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Yong Liu

Publications and source records attributed to Yong Liu.

At least 145 records · Page 8Linked to original sources
PubMed2004

[The correlation between preoperative pulmonary function and postoperative pulmonary complications in the surgical treatment of scoliosis].

OBJECTIVES: To evaluate the incidence of immediate postoperative pulmonary complications and their correlation to preoperative pulmonary function tests (PFTs), preoperative pulmonary symptoms and surgical approaches. METHODS: The case records of 298 patients, who underwent anterior or posterior fusion, were reviewed. Preoperative PFTs were recorded and abnormal PFTs were defined as forced vital capacity (FVC) is less than 80% of FVC predicted. Preoperative pulmonary symptoms (breathless on exertion) were noted, and postoperative pulmonary complications were defined when the presence of atelectasis, infiltrates, pneumothorax, hemothorax, pneumonia or requirement of postoperative ventilatory support was noted. RESULTS: The mean age of this group was 16.4 years (range from 6-62 years). The average coronal Cobb angle was 73.26 degrees (range from 45 degrees-141 degrees ). Of all the patients, 115 patients had normal preoperative PFTs, the other 183 cases had abnormal PFTs. Nineteen cases of all the patients were found with postoperative pulmonary complications including postoperative ventilatory support in 6 cases, atelectasis in 4 cases, infiltration in 2 cases, pneumothorax in 3 cases, pneumonia in 3 cases and hypoxemia in 1 case. The incidence of postoperative pulmonary complication was 6.4% in all the patients, while 18.99% in the 79 patients with thoracotomy and 1.85% in the 216 patients without. The correlation between postoperative pulmonary complications and the surgical approach was statistically significant (P=0.0000). When the patients were classified into 3 groups: 60%< FVCR <80%, 40%< FVCR <60%, FVCR <40%, the incidence of postoperative pulmonary complications were 2.72% (3/110), 7.40% (4/54) and 31.6% (6/19) respectively, which showed an increasing complication incidence. In the 115 patients with normal PFTs, 3 patients had preoperative pulmonary symptoms (2.68%), while 14 of the 183 patients with abnormal PFTs had preoperative pulmonary symptoms (7.65%). The correlation between presence of preoperative respiratory symptoms and abnormal results on PFTs was statistically significant (P=0.01). No significant correlation was found between preoperative respiratory symptoms and postoperative pulmonary complications (P=0.52). CONCLUSIONS: The incidence of postoperative pulmonary complications increases with the deterioration of PFTs. The posterior procedure has a very low incidence of postoperative pulmonary possibility of complications, but a transthoracic procedure increases the complications significantly. Preoperative respiratory symptoms usually predict abnormal results of PFTs but have no correlation with postoperative pulmonary complication.

Adolescent↗
PubMed2004

Light-regulated catalysis by an RNA-cleaving deoxyribozyme.

We describe light-induced switches for the catalytic activity of the small, RNA-cleaving 8-17 deoxyribozyme (DNAzyme), based on photochemically induced cis-trans isomerization of azobenzene (Az) moieties covalently tethered at various locations within the DNAzyme. Prior studies have shown that trans-azobenzene is able to stack comfortably within a DNA double helix, stabilizing it, while cis-azobenzene has a helix-destabilizing effect. We designed two classes of Az-modified 8-17DNAzyme constructs, in each of which two azobenzene molecules substituted for nucleotides, either in the substrate-binding arm (SBA); or, within the catalytic core. Measurement of single-turnover kinetics for RNA cleavage revealed that in the SBA constructs Ell and E13, five- to sixfold higher catalytic rates were obtained when the reaction mixture was irradiated with visible light (favouring trans-Az) as compared to ultraviolet light (which promotes cis-Az), consistent with trans-Az in these constructs stabilizing the enzyme-substrate complex. Surprisingly, the reverse result was obtained with the catalytic core construct E17, where ultraviolet irradiation resulted in a five- to sixfold faster catalytic activity relative to visible light irradiation. The development of such light-responsive nucleic acid enzymes may open new possibilities of using light as the activating or repressing agent in the control of gene expression within living cells and organisms.

Base Sequence↗
PubMed2004

Polymer grafting via ATRP initiated from macroinitiator synthesized on surface.

Macromolecular anchoring layer approach was used for preparation of an effective macroinitiator for the synthesis of grafted polymer layers by atom transfer radical polymerization (ATRP) initiated from the surface. For the initial surface modification, a thin layer of poly(glycidyl methacrylate) (PGMA) was deposited on the surface of a silicon wafer. The ATRP macroinitiator was synthesized on the substrate surface by the reaction between epoxy groups of PGMA and carboxy functionality of bromoacetic acid (BAA). Variation of the time and temperature of the BAA deposition as well as PGMA layer thickness allowed control over the amount of BAA attached to the surface. The PGMA anchoring layer allowed the achievement of initiator surface density significantly higher than that reported for a self-assembled monolayer of ATRP initiators. Polymer brushes were synthesized on the PGMA/BAA-modified substrates by ATRP. Different surface concentrations of BAA were used in our grafting experiments to acquire knowledge about the relationship between the amount of initiator anchored to the surface through PGMA and the rate of the grafted layer formation. The increase in the surface density of the initiating moieties led to the increase in the grafting rate. However, a cutoff initiator concentration beyond which no increase of the thickness of the grafted layer was observed. From comparison between the surface densities of the initiator and the attached polymer it was determined that the efficiency of the initiation from the surface was on the level of 5-15%.

Journal Article↗
PubMed2004

New mutation points in 23S rRNA gene associated with Helicobacter pylori resistance to clarithromycin in northeast China.

AIM: To investigate the resistance rate of Helicobacter pylori (H pylori ) to clarithromycin, metronidazole, amoxicillin and tetracycline to guide clinical practice, and to study the mechanism of H pylori resistant to clarithromycin. METHODS: Thirty H pylori strains were isolated from the mucosa of peptic ulcer, gastric tumor and chronic gastritis patients, then the minimal inhibitory concentration (MIC) to clarithromycin, metronidazole, amoxicillin and tetracycline was evaluated by E-test method. The sequence analysis of PCR fragments was conducted in 23S rRNA gene of H pylori resistant to clarithromycin to get the resistance mechanism of the bacteria. RESULTS: Among 30 H pylori strains, 7 cases were resistant to clarithromycin, 12 to metronidazole, 2 to tetracycline and no strain was found to be resistant to amoxicillin. The resistance rates were 23.3%, 40%, 6.7% and 0%, respectively. Three new mutation points were found to be related to the clarithromycin resistance in H pylori isolates, which were G2224A, C2245T and T2289C. CONCLUSION: In northeast China, H pylori shows high resistance to metronidazole, while sensitive to amoxicillin. The mechanism of resistance to clarithromycin may be related to the mutation of G2224A, C2245T and T2289C in the 23S rRNA gene.

Anti-Bacterial Agents↗
PubMed2004

Synthesis and protection of aryl sulfates using the 2,2,2-trichloroethyl moiety.

[reaction: see text] The 2,2,2-trichloroethyl (TCE) group was utilized as the first protecting group for aryl sulfates. Aryl sulfates, protected with the TCE group, were prepared in high yield by reacting phenols with chlorosulfuric acid TCE ester. Deprotection was accomplished using Pd/C-ammonium formate or with Zn-ammonium formate to give aryl sulfate monoesters in high yield. This approach to aryl sulfate synthesis was successfully applied to the construction of estrone sulfate derivatives, which could not be prepared by previous methodologies.

Journal Article↗
PubMed2004

Multi-species comparative mapping in silico using the COMPASS strategy.

MOTIVATION: The completion of human and mouse genome sequences provides a valuable resource for decoding other mammalian genomes. The comparative mapping by annotation and sequence similarity (COMPASS) strategy takes advantage of the resource and has been used in several genome-mapping projects. It uses existing comparative genome maps based on conserved regions to predict map locations of a sequence. An automated multiple-species COMPASS tool can facilitate in the genome sequencing effort and comparative genomics study of other mammalian species. RESULTS: The prerequisite of COMPASS is a comparative map table between the reference genome and the predicting genome. We have built and collected comparative maps among five species including human, cattle, pig, mouse and rat. Cattle-human and pig-human comparative maps were built based on the positions of orthologous markers and the conserved synteny groups between human and cattle and human and pig genomes, respectively. Mouse-human and rat-human comparative maps were based on the conserved sequence segments between the two genomes. With a match to human genome sequences, the approximate location of a query sequence can be predicted in cattle, pig, mouse and rat genomes based on the position of the match relatively to the orthologous markers or the conserved segments. AVAILABILITY: The COMPASS-tool and databases are available at http://titan.biotec.uiuc.edu/COMPASS/

Algorithms↗
PubMed2004

Changes in germinal vesicle (GV) chromatin configurations during growth and maturation of porcine oocytes.

Changes in germinal vesicle (GV) chromatin configurations during growth and maturation of porcine oocytes were studied using a new method that allows a clearer visualization of both nucleolus and chromatin after Hoechst staining. The GV chromatin of porcine oocytes was classified into five configurations, based on the degree of chromatin condensation, and on nucleolus and nuclear membrane disappearance. While the GV1 to 4 configurations were similar to those reported by previous studies, the GV0 configuration was distinct by the diffuse, filamentous pattern of chromatin in the whole nuclear area. Most of the oocytes were at the GV0 stage in the <1 and 1-1.9 mm follicles, but the GV0 pattern disappeared completely in the 2-2.9 and 3-6 mm follicles. As follicles grew, the number of oocytes with GV1 configurations increased and reached a maximum in the preovulatory follicles 4 hr post-hCG injection. During maturation in vivo, the number of GV1 oocytes decreased while oocytes undergoing GVBD increased. The percentage of oocytes with GV3 and GV4 configurations was constant during oocyte growth except at the 2-2.9 mm follicle stage, but these configurations disappeared completely after hCG injection. On the contrary, the in vitro maturing oocytes showed a large proportion of GV3 and GV4 configurations. There was no significant difference in distribution of chromatin configurations between the nonatretic and atretic follicles, and between oocytes with more than two layers of cumulus cells and those with less than one layer or no cumulus cells. Overall, our results suggested that (i) the GV0 configuration in porcine oocytes corresponded to the "nonsurrounded nucleolus" pattern in mice and other species; (ii) all the oocytes were synchronized at the GV1 stage before GVBD and this pattern might, therefore, represent a nonatretic state; (iii) the GV3 and GV4 configurations might represent stages toward atresia, or transient events prior to GVBD that could be switched toward either ovulation or atresia, depending upon circumstances; (iv) the in vitro systems currently used were not favorable for oocytes to switch toward ovulation (or final maturation); (v) the number of cumulus cells was not correlated with the chromatin configuration of oocytes, indicating that the beneficial effect of cumulus cells on oocyte maturation and development may simply be attributed to their presence during in vitro culture.

Animals↗
PubMed2004

Experimental study on allogenic decalcified bone matrix as carrier for bone tissue engineering.

The biocompatibility and osteogenic activity of allogenic decalcified bone matrix (DBM) used as a carrier for bone tissue engineering were studied. Following the method described by Urist, allogenic DBM was made. In vitro, DBM and bone marrow stromal cell (BMSC) from rabbits were co-cultured for 3-7 days and subjected to HE staining, and a series of histomorphological observations were performed under phase-contrast microscopy and scanning electron microscopy (SEM). In vivo the mixture of DBM/BMSC co-cultured for 3 days was planted into one side of muscules sacrospinalis of rabbits, and the DBM without BMSC was planted into other side as control. Specimens were collected at postoperative week 1, 2 and 4, and subjected to HE staining, and observed under SEM. The results showed during culture in vitro, the BMSCs adherent to the wall of DBM grew, proliferated and had secretive activity. The in vivo experiment revealed that BMSCs and undifferentiated mesenchymal cells in the perivascular region invaded gradually and proliferated together in DBM/BMSC group, and colony-forming units of chondrocytes were found. Osteoblasts, trabecular bone and medullary cavity appeared. The inflammatory reaction around muscles almost disappeared at the second weeks. In pure DBM group, the similar changes appeared from the surface of the DBM to center, and the volume of total regenerate bones was less than the DBM/BMSC group at the same time. The results indicated that the mixture of DBM and BMSC had good biocompatibility and ectopic induced osteogenic activity.

Animals↗
PubMed2004

Ad/CMV- hTGF-beta1 treats rabbit intervertebral discs degeneration in vivo.

To investigate therapeutic efficiency of Ad/CMV- hTGF-beta1 gene for rabbit intervertebral disc degeneration model. 60 Japanese white rabbits were selected to form the 1.5-L6 Anterior-Lateral-Anulus-Fibrosus-Incision-Induced model in order to simulate human intervertebral disc degeneration. 36 rabbits, whose corresponding intervertebral discs were injected with 20 microl (10 x 10(6) pfu) of Ad/CMV- hTGF-beta1 gene, constituted the therapy group, 12 were injected with 20 microl (10 x 10(6) pfu)of Ad/CMV-LacZ gene as comparison group, while 12 were only injected with equivalent capacity of saline for empty comparison group, 3 weeks after injection, examples were taken for investigation of HE staining, MRI, Western Blotting and immunohistochemical research TGF-beta1. Wide distribution of TGF-beta1 was detected by immunohistochemical research in the degenerated annulus fibrosus after injection. Western Blotting research showed significant increase of TGF-beta1 content in intervertebral discs treated with TGF-beta1 gene than comparison groups. MRI signal transformed from low to comparatively high and that intervertebral disc pathological degree improved. Ad/CMV- hTGF-beta1 gene transfection is a potential method to increase TGF-beta1 content and reverse intervertebral disc degeneration.

Adenoviridae↗
PubMed2004

Lithium suppressed Tyr-402 phosphorylation of proline-rich tyrosine kinase (Pyk2) and interactions of Pyk2 and PSD-95 with NR2A in rat hippocampus following cerebral ischemia.

It has been indicated that Pyk2/Src signaling pathway is involved in modulation of N-methyl-D-aspartate-type (NMDA) glutamate receptor activity. Lithium protects against glutamate-induced excitotoxicity in cultured neurons and in animal models of diseases. The neuroprotection against excitotoxicity afforded by lithium is time-dependent, requiring treatment for 6-7 days for maximal effect. In this study, we examined the time-course and the effect of lithium on Tyr-402 phosphorylation of Pyk2 and Tyr-416 phosphorylation of Src as well as the association of Pyk2 and NMDA receptor subunit 2A (NR2A) mediated by postsynaptic density protein 95 kDa (PSD-95) in the condition of cerebral ischemia, which was induced by occlusion of the four vessels in Sprague-Dawley rats. At 6 h of reperfusion following 15 min of ischemia (I/R), the effects induced by chronic lithium were observed, including the decrease in enhanced Tyr-402 phosphorylation of Pyk2, the inhibition in increased Tyr-416 phosphorylation of Src and the attenuation in enhanced interactions of Pyk2 and PSD-95 with NR2A. Our results further suggest that the activated Pyk2 potentiates NMDA receptor function during transient brain ischemia followed by reperfusion and the above inhibition induced by lithium is likely to result in the inactivation of NMDA receptor and contributes to the neuroprotection against excitotoxicity.

Animals↗
PubMed2004

Membrane-permeant, DNA-binding agents alter intracellular trafficking and increase the transfection efficiency of complexed plasmid DNA.

Nuclear delivery of extracellular DNA by nonviral vectors is inhibited by a series of cell membrane and compartmental barriers. Certain cationic amphiphiles that partition through cellular membranes to bind genomic DNA can enhance nuclear delivery of plasmid DNA. Specifically, delivering plasmid DNA complexed to the DNA-binding dye Hoechst 33258 produces cellular transfection levels similar to those achieved by cationic liposome:DNA complexes (CLDC), with less toxicity. Incorporating Hoechst into CLDC or polyethyleneimine:DNA complexes significantly increased reporter gene expression, as well as the percentage of cells transfected. Hoechst:CLDC significantly improved transfection of nondividing cells and efficiently transfected cells in the presence of anionic molecules that block cellular uptake of and transfection by CLDC alone. Hoechst:CLDC also increased gene expression in mouse tissues following intravenous delivery. Delivery of fluorescently labeled plasmid DNA via Hoechst altered its intracellular trafficking by both minimizing lysosomal sequestration and accelerating delivery into the nucleus. Agents such as Hoechst constitute a novel class of nonviral carriers that can confer their membrane-permeant properties on complexed DNA, thus redirecting its intracellular trafficking. In addition, binding of Hoechst 33258 to specific chromosomal DNA target sequences and its ability to modulate transcription may further enhance the expression of delivered genes.

Animals↗
PubMed2004

Marked prolongation of murine cardiac allograft survival using recipient immature dendritic cells loaded with donor-derived apoptotic cells.

We investigated whether recipient dendritic cells (DCs), pretreated with nuclear factor-kappaB oligodeoxyribonucleotide decoy (NF-kappaB ODN decoy) and loaded with ultraviolet B-irradiated donor apoptotic splenocytes (Apo-SCs), were able to induce murine cardiac allograft tolerance. Heterotopic vascularized heart transplantation was performed from BALB/c to C57BL/6 mice, and recipients (C57BL/6) were given one injection of recipient DCs pretreated with NF-kappaB ODN decoy and loaded with donor (BALB/c) apoptotic SCs (decoy Apo-SCs DCs) through the portal vein at 7 days, before heart transplantation in the absence of immunosuppression. The cardiac allograft survival time and the expressive levels of intragraft cytokine genes [interleukin (IL)-2, IL-10, and interferon-gamma] were evaluated. Our results indicated that injection of decoy Apo-SCs DCs significantly prolonged vascularized heart allograft survival and led to skewing of intragraft cytokine expression towards T helper 2 (IL-10). The mechanisms can be useful for therapy of allograft rejection with minimization of systemic immunosuppression.

Animals↗
PubMed2004

The inhibitory effect of intestinal bacterial metabolite of ginsenosides on CYP3A activity.

The intestinal bacterial metabolites of ginsenosides are responsible for the main pharmacological activities of ginseng. The purpose of this study was to find whether these metabolites influence hepatic metabolic enzymes and to predict the potential for ginseng-prescription drug interactions. Utilizing the probe reaction of CYP3A activity, testosterone 6beta-hydroxylation, the effects of derivatives of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol families on CYP3A activity in rat liver microsomes were assayed. Our results showed that ginsenosides from the 20(S)-protopanaxadiol and 20(S)-protopanaxatriol family including Rb1, Rb2, Rc, Compound-K, Re, and Rg1 had no inhibitory effect, whereas Rg2, 20(S)-panaxatriol and 20(S)-protopanaxatriol exhibited competitive inhibitory activity against CYP3A activity in these microsomes with the inhibition constants (Ki) of 86.4+/-0.8 microM, 1.7+/-0.1 microM, and 3.2+/-0.2 microM, respectively. This finding demonstrates that differences in their chemical structure might influence the effects of ginsenosides on CYP3A activity and that ginseng-derived products might have potential for significant ginseng-drug interactions.

Animals↗
PubMed2004

[Resistance surveillance of common community respiratory pathogens isolated in China, 2002 - 2003].

OBJECTIVE: To investigate antimicrobial resistance of common community respiratory pathogens isolated in China, 2002 - 2003. METHODS: 779 strains of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Group A beta-haemolytic Streptococci and oxacillin-susceptible Staphylococcus aureus (MSSA) were isolated from patients with community-acquired respiratory tract infections at 5 hospitals in China from April 2002 to 2003. Meanwhile, 185 strains of S. pneumoniae, H. influenzae and M. catarrhalis were isolated from nasopharynx swabs at 2 day-care centers in Beijing. Agar dilution method was used to determine the minimal inhibitory concentration (MICs) of cefprozil and other 9 antibiotics against these strains. RESULTS: The prevalence of penicillin-intermediate S. pneumoniae (PISP) was 23.9% and that of penicillin-resistant S. pneumoniae (PRSP) was 22.7% at 5 cities in China. The prevalence of PISP were 44.1% in Hangzhou, 26.2% in Wuhan, 21.5% in Shenyang, 20.8% in Shanghai, 18.5% in Beijing, and 12.7% at day-care centers in Beijing;the prevalance of PRSP were 34.9% in day-care centers, 31.9% in Shanghai, 27.9% in Wuhan, 22.1% in Hangzhou, 13.8% in Shenyang and 8.6% in Beijing. The susceptible rate of levofloxacin in S. pneumoniae was 96.3%. 9.5% of H. influenzae and 87.4% of M. catarrhalis produced beta-lactamases. The susceptibility of amoxicillin/clavulanate, cefaclor, cefprozil, cefuroxime, ceftriaxone, azithromycin, and levofloxain in these two species ranged from 96.4% to 100%. The resistance rate of azithromycin in S. pneumoniae was higher than 60%. Cefprozil MICs against PISP, Group A beta-haemolytic Streptococci and MSSA were 4 - 16 fold lower than cefaclor. CONCLUSIONS: Antimicrobial resistance in respiratory pathogens, especially S. pneumoniae is increasing. It brings concerns that high macrolide resistance was found in gram-positive cocci. Cefprozil was more active than cefaclor against respiratory pathogens.

Anti-Bacterial Agents↗
PubMed2004

Activation and involvement of JNK1/2 in hydrogen peroxide-induced neurotoxicity in cultured rat cortical neurons.

AIM: To investigate the role of c-Jun N-terminal protein kinase 1 and 2 (JNK1/2) and the main signal pathway for its activation in hydrogen peroxide (H(2)O(2)) induced apoptotic-like cortical cell death. METHODS: Using the model of oxidative stress induced by H(2)O(2), the expression and diphosphorylation of JNK1/2 was examined by immunoblotting analysis, and neuronal apoptotic like cell death was determined by 4',6-diamidino-2-phenylindole (DAPI) staining. RESULTS: The elevation in diphosphorylation level of JNK1/2 (4.40-/5.61-fold vs sham control) was associated with the concentration of H(2)O(2) (0-100 micromol/L) and the development of apoptotic-like cell death (11.04 %-81.01 %). There was no alteration of JNK1/2 protein expression following H(2)O(2) treatment and recovery at different time points. Administration with JNK1/2 antisense oligonucleotides not only significantly decreased JNK1/2 protein expression and activation level, but also significantly reduced cortical cell death induced by H(2)O(2) exposure. Furthermore, both JNK1/2 diphosphorylation and apoptotic-like cell death were largely prevented by pretreatment with (5S,10R)-(-)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) or omission of Ca(2+) in incubation medium with ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA). CONCLUSION: JNK1/2 is activated and participates in H(2)O(2)-induced apoptotic-like death in cultured rat cortical neurons mainly via N-methyl-D-aspartate (NMDA) receptor-mediated influx of extracellular Ca(2+).

Animals↗