Biomedical subjects

Kun Zhang

Publications and source records attributed to Kun Zhang.

At least 37 records · Page 2Linked to original sources

PubMed2006

The anticancer activities of wogonin in murine sarcoma S180 both in vitro and in vivo.

The anticancer effects of wogonin on murine sarcoma S180 both in vitro and in vivo were investigated, and its pro-apoptotic molecular mechanism was further studied. Wogonin treatment resulted in significant inhibition of S180 cells in a concentration-dependent manner detected by MTT assay. The IC50 value for 48 h was (7.37+/-1.53) x 10(-5) M. Typical morphological changes and apoptosis bleb phenomenon in S180 cells exposed to wogonin were distinctly observed by the inverted light microscope and the fluorescence microscope, respectively. According to protocols of transplanted tumor research, mice were transplanted with tumor cells S180. The weight of tumor and the peripheral leucocyte count were observed after the treatment of wogonin. The significant suppression of tumor growth was observed, and the peripheral leucocyte count of S180-bearing mice remained no significant changes compared with control group. After the treatment of 40 mg/kg wogonin, the inhibitory rate of tumor weight was 53.01%. Additional DNA fragmentation assay showed that wogonin induced apoptosis on murine sarcoma S180 tissue. RT-PCR results indicated that the increasing mRNA levels of bax and p53 and the decreasing mRNA level of bcl-2 were induced by wogonin. Western-blot assay showed that the increasing protein level of bax and the decreasing protein level of bcl-2 were induced by wogonin. Collectively, wogonin could induce apoptosis in murine sarcoma S180 thereby inhibiting the tumor growth both in vitro and in vivo. The pro-apoptotic effects might be related to the improvement of mRNA level of p53, the improvement of mRNA and protein levels of bax, and the reduction of mRNA and protein levels of bcl-2.

Animals↗

PubMed2006

[Mentality and behavior of children suffering from viral myocarditis].

OBJECTIVE: The present study was designed to investigate the influence of viral myocarditis on mental behavior of the children. METHODS: Mentality and behavior of the 178 children suffering from viral myocarditis were examined with Achenbach Child Behavior Checklist (CBCL) edited by Gong Yao-xian in 1986 and 104 sex, age, education and achievement-matched children with pneumonia or upper respiratory infection were enrolled as controls. RESULTS: The mentality and behavior of the children with viral myocarditis were distinctly abnormal. The abnormal rates of boys and girls suffering from acute and deferment viral myocarditis were evidently higher than those of control children (P < 0.01). The behavioral abnormalities of boys were hypochondria, social difficulties, unwell of body and attack. Whereas, the girls presented hypochondria, unwell of body, social flinch and disobeyed discipline, which was significantly different from the control children. The total and hypochondria cursory mark of the second check result of deferment boys were evidently higher than those of the first check (P < 0.05). The total cursory mark of the second check result of deferment girls was higher than that of the first check (P < 0.05) and evidently higher than that of the acute second check result (P < 0.01). The abnormal rates of mentality and behavior correlated positively with the age of children and they were associated with the severity of the illness. CONCLUSION: Viral myocarditis evidently affected the mentality and behavior of children, which should be paid great attention to.

Acute Disease↗

PubMed2006

[Inhibitive effects of gastric cancer cell-dendritic cell fusion vaccine on tumor cell proliferation cycle].

OBJECTIVE: To study the inhibitive effects of gastric cancer cell-dendritic cell fusion vaccine on tumor cells of proliferation cycle. METHODS: Peripheral blood mononuclear cells were separated from gastric cancer patients and co-cultured with granulocyte macrophage colony stimulating factors(GM-CSF), interleukin-4(IL-4) and tumor necrosis factor-alpha(TNF-alpha) to generate mature dendritic cells. The dendritic cells and SGC7901 cells were fused by polyethylene glycol, and the pure fusion cells were screened out by selective culture systems. The inhibitive effects of gastric cancer cell-dendritic cell fusion vaccines on tumor cell proliferation cycle in vivo and in vitro were detected by flow cytometry. RESULTS: Treated with the fusion vaccine in vitro, the percentages of G(0)/G(1), S and G(2)/M cells of tumor cells were (76.77+/- 4.38)%, (16.50+/- 2.90)% and (6.73+/- 1.59)% respectively. There were significant differences in the percentages of different cell cycle tumor cells between the tumor cells treated with the fusion vaccine and those co-cultured with dendritic cell or T cells alone(P< 0.01). The proliferative index of the tumor cells treated with the fusion vaccine was 23.34+/- 3.51, significantly lower than those co-cultured with dendritic cell and controls (P< 0.05). CONCLUSIONS: Fusion vaccines can affect cell cycle of the tumor cells, thus inhibit tumor cell proliferation and growth.

Cancer Vaccines↗

PubMed2005

Dibenzocyclooctadiene lingnans: a class of novel inhibitors of P-glycoprotein.

PURPOSE: To determine if five dibenzocyclooctadiene lingnans, a class of naturally occurring compounds from Schisandra chinensis (Turcz.) Baill, have the activities to reverse P-glycoprotein (P-gp) mediated multidrug resistance (MDR). METHODS: The IC(50)s of four MDR cell lines (K562/Adr, MCF-7/Adr, KBv200, and Bcap37/Adr) toward daunorubicin, vincristine, and paclitaxel in the presence or absence of one of the dibenzocyclooctadiene lingnans were determined by a FACscan assay. The intracellular daunorubicin accumulation in the four MDR cell lines was determined by incubation of cells with daunorubicin (2 microg/ml) in the presence or absence of one of the dibenzocyclooctadiene lingnans by a FACscan assay. The interaction of the five dibenzocyclooctadiene lingnans with P-gp was assayed by their inhibition of (3)H-azidopine photoaffinity labeling of P-gp. RESULTS: Among the five lingnans, while schisandrin A and B, and schisantherin A demonstrated strong and comparable activities to reverse the drug resistance and the intracellular drug accumulation in four MDR cell lines, schisandrol A and B showed very limited activities. The poor activities of schisandrol A and B are possibly caused by the hydroxyl groups on the cyclooctadiene ring, because the activities of the molecules resumed when the hydroxyl group was esterified to form a benzoate. Further studies demonstrated that these compounds physically interacted with P-gp. CONCLUSION: Schisandrin A and B, and schisantherin A are potent P-gp inhibitor and is of potential for future clinical application.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Accurate multiplex polony sequencing of an evolved bacterial genome.

We describe a DNA sequencing technology in which a commonly available, inexpensive epifluorescence microscope is converted to rapid nonelectrophoretic DNA sequencing automation. We apply this technology to resequence an evolved strain of Escherichia coli at less than one error per million consensus bases. A cell-free, mate-paired library provided single DNA molecules that were amplified in parallel to 1-micrometer beads by emulsion polymerase chain reaction. Millions of beads were immobilized in a polyacrylamide gel and subjected to automated cycles of sequencing by ligation and four-color imaging. Cost per base was roughly one-ninth as much as that of conventional sequencing. Our protocols were implemented with off-the-shelf instrumentation and reagents.

Acrylic Resins↗

PubMed2005

Quantifying kinetic paths of protein folding.

We propose a new approach to activated protein folding dynamics via a diffusive path integral framework. The important issues of kinetic paths in this situation can be directly addressed. This leads to the identification of the kinetic paths of the activated folding process, and provides a direct tool and language for the theoretical and experimental community to understand the problem better. The kinetic paths giving the dominant contributions to the long-time folding activation dynamics can be quantitatively determined. These are shown to be the instanton paths. The contributions of these instanton paths to the kinetics lead to the "bell-like" shape folding rate dependence on temperature, which is in good agreement with folding kinetic experiments and simulations. The connections to other approaches as well as the experiments of the protein folding kinetics are discussed.

Algorithms↗

PubMed2005

Down-regulation of DNA polymerases kappa, eta, iota, and zeta in human lung, stomach, and colorectal cancers.

Human DNA polymerases kappa, eta, iota, and zeta are responsible for the translesion DNA synthesis. Numerous in vitro studies indicated that these enzymes may contribute to DNA lesion-triggered and spontaneous mutation. We measured the transcripts of these 4 enzymes in 131 self-paired cancerous and non-tumor samples, including 23 lung cancers, 49 stomach cancers, and 59 colorectal cancers. Our results indicated that, except pol eta in colorectal cancers, these enzymes are all significantly down-regulated in human lung, stomach, and colorectal cancers, suggesting that these enzymes are probably not closely associated with the elevated mutations in human cancer.

Colorectal Neoplasms↗

PubMed2005

Phthalide Lactones from Ligusticum chuanxiong inhibit lipopolysaccharide-induced TNF-alpha production and TNF-alpha-mediated NF-kappaB Activation.

The dried rhizome of Ligusticum chuanxiong Hort. (Umbelliferae) is a traditional Chinese medicine (TCM) herb for the prevention and treatment of inflammatory and cardiovascular diseases. However, the role of phthalide lactones from Ligusticum chuanxiong in the therapeutic actions is not yet fully understood. In the present study, two phthalide lactones from the herb, Z-ligustilide and senkyunolide A, were identified and characterized as inhibitors of lipopolysaccharide (LPS)-induced TNF-alpha production in monocytes. The results of gene expression studies showed that the observed TNF-alpha suppression was related to their inhibitory activity on TNF-alpha mRNA transcription. Furthermore, the two phthalides exhibited significant suppressive effects on TNF-alpha-mediated nuclear factor-kappaB (NF-kappaB) activation in reporter gene assays. Taken together, the results suggest that Z-ligustilide and senkyunolide A may have potential applications in the treatment of inflammation and related diseases based on their inhibitory activity on TNF-alpha production and TNF-alpha bioactivity. New insights into the therapeutic basis of the TCM herb, Ligusticum chuanxiong, are presented.

Benzofurans↗

PubMed2005

[The application of BP neural network improved with LM algorithm in surface EMG signal classification].

The method of BP neural network improved by Levenberg-Marquardt algorithm in surface EMG signal classification is proposed. The data reduction and preprocessing operations of the signals are performed by means of the wavelet transform. The classifier can identify four classes of forearm movement: hand extension, hand grasp,forearm pronation and forearm supination with a high accuracy.Experimental result shows that the BP neural netwok improved by LM algorithm has greatly increased the speed and the accuracy of signal classification in practical application of prothesis control.

Algorithms↗

PubMed2004

Regulation of activities of NK cells and CD4 expression in T cells by human HNP-1, -2, and -3.

Human neutrophil defensin alpha (HNP) is a group of cationic peptides of diverse physiological roles. Recent studies revealed the nature of HNPs as the dominant HLA-DR binding peptides on malignant cancer cells, which may block the major histocompatibility complex for antigen presentation. Here we show that HNPs may inhibit T cells by downregulating CD4 expression, a molecule of critical importance for T cell's interaction with the target cell. HNPs also inhibited tumor-cell-lysis activities of NK cells by downregulating CD16-CD56 expression. More importantly, HNPs were markedly elevated in 14 cancer tissues out of 15 self-paired human colorectal cancers and their adjacent noncancerous tissues. The subset compositions of HNPs extracted from cancer tissues and neutrophils were identical. Immunohistochemical studies indicated that HNPs mainly distributed in the infiltrated neutrophils in the interstitium. The elevated HNPs in cancer tissues may create a microenvironment unfavorable for adaptive immune reaction, implicating the cancer evasion.

CD4 Antigens↗

PubMed2004

Selenium-containing 15-mer peptides with high glutathione peroxidase-like activity.

Glutathione peroxidase (GPX) is one of the most crucial antioxidant enzymes in a variety of organisms. Here we described a new strategy for generating a novel GPX mimic by combination of a phage-displayed random 15-mer peptide library followed by computer-aided rational design and chemical mutation. The novel GPX mimic is a homodimer consisting of a 15-mer selenopeptide with an appropriate catalytic center, a specific binding site for substrates, and high catalytic efficiency. Its steady state kinetics was also studied, and the values of k(cat)/K(m)(GSH) and k(cat)/ K(mH(2)O(2)) were found to be similar to that of native GPX and the highest among the existing GPX mimics. Moreover, the novel GPX mimic was confirmed to have a strong antioxidant ability to inhibit lipid peroxidation by measuring the content of malondialdehyde, cell viability, and lactate dehydrogenase activity. Importantly, the novel GPX mimic can penetrate into the cell membrane because of its small molecular size. These characteristics endue the novel mimic with potential perspective for pharmaceutical applications.

Amino Acid Sequence↗

PubMed2004

Performance analysis of an iSCSI-based unified storage network.

In this paper, we introduced a novel storage architecture "Unified Storage Network", which merges NAC(Network Attached Channel) and SAN(Storage Area Network), and provides the file I/O services as NAS devices and provides the block I/O services as SAN. To overcome the drawbacks from FC, we employ iSCSI to implement the USN(Unified Storage Network). To evaluate whether iSCSI is more suitable for implementing the USN, we analyze iSCSI protocol and compare it with FC protocol from several components of a network protocol which impact the performance of the network. From the analysis and comparison, we can conclude that the iSCSI is more suitable for implementing the storage network than the FC under condition of the wide-area network. At last, we designed two groups of experiments carefully.

Computer Communication Networks↗

PubMed2004

[Study on the synthesis and spectra of 2-thenoyl-2-carbazolyl-N-butyltrifluoroacetone].

In phene-50% NaOH medium, 1,4-dibromobutane reacts with carbazole (CZ) to form N-bromobutylcarbaole (BCZ) at 70-80 degrees C. The 2-thenoyl-2-carbazolyl-N-butyltrifluoroacetone (TCBTA) was synthesized by reaction of BCZ with 2-thenoyltrifluoroacetone (TTA) in acetone-K2CO3 medium at 50 degrees C. The TCBTA is a light brown crystal with m.p. of 211-214 degrees C. The structure of the synthesized TCBTA was characterized by UV, IR and GC/MS, and the UV and IR spectra of CZ, BCZ and TTA have been studied. In chloroform, TCBTA has three maximum absorptions at 241, 265 and 295 nm whose molar absorptivity is 1.88 x 10(5), 1.25 x 10(5) and 1.08 x 10(5) L x mol(-1) x cm(-1), respectively. Extraction rate of iron(III) and neodymium(III) by TCBTA in chloroform rises by 3 and 1.6 times compared with TTA. The fluorescence of TCBTA-Nd(III) complex is 5 times higher than TTA-Nd(III) complex. It was shown that TCBTA has excellent photosensitivity.

Carbazoles↗

PubMed2003

HaploBlockFinder: haplotype block analyses.

UNLABELLED: Recent studies have unveiled discrete block-like structures of linkage disequilibrium (LD) in the human genome. We have developed a set of computer programs to analyze the block-like LD structures (haplotype blocks) based on haplotype data. Three definitions of haplotype block are supported, including minimal LD range, no historic recombination, and chromosome coverage. Tagged SNPs that uniquely distinguish common haplotypes are identified. A greedy algorithm was used to improve the efficiency. Two separate utilities were also provided to assist visual inspection of haplotype block structure and pattern of linkage disequilibrium. AVAILABILITY: A web interface for the HaploBlockFinder is available at http://cgi.uc.edu/cgi-bin/kzhang/haploBlockFinder.cgi the source codes are also freely available on the web site.

Algorithms↗

PubMed2003

Randomly distributed crossovers may generate block-like patterns of linkage disequilibrium: an act of genetic drift.

There is considerable interest in identifying and characterizing block-like patterns of linkage disequilibrium (LD; haplotype blocks) in the human genome as these may facilitate the identification of complex disease genes via genome-wide association studies. Although recombination hot-spots have been suggested as the primary mechanism to explain the block-like pattern of LD, other forces, such as genetic drift, may also be important. To this end, we have studied the effect of various recombination models on patterns of LD by using extensive simulations. As expected, haplotype blocks were observed under a model allowing recombination hot-spots. However, we also observed similar block-like patterns in the models where recombination crossovers are randomly and uniformly distributed, and we demonstrate that these blocks are generated by genetic drift. We caution that genetic drift may be an alternative mechanism (in addition to recombination hot-spots) that can lead to block-like patterns of LD. Our findings highlight the necessity of characterizing haplotype blocks in world-wide populations.

Computer Simulation↗

PubMed2003

Protection of epidermal cells against UVB injury by the antioxidant selenium-containing single-chain Fv catalytic antibody.

The antioxidant effect of selenium-containing single-chain Fv catalytic antibody (Se-scFv2F3), a new mimic of glutathione peroxidase, was confirmed using a model system in which cultured rat skin epidermal cells were injured by ultraviolet B (UVB). The cell damage was characterized in terms of lipid peroxidation of the cells, cell viability, and cell membrane integrity. The injury effects of UVB and protection effects of Se-scFv2F3 on the cells were studied using the model system. UVB can damage the cells severely. Upon precultivation of the cells with 0.4U/ml Se-scFv2F3, however, the damage was significantly reduced as shown by the increase in cell viability, the decrease in the malondialdehyde and hydrogen peroxide levels, and the normalization of lactate dehydrogenase activity. In addition, a novel finding that Se-scFv2F3 can stimulate cultured epidermal cells to proliferate under certain conditions was observed.

Animals↗

PubMed2003

Comparison of gene expression between metastatic derivatives and their poorly metastatic parental cells implicates crucial tumor-environment interaction in metastasis of head and neck squamous cell carcinoma.

Metastasis of human head and neck cancer is a multistep and highly heterogeneous process requiring activation and deactivation of multiple and specific genes. To identify these genes, we established highly metastatic head and neck squamous cell carcinoma (HNSCC) cell lines from poorly metastatic HNSCC cells through in vivo selection using a lymph node metastatic mouse model. The very close genetic relationship between these highly metastatic cell lines and the parental cell line provided an excellent model for differential gene expression analysis using cDNA microarrays. Comparison of 6 cell lines established individually from the lymph node metastases with their poorly metastatic parental cell line revealed 33 differentially expressed genes. Some of these genes are involved in cellular signal transduction and matrix modeling. Differences in expression of members of the tumor necrosis factor, interleukin, caspase, and matrix metalloproteinase families were also examined. We found that two upregulated genes participated in the NF-kappaB regulatory pathway. Furthermore, differences in gene expression between six cell lines derived from primary tumors and six cell lines derived from lymph node metastases in the mouse model were analyzed statistically. Tissue growth factor-beta and tumor necrosis factor-related genes showed significantly altered expression in cells derived from lymph node metastases as compared with cells derived from primary tumors, suggesting that the differential growth advantage of metastatic cells requires more aggressive responses to their environment, such as a lymph node tissue.

Animals↗

PubMed2003

The effect of single nucleotide polymorphism identification strategies on estimates of linkage disequilibrium.

At present there is tremendous interest in characterizing the magnitude and distribution of linkage disequilibrium (LD) throughout the human genome, which will provide the necessary foundation for genome-wide LD analyses and facilitate detailed evolutionary studies. To this end, a human high-density single-nucleotide polymorphism (SNP) marker map has been constructed. Many of the SNPs on this map, however, were identified by sampling a small number of chromosomes from a single population, and inferences drawn from studies using such SNPs may be influenced by ascertainment bias (AB). Through extensive simulations, we have found that AB is a potentially significant problem in estimating and comparing LD within and between populations. Specifically, the magnitude of AB is a function of the SNP discovery strategy, number of chromosomes used for SNP discovery, population genetic characteristics of the particular genomic region considered, amount of gene flow between populations, and demographic history of the populations. We demonstrate that a balanced SNP discovery strategy (where equal numbers of chromosomes are sampled from multiple subpopulations) is the optimal study design for generating broadly applicable SNP resources. Finally, we validate our theoretical predictions by comparing our results to publicly available data from ten genes sequenced in 24 African American and 23 European American individuals.

Biological Evolution↗