Biomedical subjects

Lei Li

Publications and source records attributed to Lei Li.

At least 109 records · Page 6Linked to original sources

PubMed2005

[Application of adjustable oblique position for microendoscopic discectomy].

OBJECTIVE: To compare the adjustable oblique position with prone position in microendoscopic discectomy (MED) and to evaluate its advantages. METHODS: One hundred and twenty-eight patients who underwent MED during August 2000 and August 2002 were studied. Forty-seven cases were positioned prone, 81 cases were positioned with adjustable oblique position. Operating time, blood loss and patient endurance were recorded and compared. The airway resistance of 29 lumbar disorder patients was measured when they were positioned supine, lateral and prone respectively after general anesthesia. RESULTS: There was statistically significant difference between 2 groups in operating time, blood loss and endurance. In prone position group, when operating time lasted for more than 50 min, 75% patients felt hurt on the skin of rib arch, and 38% patients presented dizzy and nausea. And all the patients had erythema on the rib arch. In the adjustable oblique position group, 3 cases had shoulder pain after operation, and 1 case had 4 days' common poroneal nerve paralysis. The airway resistance of patients with prone position was significantly higher than those with supine and lateral positioned patients. (P < 0.05). CONCLUSION: The adjustable oblique position in MED had the following advantages: (1) Do not limit the movement of chest and help reduce intra-abdominal pressure and epidural bleeding; (2) Give the lumbar spine the largest degree of flexion and the largest interlaminar space, which prevents injury of facet joint; (3) Increase posterior intervertebral space and make disectomy easier and exposure of nerve root and nerve root canal clearer; (4) The patients feel comfortable and can adjust the position of lumbar spine and lower extremity; (5) The monitor has the same direction with doctor, and it is easy for the doctor to operate; (6) Doctor can sit during operation.

Adolescent↗

PubMed2005

[The molecular mechanism of PML in inducing apoptosis of bladder cancer cell line].

OBJECTIVE: Study the affection of inducing expression of PML in the apoptosis and the molecular mechanism of bladder cancer. METHODS: PMEP4/PML inducible expression vector was transfected into bladder cancer UM-UC-2 cells by lipofectamine 2000 system. The positive clone cells were selected by 300 microg/ml hygromycin B and confirmed by laser confocal imaging system. Then, using the in vitro DNA ladder apoptotic assay and Western blot, the affection of inducing expression of PML on apoptosis and its molecular mechanism of bladder cancer cell was studied. RESULTS: Comparing with the vector control group, PML specific nuclear speckle significantly increased in the PMEP4/PML bladder cells. DNA ladder assay demonstrated bladder cancer cell expressing PML occurred apoptosis while the control vector cells were not influenced. Overexpression of PML could reduce Survivin expression and upregulate caspase3 and cleaved PARP protein expression CONCLUSION: Our results demonstrated that overexpression of PML could induce bladder cancer cell apoptosis through the caspase dependent pathways.

Apoptosis↗

PubMed2005

Preoperative evaluation of pancreaticobiliary tumor using MR multi-imaging techniques.

AIM: To evaluate the clinical value of MR multi-imaging techniques in diagnosing and preoperative assessment of pancreaticobiliary tumor. METHODS: MR multi-imaging techniques, including MR cross-sectional imaging, MR cholangiopancreatography (MRCP) and 3D dynamic contrast-enhanced MR angiography (3D DCE MRA), were performed to make prospective diagnosis and preoperative evaluation in 28 patients with suspected pancreaticobiliary tumors. There were 17 cases of pancreatic adenocarcinoma, 8 cases of biliary system carcinoma and 3 cases of non-neoplastic lesions. RESULTS: Using MR multi-imaging techniques, the accuracy in diagnosing the patients with pancreaticobiliary tumors was 89.3% (25/28). The accuracy in detecting the range of tumor invasion was 80.3% (57/71). The sensitivity, specificity, accuracy, positive and negative predictive value of MR multi-imaging techniques in preoperative assessment of the resectability of pancreaticobiliary tumor were 83.3%, 89.5%, 88.0%, 71.4%, and 94.4%, respectively. There was well diagnostic consistency between MR multi-imaging techniques and CT (kappa = 0.64, P<0.01). The fusion image could be made from MRCP and 3D DCE MRA images. CONCLUSION: MR multi-imaging techniques can integrate the advantages of various MR images. The non-invasive "all-in-one" MR imaging protocol is the efficient method in diagnosing, staging and preoperative assessment of pancreaticobiliary tumor.

Adult↗

PubMed2005

An approach to studying lung cancer-related proteins in human blood.

Early stage lung cancer detection is the first step toward successful clinical therapy and increased patient survival. Clinicians monitor cancer progression by profiling tumor cell proteins in the blood plasma of afflicted patients. Blood plasma, however, is a difficult cancer protein assessment medium because it is rich in albumins and heterogeneous protein species. We report herein a method to detect the proteins released into the circulatory system by tumor cells. Initially we analyzed the protein components in the conditioned medium (CM) of lung cancer primary cell or organ cultures and in the adjacent normal bronchus using one-dimensional PAGE and nano-ESI-MS/MS. We identified 299 proteins involved in key cellular process such as cell growth, organogenesis, and signal transduction. We selected 13 interesting proteins from this list and analyzed them in 628 blood plasma samples using ELISA. We detected 11 of these 13 proteins in the plasma of lung cancer patients and non-patient controls. Our results showed that plasma matrix metalloproteinase 1 levels were elevated significantly in late stage lung cancer patients and that the plasma levels of 14-3-3 sigma, beta, and eta in the lung cancer patients were significantly lower than those in the control subjects. To our knowledge, this is the first time that fascin, ezrin, CD98, annexin A4, 14-3-3 sigma, 14-3-3 beta, and 14-3-3 eta proteins have been detected in human plasma by ELISA. The preliminary results showed that a combination of CD98, fascin, polymeric immunoglobulin receptor/secretory component and 14-3-3 eta had a higher sensitivity and specificity than any single marker. In conclusion, we report a method to detect proteins released into blood by lung cancer. This pilot approach may lead to the identification of novel protein markers in blood and provide a new method of identifying tumor biomarker profiles for guiding both early detection and therapy of human cancer.

Adolescent↗

PubMed2005

Purification of astilbin and isoastilbin in the extract of smilax glabra rhizome by high-speed counter-current chromatography.

Purification of astilbin from the rhizome extract of Smilax glabra was conducted using a high-speed counter-current chromatograph equipped with a 700 mL column. In a single operation, 1.5 g of crude sample was separated to yield 105 mg of component astilbin and 48 mg of isoastilbin while the upper phase of the two-phase solvent system composed of n-hexane-n-butanol-water (1:1:2, v/v/v) was used for stationary phase. The chemical structures of the two flavonoid glycosides were confirmed by electrospray ionization ion trap multiple mass spectrometry and nuclear magnetic resonance experiments.

Countercurrent Distribution↗

PubMed2005

Tiling microarray analysis of rice chromosome 10 to identify the transcriptome and relate its expression to chromosomal architecture.

BACKGROUND: Sequencing and annotation of the genome of rice (Oryza sativa) have generated gene models in numbers that top all other fully sequenced species, with many lacking recognizable sequence homology to known genes. Experimental evaluation of these gene models and identification of new models will facilitate rice genome annotation and the application of this knowledge to other more complex cereal genomes. RESULTS: We report here an analysis of the chromosome 10 transcriptome of the two major rice subspecies, japonica and indica, using oligonucleotide tiling microarrays. This analysis detected expression of approximately three-quarters of the gene models without previous experimental evidence in both subspecies. Cloning and sequence analysis of the previously unsupported models suggests that the predicted gene structure of nearly half of those models needs improvement. Coupled with comparative gene model mapping, the tiling microarray analysis identified 549 new models for the japonica chromosome, representing an 18% increase in the annotated protein-coding capacity. Furthermore, an asymmetric distribution of genome elements along the chromosome was found that coincides with the cytological definition of the heterochromatin and euchromatin domains. The heterochromatin domain appears to associate with distinct chromosome level transcriptional activities under normal and stress conditions. CONCLUSION: These results demonstrated the utility of genome tiling microarray in evaluating annotated rice gene models and in identifying novel transcriptional units. The tiling microarray sanalysis further revealed a chromosome-wide transcription pattern that suggests a role for transposable element-enriched heterochromatin in shaping global transcription in response to environmental changes in rice.

Chromosomes, Plant↗

PubMed2005

Semi-industrial isolation of salicin and amygdalin from plant extracts using slow rotary counter-current chromatography.

Salicin in the bark extract of Salix alba and amygdalin in the fruit extract of Semen armeniacae were each separated by slow rotary counter-current chromatography (SRCCC). The apparatus was equipped with a 40-L column made of 17 mm i.d. convoluted Teflon tubing. A 500g amount of crude extract containing salicin at 13.5% was separated yielding 63.5 g of salicin at 95.3% purity in 20h using methyl tert-butyl ether-l-butanol (1:3) saturated by methanol-water (1:5) as a stationary phase and methanol-water (1:5) saturated by methyl tert-butyl ether-1-butanol (1:3) as a mobile phase. A 400g amount of crude extract containing amygdalin at 55.3% was isolated to yield 221.2g of amygdalin at 94.1% purity in 19h using ethyl acetate-1-butanol (1:2) saturated by water as a stationary phase and water saturated by ethyl acetate-1-butanol (1:2) as a mobile phase. The flow rate of the mobile phase was 50 ml/min. The results show that industrial SRCCC separation of salicin and amygdalin is feasible using a larger column at a higher flow rate of the mobile phase.

Amygdalin↗

PubMed2005

Predicting adsorption isotherms for aqueous organic micropollutants from activated carbon and pollutant properties.

A method based on the Polanyi-Dubinin-Manes (PDM) model is presented to predict adsorption isotherms of aqueous organic contaminants on activated carbons. It was assumed that trace organic compound adsorption from aqueous solution is primarily controlled by nonspecific dispersive interactions while water adsorption is controlled by specific interactions with oxygen-containing functional groups on the activated carbon surface. Coefficients describing the affinity of water for the activated carbon surface were derived from aqueous-phase methyl tertiary-butyl ether (MTBE) and trichloroethene (TCE) adsorption isotherm data that were collected with 12 well-characterized activated carbons. Over the range of oxygen contents covered by the adsorbents (approximately 0.8-10 mmol O/g dry, ash-free activated carbon), a linear relationship between water affinity coefficients and adsorbent oxygen content was obtained. Incorporating water affinity coefficients calculated from the developed relationship into the PDM model, isotherm predictions resulted that agreed well with experimental data for three adsorbents and two adsorbates [tetrachloroethene (PCE), cis-1,2-dichloroethene (DCE)] that were not used to calibrate the model.

Adsorption↗

PubMed2005

Generation of a dataset for studying ligand effect on homodimer interface.

Protein dimer interfaces (homodimer - same polypeptide and heterodimer - different polypeptide) display geometric and chemical properties that give the non-covalent assembly its stability and specificity. Therefore, it is important to understand the molecular principles of dimer interaction. Several studies on homodimer interaction are available. However, a study on the effect of ligands (i.e. non-peptide compounds) on subunit interactions is not available. Hence, we generated a dataset of 62 identical homodimer pairs (one structure determined with an interface ligand and the other without an interface ligand) and analyzed the effect of interface ligands on dimer interface. The analysis suggests that homodimer interfaces having ligands are less hydrophobic with small interface area compared to those without ligands. We also found that ligands occupying = 7% interface area have negligible effect on dimer interaction.

Binding Sites↗

PubMed2005

A tiling microarray expression analysis of rice chromosome 4 suggests a chromosome-level regulation of transcription.

The complete genome sequence of cultivated rice (Oryza sativa) provides an unprecedented opportunity to understand the biology of this model cereal. An essential and necessary step in this effort is the determination of the coding information and expression patterns of each sequenced chromosome. Here, we report an analysis of the transcriptional activity of rice chromosome 4 using a tiling path microarray based on PCR-generated genomic DNA fragments. Six representative rice organ types were examined using this microarray to catalog the transcribed regions of rice chromosome 4 and to reveal organ- and developmental stage-specific transcription patterns. This analysis provided expression support for 82% of the gene models in the chromosome. Transcriptional activities in 1643 nonannotated regions were also detected. Comparison with cytologically defined chromatin features indicated that in juvenile-stage rice the euchromatic region is more actively transcribed than is the transposon-rich heterochromatic portion of the chromosome. Interestingly, increased transcription of transposon-related gene models in certain heterochromatic regions was observed in mature-stage rice organs and in suspension-cultured cells. These results suggest a close correlation between transcriptional activity and chromosome organization and the developmental regulation of transcription activity at the chromosome level.

Chromosome Mapping↗

PubMed2005

Protein-protein coupling/uncoupling enables dopamine D2 receptor regulation of AMPA receptor-mediated excitotoxicity.

here is considerable evidence that dopamine D2 receptors can modulate AMPA receptor-mediated neurotoxicity. However, the molecular mechanism underlying this process remains essentially unclear. Here we report that D2 receptors inhibit AMPA-mediated neurotoxicity through two pathways: the activation of phosphoinositide-3 kinase (PI-3K) and downregulation of AMPA receptor plasma membrane expression, both involving a series of protein-protein coupling/uncoupling events. Agonist stimulation of D2 receptors promotes the formation of the direct protein-protein interaction between the third intracellular loop of the D2 receptor and the ATPase N-ethylmaleimide-sensitive factor (NSF) while uncoupling the NSF interaction with the carboxyl tail (CT) of the glutamate receptor GluR2 subunit of AMPA receptors. Previous studies have shown that full-length NSF directly couples to the GluR2CT and facilitates AMPA receptor plasma membrane expression. Furthermore, the CT region of GluR2 subunit is also responsible for several other intracellular protein couplings, including p85 subunit of PI-3K. Therefore, the direct coupling of D2-NSF and concomitant decrease in the NSF-GluR2 interaction results in a decrease of AMPA receptor membrane expression and an increase in the interaction between GluR2 and the p85 and subsequent activation of PI-3K. Disruption of the D2-NSF interaction abolished the ability of D2 receptor to attenuate AMPA-mediated neurotoxicity by blocking the D2 activation-induced changes in PI-3K activity and AMPA receptor plasma membrane expression. Furthermore, the D2-NSF-GluR2-p85 interactions are also responsible for the D2 inhibition of ischemia-induced cell death. These data may provide a new avenue to identify specific targets for therapeutics to modulate glutamate receptor-governed diseases, such as stroke.

Animals↗

PubMed2005

Effects of activated carbon characteristics on the simultaneous adsorption of aqueous organic micropollutants and natural organic matter.

The overall objective of this research was to determine the effects of physical and chemical activated carbon characteristics on the simultaneous adsorption of trace organic contaminants and natural organic matter (NOM). A matrix of 12 activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels (acid-washed, oxidized, hydrogen-treated, and ammonia-treated) was studied to systematically evaluate pore structure and surface chemistry phenomena. Also, three commercially available granular activated carbons (GACs) were tested. The relatively hydrophilic fuel additive methyl tertiary-butyl ether (MTBE) and the relatively hydrophobic solvent trichloroethene (TCE) served as micropollutant probes. A comparison of adsorption isotherm data collected in the presence and absence of NOM showed that percent reductions of single-solute TCE and MTBE adsorption capacities that resulted from the presence of co-adsorbing NOM were not strongly affected by the chemical characteristics of activated carbons. However, hydrophobic carbons were more effective adsorbents for both TCE and MTBE than hydrophilic carbons because enhanced water adsorption on the latter interfered with the adsorption of micropollutants from solutions containing NOM. With respect to pore structure, activated carbons should exhibit a large volume of micropores with widths that are about 1.5 times the kinetic diameter of the target adsorbate. Furthermore, an effective adsorbent should possess a micropore size distribution that extends to widths that are approximately twice the kinetic diameter of the target adsorbate to prevent pore blockage/constriction as a result of NOM adsorption.

Adsorption↗

PubMed2005

[A frame shift mutation, Arg346fs mutation, is identified in cardiac myosin-binding protein C gene in a Chinese family with hypertrophic cardiomyopathy].

OBJECTIVE: To explore the disease-causing gene mutation in Chinese with hypertrophic cardiomyopathy (HCM). METHODS: The peripheral venous blood samples were collected from 5 HCM families without consanguinity, including 5 probands, 2 males and 3 females, 28 sporadic HCM patients, 18 males and 10 females, and 80 healthy controls. The exons in the functional regions of cardiac myosin-binding protein C (MYBPC3) were amplified with PCR and the amplified products were sequenced. RESULTS: A frame shift mutation-Arg346fs mutation in exon 13, the first mutation identified in Chinese-was discovered in one family with HCM. However, the members of the same HCM family with the Arg346fs mutation showed differences in phenotype and prognosis. CONCLUSION: Cardiac myosin-binding protein C (MYBPC3) may be one of the main disease-causing genes. The heterogeneity of phenotype suggests that multiple factors may be involved in the pathogenesis.

Adolescent↗

PubMed2005

Sensitivity to phosphonoacetic acid: a new phenotype to probe DNA polymerase delta in Saccharomyces cerevisiae.

A mutant allele (pol3-L612M) of the DNA polymerase delta gene in Saccharomyces cerevisiae that confers sensitivity to the antiviral drug phosphonoacetic acid (PAA) was constructed. We report that PAA-sensitivity tagging DNA polymerases is a useful method for selectively and reversibly inhibiting one type of DNA polymerase. Our initial studies reveal that replication by the L612M-DNA pol delta requires Rad27 flap endonuclease activity since the pol3-L612M strain is not viable in the absence of RAD27 function. The L612M-DNA pol delta also strongly depends on mismatch repair (MMR). Reduced viability is observed in the absence of any of the core MMR proteins-Msh2, Mlh1, or Pms1-and severe sensitivity to PAA is observed in the absence of the core proteins Msh6 or Exo1, but not Msh3. We propose that pol3-L612M cells need the Rad27 flap endonuclease and MMR complexes composed of Msh2/Msh6, Mlh1/Pms1, and Exo1 for correct processing of Okazaki fragments.

Adaptor Proteins, Signal Transducing↗

PubMed2005

BLAP75, an essential component of Bloom's syndrome protein complexes that maintain genome integrity.

Bloom's syndrome (BS) is a rare human genetic disorder characterized by dwarfism, immunodeficiency, genomic instability and cancer predisposition. We have previously purified three complexes containing BLM, the helicase mutated in this disease. Here we demonstrate that BLAP75, a novel protein containing a putative OB-fold nucleic acid binding domain, is an integral component of BLM complexes, and is essential for their stability in vivo. Consistent with a role in BLM-mediated processes, BLAP75 colocalizes with BLM in subnuclear foci in response to DNA damage, and its depletion impairs the recruitment of BLM to these foci. Depletion of BLAP75 by siRNA also results in deficient phosphorylation of BLM during mitosis, as well as defective cell proliferation. Moreover, cells depleted of BLAP75 display an increased level of sister-chromatid exchange, similar to cells depleted of BLM by siRNA. Thus, BLAP75 is an essential component of the BLM-associated cellular machinery that maintains genome integrity.

Adenosine Triphosphatases↗

PubMed2005

Effects of changing orders in the update rules on traffic flow.

Based on the Nagel-Schreckenberg (NaSch) model of traffic flow, we study the effects of the orders of the evolutive rule on traffic flow. It has been found from simulation that the cellular automaton (CA) traffic model is very sensitively dependent on the orders of the evolutive rule. Changing the evolutive steps of the NaSch model will result in two modified models, called the SDNaSch model and the noise-first model, with different fundamental diagrams and jamming states. We analyze the mechanism of these two different traffic models and corresponding traffic behaviors in detail and compare the two modified model with the NaSch model. It is concluded that the order arrangement of the stochastic delay and deterministic deceleration indeed has remarkable effects on traffic flow.

Journal Article↗

PubMed2005

Sensing, signaling, and responding to DNA damage: organization of the checkpoint pathways in mammalian cells.

The DNA damage and replication checkpoints are signaling mechanisms that regulate and coordinate cellular responses to genotoxic conditions. Unlike typical signal transduction mechanisms that respond to one or a few stimuli, checkpoints can be activated by a broad spectrum of extrinsically or intrinsically derived DNA damage or replication interference. Recent investigations have shed light on how the damage and replication checkpoints are able to respond to such diverse stimuli. The activation of checkpoints not only attenuates cell cycle progression but also facilitates DNA repair and recovery of faltered replication forks, thereby preventing DNA lesions from being converted to inheritable mutations. Recently, more checkpoint targets from the cell cycle and DNA replication apparatus have been identified, revealing the increasing complexity of the checkpoint control of the cell cycle. In this article, we discuss current models of the DNA damage and replication checkpoints and highlight recent advances in the field.

Animals↗

PubMed2005

Changing selectivity of DNA oxidation from deoxyribose to Guanine by ligand design and a new binuclear copper complex.

A dinuclear copper complex [CuII2(PD'O)(H2O)2]3+ (1) (where PD'OH is a pyridylalkylamine containing binucleating ligand) promotes guanine oxidation in single-stranded DNA in the presence of 3-mercaptopropionic acid and dioxygen. This reaction is detected after subsequent piperidine treatment. Little spontaneous strand scission indicative of deoxyribose oxidation is observed in contrast to the results known for other copper complexes. Chemical characterization and nanospray ionization mass spectrometry analysis of oligodeoxynucleotides treated with 1 suggest conversion of guanine residues to their 2,6-diamino-5-formamidino-4-hydroxypyrimidine (+18 amu) and possibly 5,8-dihydroxy-7,8-dihydroguanine (+34 amu) derivatives. The selectivity toward nucleobase rather than deoxyribose oxidation is discussed in terms of the specific nature of the dicopper (hydro)peroxo species formed with the PD'OH ligand versus the intermediates formed in the presence of other binucleating ligands.

Copper↗