals↗