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Biomedical subjects

Yong Liu

Publications and source records attributed to Yong Liu.

At least 127 records · Page 7Linked to original sources
PubMed2005

[Ditches protection in lake network based on landscape ecology].

As a typical corridor landscape in lake network, ditch is an important component of lake ecosystem. In recent years, the ecosystem quality of Hanyang lake network in Wuhan City becomes worse and worse, mainly caused by the degradation of ditch corridor's function. In order to restore its function, this paper made an optimized design of the ditches' landscape pattern on the basis of landscape ecology theories such as corridor scale effect, heterogeneity, edge effect and ecological rehabilitation, and the analyses of ditches status. The contents were to control the water quality in the whole area in a larger scale, to dredge and rebuild the ditches to strengthen the corridor function, and to project the banks of ditches to enhance the anti-disturbance ability. The study indicated that the theories of landscape ecology should be used reasonably in the ditches protection in lake networks.

Agriculture↗
PubMed2005

[Expression of collagen type I in the articular processes of apex from adolescent idiopathic scoliosis patients].

OBJECTIVE: To investigate the characteristic of the expression of collagen type I in the articular processes of apex from adolescent idiopathic scoliosis (AIS) patients. METHODS: The apical processes of 11 AIS patients were collected. The techniques of HE staining and In-cell Western were adopted in this research. We studied the pathological changes of the apical processes and collected and cultured the osteoblast from the apical processes on both sides in vitro separately. After cell identification, we compared the secretion of collagen type I in the osteoblast from concave side to that of convex side. RESULTS: The cartilages of the apical processes showed some signs of regression. The secretion of collagen type I of the osteoblast in vitro from the concave side of the apical articular process was significantly higher than that from the convex side (P < 0.05). CONCLUSION: Significant difference of the gene expression of the osteoblasts from the apical process exists between the concave side and the convex side.

Adolescent↗
PubMed2005

[Studies on chemical constituents from Salvia roborowskii Maxim].

OBJECTIVE: To study the chemical constituents from Salvia roborowskii Maxim. METHODS: Chromatography and spectroscopic analysis were employed to isolate and elucidate the chemical constituents in the plant. RESULTS: Three compounds were isolated and elucidated as 1 beta-hydroxy-lupeol (I), quercetin-3-O-beta-D-glucoside (II), rutin (III). CONCLUSION: I - III were isolated from this plant for the first time.

Chromatography, Thin Layer↗
PubMed2005

[Expression in Pichia pastoris, fermentation and purification of HIV-1 CN54 Gag antigen].

OBJECTIVE: To express the Gag protein of HIV-1 strain CN54 in Pichia pastoris (P.pastoris), optimize fermentation parameters and purify Gag antigen. METHODS: The Gag gene was subcloned into downstream of aox1 promoter of Pichia expression vector pPS1.0, an integrative vector which possesses an identical 5' untranslated region as the natural aox1 gene and employs both in vitro construction and in vivo selection for multi-copy integrants. The recombinant vector was introduced into P.pastoris strain GS115 by electroporation and selected with G418 for Gag gene integration. Super G418 resistant clones were selected and screened for Gag expression. The engineered P.pastoris was cultured to high cell density (>300 A600 Units/ml) in a 5L fermentor. Through methanol induction, the expression level of Gag reached 120 mg/L. Intracellularly expressed Gag was released by high-pressure homogenization and purified through Sepharose FF and DEAE Sepharose FF column chromatography, the purity of Gag reached up to 90%. RESULTS: Western-blotting suggested that purified Gag expressed in P.pastoris could react specifically with serum from HIV infected individual. CONCLUSION: Gag antigen expressed in P.pastoris has provided a good basis for the development of a new generation of HIV vaccine candidates against some Chinese prevalent strains.

Blotting, Western↗
PubMed2005

[Identification of genes related to resistance to Magnaporthe grisea using differential display technique in rice].

Rice blast caused by Magnaporthe grisea is one of the most serious constraints on high productivity. Understanding the mechanism of the infection of Magnaporthe grisea and the change of gene expression after infection is useful to control blast disease in rice. This work presents the isolation of differentially expressed cDNA fragments from rice leaf induced by the inoculum suspension of Magnaporthe grisea using mRNA differential display technique. Total 87 differential expressed cDNA fragments were recoveried and reamplified. The dot-blotting results showed that 6 fragments of 81 were confirmed to be the expression induced by Magnaporthe grisea inoculum. Those fragments were then cloned into vectors for sequencing. Sequence analysis through Internet Blast searching showed that 3 fragments were novel gene fragments. One was homologous with a putative malate synthase gene on rice chromosome 4 with 78% identities of amino acid; one was highly homologous (75% identity) with rice RPR1 gene on chromosome 11, which has a conservative structure of NBS-LRR domain and may be related to signal transduction of rice defense reaction;another one was homologous with a putative thioredoxin gene on rice chromosome 6 with the identity of 72%.

Base Sequence↗
PubMed2005

[Expression of gastrin and gastrin releasing peptide in patient's with gastric cancer by using tissue chip technique].

OBJECTIVE: To study the expression of gastrin(GAS) and gastrin releasing peptide(GRP) in patients with gastric cancer and investigate the clinical significance. METHODS: The expression of GAS and GRP in sixty patients with gastric cancer was detected by using tissue chip technique and immunohistochemical methods. RESULTS: The positive rates of GAS and GRP were 30.0% and 11.7% respectively in 60 cases with gastric cancer. The positive rates of GAS and GRP were higher in moderately and poorly differentiated cancers than those in well differentiated cancer (P< 0.05). The positive rates of GAS and GRP were significantly higher in mucinous adenocarcinoma and signet-ring cell carcinoma than those in other types of gastric cancer (P< 0.05). The positive expression of GAS and GRP in gastric cancer was correlated with lymph node metastasis (P< 0.05). CONCLUSION: Tissue chip technique is a feasible,rapid,economic and accurate approach for screening clinical tissue specimens on a large scale.

Adult↗
PubMed2005

[Research advance on lake ecosystem dynamic models].

Starting with the role of system analysis in lake ecosystem research, this paper summarized the tentative procedures and softwares for studying the dynamics of lake ecosystem. There are several main stages in modeling the dynamics of lake ecosystem, namely, problems identification, mathematical formulation, computation, validation, sensitive analysis, calibration, and verification. In the modeling, selecting temporal and spatial scales is essential but complex. Since 1960s, a rapid progress has been made in modeling the dynamics of lake ecosystem, being developed from simple zero-dimension models to complex ecological-aquatic-hydrodynamic ones, among which, exergy was applied popularly as an objective function in modeling. In this paper, LakeWeb and LEEDS (Lake Eutrophication, Effect, Dose, and Sensitivity model) were analyzed as examples. In China, the development of lake ecosystem dynamic models could be traced back to 1980s, and most of them were focused on Lake Dianch, Lake Taihu, Lake Chaohu and Lake Donghu. Some softwares such as CE-QUAL-ICM, WASP, AQUATOX, PAMOLARE and CAEDYM were developed to simulate lake ecosystem dynamics, among which, CE-QUAL-ICM is more suitable for long and narrow water bodies. WASP consists of three parts, i. e., DYNHYD, EUTRO, and TOXI. AQUATOX is an ecological risk model, and the parameters are mainly calibrated in U. S. A, which has limited its further application in China. The software ECOPATH for simulating the energy flows in lakes was also described in this paper. There are still many shortages in the lake ecosystem dynamic models, e. g., the lack of sufficient monitoring data for validation, insufficient consideration of uncertainties and the role of bacteria, and inconsistent relationship with watershed changes. The uncertainties are mainly from the intrinsic uncertainties in aquatic ecosystem, in modeling, in parameters selection, and also in forecast and application. Setting up long-term monitoring and data sharing mechanism, using interpolation to make data more densely, introducing objective functions, dealing with uncertainties, and constructing watershed-lake ecosystem dynamic model could be the available ways for overcoming the shortages.

China↗
PubMed2005

Ependymal/subventricular zone cells migrate to the peri-infarct region and differentiate into neurons and astrocytes after focal cerebral ischemia in adult rats.

OBJECTIVE: To investigate the migration and differentiation of ependymal/subventricular zone cells after focal cerebral ischemia in rats, and reveal the origin of the newly generated neural cells in the peri-infarct region. METHODS: Normal adult male Sprague Dawley rats weighing 250-350 g were used in this study. Before middle cerebral artery occlusion (MCAO), 10 microl of 0.2% DiI was injected into the lateral ventricle for prelabeling the ependymal/subventricular zone cells. After ischemia, cumulative BrdU labeling was employed to detect the newly generated cells and double immunofluorescent staining to identify cell differentiation. The labeled cells were observed with laser confocal microscopy. RESULTS: In the non-ischemic control rats, DiI-labeled cells resided in the ependyma/subventricular zone. After focal cerebral ischemia, DiI-labeled cells were found in the corpus callosum, adjacent striatum and cortex, and some DiI/BrdU/glial fibrillary acidic protein (GFAP)-positive cells or DiI/BrdU/ neuronal nuclear antigen (NeuN)-positive cells were observed in the peri-infarct region in the striatum or cortex since day 14 after MCAO. CONCLUSION: After focal cerebral ischemia, ependymal/subventricular zone cells migrate into the peri-infarct region where they differentiate into neurons and astrocytes. This finding may be important for understanding the source of adult neural stem cells and for developing new therapeutic intervention strategy through enhancing endogenous neurogenesis after brain injury.

Animals↗
PubMed2005

Stress-related racial discrimination and hypertension likelihood in a population-based sample of African Americans: the Metro Atlanta Heart Disease Study.

OBJECTIVE: Exposure to racial discrimination has been identified as an adverse biopsychosocial stressor that may be related to the prevalence of hypertension in African Americans. The overall objective of this research was to estimate aspects of the effects of self-reported exposure to stress-related racial discrimination and hypertension likelihood in a sample of African Americans. DATA: Physiologic and self-reported cross-sectional data were collected on a stratified sample of hypertensive (n=174) and normotensive (n=182) African Americans, aged > or =21 years, residing in metropolitan Atlanta, Georgia from 1999 through 2001. METHOD: Separate, multivariate logistic regression models were fit, including relevant covariates, to ascertain the effects of exposure to incidents of stress-related racial discrimination and level of generally derived stress with hypertension likelihood. RESULTS: Exposure to incidents of racial discrimination was not significantly associated with an increased likelihood of hypertension. More than 74% of respective normotensive and hypertensive respondents reportedly experienced stress-provoking encounters of racial discrimination. Magnitude of stress generally derived from exposure was, however, a highly significant predictor. Respondents reporting "moderate" and a "high to very high" level of derived stress were more than twice as likely to be hypertensive when compared to those reporting "no to low" derived stress (P value=.02 and .01, respectively). CONCLUSION: Exposure to racial discrimination is a prevalent psychosocial stressor in African Americans but may not be significantly associated with hypertension prevalence; degree of stress derived from encounters may be an important determinant. More research is needed to clarify the complex relationship between stress-related racial discrimination and hypertension in African Americans.

Adult↗
PubMed2005

The expression of CD97EGF and its ligand CD55 on marginal epithelium is related to higher stage and depth of tumor invasion of gastric carcinomas.

CD97EGF is a member of the EGF-TM7 family of class II seven-transmembrane (7TM), and its cellular ligand CD55 (also known as decay accelerating factor; DAF) protects host cells from complement attack. To determine whether the expression levels of these two molecules are correlated with the clinicopathological features of gastric carcinomas, a total of 35 gastric carcinomas and their corresponding margins and normal specimens were investigated by RT-PCR, Western blot analysis and immunohistochemistry. Transcript levels of CD97EGFand CD55 were higher in tumors than those in the margin and normal epithelial mucous tissues (P<0.05). However, the expression levels of CD97EGF and CD55 mRNA had no correlation with the clinicopathological features of gastric carcinoma patients. All three groups of specimens were immunoreactive for CD97EGF and the CD55 protein. Strong and specific immunoreactivities of CD97EGF were located in the mucosal epithelia of the marginal basal membrane. Expression of CD97(EGF) in the margins showed a marked difference between the depth of tumor invasion T1 and T2, 3 and 4, and stages I and II/III/IV of gastric carcinomas (P<0.05). The expression of CD55 protein was highly correlated with CD97EGF (R=0.6483, P<0.001). Western blot analysis confirmed the expression and distribution patterns of CD97EGF and CD55. Our findings suggest that CD97EGF may play a role in the development and invasion of gastric carcinomas by binding its cellular ligand CD55. Detection of the CD97EGF expression in the tumor margin could be referred to as the molecular edge of gastric carcinomas.

Antigens, CD↗
PubMed2005

Preparation of monoclonal antibodies against prion proteins with full-length hamster PrP.

OBJECTIVE: To prepare the PrP specific monoclonal antibodies (mAbs) that can be used for the detection of mammalian prions and study of pathogenesis of prion diseases. METHODS: Several BALB/c mice were immunized with recombinant hamster prion protein (HaPrP). Three hybridoma cell lines designated as B7, B9, and B10, secreting monoclonal antibodies against HaPrP, were established by hybridoma technique. The mAbs reactivities were evaluated with ELISA, Western blot, and immunohistochemistry. RESULTS: The mAbs produced by these cell lines reacted well with different recombinant hamster PrP proteins. Western blot analyses showed that mAbs B7 and B9 reacted with PrPSc from the scrapie-infected animals after proteinase K digestion with three glycosylated forms. The mAbs exhibited cross-reactivity with various PrPC from several other mammalian species, including humans and cattles. Immunohistochemistry assays confirmed that mAbs B7 and B9 could recognize not only extracellular but also intracellular PrPsSc. CONCLUSION: The mAbs of prion protein are successfully generated by hybridoma technique and can be applied for the diagnosis of prion associated diseases.

Animals↗
PubMed2005

[A controlled randomized trial of the use of combined L-carnitine and acetyl-L-carnitine treatment in men with oligoasthenozoospermia].

OBJECTIVE: To determine the efficacy and safety of combined L-carnitine and acetyl-L-carnitine therapy in infertile males with oligoasthenozoospermia. METHODS: One hundred fifty patients with oligoasthenozoospermia were randomized selected into treatment and control groups. The treatment group with 90 patients were given L-carnitine (2 g/d) and acetyl-L-carnitine (1 g/d) orally, twice a day. The patients in control group were given Vitamin E 100 mg plus Vitamin C 100 mg, tid. The oral therapy lasted three months and patients accepted sperm analysis every one month. The L-carnitine level in seminal plasma was examined by high performance liquid chromatography (HPC). Side effects as well as pregnant rate were observed. RESULTS: In the treatment group, 85 patients out of 90 finished the three month treatment. Female spouses of 10 patients (11.6%) achieved pregnancy. Moreover, their forward motile sperm per ejaculation, total motile sperm, as well as the concentration of L-carnitine in seminal plasma were increased significantly (P < 0.01). In control group, 53 patients out of 60 completed three months therapy. Two pregnancy (3.7%) was observed. Though some increase was seen in number of forward motile sperm and total motile sperm per ejaculation, the changes were not statistically significant (P > 0.05). The difference of the pregnant rate between two groups was statistically significant. No side effects were found. CONCLUSION: Combined treatment with L-carnitine and acetyl-L-calmitine can be an effective and safe option for treating oligoasthenozoospermia by means of significantly improving forward motile sperm and total motile sperm per ejaculation, as well as increasing pregnant rates.

Acetylcarnitine↗
PubMed2005

[Nerve regeneration of hypertrophic scars and keloids after deep burns].

OBJECTIVE: To disclose whether there is difference in nerve regeneration between human hypertrophic scars and keloids after deep burns so as to provide a basis for new clinical treatment. METHODS: Fifty-seven samples that were clinically and pathologically diagnosed as hypertrophic scars or keloids after deep burns were examined by use of two-label immunohistochemistry to define the nerves in scars. Then, the Mean Integrated Optical Density (MIOD) of S-100 and the MIOD of neurofilament (NF) proteins were measured and analyzed. RESULTS: In hypertrophic scars or keloids, the nerve regeneration was growing gradually. The speed was high 3-5 months after burn and it slowed down 18 months after burn. The expression of S-100 and NF varied with different period of time (P<0.05). The expression of S-100 and NF in hypertrophic scars was higher than that in keloids. There was no difference 3-5 months after burn, but there was difference 6 months after burn. CONCLUSION: S-100 and NF are good markers to define the nerve regeneration in scars. The nerve regeneration in hypertrophic scars or keloids changes with the times. The nerve regeneration is more conspicuous in hypertrophic scars than in keloids.

Adolescent↗
PubMed2005

[Experimental study on the mechanism of the apoptosis of leukemic cells induced by valproic acid].

OBJECTIVE: To overcome the drug-resistance of tumor cells is one of the methods of improving the therapeutic results. Histone deacetylase inhibitors (HDACIs) is a novel class of chemotherapeutic agents which can induce apoptosis of tumor cells. Valproic acid (VPA) is a common drug used in the treatment of epilepsy. It has been shown that VPA has a marked HDACIs effect at the pharmaceutical level, and can induce the differentiation and apoptosis of transformed cells. But the mechanism of its effect has not been clarified. The aim of this study was to investigate the mechanism of VPA in inducing the apoptosis of leukemic cells at molecular level. METHODS: The cell lines U937, Jurkat clone E6 - 1 (Jurkat) and BALL-1 were cultured in RPMI 1640 medium containing 20% calf serum, then divided into three groups (control group, 1 mmol/L VPA group and 1 mmol/L VPA + 1 micromol/L Pan-caspase inhibitor zVAD-fmk group). At 72 hours after the treatment, the cells were double stained with Aunexin and PI (propidium iodide) and then were analyzed with the flow cytometry (FCM) to detect apoptosis. Before and after treatment with VPA the mean fluorescence index (MFI) of Bcl-2, Bax, Bcl-xl and the levels of caspase 8, 9 and 3 were also detected with the FCM. The changes of P(44/42) mitogen activating protein kinase (MAPK) and phosphorylated P(44/42) MAPK were determined by Western blotting. RESULTS: Seventy-two hours after the treatment, 1 mmol/L VPA induced apoptosis of U937 and Jurkat. The apoptotic rate of U937 was (75.78 +/- 4.20)% and that of Jurkat was (53.50 +/- 5.87)% (P < 0.01, vs. control group); zVAD-fmk could fully inhibit the apoptosis of U937, and the apoptotic rate was (2.89 +/- 0.36)%; while it could partly inhibit the apoptosis of Jurkat, and the apoptotic rate was (15.38 +/- 1.40)% (P < 0.01). 1 mmol/L VPA could not induce the apoptosis of BALL-1 which had a high expression level of Bcl-2. The MFI of Bcl-2, Bax and Bcl-xl in these three cell lines did not change significantly with VPA (P > 0.05). After treatment with VPA, the level of caspase 3 in U937 increased from (14.09 +/- 1.19)% to (32.30 +/- 2.47)%, and caspase 8 from (4.58 +/- 1.41)% to (86.47 +/- 3.26)% (P < 0.01), but there was no significant change in caspase 9 [(13.25 +/- 3.11)% and (10.95 +/- 1.30)%]. In Jurkat, the level of caspase 3 increased from (12.01 +/- 1.63)% to (35.56 +/- 0.27)%, and caspase 9 from (13.89 +/- 1.71)% to (75.89 +/- 4.08)% (P < 0.01 for both); no significant change was observed for caspase 8 [(5.94 +/- 1.38)% and (5.44 +/- 0.72)%]. In BALL-1, there was a slight decline in caspase 3 (P < 0.05). With the effect of VPA, levels of P(44/42) MAPK and phosphorylated P(44/42) MAPK decreased in all three cell lines (P < 0.01). CONCLUSION: VPA could induce apoptosis of U937 through the activation of caspase 3 and 8; and it induced the apoptosis of Jurkat involving the activation of caspase 3 and 9. P(44/42) MAPK pathway also plays an important role in this course. VPA induced apoptosis of these cell lines without the alteration of Bcl-2, Bax and Bcl-xl. High level of Bcl-2 could antagonize the effect of VPA.

Apoptosis↗
PubMed2005

[Analysis of complications induced by polyacrylamide hydrogel injection for augmentation mammaplasty].

OBJECTIVE: To analyze the complications induced by polyacrylamide hydrogel injection for augmentation mammaplasty, explore the reason of the complication. METHODS: Twenty three patients with complications after polyacrylamide hydrogel injection were classified by signs and symptoms, ultrasound and pathologic examinations were made. RESULTS: The main complications were pain, hard nodule, asymmetry and breast deformation. The injected material was distributed diffusely behind gland, in gland, in muscles subcutaneous, even out of breast, caused some pathologic changes and it's hard to be cleaned completely from normal tissue. CONCLUSIONS: The complications were caused mainly by incorrect manipulation during operation, others might be relative to the injected material. The reliability of this injection method for augmentation should be cautiously observed.

Acrylic Resins↗
PubMed2004

[Clinical medicine].

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Attitude of Health Personnel↗
PubMed2004

Synthesis of alpha-fluorosulfonamides by electrophilic fluorination.

Alpha-fluorosulfonamides were prepared by electrophilic fluorination of tertiary sulfonamides using N-fluorobenzenesulfonimide as fluorinating agent and utilizing the dimethoxybenzyl group (DMB) as a new sulfonamide protecting group. Removal of the DMB group with TFA/CH(2)Cl(2) gave primary and secondary alpha-fluorosulfonamides.

Journal Article↗