Biomedical subjects
Publications and source records attributed to Y Lan.
We formulate a fictitious-time-flow equation which drives an initial guess torus to a torus invariant under a given dynamics, provided such a torus exists. The method is general and applies in principle to continuous time flows and discrete time maps in arbitrary dimension and to both Hamiltonian and dissipative systems.
In an attempt to obtain the transcriptional profile of shrimp white spot syndrome virus (WSSV) genes, DNA microarray analysis was performed using amplified DNA fragments of the WSSV genome that covered most of the presumptive open reading frames (ORFs). Total RNAs were extracted from WSSV-infected crayfish (Cambarus clarkii) and reverse transcribed into cDNA and labeled with 32P-dATP. The DNA microarray detected 81.1% of the ORFs, and 47 of these were transcribed at 6 h post infection, suggesting they may be early genes. Some early genes were further confirmed by temporal analyses of gene transcription. Results in this study indicated the effectiveness of DNA microarray for discovering early viral genes.
Titanate nanofibers of various sizes and layered structure were prepared from inorganic titanium compounds by hydrothermal reactions. These fibers are different from "refractory" mineral substances because of their dimension, morphology, and significant large ratio of surface to volume, and, surprisingly, they are highly reactive. We found, for the first time, that phase transitions from the titanate nanostructures to TiO(2) polymorphs take place readily in simple wet-chemical processes at temperatures close to ambient temperature. In acidic aqueous dispersions, the fibers transform to anatase and rutile nanoparticles, respectively, but via different mechanisms. The titanate fibers prepared at lower hydrothermal temperatures transform to TiO(2) polymorphs at correspondingly lower temperatures because they are thinner, possess a larger surface area and more defects, and possess a less rigid crystal structure, resulting in lower stability. The transformations are reversible: in this case, the obtained TiO(2) nanocrystals reacted with concentrate NaOH solution, yielding hollow titanate nanotubes. Consequently, there are reversible transformation pathways for transitions between the titanates and the titanium dioxide polymorphs, via wet-chemical reactions at moderate temperatures. The significance of these findings arises because such transitions can be engineered to produce numerous delicate nanostructures under moderate conditions. To demonstrate the commercial application potential of these processes, we also report titanate and TiO(2) nanostructures synthesized directly from rutile minerals and industrial-grade rutiles by a new scheme of hydrometallurgical reactions.
We report an analysis of intramolecular dynamics of the highly excited planar carbonyl sulfide below and at the dissociation threshold by the fast Lyapunov indicator method. By mapping out the variety of dynamical regimes in the phase space of this molecule, we obtain the degree of regularity of the system versus its energy. We combine this stability analysis with a periodic orbit search, which yields a family of elliptic periodic orbits in the regular part of phase space and a family of in-phase collinear hyperbolic orbits associated with the chaotic regime.
This experiment was conducted to test whether dietary soybean meal oligosaccharides (SMO) and water-soluble polysaccharides (SMP) can assist broiler chickens in resisting Eimeria tenella, and to determine the survival of lactic acid bacteria in cecal contents postinfection. All birds received a soybean meal-free diet. The 6 experimental treatments were as follows: positive (COR) and negative (COW) control groups, 2 groups fed diets containing either 1% SMO or 0.5% SMP from 1 to 11 d of age; a vaccinated group (VAC), and an anticoccidial medicated group (ANT). Chickens of all treatments except COW were orally infected with 1000 sporulated oocysts of E. tenella on d 15. Fecal oocyst shedding was monitored per treatment group between d 5 and 13 postinfection. Lactic acid bacteria (LAB) in cecal contents were evaluated by a real-time PCR technique on d 7 postinfection. The results showed that the SMO and SMP groups had a lower number of oocysts per gram of feces during the monitoring period than the COR group. Threshold cycles were 22.21, 27.68, 13.99, 14.92, 12.97, and 14.85, for COW, COR, SMO, SMP, VAC, and ANT groups, respectively; specific PCR products were confirmed by the results of melting curve analysis and agarose gel electrophoresis. The results suggest that these LAB communities were promoted by SMO and SMP and have a competitive exclusion function when broiler chickens are infected with E. tenella.
One of the important approaches to prevent pyrite (FeS(2)) oxidation and subsequent formation of acid mine drainage (AMD) is to create a surface coating on pyrite. In this study, a coating of iron 8-hydroxyquinoline was formed by leaching pyrite with a 0.10 M H(2)O(2)/0.0034 M 8-hydroxyquinoline solution; stability of the coated pyrite was tested under various pH and temperature conditions. The results showed that iron 8-hydroxyquinoline coating could significantly suppress further pyrite oxidation by both chemical (H(2)O(2)) and biological ( e.g., Thiobacillus ferrooxidans) processes. At pH from 3.0 to 5.0 and temperature from 10-40 degrees C, the amount of SO(4)(2-) leached out by 0.10 M H(2)O(2) from the coated pyrite samples was 54.8-70.1% less than that from the uncoated controls. The oxidation of pyrite followed a pseudo-zero-order kinetics under the constant concentration of H(2)O(2). In the presence of microorganisms, sulfate leached out of the uncoated pyrite in 1 year accounted for 5.32% of the total pyrite in the system, with a concurrent pH drop to 2.35 under the ambient room temperatures. In contrast, the amount leached out from the coated samples was only 0.15% of the total pyrite and the final pH was 5.48. Thus, the coating decreased the leachability of pyrite by 97% in the inoculated systems. In comparison to the more widely studied iron phosphate coating, the advantage of iron 8-hydroxyquinoline coating was that it inhibited both chemical and biological pyrite oxidation, whereas iron phosphate coating could only inhibit chemical pyrite oxidation.
We have isolated a new mouse gene, odd-skipped related 2 (Osr2), that encodes a zinc finger containing protein related to Drosophila Odd-skipped. The putative OSR2 protein shares 65% amino acid sequence identity overall and 98% sequence identity in the zinc finger region, respectively, with the previously reported Osr1 gene product. During mouse embryonic development, Osr2 expression is first detected at E9.25, specifically in the mesonephric vesicles. By E10.0, Osr2 expression is also observed in the rostro-lateral mandibular mesenchyme immediately adjacent to the maxillary processes. In the developing limb buds, Osr2 is expressed in a unique mesenchymal domain and the onset of Osr2 expression follows a distinct dorsal to ventral developmental time sequence beginning in the forelimb and then in the hindlimb. Osr2 exhibits a dynamic expression pattern during craniofacial development, in the mandibular and maxillary processes as well as the developing palate. Osr2 is also expressed at sites of epithelial-mesenchymal interactions during tooth and kidney development.
Clinical application of interleukin (IL)-2-based immunotherapy of cancer has been limited by a major side-effect known as 'capillary leak syndrome', resulting from nitric oxide (NO) overproduction. A galactoside-specific lectin from Viscum album L. (VAA) has been reported to induce certain lymphokines and upregulate IL-2 receptors on lymphocytes. Present study was, therefore, designed to compare the effects of combination therapy with IL-2 (10(4) Cetus units/mouse, intraperitoneal (i.p). every 8 h, given as 5 day rounds per week, for one or two rounds) and VAA (1 ng/kg subcutaneous (s.c.), biweekly) with those of IL-2 or VAA therapy alone in C3H/HeJ female mice bearing s.c. transplants of a highly metastatic C3L5 mammary adenocarcinoma. IL-2 therapy alone reduced tumour growth and metastasis, but caused significant water retention indicative of capillary leakage in the kidneys after both rounds of therapy, whereas pleural effusion was only evident after the first round and not the second round. A sharp rise in the systemic NO levels after the first round, followed by a decline after the second round of IL-2 therapy suggested a causal relationship of increased NO levels to pleural effusion. A strong immunostaining for nitrotyrosine (a marker for the production of peroxynitrite) was noted in the renal tubules at the end of both rounds of therapy suggestive of a causal association of this toxic NO-metabolite with capillary leakage in the kidneys. Addition of VAA to IL-2 therapy had no effect on any of the above parameters. Unexpectedly, however, VAA therapy alone stimulated tumour growth as well as lung metastases. NO induction in the C3L5 cells by VAA was excluded as a possible reason for this stimulation. Present results suggest the need for exercising caution in the use of VAA as an immunoadjuvant in human cancer therapy.
Snail family genes encode DNA binding zinc finger proteins that act as transcriptional repressors. Mouse embryos deficient for the Snail (Sna) gene exhibit defects in the formation of the mesoderm germ layer. In Sna(-/-) mutant embryos, a mesoderm layer forms and mesodermal marker genes are induced but the mutant mesoderm is morphologically abnormal. Lacunae form within the mesoderm layer of the mutant embryos, and cells lining these lacunae retain epithelial characteristics. These cells resemble a columnar epithelium and have apical-basal polarity, with microvilli along the apical surface and intercellular electron-dense adhesive junctions that resemble adherens junctions. E-cadherin expression is retained in the mesoderm of the Sna(-/-) embryos. These defects are strikingly similar to the gastrulation defects observed in snail-deficient Drosophila embryos, suggesting that the mechanism of repression of E-cadherin transcription by Snail family proteins may have been present in the metazoan ancestor of the arthropod and mammalian lineages.
The Notch gene family encodes large transmembrane receptors that are components of an evolutionarily conserved intercellular signaling mechanism. To assess the in vivo role of the Notch2 gene, we constructed a targeted mutation, Notch2(del1). Unexpectedly, we found that alternative splicing of the Notch2(del1) mutant allele leads to the production of two different in-frame transcripts that delete either one or two EGF repeats of the Notch2 protein, suggesting that this allele is a hypomorphic Notch2 mutation. Mice homozygous for the Notch2(del1) mutation died perinatally from defects in glomerular development in the kidney. Notch2(del1)/Notch2(del1 )mutant kidneys were hypoplastic and mutant glomeruli lacked a normal capillary tuft. The Notch ligand encoded by the Jag1 gene was expressed in developing glomeruli in cells adjacent to Notch2-expressing cells. We show that mice heterozygous for both the Notch2(del1) and Jag1(dDSL) mutations exhibit a glomerular defect similar to, but less severe than, that of Notch2(del1)/Notch2(del1 )homozygotes. The co-localization and genetic interaction of Jag1 and Notch2 imply that this ligand and receptor physically interact, forming part of the signal transduction pathway required for glomerular differentiation and patterning. Notch2(del1)/Notch2(del1 )homozygotes also display myocardial hypoplasia, edema and hyperplasia of cells associated with the hyaloid vasculature of the eye. These data identify novel developmental roles for Notch2 in kidney, heart and eye development.
PURPOSE: Immune-based therapies, such as the immunocytokine huKS-IL2, exert potent antitumor responses in some animal models by targeting cytokine activity to the tumor microenvironment. We found that certain chemotherapy agents in the appropriate dose and schedule can augment the antitumor activity of huKS-IL2. EXPERIMENTAL DESIGN: Chemotherapy agents were given in a single dose followed 1 day (paclitaxel) or 3 days (cyclophosphamide) later with five daily doses of huKS-IL2 in mice bearing established s.c. tumors, liver metastases, or lung metastases. Tumor models used were CT26/KSA colon, 4T1/KSA mammary, or LLCKSA Lewis lung carcinomas. To measure huKS-IL2 distribution, radiolabeled protein was given to CT26/KSA tumor-bearing mice 1 or 24 h after paclitaxel. huKS-IL2 levels in the tumors were evaluated. RESULTS: Both paclitaxel and cyclophosphamide followed by huKS-IL2 resulted in enhanced antitumor responses compared with either of the treatments alone in the three different tumor models. Results from studies to determine whether the role of the cytotoxic agents in antitumor activity enhancement was related to tumor uptake indicated that a larger fraction of the radiolabeled huKS-IL2 penetrated the tumors when it was administered 24 h after cytotoxic drug "sensitization." CONCLUSION: These data support the idea that prior drug therapy serves to decompress the tumor and lower the diffusion barrier for macromolecules, thus allowing for increased uptake of the huKS-IL2 immunocytokine into the tumor microenvironment. Because the toxicity of the immunocytokine is relatively low at optimal doses, the therapeutic index would likely be greater with the combination treatments.
OBJECTIVE: To establish efficient eukaryotic expression system of HBsAg in immortalized B-cell line from a chronic hepatitis B patient, as autologous HLA target cells for detecting HBsAg-specific cytotoxic T-lymphocyte (CTL) response. METHODS: Four eukaryotic expression plasmids inserted HBsAg gene were transfected into immortalized B-cell line from a chronic hepatitis B patient, then cells were selected with G418 or hygromycin B. HBsAg in culture supernatants and cell lysates were detected with enzyme-linked immunosorbent assay (ELISA). RESULTS: All eukaryotic expression vectors-transfected immortalized B-cells produced HBsAg, which was readily detectable in culture supernatants and cell lysates. CONCLUSIONS: Transfection of EBV-immortalized B-cell line with four eukaryotic expression plasmids leads to stable expression of HBsAg, which can be used as autologous HLA target cells for detecting HBsAg-specific CTL response.
OBJECTIVE: To explore the status of the resources coping with occupational stress in teachers. METHODS: Occupational stress inventory revised edition (OSI-R) was used to measure their occupational stress, strain and psychological coping resources for 1,460 teachers in primary and secondary schools and 319 non-teacher intellectuals. Analyses were focused on coping resources of teachers. RESULTS: The higher the level of coping resource of teachers, the lower the personal strain in them, with an inverse correlationship. Coping resource in the teacher group was significantly higher than that in the non-teacher group, with scores of (130.4 +/- 18.2) and (126.9 +/- 19.1), respectively. Coping resource in teachers decreased with the increase of age, with the scores from (134.1 +/- 18.1) in the group aged less than 30 to (128.5 +/- 17.5) in the group aged 50. Coping resource in the female teachers was significantly higher than that in the male teachers, with scores of (131.4 +/- 18.3) and (129.4 +/- 18.1), respectively. Coping resource in the primary school teachers was significantly higher than that in the secondary school teachers, with scores of (132.7 +/- 18.1) and (128.5 +/- 18.1), respectively. CONCLUSION: It is important to enhance teacher's coping resource, especially for the male teachers in the secondary schools, for improving their teaching efficiency.
OBJECTIVE: This study was conducted to assess occupational stress and strain in primary and secondary school teachers. METHODS: A test of occupational stress and strain was carried out by using Occupational Stress Inventory Revised Edition (OSI-R) in 1460 primary and secondary school teachers (teacher group) and 319 mental workers in non-educational area (non-teacher group as control). RESULTS: The results showed the level of occupational stress in role overload and physical environment in the teacher group was significantly higher than that in the non-teacher group (P < 0.05). In teacher group the level of occupational stress and strain increased with age; the occupational stress and strain in male teachers were significantly higher than those in female teachers (P < 0.01); the occupational stress and strain in secondary school teachers were significantly higher than those in primary school teachers. CONCLUSION: These results indicate: to protect and promote primary and secondary school teacher's health, particularly male teachers' health, to mitigate their work pressure and to raise the quality of education are important tasks in the area of occupational health.
The relationship between occupational stress and working ability and their influence factors have been studied. 1230 oil workers in 122 work types of oil industry were selected and an occupational stress questionnaire (OSQ) was filled. The working ability index (WAI) in the female was significantly higher than that in the male (P < 0.0001). The working ability of petroleum workers became lower with the increasing of age, the duration of working time and stress levels (P < 0.001). The correlation on the labor load, adverse factors in the working environment and WAI was negative. It was concluded that the occupational stress could decrease the working ability of petroleum workers.
PURPOSES: To evaluate the effect of phacoemulsification in the patients with uveitis, secondary glaucoma and complicated cataract. METHODS: Phacoemulsification and implantation of a foldable intraoucular len was performed in 12 patients(13 eyes) with uveitis, secondary glaucoma and complicated cataract. The complications, intraocular pressures (IOP), and visual acuity were observed postoperatively. RESULTS: No severe complication was found in the patients postoperatively or within the operation procedure. The visual acuity was improved after the operation (P < 0.05). The intraocular pressures and/or the number of antiglaucoma medications reduced in 3 months of the follow-up time. CONCLUSION: Phacoemulsification is the best way to treat the patients with secondary glaucoma and complicated cataract caused by uveitis.
PURPOSE: To construct the enhanced yellow fluorescent protein (EYFP) vector carrying interferon-gamma gene (ifn-gamma) in order to provide an ideal reporter in the expression of ifn-gamma and location of protein in vitro and in vivo. METHOD: According to the nucleotide sequence of ifn-gamma gene, a pair of oligonucleotides was designed as primer whose two end contained nucleotide sequence of EcoR V and Not I restriction endonuclease respectively. The gene encoding for inf-gamma was amplified using PCR technqiue. After the PCR product was retrieved and purified, it was digested with EcoR V and Not I restriction endonuclease, and then cloned into the plasmid pIRES-EYFP. The recombinant plasmid pIRES-EYFPIFN-gamma was identified by restriction endonuclease enzyme analysis and DNA sequence analysis. RESULTS: The ifn-gamma was successfully amplified and verified by partial DNA sequence analysis. The recombinant plasmid was correctly screened. CONCLUSION: The EYFP expression vector carrying ifn-gamma gene was successfully established. This research work has formed a base for monitoring the ifn-gamma gene expression and protein position in living cells.
PURPOSE: To investigate the influence of dexamethesone (Dex) on cell cycle in human trabecular cells(HTC). METHODS: The trabecular specimens from human eyes were cultured in vitro. Then the cultured cells were immersed in DMEM solution containing 10(-7) M dexamethesone for three, five and seven days. The cell cycle was detected by Flow Cycometry. RESULTS: The G2 phase of cell cycle in HTC increased when HTC were treated by Dex. The G2 phase was 2% in control group. For three, five and seven days treated by Dex, the G2 phase were 8%, 16.3 and 19.4%. CONCLUSION: The influence of cell cycle might be induced by Dex, it may be related with the pathogenesis of glucocorticoid induced glaucoma.