Phase locking in on-off intermittency

Dynamical behavior of on-off intermittency around chaos synchronization-desynchronization bifurcation parameter line is investigated in coupled identical chaotic oscillators. Along this parameter line, we find that on-off intermittency can transit from phase-unlocking status to phase-locking one in the phase space of variable differences, which can be regarded as a codimension-two bifurcation, i.e., combinative bifurcations of desynchronization and phase locking. In the phase-locking case, the motions of all oscillators are chaotic and they show on-off intermittency with respect to the synchronous manifold, however, spatial phase order of variable differences is clearly established.

Wild type p53 sensitizes soft tissue sarcoma cells to doxorubicin by down-regulating multidrug resistance-1 expression

BACKGROUND

p53 mutations occur in almost half of all soft tissue sarcomas (STS) and may contribute to multidrug resistance (MDR) in patients with STS. Doxorubicin (Dox) is one of the most active single agents in STS but is less effective in STS with p53 mutations. The effect of reintroducing wild type (wt) p53 into STS cells harboring p53 mutations on the cytotoxicity of DOX in vitro and in vivo was studied.

METHODS

The following cell lines were used in this study: SKLMS-1 STS cells, which do not express wt p53; two wt p53 stable transfectant cells derived from SKLMS-1 cells; and SKLMS-1 transfectant cells from a p53 temperature-sensitive mutant that expresses wt p53 at 32 degrees C and mutant p53 at 38 degrees C. The cytotoxicity of Dox was examined by [3-(4,5-dimethylthiazzol-2-yl)-2,5-diphenltetrazolium] (MTT) and clonogenetic assay, and the effect of reintroducing wt p53 on tumor suppression by Dox was evaluated with a tumorigenicity assay. DNA fragmentation was used to detect apoptosis. MDR-1 P-glycoprotein (P-gp) expression was detected by Western blot and immunohistochemical analyses of protein levels and by Northern blot analysis of mRNA levels, respectively. The intracellular accumulation of Dox was detected by flow cytometric analysis.

RESULTS

The 50% inhibitory concentration (IC(50)) of Dox for the SKLMS-1 wt p53 transfectants decreased 16-fold compared with SKLMS-1 parental cells expressing mutant p53. Colony formation of SKLMS-1 cells after Dox treatment also was inhibited by wt p53 reintroduction. The tumorigenicity of SKLMS-1 cells was inhibited by wt p53 reintroduction alone or by Dox treatment alone and was inhibited further when p53 introduction was combined with Dox treatment in severe combined immunodeficient mice. Although no difference in DNA fragmentation, Bax expression, or Bcl-2 expression was detected among wt p53 transfectants and parental SKLMS-1 cells after Dox treatment, MDR-1 P-gp expression was decreased in wt p53 transfectants compared with parental SKLMS-1 cells. Furthermore, higher intracellular accumulations of Dox were found in wt p53 transfectants than that in SKLMS-1 cells.

CONCLUSIONS

Reintroduction of wt p53 into STS cells harboring p53 mutations can enhance their chemosensitivity to Dox through the inhibition of MDR-1 P-gp expression. Thus, the combination of p53 gene therapy and chemotherapy may increase the therapeutic efficacy in the treatment of patients with STS.

[Measurement of the absorption coefficient of barium using cavity ringdown spectroscopy]

An apparatus for cavity ringdown spectroscopy was constructed and used for atomic absorption measurement. The transition probability for 6s6p1P1<--6s6s1S0 transition of barium atoms was obtained in the self-made apparatus. The relation between atomic absorption coefficient and atomic oven temperature was also analysed.

Generalized splay state in coupled chaotic oscillators induced by weak mutual resonant interactions

Dynamic behavior of coupled chaotic oscillators is investigated. A transition from high-dimensional hyperchaos to a generalized periodic splay state is found for extremely weak coupling. Chaotic nature of a single oscillator and mutual resonant interactions are regarded to be responsible for this self-organized ordering. The functional phase distribution of the generalized splay state, which is essentially different from the equal-phase-separation distribution of the conventional splay states, can be well predicted by analyzing a single periodically forced oscillator.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

[Preliminary study on pathogenicity of hepatitis G virus]

OBJECTIVE

To study the clinical, enzymatic and liver pathological changes in patients with hepatitis G virus (HGV) infection.

METHODS

RT- nested PCR was applied to detect HGV RNA in 368 patients with hepatic diseases. The liver biopsy tissue from one liver cirrhosis patient with simple HGV infection was examined.

RESULTS

Simple HGV RNA positive were found in 7 cases of 71 acute hepatitis jaundice, in 22 cases of 155 chronic hepatitis and in 3 cases of 51 liver cirrhosis. The immunohistochemistry of the liver biopsy tissue from a liver cirrhosis patient showed HGV NS5 antigen positive. However, HGV infection might occur simply or in combination with hepatitis B or C virus or super infected.

CONCLUSIONS

HGV RNA could be detected in acute hepatitis jaundice, chronic hepatitis, hepatitis B or C carriers, liver cirrhosis and hepatocellular carcinoma. HGV is proved to be a hepatotropic virus by pathological examination and immunohistochemistry, the virus located in the cytoplasm of the liver cells. It may cause chronic hepatitis and even liver cirrhosis, so HGV is pathogenic to liver tissue.

Nonlocal chaotic phase synchronization

A novel synchronization behavior, nonlocal chaotic phase synchronization, is investigated. For two coupled Rossler oscillators with only one forced by an injected periodic signal, the phase of the unforced oscillator can be locked to the phase of the periodic signal while the forced one is well unlocked by the signal; in a chain of coupled chaotic oscillators with nearest coupling, the phase of an oscillator (or a cluster) can be locked to another nonneighbor one. Moreover, the mechanism underlying the transition to nonlocal synchronization is discussed in detail.

Optimizing human demineralized bone matrix for clinical application

The use of human demineralized bone matrix (DBM) powder in periodontal and orthopedic applications is limited by the variability in the osteoinductive or osteoconductive properties of the material. The goal of the present study was to establish simple in vitro and in vivo assays of DBM that would allow us to screen different lots of the material prior to testing in more rigorous animal models. The results demonstrate a wide variability in the performance of individual lots of DBM powder obtained from a single tissue bank. The studies also demonstrate that relatively simple screening can be used to establish the quality of the different lots, and that performance and ease of handling can be improved by using relatively small particle sizes delivered in a fibrin sealant matrix.

Synchronization of chaos in coupled systems

The stability of synchronous chaos of coupled oscillators with diffusive and gradient couplings is investigated. The stability boundaries of all transverse modes can be simultaneously drawn by justifying the boundary of a single mode, according to a scaling relation. Therefore, the distribution of stable and unstable regions can be explicitly shown in control parameter space. Bifurcations through different unstable modes, leading to different spatial orders, are analyzed.

Intermingled basins and on-off intermittency in a multistate system

We consider a dynamical system containing infinite low-dimensional symmetric invariant subspaces, each of which has a chaotic state. Intermingled basins are found between these multiple chaotic states when they are stable in the subspaces. As a parameter of the system varies, the largest Lyapunov exponent transverse to the invariant subspace can change from negative to positive; then, the system dynamics changes from an intermingled basin state to a multistate on-off intermittency. The statistical behavior and physical transportation property for different dynamic states are investigated in detail.

[Coexpression of the preS1(1-42) and the Core(1-144) antigen of HBV in E. coli]

OBJECTIVE

To study the therapeutic T cell vaccine for the treatment of chronic hepatitis B.

METHODS

The genes of HBcAg (1-144) and preS1 Ag (1-42) were amplified and fused by PCR. This fusion gene was inserted in the prokaryotic expression vector pET-11d and expressed in E. coli.

RESULTS

It was showed by SDS-PAGE that the protein molecular weight of the coexpression product was about 20,000, twenty percent of all bacteria protein. The monoclone antibody against Core and preS1 antigen could react with this fused protein by Western-blot technique respectively. The fused gene was verified by sequencing. Under the immune electron microscopy, this fused protein is a typical particle of HBcAg but in an aggregated form.

CONCLUSIONS

The results may aid for studying T cell immunotherapeutic vaccine to chronic hepatitis B.

The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

A whole-genome assembly of Drosophila

We report on the quality of a whole-genome assembly of Drosophila melanogaster and the nature of the computer algorithms that accomplished it. Three independent external data sources essentially agree with and support the assembly's sequence and ordering of contigs across the euchromatic portion of the genome. In addition, there are isolated contigs that we believe represent nonrepetitive pockets within the heterochromatin of the centromeres. Comparison with a previously sequenced 2.9- megabase region indicates that sequencing accuracy within nonrepetitive segments is greater than 99. 99% without manual curation. As such, this initial reconstruction of the Drosophila sequence should be of substantial value to the scientific community.

Easy detection of all T cell receptor gamma (TCRG) gene rearrangements by Southern blot analysis: recommendations for optimal results

Southern blot analysis of T cell receptor (TCR) gene rearrangements has proven to be a helpful tool to establish clonality in T cell leukemias and lymphomas. To improve the detection of clonal TCR gamma (TCRG) gene rearrangements by Southern blot analysis, we designed four new Jgamma probes and determined the most optimal restriction enzymes to be used with these probes. Based on detailed analysis of the sequences as well as on hybridization experiments with the TCRGJ21 probe, the Jgamma1.2 and Jgamma2.1 downstream areas were found to be highly homologous, suggesting that during evolution the duplication of the Jgamma region was followed by deletion of the tentative Jgamma2.2 gene segment. Southern blot analysis of 51 T cell acute lymphoblastic leukemias (T-ALL) revealed that all TCRG gene rearrangements can be detected by use of the TCRGJ13 probe in EcoRI digests and the TCRGJ21 probe in PstI digests. Additional probes and digests allow a more precise identification of the exact type of TCRG gene rearrangements in the majority of cases. Almost 90% of the TCRG gene rearrangements in T-ALL involved the Jgamma2 region (16% Jgamma2.1 and 72% Jgamma2.3), whereas Jgamma1 region rearrangements were particularly found in TCRgammadelta+ T-ALL. This information has implications for design of primer sets for PCR analysis at diagnosis and for PCR target choice in detection of minimal residual disease during follow-up of T-ALL patients.

cDNA cloning and sequence analysis of hepatitis G virus genome isolated from a Chinese blood donor

OBJECTIVE

To obtain full-length sequence of a Chinese hepatitis G virus (HGV) strain (HGVch) and investigate the genetic characteristic of HGVch and its identity to other isolates.

METHODS

Reverse transcription (RT) and nested-PCR were used to screen HGV RNA positive serum and amplify cDNA fragments. A positive serum without known hepatitis virus markers was selected for isolating HGV RNA template. The HGV genome was divided into 12 overlapping fragments and directly cloned into pGEM-T vector. Sequences were determined by dideoxy terminus-end method of DNA sequencing and then analyzed by computer.

RESULTS

The twelve fragments of HGVch cover 9213 nucleotides in length, containing a large open reading frame (ORF) encoding 2873 animo acids polyprotein that began with a methonine residue and ended at termination codon. HGVch is about 86.5%-89.5% identical to other known HGV isolates at the nucleotide level and about 93.9%-96.2% at the deduced animo acid level.

CONCLUSION

HGV is a non-A-E hepatitis causal agent, proved to be related with posttransfusion hepatitis in all over the world. Chinese HGV isolate has very close relationship to other isolates from Africa, Europe, Japan, without significant difference across the entire genome. It is suggested that the sequences of HGV isolates are very conservative and the evolution is very slow.

[Expression of non-structural region 3 gene of the Chinese HGY and analysis of the antigenicity of the recombinant proteins]

OBJECTIVE

This study is to analyze the antigenicity of the NS3 proteins of Chinese HGV and their potential use in the serological diagnosis.

METHODS

All three gene fragments of NS3 region of Chinese HGV were cloned into the pRSET vectors to construct recombinant plasmids. In E. coli BL21, all three recombinant plasmids achieved a high expression level with induction of IPTG. The expressed products were analyzed with Western blot and ELISA.

RESULTS

The recombinant protein PA, P3 and P4 have a molecular weight of 42,000, 30,000 and 24,000, respectively. They all could react with HGV positive sera in Western blot and ELISA. Among them, the protein that covers the N terminal of NS3 region of HGV had a stronger reaction with HGV positive sera than the other two proteinsdid.

CONCLUSION

The N terminal in the NS3 region of Chinese HGV includes an dominant antigenic determinant, and its gene product has relatively strong antigenicity.

Schedule-dependent reversion of cisplatin resistance by 5-fluorouracil in a cisplatin-resistant human lung adenocarcinoma cell line A549DDP

OBJECTIVE

To study the schedule-dependent reversion of cis-diamminedichloroplatinum (CDDP) resistance by 5-fluorouracil (5-Fu) in a CDDP resistant human lung adenocarcinoma cell line A549DDP.

METHODS

Dimethylthiazol dipheryltetrazolium bromide (MTT) assay and immunocytochemistry were used.

RESULTS

After the A549DDP was treated with CDDP, followed immediately by exposure to 5-Fu, cytotoxicity of CDDP increased 1.8 fold. After pretreatment of A549DDP with 5-Fu, followed immediately by exposure to CDDP, the cytotoxicity of CDDP increased 3.9 fold. After pretreatment of A549DDP with 5-Fu, after a 24- or 48-hour drug-free interval, followed by exposure to CDDP, the cytotoxicity of CDDP increased 20 and 250 fold, respectively, and the A549DDP was rendered more sensitive than its parental cell line A549. In parallel with the increased cytotoxicity, the cellular GSH content was significantly reduced at 24 or 48-hour after 5-Fu pretreatment. However, depletion of GSH by buthionine sulfoximine (BSO) only resulted in partial reversion of CDDP resistance. 5-Fu could also inhibit the expression of MRP, but had no effect on the expression of GST pi. The effect of 5-Fu on the parental cell line A549 was much smaller than that in A549DDP.

CONCLUSION

Scheduled administration of 5-Fu can reverse CDDP resistance completely through reduction of GSH and inhibition of MRP expression.

Sequence heterogeneity within three different regions of the hepatitis G virus genome

Two sets of primers derived from the 5'-terminal region and the NS5 region of the hepatitis G virus (HGV) genome were used to amplify PCR fragments from serum specimens obtained from different parts of the world. All PCR fragments from the 5'-terminal region (5'-PCR, n = 56) and from the NS5 region (NS5-PCR, n = 85) were sequenced and compared to corresponding published HGV sequences. The range of nucleotide sequence similarity varied from 74 and 78% to 100% for 5'-PCR and NS5-PCR fragments, respectively. Additionally, five overlapping PCR fragments comprising an approximately 2.0-kb structural region of the HGV genome were sequenced from each of five sera obtained from three United States residents. These sequences were compared to 20 published sequences comprising the same region of the HGV genome. Nucleotide and deduced amino acid sequences obtained from different individuals were homologous from 82.9 to 93. 6% and from 90.4 to 99.0%, respectively. Sequences obtained from follow-up specimens were almost identical. Comparative analysis of deduced amino acid sequences of the HGV structural proteins and hepatitis C virus (HCV) structural proteins combined with an analysis of predicted secondary structures and hydrophobic profiles allowed prediction of processing sites within the HGV structural proteins. A phylogenetic sequence analysis performed on the 2.0-kb structural region supports the existence of three previously identified HGV genetic groups. However, phylogenetic analysis performed on only small DNA fragments yielded inconsistent genetic grouping and failed to confirm the existence of genetic groups. Thus, in contrast to HCV where almost any region can be used for genotyping, only large or carefully selected genome fragments can be used to identify consistent HGV genetic groups.

[Clinical significance of multidrug resistance-associated protein(MRP) gene expression in non-small cell lung cancer]

OBJECTIVE

To investigate expression of multidrug resistance-associated protein (MRP) in non-small cell lung cancer and its relation to histological type, TNM staging and prognosis.

METHODS

In situ hybridization was used to examine mRNA expression of MRP.

RESULTS

The overall positive rate of MRP expression was 74.1%, with 73.3% and 72.0% in adenocarcinoma and squamous-cell carcinoma, respectively. The expression of MRP was not related to histological subtypes, TNM staging and cell differentiation. In 47 patients who received chemotherapy, 35 patients with positive MRP expression(+(-)++) showed worse prognosis than in those with negative expression (P < 0.05). The median survival time was 8.7 months and 21 months in patients with positive and negative MRP expession, respectively. In patients with squamous-cell carcinoma, the survival rate was significantly lower in patients (n = 12) with positive MRP expression than in those (n = 7) with negative MRP expression (P < 0.05). Their median survival time was 6 months and 19.5 months, respectively (P < 0.05).

CONCLUSION

The expression of MRP gene is negatively correlated with survival of patients with squamous-cell carcinoma, but not adenocarcinoma, who received chemotherapy.

[The clinical and enzymatic changes in patients with viral hepatitis G infection]

For the purpose of making sure the clinical significance of hepatitis G virus, RT-nested PCR was applied to detect HGV RNA in 165 hepatitis patients, which included 24 acute hepatitis, 78 chronic hepatitis, 18 hepatitic cirrhosis, 4 hepatocellularcarcinom and 41 HBV and HCV carriers. The results showed that the infection of HGV existed in all kinds of hepatitis patients. Among the acute hepatitis 12.5% (3/24) was HGV RNA positive. 19 (24.4%) cases were HGV RNA positive in chronic hepatitis, among which 4 cases were simply HGV RNA positive (5.13%). The serum ALT level in 3 cases of simple acute HGV patients was between 488 +/- 65 U/L, the value of AST between 452 +/- 71 U/L, the TBiL at about 77.1 +/- 14.3 mumol/L. All these showed that only HGV infection could lead to acute hepatitis. The rising enzyme dropped to normal about a month later in acute hepatitis while HGV RNA would remain. The problem whether HGV infection is caused by simple acute and chronic hepatitis infection is under investigation.

[Cloning and sequencing of cDNA in NS3 region of Chinese hepatitis G virus isolated from Henan Province]

To study the genetic characteristics of non-structural region 3 of HGV in China, a HGV-RNA positive sample was collected from Henan. HGV RNA was extracted and amplified by RT-nested-PCR. We got four overlap fragments and they were cloned into plasmid vector pcDNA II. The cDNA was sequenced by the Sanger's method. Nucleotide homology between Henan strain and other reported HGV isolates (PNF2161, R10291, GBV-C) was 85.7% to 93.8% over the 2137 nucleotides examined. Comparison of amino acid sequence deduced from Henan strain with that of other isolates showed 96.1% to 97.7% homology. Three amino acid variations were found in NS3 region of all the three Chinese isolates of HGV. In addition, a N-glycosylation site was found in the NS3 region of all the six isolates.

[Core protein of hepatitis C virus expressed in transgenic mice is associated with the expression of Fas molecule]

Hepatitis C virus (HCV) is a leading cause of morbidity and mortality worldwide but the pathogenesis of liver cell injury and the molecular mechanism of persistent infection of HCV are not well understood. The aim of this work is to establish the animal model of HCV infection for studying the biosynthesis and pathogenesis of HCV structural protein in transgenic mice. The structural genes (C+ E1 + E2) and 5'-uncoding region gene (5'UCR) of HCV isolated from China was inserted into pcDNA3 vector. The transgenic mice were produced by microinfecting this plasmid into mouse (C57BL/6 x ICR) embryos and the integrated mice were identified. The expression of core protein of HCV and mFas molecule were confirmed by immunohistochemical analysis using monoclonal antibody. The results revealed that the expression of core protein was detected in many mouses' tissues with nuclear staining, while the heart tissue was with cytoplasmic staining. The expression level in tissues was indicated as: heart>lung>kidney>liver. At meantime, Fas molecule was detected in heart, kidney and liver tissues, and the expression of Fas was parallel to that of core protein. Transgenic mouse containing HCV structural gene was established and the expression of Fas molecule may be associated with the expression of core protein of HCV. The Fas system or other signaling pathway to the programmed cell death may play important roles in HCV infection. Our transgenic mouse will provide a useful animal model to critically address issues of immune pathogenesis, direct cytopathic potential and carcinogenesis of the structural protein of HCV.

[Dynamic changes of serum antibody titer and liver ultrastructural pathology in acute sporadic hepatitis E virus infected patients]

7 acute hepatitis E patients were tested for anti-HEV IgM and IgG antibodies by EIA. It revealed that anti-HEV IgM and IgG antibody titers were the highest at day 10-45 of the illness, and anti-HEV IgM declined gradually and totally lost within 2 months. Anti-HEV IgG had a similar condition to anti-HEV IgM, but at 7th month there still had 3 cases (40%) remained to be antibody positive. One case was examined for ultrastructural pathology. The swelling of liver cells on the fortieth day of illness was still to be found, the vacuolation of cytoplasm and condensation of mitochondria were present in liver cells.

[Diagnosis of hepatitis E virus infection in sporadic acute hepatitis]

The solid-phase enzyme immunoassay (EIA) was used for detecting anti-HEV immunoglobulin G (IgG) and M (IgM) by using a recombinant chimeric antigen (ORF3-2) from the open reading frame (ORF) 2 and 3 of hepatitis E virus gene. These sera were collected from the patients with sporadic acute viral hepatitis. The positive rate for anti-HEV IgG was 15.22% (7) among 46 patients with acute hepatitis, 5 of the 7 IgG positive sera were also positive (71.4%) for anti-HEV IgM. 91.8% (93) and 76.4% (78) were positive separately for anti-HEV IgG and IgM among 102 patients of suspected HEV infection (these patients were negative for anti-HAV, anti-HBV and anti-HCV), about 2/3 patients of HEV infection detected were simultaneously HEV-IgG and IgM positive. In control group of 98 normal persons, 4 (4.08%) were positive for anti-HEV IgG, but none were IgM positive. Paired sera of the patients in the acute phase and convalescent phase were detected, the titers of anti-HEV IgG with 4-16 fold decrease were seen in 6 cases and with 2-fold rise in 1 case.