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Biomedical subjects

Li Zhou

Publications and source records attributed to Li Zhou.

At least 91 records · Page 5Linked to original sources
PubMed2005

[Antitumor effect of endothelial progenitor cells with TRAIL gene transfection on ovarian carcinoma xenografts in nude mice].

BACKGROUND & OBJECTIVE: Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) can induce apoptosis in various cancer cell lines with little toxicity toward normal cells. It offers a promising therapeutic method against ovarian cancer. Endothelial progenitor cells (EPCs) could home to tumor lesion, and take part in angiogenesis. This study was to observe antitumor effect of EPCs with TRAIL gene transfection on human ovarian epithelial cancer xenografts in nude mice. METHODS: EPCs were isolated from human cord blood by magnetic bead selection, and cultured and amplified in vitro. Human ovarian epithelial cancer cell line 3AO cells were transplanted subcutaneously in immunodeficiency nude mice. EPCs were transfected with hTRAIL plasmid (TRAIL-EPCs). TRAIL-EPCs, TRAIL, or culture media IMDM (control) was injected into the mice model of 3AO xenograft by caudal vein. The changes of tumor volume were observed, and the tumor growth inhibition rate was calculated. RESULTS: EPCs with TRAIL gene transfection obviously inhibited the growth of 3AO xenograft in nude mice; the tumor weight of control, TRAIL, and TRAIL-EPCs groups were (0.226 +/- 0.209) g, (0.118 +/- 0.164) g, and (0.075 +/- 0.084) g, respectively, the maximum tumor growth inhibition rate was significantly higher in TRAIL-EPCs group than in TRAIL group (66.9% vs. 48.1%, P < 0.05). HE staining showed that there were more hemorrhage and necrosis regions in TRAIL and TRAIL-EPCs groups than in control group. No severe toxic reaction was observed in the 2 groups. CONCLUSIONS: Both TRAIL and TRAIL-EPCs can inhibit the growth of ovarian epithelial carcinoma xenograft in nude mice. EPCs have certain guidance effect in tumor xenografts in nude mice.

Animals↗
PubMed2005

[Electroanatomical systems guided circumferential pulmonary veins ablation for atrial fibrillation: initial experience from comparison between the EnSite-NavX and CARTO system].

OBJECTIVE: The circumferential pulmonary vein ablation (CPVA) has been proved effective for atrial fibrillation (AF) and is becoming more widely accepted. This study aims to evaluate the effectiveness of the CARTO and the EnSite-NavX system and to compare between them on procedural parameters and clinical characteristics. METHODS: Seventy-five patients with paroxysmal or persistent symptomatic AF were randomly assigned to CPVA procedure guided by either the EnSite-NavX system (group I, n = 40) or the CARTO system (group II, n = 35). After successful transseptal procedure, a geometry of left atrium was created under the guidance of the two systems. Radiofrequency energy was applied to circumferential tissues out of pulmonary veins (PVs) ostia. In cases with persistent AF, linear ablation was applied to modify the substrate of LA. The endpoint of the procedure was complete PVs isolation. RESULTS: Seventy-four cases underwent a successful procedure. The total procedure and fluoroscopic time in group II was significantly shorter than those in group I (150 min +/- 23 min and 18 min +/- 17 min vs 170 min +/- 34 min and 25 min +/- 16 min, P = 0.03 and 0.04, respectively). There was no significant difference in the fluoroscopic and procedure durations for geometry creation between the groups I and II (8 min +/- 4 min and 16 min +/- 11 min vs 5 min +/- 4 min and 14 min +/- 8 min, respectively). The fluoroscopic time for CPVA was 15 min +/- 5 min in group I vs 10 min +/- 6 min in group II (P = 0.05), and the CPVA procedural durations were significantly shorter in group II than those in group (86 min +/- 11 min vs 110 min +/- 15 min, P = 0.04). AF was terminated by RF delivery in 14 cases (35%) in group Ivs 5 cases (14%) in group II (P = 0.04). Complete PV isolation was obtained in 26 cases (65%) in group Ivs 11 cases (31%) in group II (P = 0.004). During a mean follow-up of 7 months, 32 (80%) cases in group I and 24 (69%) cases in group II were arrhythmia-free (P = 0.06). One case developed pericardial tamponade and 1 case was found to have intestinal artery thrombosis in group II. One case had moderate hemothorax in group I. All the complications were cured and no PV stenosis was observed. CONCLUSIONS: The CPVA procedure for atrial fibrillation is effective and safe. Although there is a difference between the CARTO and the EnSite-NavX system, the CPVA procedure guided by either of them yields similar clinical results.

Adult↗
PubMed2005

System architecture for temporal information extraction, representation and reasoning in clinical narrative reports.

Exploring temporal information in narrative Electronic Medical Records (EMRs) is essential and challenging. We propose an architecture for an integrated approach to process temporal information in clinical narrative reports. The goal is to initiate and build a foundation that supports applications which assist healthcare practice and research by including the ability to determine the time of clinical events (e.g., past vs. present). Key components include: (1) an annotation schema for temporal expressions and the development of an associated tagger; (2) a natural language processing (NLP) system for encoding and extracting medical events and associating them with formalized temporal data; (3) a post-processor, with a knowledge-based subsystem to help discover implicit information, that resolves temporal expressions and deals with issues such as granularity and vagueness; and (4) a reasoning mechanism which models clinical reports as Simple Temporal Problems (STPs).

Humans↗
PubMed2005

Concept space comparisons: explorations with five health domains.

This paper explores methods to compare concept spaces derived from different discourses in a common health domain. The concept spaces are generated from the research literature and from message board discussions on the Internet. We explore a number of methods for comparing and contrasting concept space pairs. We experiment with five select health domains in this exploratory research: Autism, AIDS, Fibromyalgia, Irritable Bowel Syndrome and Multiple Sclerosis. The paper concludes with a discussion about the potential of our methods. Future work on refinements to our techniques is also outlined.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Modeling electronic discharge summaries as a simple temporal constraint satisfaction problem.

OBJECTIVE: To model the temporal information contained in medical narrative reports as a simple temporal constraint satisfaction problem. DESIGN: A constraint satisfaction problem is defined by time points and constraints (inequalities between points). A time interval comprises a pair of points and a constraint. Five complete electronic discharge summaries and paragraphs from 226 other discharge summaries were studied. Medical events were represented as intervals, and assertions about events were represented as constraints. Through a consensus process, a set of encoding procedures and a list of issues related to encoding were generated. MEASUREMENTS: Instances of temporal disjunction and contradiction and distribution of temporal constraints were used. RESULTS: An average of 95 medical events (range, 46-151) and 234 temporal assertions (range, 118-388) were identified per complete discharge summary. Nondefinitional assertions were explicit (36%) or implicit (64%) and absolute (17%), qualitative (72%), or metric (11%). Implicit assertions were based on domain knowledge and assumptions, e.g., the section of the report determined the ordering of events. Issues included linking events, intermittence, periodicity, granularity, vagueness, ambiguity, uncertainty, and plans. ions such as intermittence were not represented explicitly. The temporal network was sparse: Only 0.80% (range, 0.42%-1.38%) of possible constraints were instantiated. No instances of discontinuous temporal disjunction were found in the complete summaries or the 226 paragraphs. One instance of temporal contradiction was found (intrareport rate of 0.2 with a 95% confidence interval of 0.005-1.114). CONCLUSION: A simple temporal constraint satisfaction problem appears sufficient to represent most temporal assertions in discharge summaries and may be useful for encoding electronic medical records.

Algorithms↗
PubMed2004

Neurogenesis response to hypoxia-induced cell death: map kinase signal transduction mechanisms.

Hypoxic stress induces apoptosis of hippocampal CA1 neurons while selectively sparing those in CA2-3. Proliferation and differentiation of local stem cells may potentially replace lost neurons. We examined MAP kinase signaling regulation of these dual responses. Rat organotypic hippocampal cultures were exposed to hypoxia for up to 6 h followed by reoxygenation. JNKs and ERKs were maximally activated by 4 h, returning approximately to basal levels by 6 h. Apoptosis of CA1 neurons was maximal by 6-h hypoxia, although JNK activation had returned to basal levels. A neuroprotective protein, JNK-interacting protein 1 (JIP1), an inhibitor of JNK-mediated apoptosis, was reduced by 6-h hypoxia and markedly decreased by 24-h reoxygenation in CA1 neurons as was DENN/MADD, which also modulates JNK-mediated cell death. A second peak of ERK1 activation occurred at 24-h reoxygenation and declined to control levels by 48 h. Stem cells were detected by antinestin and cell proliferation confirmed with anti-PCNA immunohistochemistry and BrdU incorporation. With U0126, an inhibitor of ERK activation, BrdU labeling was strikingly reduced implicating ERKs in the proliferation response. Antidoublecortin (DCX), which detects neural progenitor cells, colabeled a subset of BrdU-positive cells that extended from the dentate granule neurons into CA1. Astrocytes were colabeled with BrdU. Thus, hypoxia concurrently triggered both JNK and ERK signaling, and with reoxygenation, ERK1 activation and stem cell proliferation followed by neuronal progenitor cell differentiation and targeted migration to the site of pyramidal neuronal loss.

Animals↗
PubMed2004

Prediction of the adsorption equilibrium of mixtures composed of supercritical gases.

A new model was proposed to predict the adsorption equilibrium of mixtures composed of supercritical gases. The adsorbed phase was visualized as a two-dimensional nonideal compressed gas. Pore size distribution was used to describe the energetic heterogeneity of the surface, and the two-dimensional virial equation was used as the local adsorption isotherm. The new model obtained is thermodynamically rigorous because it reduces to Henry's law as pressure approaches zero. The prediction performance of the new model was verified and compared with other models using the experimental data of a ternary mixture of CH4/N2/H2 and two binary mixtures of CH4/C2H4 and CH4/N2. Better performance was shown for all systems tested.

Journal Article↗
PubMed2004

Analytical performance of a venturi device integrated into an electrospray ionization fourier transform ion cyclotron resonance mass spectrometer for analysis of nucleic acids.

A voltage-assisted venturi device modeled after an industrial air amplifier was used to improve the ion transmission efficiency of a 16.2 kDa oligonucleotide and a 53-mer PCR product in the high-pressure region between an electrospray ionization (ESI) emitter and the sampling orifices of two Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR-MS). The venturi device increased the total ion abundance of the oligonucleotide and the PCR product by more than 6-fold relative to the best achievable signal without the device. Furthermore, the average charge states of the oligonucleotide and PCR product shifted from 12.5- to 14.5- and 10.9- to 12.6-, respectively, with the addition of the venturi device. Specific to FT-ICR mass spectrometry, this increase in the charge state directly translates to an increase in theoretical mass resolving power (>10000 full width half-maximum for the results presented here at 7 T). Adduction was still observed while using the device, suggesting that it is "soft" relative to other high-pressure ion focusing methods.

Cyclotrons↗
PubMed2004

Glutathione-S-transferase pi inhibits As2O3-induced apoptosis in lymphoma cells: involvement of hydrogen peroxide catabolism.

Arsenic trioxide (As(2)O(3)) is an effective agent for the treatment of relapsed and refractory acute promyelocytic leukemia by induction of partial differentiation and apoptosis. As(2)O(3), at therapeutic concentrations (1-2 microM), induced apoptosis in Raji lymphoma cells but not in Jurkat lymphoma cells, which inversely correlated with the levels of glutathione-S-transferase pi (GSTP1), but not GSTpi(1) and GSTM(1), expression and activity. GSTP1 mRNA, protein level, and activity were high in Jurkat cells but undetectable in Raji cells. Stable transfection of GSTP1 into Raji cells decreased the amount of As(2)O(3)-induced apoptosis. Apoptosis induced by therapeutic concentrations of As(2)O(3) in Raji cells is related to increasing H(2)O(2) intracellular accumulation but not to JNK activation. Forced expression of GSTP1 by transfection of Raji cells significantly decreased the basal amount of H(2)O(2) and its levels after therapeutic concentration of As(2)O(3) treatment. Added exogenous H(2)O(2) was removed more rapidly, which correlated with a greater decrease in reduced glutathione level in Raji clones expressing GSTP1 than in those clones without GSTP1 expression. Overexpression of GSTP1 in transfected Raji clones was also found to decrease the retention of As(2)O(3). These data suggest that GSTP1 blocks As(2)O(3)-induced apoptosis in lymphoma cells by decreasing intracellular amounts of H(2)O(2) by catabolism and H(2)O(2) production by decreasing the intracellular retention of As(2)O(3).

Apoptosis↗
PubMed2004

Differential expression of thyroid-stimulating hormone beta subunit in gonads during sex reversal of orange-spotted and red-spotted groupers.

We have cloned and characterized the full-length cDNA encoding thyroid-stimulating hormone beta-subunit (TSHbeta) from orange-spotted grouper Epinephelus coioides. It contains 913 nucleotides with an open reading frame encoding 146 amino acids with a 20 amino acid signal peptide. The grouper mature TSHbeta has 75, 70, 61, 59, 41, 42 and 40% identities to that of rainbow trout, Atlantic salmon, zebrafish, European eel, chicken, mouse and human, respectively. RT-PCR analysis indicated that the TSHbeta mRNA was expressed abundantly not only in pituitary but also in gonads. A more interesting finding is to reveal the differential TSHbeta expressions between the ovaries and the transitional gonads or testes in natural individuals of orange-spotted grouper and red-spotted grouper Epinephelus akaara, and in artificial sex reversal individuals of red-spotted grouper induced by MT feeding. In situ hybridization localization provided direct evidence that the TSHbeta was transcribed in the germ cells. In the growing oocytes, the TSHbeta transcripts were concentrated on the ooplasm periphery. In testicular tissues, the intensively expressed TSHbeta cells were found to be spermatogonia and spermatocytes in the spermatogenic cysts. This is the first report of a TSHbeta expressed in the gonads of any vertebrates in addition to the expected expression in the pituitary, and it expresses more transcripts in the gonads during sex reversal or testis than in the ovaries both in E. coioides and E. akaara. Importantly, the TSHbeta identification in germ cells allows us to further investigate the functional roles and the molecular mechanisms in gametogenesis of groupers, especially in sex reversal and in spermatogenesis.

Amino Acid Sequence↗
PubMed2004

High-level expression of codon optimized foot-and-mouth disease virus complex epitopes and cholera toxin B subunit chimera in Hansenula polymorpha.

A codon optimized DNA sequence coding for foot-and-mouth disease virus (FMDV) capsid protein complex epitopes of VP1 amino acid residues 21-40, 135-160, and 200-213 was genetically fused to the N-terminal end of a 6x His-tagged cholera toxin B subunit (CTB) gene with the similar synonymous codons preferred by the methylotropic yeast Hansenula polymorpha. The fusion gene was synthesized based on a polymerase chain reaction (PCR) and subsequently overexpressed in H. polymorpha. The chimeric protein was successfully secreted into the culture medium (up to 100mg/L) and retained the antigenicity associated with CTB and FMDV antibodies by Western blot analysis. The chimera after purification through Co(2+)-charged resin column bound specifically to GM1 ganglioside receptor and thus retained the biological activity of CTB. This study has important implications in the construction of CTB chimera for mucosal vaccines against FMDV.

Base Sequence↗
PubMed2004

Fish proglucagon genes have differing coding potential.

Regulation of tissue-specific hormone production involves transcription, post-translational and physiological regulation. The proglucagon gene has been an ideal molecule for understanding many aspects of regulation of hormone production. Gene duplications often allow the evolution of new gene function, and the proglucagon gene has been duplicated on the lineage leading to teleost fish, while most other vertebrates have only a single proglucagon gene. The recent characterization of near complete pufferfish and zebrafish genomes allowed us to determine the structure of the duplicated genes. We searched the pufferfish and zebrafish genomes for proglucagon-like sequences. Our searches identified two proglucagon-like genes in both the pufferfish and zebrafish genomes. In pufferfish the proglucagon-like genes are surrounded by genes that are similar to genes that flank the proglucagon gene in mammalian genomes, indicating that gene order near the proglucagon gene has been maintained since the fish-mammal divergence approximately 450 million years ago. Characterization of the duplicated fish proglucagon genes indicates that one of the two genes is predicted to encode glucagon, GLP-1 and GLP-2. In contrast, the second proglucagon gene is predicted to encode only glucagon and GLP-1, but not GLP-2. Thus the two fish proglucagon genes have different coding potential, and, therefore likely differ in function. Regulation of gene expression potentially has a role in the regulation of production of proglucagon derived peptides in fish.

Amino Acid Sequence↗
PubMed2004

Liver injury after intermittent or continuous hepatic pedicle clamping and its protection by reduced glutathione.

BACKGROUND: The debate is still going on about selection of several clamping patterns during hepatectomy. The aim of this study was to assess the safety and preference of normothermic intermittent or continuous hepatic pedicle clamping and confirm the protective effect of reduced glutathione (GSH). METHODS: Thirty-two adult male healthy Sprague-Dawley (SD) rats were divided into groups of intermittent clamping and GSH absent (IA), continuous clamping and GSH absent (CA), intermittent clamping and GSH present (IP) and continuous clamping and GSH present (CP). The clamping manners were successively 40 minutes in continuous clamping groups and two cycles of 20 minutes with an interval of 5 minutes in intermittent clamping groups, and reperfusion periods were 60 minutes. Experimental parameters included levels of malonaldehyde (MDA) and Cu/Zn superoxide dismutase (SOD), pathological and ultrastructural changes in liver tissues, activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in sera. RESULTS: In the same group, the activities of ALT and AST were significantly higher in post-clamping rats than in pre-clamping rats (P<0.05), but no significant differences were noted in levels of MDA and Cu/Zn SOD (P>0.05). The differences of all values between post-reperfusion rats and pre-clamping rats were significant (P<0.05). Pathological and ultrastructural changes could be observed, but no irreversible injury was present. The comparison of the groups showed that the values at relevant time points between the intermittent and continuous groups were not significantly different (P>0.05). The values were significantly different between the GSH absent and present groups after reperfusion (P<0.05). The morphological damages were also obviously alleviated in the GSH present group. CONCLUSIONS: Normothermic intermittent or continuous hepatic pedicle clamping could cause reversible liver ischemia/reperfusion injury when the clamping time lasts 40 minutes. The injury extent seems to be similar. Continuous clamping should be regarded as a proper method in liver surgery. GSH has been confirmed as an effective agent in preventing post-clamping liver injury.

Animals↗
PubMed2004

Major hepatectomy without blood transfusion: report of 51 cases.

BACKGROUND: Blood transfusion has been found to be a devastating factor for outcomes of hepatectomy. This study was to assess the value of major hepatectomy without blood transfusion. METHODS: We retrospectively studied 51 patients who had undergone major hepatectomy without blood transfusion, including 29 patients with primary liver cancer, from August 1997 to December 2000. Sixty patients undergoing major hepatectomy with blood transfusion including 48 patients with primary liver cancer served as controls. Hepatectomy was performed through normothermic interruption of the porta hepatis. Intraoperative ultrasonography was performed to define tumor margins, and an ultrasound dissector was used to dissect liver parenchyma. RESULTS: In the study group, the operative mortality and morbidity and 1-, 2-, and 3-year recurrence rates were 0%, 9.8%, 24.1%, 27.6% and 31.0%, respectively. In the control group, they were 3.3%, 28.3%, 43.5%, 54.3% and 58.7%, respectively. Significant differences were seen in morbidity and recurrence rates of patients with liver cancer between the two groups (P < 0.05). CONCLUSION: Major hepatectomy without blood transfusion can reduce postoperative morbidity and recurrence rate of patients with liver cancer.

Adult↗
PubMed2004

[Dynamics of soil nutrient contents in cutting forestlands of broad-leaved Korean pine forest on Changbai Mountains].

A comparative study was made to analyze the dynamics of soil nutrient contents in different cutting forestlands of broad-leaved Korean pine forest on Changbai Mountains. The results showed that soil nutrient contents in different forestlands with different cutting times had obvious differences. With the cutting time going on after logging, soil pH value had the trend of declining firstly and increasing afterwards. The acidity of the topsoil was the highest after cutting for five years, and that of 10-20 cm soil layer was the strongest after cutting for ten years. The organic matter content as well as the total and available contents of nutrients increased at the first 2-5 years, and then declined rapidly, especially for those in topsoils. The cation exchange capacity (CEC), exchangeable Ca and exchangeable Mg had the same trend. Therefore, after forest cutting, artificial planting and regeneration should be carried out in time to resume the vegetation to reduce and prevent soil nutrient loss.

Calcium↗
PubMed2004

[Application of fluorescent real-time reverse transcriptase-polymerase chain reaction in detecting influenza viruses].

OBJECTIVE: To apply fluorescent real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in detecting influenza viruses. METHODS: A total of 207 oral swab samples were obtained in 16 collections from SARS patients and suspected influenza outbreak cases. They were subjected to influenza virus detection by fluorescent real-time RT-PCR, MDCK cell culture, and hemagglutinin inhibition assay. RESULTS: Out of 207 samples, 79 (38.16%) were positive for influenza viruses when tested by fluorescent real-time PCR, and 62 (29.95%) positive when tested by MDCK cell culture. There was a statistically significant difference between them (chi square=8.64, P less than 0.005). From 104 cases in 9 collections dual serum samples were obtainable. When tested with hemagglutinin inhibition assay, 64 cases (61.54%) showed a 4-fold increase against H3N2 antigen. CONCLUSION: This study showed that fluorescent real-time PCR is a reliable, sensitive, and fast method for detecting influenza viruses.

Cell Culture Techniques↗