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Biomedical subjects

Yan Sun

Publications and source records attributed to Yan Sun.

At least 127 records · Page 7Linked to original sources
PubMed2004

Refolding kinetics of denatured-reduced lysozyme in the presence of folding aids.

The refolding kinetic behavior of denatured-reduced lysozyme in the presence of folding aids (acetamide, acetone, thiourea, L-arginine or glycerol) was studied utilizing a simplified model describing the competition between first-order folding reaction and third-order aggregation. It was found that the protein folding aids could be categorized into two groups. One of them at proper concentrations, such as acetamide, acetone, thiourea and L-arginine, stabilized unfolded protein or folding intermediates. In the presence of these additives, the folding rate decreased with increasing their concentration, and there existed a concentration where the aggregation rate constant was minimized. So, there was an optimum concentration for the folding aids to produce a high yield. The other group was protein stabilizers such as glycerol. In the presence of this kind of folding aids, both the refolding rate and yield were enhanced by increasing their concentration to a proper value. Moreover, their effect on improving protein refolding was additive to those of the first group. So the cooperative application of the two kinds of folding aids could result in favorable refolding rate and yield of protein.

Complex Mixtures↗
PubMed2004

Biodegradation of seven polychlorinated biphenyls by a newly isolated aerobic bacterium (Rhodococcus sp. R04).

An aerobic bacterial strain, designated R04, belonging to the genus Rhodococcus has been isolated and characerized by 16S rDNA analysis. The capability of this strain to degrade seven different polychlorinated biphenyls (CBs), 500 ppm 3-CB, 3,4-CB, 4,4'-CB, 2,4,6-CB, 2,4',5-CB, 2,3,4,5-CB and 3,4,3',4'-CB in liquid medium, was evaluated. After 5 days of incubation, the concentration of chloride increased to 0.35 mM in cultures containing 3-CB and R04, whereas in cultures with 3,4-CB, 2,3,4,5-CB or 3,4,3',4'-CB plus R04 the chloride content increased to 0.1 mM. However, non-stoichiometric amounts of chloride were produced in cultures with R04 and 4,4'-CB, 2,4,6-CB and 2,4',5-CB. The spectrum of supernatants from R04 grown on seven PCBs had a UV-visible (UV-VIS) absorption at 200-500 nm, characteristic of biphenyl-derived cleavage products. Gas-chromatographic (GC) analysis showed that R04 was able to transform 100% of 3-CB and 3,4-CB after 1 day of incubation, and 95% of 4,4'-CB, 2,4,6-CB, 2,4',5-CB, 2,3,4,5-CB and 3,4,3',4'-CB after 5 days of incubation. The position of the chlorine substituents on the rings strongly influenced the degradation of polychlorinated biphenyls (PCBs) and their intermediate metabolites by Rhodococcus sp. R04. The degradation of PCBs was further evaluated by monitoring intermediate metabolites of PCBs.

Biodegradation, Environmental↗
PubMed2004

Facilitating arrhythmia simulation: the method of quantitative cellular automata modeling and parallel running.

BACKGROUND: Many arrhythmias are triggered by abnormal electrical activity at the ionic channel and cell level, and then evolve spatio-temporally within the heart. To understand arrhythmias better and to diagnose them more precisely by their ECG waveforms, a whole-heart model is required to explore the association between the massively parallel activities at the channel/cell level and the integrative electrophysiological phenomena at organ level. METHODS: We have developed a method to build large-scale electrophysiological models by using extended cellular automata, and to run such models on a cluster of shared memory machines. We describe here the method, including the extension of a language-based cellular automaton to implement quantitative computing, the building of a whole-heart model with Visible Human Project data, the parallelization of the model on a cluster of shared memory computers with OpenMP and MPI hybrid programming, and a simulation algorithm that links cellular activity with the ECG. RESULTS: We demonstrate that electrical activities at channel, cell, and organ levels can be traced and captured conveniently in our extended cellular automaton system. Examples of some ECG waveforms simulated with a 2-D slice are given to support the ECG simulation algorithm. A performance evaluation of the 3-D model on a four-node cluster is also given. CONCLUSIONS: Quantitative multicellular modeling with extended cellular automata is a highly efficient and widely applicable method to weave experimental data at different levels into computational models. This process can be used to investigate complex and collective biological activities that can be described neither by their governing differentiation equations nor by discrete parallel computation. Transparent cluster computing is a convenient and effective method to make time-consuming simulation feasible. Arrhythmias, as a typical case, can be effectively simulated with the methods described.

Anisotropy↗
PubMed2004

Comparison of the shape parameters of DNA-cationic lipid complexes and model polyelectrolyte-lipid complexes.

In this study, we used a rheological method to study the shape of DNA-cationic lipid complexes and model polyelectrolyte-lipid complexes. We introduced two kinds of anionic polyelectrolytes, sodium polygalacturonate (PGU) and sodium dextran sulfate (DSS), of varying size, as models for DNA. The prepared complexes were incubated under laminar flow conditions. The results show the same quantitative relation between the shape parameter of lipoplexes and the length of anionic polyelectrolytes, including DNA. The rheological behavior of PGU and DSS were similar to that of DNA.

Anions↗
PubMed2004

Asynchronous adaptive time step in quantitative cellular automata modeling.

BACKGROUND: The behaviors of cells in metazoans are context dependent, thus large-scale multi-cellular modeling is often necessary, for which cellular automata are natural candidates. Two related issues are involved in cellular automata based multi-cellular modeling: how to introduce differential equation based quantitative computing to precisely describe cellular activity, and upon it, how to solve the heavy time consumption issue in simulation. RESULTS: Based on a modified, language based cellular automata system we extended that allows ordinary differential equations in models, we introduce a method implementing asynchronous adaptive time step in simulation that can considerably improve efficiency yet without a significant sacrifice of accuracy. An average speedup rate of 4-5 is achieved in the given example. CONCLUSIONS: Strategies for reducing time consumption in simulation are indispensable for large-scale, quantitative multi-cellular models, because even a small 100 x 100 x 100 tissue slab contains one million cells. Distributed and adaptive time step is a practical solution in cellular automata environment.

Animals↗
PubMed2004

Identification and functional analysis of a novel human KRAB/C2H2 zinc finger gene ZNF300.

A novel human zinc finger gene, ZNF300, was isolated from human embryos on the base of the enrichment of C2H2-specific mRNAs. The ZNF300 cDNA is 3104 bp long and encodes a 604-amino acid protein with an amino-terminal KRAB domain, and 12 carboxyl-terminal C2H2 zinc finger motifs. According to the genome database, ZNF300 is assigned to chromosome 5q33.1. Northern blot analysis revealed that the ZNF300 transcripts are expressed mostly in heart, skeletal muscle and brain. ZNF300 is localized to the nucleus and the KRAB domain of ZNF300 protein exhibits transcription repressor activity. These results suggest that ZNF300 is a ubiquitous transcription repressor in the nucleus.

Amino Acid Sequence↗
PubMed2004

8302A/C and (TTA)n polymorphisms in the HMG-CoA reductase gene may be associated with some plasma lipid metabolic phenotypes in patients with coronary heart disease.

HMG-CoA reductase (HMGCR) is a rate-limiting enzyme that participates in cholesterol metabolism. Here we analyzed the 8302A/C and the (TTA)n polymorphisms in the HMGCR gene in 169 Chinese patients with coronary heart disease (CHD) and 161 age-matched controls. Results indicated that the levels of plasma VLDL and TG in patients with the AA genotype of the 8302A/C locus were significantly higher than in patients with other genotypes (P < 0.05). In addition, the frequency of allele A4 of the (TTA)n locus was higher (P < 0.05) and the frequency of allele A5 was lower (P = 0.002) in CHD patients than in the controls. This suggests that both polymorphisms in the HMGCR gene may be associated with lipid and lipoprotein abnormalities in CHD in the Chinese.

Asian People↗
PubMed2004

Hepatitis B virus (HBV) vaccine-induced escape mutants of HBV S gene among children from Qidong area, China.

Hepatitis B virus (HBV) infection is the main factor, which induces hepatocellular carcinoma (HCC) in Qidong high-risk area, China. To prevent HBV infection is the most important strategy to inhibit the HCC carcinogenesis. A large project was performed in Qidong area to protect newborn babies from the HBV infection that 80,000 children born between 1984 and 1990 were vaccinated. After three times of follow-up studies, 15 screened children were found to have symptoms of illness showing persistent elevation of serum glutamic-pyruvic transaminase (ALT). From these previously collected data, we found that the ALT levels of five vaccinees with negative hepatitis B surface antigen (HBsAg) were significantly higher than those of 10 vaccinees with positive HBsAg. Furthermore, with the passage of time, the difference of ALT levels between the two groups (HBsAg negative and positive groups) diminishes. After cloning and sequencing of the HBsAg "a" epitope coding sequences, we found that mutations in "a" epitope were correlated with the absence of detectable anti-HBsAg, while no mutations were seen in the anti-HBsAg positive infections. We also found that majority of point mutations were occurred in the coding sequences of the first loop structure in "a" epitope. The structure of double loop conformation in "a" epitope was conservative, and important for HBV antigenicity. These changes in a double loop conformation would escape neutralization by vaccine-induced antibody.

Alanine Transaminase↗
PubMed2004

1,3-Propanediol production by Klebsiella pneumoniae under different aeration strategies.

1,3-Propanediol production by Klebsiella pneumoniae was studied in batch cultures under N2 flow and four airflow systems. Different byproducts were formed under different aeration conditions. An anaerobic/aerobic combined fed-batch culture was developed giving 70 g 1,3-propanediol l(-1) and 16 g 2,3-butanediol l(-1) with total diol yield of 0.6 mol(-1) glycerol.

Aerobiosis↗
PubMed2004

Characterization of the brassinosteroid insensitive 1 genes of cotton.

Suppression of brassinosteroid (BR) biosynthesis in cotton ovules by treatment with brassinazole inhibits fiber formation, indicating that BR plays an important role in cotton fiber development. Plant responses to brassinosteroids (BR) are mediated through a plasma membrane-bound leucine-rich repeat (LRR) receptor-like protein kinase known as BRI1. Mutations in the BRI1 genes of several species result in dwarfed plants with reduced sensitivity to BR. A single expressed sequence tag (EST) from cotton with strong sequence similarity to Arabidopsis BRI1 ( AtBRI1 ) was identified in a search of publicly available databases. With this EST as a starting point, full-length cDNAs and genomic coding sequences from upland cotton ( Gossypium hirsutum ) BRI1 ( GhBRI1 ) were obtained and characterized. Ectopic expression of this coding sequence in BR-insensitive Arabidopsis plants resulted in recovery of normal growth indicating that GhBRI1 is a functional homologue of AtBRI1. G. hirsutum is an allotetraploid (AADD) derived from diploid ancestors. Analysis of several GhBRI1 cDNAs showed two distinct sequences indicating the presence of two GhBRI1 genes, denoted GhBRI1-1 and GhBRI1-2. Sequence comparisons between these GhBRI1 coding sequences and those from related A and D genome diploid Gossypium species ( G. arboreum and G. thurberi ) indicated that GhBRI1-1 is likely to the A sub-genome orthologue while GhBRI1-2 is from the D sub-genome.

Amino Acid Sequence↗
PubMed2004

Up-regulation of P2X3 receptor during stretch of bladder urothelial cells from patients with interstitial cystitis.

PURPOSE: Extracellular adenosine triphosphate (ATP) can act through the purinergic receptor subtype P2X3 to transmit a pain signal to the central nervous system. Bladder urothelial cells (BUCs) from patients with interstitial cystitis (IC) patients have augmented release of ATP during in vitro stretch. We queried whether P2X3 receptor subtype exists on cultured BUCs. Furthermore, we asked whether P2X3 expression can be altered by in vitro stretch and whether there exists a difference in expression between IC and control BUCs. MATERIALS AND METHODS: BUCs from 4 IC and 5 control subjects were cultured according to established cell culture techniques. After cells were grown to confluence they were stretched on an in vitro stretch machine at 20% elongation for up to 96 hours. Cells were harvested at various times, and immunofluorescence and Western blots were performed for P2X3 expression. Band densitometry normalized to the actin band was performed using software. To confirm P2X3 expression in a whole cell preparation flow cytometry and fluorescence activated cell sorter analysis were used. RESULTS: P2X3 was expressed in cultured BUCs. With stretch P2X3 expression increased in IC BUCs more than in control BUCs. Using relative densitometry units normalized for actin expression in the Western blots stretch of IC BUCs resulted in 66% more expression of P2X3 than any other experimental condition (p = 0.003). By fluorescence activated cell sorter analysis stretched IC BUCs had the highest P2X3 fluorescence activity (30%) compared with unstretched IC (2.4%, p = 0.003), stretched control (9.7%, p = 0.009) and unstretched control (2.3%, p = 0.003) BUCs. CONCLUSIONS: These data show that P2X3 subunits expressed by cultured IC BUCs are up-regulated during in vitro stretch. Augmented ATP signaling in the bladder may explain IC symptoms. Furthermore, this study further supports the hypothesis that urothelial cells can phenotypically mimic sensory neurons.

Cells, Cultured↗
PubMed2004

Wolbachia-induced neutrophil activation in a mouse model of ocular onchocerciasis (river blindness).

Endosymbiotic Wolbachia bacteria are abundant in the filarial nematodes that cause onchocerciasis (river blindness), including the larvae (microfilariae) that migrate into the cornea. Using a mouse model of ocular onchocerciasis, we recently demonstrated that it is these endosymbiotic bacteria rather than the nematodes per se that induce neutrophil infiltration to the corneal stroma and loss of corneal clarity (Saint Andre et al., Science 295:1892-1895, 2002). To better understand the role of Wolbachia organisms in the pathogenesis of this disease, we examined the fate of these bacteria in the cornea by immunoelectron microscopy. Microfilariae harboring Wolbachia organisms were injected into mouse corneas, and bacteria were detected with antibody to Wolbachia surface protein. Within 18 h of injection, neutrophils completely surrounded the nematodes and were in close proximity to Wolbachia organisms. Wolbachia surface protein labeling was also prominent in neutrophil phagosomes, indicating neutrophil ingestion of Wolbachia organisms. Furthermore, the presence of numerous electron-dense granules around the phagosomes indicated that neutrophils were activated. To determine if Wolbachia organisms directly activate neutrophils, peritoneal neutrophils were incubated with either parasite extracts containing Wolbachia organisms, parasite extracts depleted of Wolbachia organisms (by antibiotic treatment of worms), or Wolbachia organisms isolated from filarial nematodes. After 18 h of incubation, we found that isolated Wolbachia organisms stimulated production of tumor necrosis factor alpha and CXC chemokines macrophage inflammatory protein 2 and KC by neutrophils in a dose-dependent manner. Similarly, these cytokines were induced by filarial extracts containing Wolbachia organisms but not by Wolbachia-depleted extracts. Taken together, these findings indicate that neutrophil activation is an important mechanism by which Wolbachia organisms contribute to the pathogenesis of ocular onchocerciasis.

Animals↗
PubMed2004

[Experimental study of the effect of Astragalus membranaceus against herpes simplex virus type 1].

OBJECTIVE: To study the inhibitory effects of Astragalus membranaceus on herpes simplex virus type 1(HSV-1). METHODS: In the 2BS cells infected with HSV-1, the antiviral effect of Astragalus membranaceus decoction was investigated by observing the inhibition of HSV-1-induced cytopathic effect in response to treatment with the decoction. RESULTS: The half inhibition concentration (IC50) and minimal inhibition concentration (MIC) of Astragalus membranaceus were 0.98 and 1.95 g/ml respectively, with the therapeutic index (TI) of 128. CONCLUSION: Astragalus membranaceus has obvious HSV-1-inhibiting efficacy and low cytotoxicity.

Antiviral Agents↗
PubMed2004

Percutaneous intratumoral injection of traditional Chinese herbal compound medicine Star-99 in treatment of hepatocellular carcinoma of mice.

BACKGROUND: Unresectable hepatocellular carcinoma (HCC) lacks effective therapy and entails very poor progress. In 1991, we found that Chinese herbal compound Star-99 has potentially effect on HCC. The purpose of this study was to probe the anti-cancer effect and the mechanism of focal injection of Chinese herbal compound Star-99 into HCC of mice. METHODS: In 32 nude mice transplanted with human hepatocellular carcinoma SMMC-7721, 16 received hypodermic implant and the other 16 orthotopic liver transplant. They were randomly divided into three groups: Star-99 group (Chinese herbal compound, 16 mice), alcohol group (8) and saline group (8), respectively. Intratumoral injection of Star-99, alcohol and saline was carried out 10 days after transplantation of HCC. Twenty days after the first injection, the nude mice were killed after being injected every 5 days with a total of 4 injections in each mouse. Tumor tissues were examined pathologically or via an electron microscope and flow cytometrical (FCM) DNA analysis. The three diameters of the tumor were measured with high-frequency ultrasound before and after injection, and the growth index was calculated with the following formula: volume of tumor (after treatment-before treatment)/volume of tumor (before treatment). Double-blind method was applied in the experiment. RESULTS: The growth index of the Star-99 group (0.068+/-0.022) and the alcohol group (0.079+/-0.024) was markedly lower than that of the saline group (4.345+/-1.453, P<0.01), but there was no significant difference between the Star-99 and alcohol groups. Coagulation (8/8) was the major pathological change in the alcohol group. In the Star-99 group, however, the phenomenon of lymphocytes attacking cancer cells could even be seen under the electron microscope. The typical apoptosis cells and apoptosis bodies as well as the collagen fibrae lined in mass could also be seen in the group (14/16). FCM DNA analysis showed that the rate of apoptosis in the Star-99 group (93.8%) was significantly higher than that in the alcohol (12.5%) and saline groups (12.5%) (P<0.01). CONCLUSIONS: This study shows that Star-99 markedly inhibits and destructs hepatocellular cancer cells. Star-99 is effective to directly destroy the membrane, cytoplasm and nuclei of tumor cells, causing their crumbling, activate the immune function and inflammatory reaction of nude mice, and induce the apoptosis of cancer cells. The effect of Star99 is significantly different from that of alcohol that mainly causes coagulation of cancer cells. Star-99 is feasible in the treatment of HCC.

Administration, Cutaneous↗
PubMed2004

[The impact of malocclusion on self-esteem of adolescents].

OBJECTIVE: To assess the relationship between malocclusions and self-esteem of adolescents. METHODS: 344 subjects with normal occlusion and different types of malocclusion were classified into four groups by Angle's classification, (91 students in class I group, 93 students in class II group, 82 students in class III group, and 78 in normal group). 344 school students aged 12 to 18 years in Dalian were assessed one by one using the Children Self-Esteem Scale (CSES). The statistic analyses were performed with, single-factor analysis, multivariate linear regression and unconditional logistic regression. RESULTS: Malocclusions negatively affect self-esteem. Class II malocclusion has higher risk than class I and class III malocclusions. The patients with severe dentofacial deformity are at highest risk for low appearance self-esteem. CONCLUSIONS: Malocclusion negatively affects self-esteem of adolescents. Serious dentofacial deformity is the highest risk factor in the low appearance self-esteem.

Adolescent↗
PubMed2004

[Evaluation of health-related quality of life in chronic hepatitis C women patients].

OBJECTIVE: To evaluate the health-related quality of life (HRQOL) in chronic hepatitis C (CHC) female patients, and to identify factors associated with impairment in HRQOL. METHODS: We enrolled 41 women cases with hepatitis C for 10 to 15 years and 51 health women in Guan area of Hebei province, China. HRQOL was assessed by the SF-36 by an interview. RESULTS: CHC female patients had significantly lower SF-36 scors in all subscales when compared to those of the non-HCV infected female population. CONCLUSION: CHC female patients have a reduced HRQOL. CHC alone is associated with significant impairment in HRQOL.

Adult↗
PubMed2004

Cloning and functional analysis of the promoter of ZNF268 gene.

The human ZNF268 gene is a novel C2H2 zinc finger gene restrictively expressed in the liver of human embryo. As an initial study on the regulation of its expression, 2.5 kb fragment of the ZNF268 5'-flanking region was cloned from human genome by PCR. This fragment was inserted into pEGFP1 vector and then the recombinant plasmid was transfected into several cell lines by liposomal transfection method. EGFP expression was observed in four cell lines under confocal laser scanning microscope. A series of 5'-deletion fragments from -2456(-)+77 bp to -20(-)+77 bp were inserted into pCAT-Basic vector to construct recombinant reporter plasmids, which were then transfected into Hela cells for deletion analysis. Results of deletion analysis revealed that an important region for transcriptional activity lies between -156 and -20 bp.

Cloning, Molecular↗