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Biomedical subjects

Li Chen

Publications and source records attributed to Li Chen.

At least 217 records · Page 12Linked to original sources
PubMed2004

[Changes of amino acid content in hippocampus of epileptic rats treated with volatile oil of Acorus tatarinowii].

OBJECTIVE: To study the changes of excitatory and inhibitory amino acid content in hippocampus of epileptic rats treated with volatile oil of A. tatarinowii, and explore the possible antiepiletic mechanism. METHOD: The volatile oil was extracted through Supercritical-CO2 Fluid Extraction (SFE-CO2), and epileptic models were built up by kainic acid (KA) lateral ventricle injection. The content of amino acid in hippocampus of epileptic rats treated with volatile oil was calculated. RESULT: The content of GABA increased and Glu decreased prominently (P < 0.05) after volatile oil 35 mg x kg(-1) intraperitoneal injection. CONCLUSION: The volatile oil of A. tatarinowii can modulate the balance of excitatory and inhibitory amino acid in epileptic rats, thereby exerting its antiepileptic effect.

Acorus↗
PubMed2004

[Clinical characteristics of and the related factors to the relapse of chronic hepatitis B after lamivudine withdrawal].

OBJECTIVES: To investigate the cases of chronic hepatitis B relapse after lamivudine withdrawal, and to find clinical characteristics and related factors to them. METHODS: 46 cases of chronic hepatitis B relapse after lamivudine withdrawal were investigated and followed up. The diagnosis and the course of the diseases before therapy with lamivudine, the dosage, effects, period of treatment, the reasons for lamivudine withdrawal, the biochemistry, immunological and virulogical data in each period, YMDD mutation, pre-C mutation and prognosis after relapse were recorded. RESULTS: The periods of treatment of 32.6% of patients in this group were shorter than 52 weeks. The HBV DNA of 93.6% of patients turned negative at the time of lamivudine withdrawal and returned to positive in all of those patients when relapsed; of the 6.4% of patients who did not turn negative at the time of lamivudine withdrawal, their HBV DNA was elevated more than 2 log when relapsed. A majority of patients (71.7%) did not ask their physicians when they decided to withdraw from lamivudine. There were 61.5% of the other patients who withdrew from lamivudine on the advice of physicians but they were not followed up. The state of their illness in 71.7% (33/46) patients was more severe than before their lamivudine therapy. In these cases, the YMDD mutation was detected in 78.8% of patients (chi2 = 23.23, P<0.01), and pre-C mutation was detected in 84.8% of patients (chi2 = 21.04, P<0.01), higher than that in the cases with aggrevation of their illnesses before the lamivudine therapy. The median time between lamivudine withdrawal and relapse was 12 weeks; it was negatively correlated with ALT (r = 0.32, P<0.05) detected at the time of lamivudine withdrawal. The severity of the illness at the time of relapse was related with age (r = 0.40, P<0.01) and YMDD mutation (r = 0.31, P<0.05). The prognosis was related with the age of the patient (r = 0.49, P<0.01), the diagnosis (r = 0.39, P<0.01), TBil (r = 0.46, P<0.05) and ALT (r = 0.32, P<0.05) detected before lamivudine therapy, HBeAg became negative when lamivudine was withdrawn (r = 0.31, P<0.05), TBil (r = 0.55, P<0.01) and PTA (r = 0.57, P<0.01) detected when relapsed. CONCLUSION: A majority of patients did not follow the lamivudine treatment recommendation of the experts group on lamivudine clinical practice in China. The major reason for relapse perhaps was revived HBV DNA multiplication, which induces damage of hepatocytes after lamivudine withdrawal. The YMDD mutation and/or pre-C mutation may be one of the factors that aggravate the damage of hepatocytes during the relapse. The factors including age of the patient, diagnosis before the treatment, TBil and ALT detected before lamivudine therapy, HBeAg turning to negative when lamivudine is withdrawn, and TBil and PTA detected during relapse may all impact the prognosis.

Adolescent↗
PubMed2004

[Synergistic inhibitory effect of STI571 in combination with arsenic trioxide on a multidrug-resistant leukemia cell line expressing bcr-abl].

OBJECTIVE: To study the synergistic effect of STI571, an inhibitor of tyrosine kinase in combination with arsenic trioxide (As(2)O(3)) on a multidrug-resistant leukemia cell line expressing bcr-abl. METHODS: The cytotoxic effect of STI571 alone or in combination with different concentrations of As(2)O(3) on both bcr-abl and mdr1 positive leukemia cell line K562-n/VCR was detected by MTT method. RESULTS: The cytotoxic effect of STI571 (1 micromol/L) combined with As(2)O(3) at concentrations 10(-5), 10(-6), 10(-7), 10(-8) mol/L (IC(50) 0.155 micromol/L) on K562-n/VCR cells was significantly higher than that of As(2)O(3) alone (IC(50) 1.879 micromol/L). The synergistic interaction on K562-n/VCR cells increased the cytotoxic effect by 12.1-fold. CONCLUSION: Combination of STI571 with As(2)O(3) has a synergistic inhibiting effect on leukemia cells expressing bcr-abl and mdr1.

Antineoplastic Agents↗
PubMed2004

Quality of life in patients with liver cancer after operation: a 2-year follow-up study.

BACKGROUND: Quality of life (QL) is a concept which reflects the physical, social, and emotional attitudes and behaviours of an individual. QL assessment is becoming increasingly recognised as an outcome and predictor for cancer patients. Although hepatectomy has been widely accepted as treatment of choice to offer a chance of cure for patients with liver cancer, little is known about the subjective clinical results after this operation. This prospective study was designed to evaluate the Pre- and postoperative quality of life in patients with liver cancer. METHODS: The quality of life of 36 consecutive patients was measured using gastrointestinal quality of life index (GQLI) regularly 2 years after the operation, starting with a preoperative measurement. RESULTS: The score of mean preoperative GQLI was 106+/-13 points, and it was reduced significantly 2-10 weeks after the operation (86-98) (P<0.05-0.001). The quality of life recovered gradually. The GQLI score was 101+/-21 points 4 months after operation and increased to the preoperative level (P>0.05). In the patients who survived more than 9 months, the GQLI score was higher than that before the operation. Major hepatectomy (lobectomy and combined segmentectomy) reduced the GQLI score more evidently than did minor hepatectomy (simple segmentectomy) in 2-5 weeks after the operation (P<0.05). The age and preoperative liver function of the patients played an important role in the recovery of the quality of life in the early postoperative stage (P<0.05). The patients with tumor recurrence showed a continuous decrease of the quality of life (P<0.05-0.001). CONCLUSIONS: The assessment of the quality of life is meaningful for patients with liver cancer. Tumor recurrence, poor liver function and major operation are the most important factors for reducing the quality of life. Hepatic resection is justified by its effects on the survival and the quality of life of the patients.

Adult↗
PubMed2004

[Preparation of rAAV2/hFIX and experimentally application to gene therapy for hemophilia B].

OBJECTIVE: To prepare the rAAV2/hFIX and evaluate the efficiency of the preparation on gene therapy of hemophilia B model mice. METHODS: The rAAV-2/hFIX was prepared by "one helper virus-one vector cell line" strategy and transfected both BHK-21 and C2C12 cells in vitro. The hFIX antigen level in cell culture supernatant was assayed. The rAAV-2/hFIX was injected into muscles of hemophilia B model mice and assayed the serum hFIX levels, hFIX clotting activity, bleeding time, 5 min bleeding volume. RESULTS: The hFIX antigen could be detected from 24 h till 120 h after BHK-21 and C2C12 cells were transfected with highest levels at 24 h reaching (51.0 +/- 6.5) ng/10(5) cells and (68.0 +/- 7.2) ng/10(5) cells, respectively. The rAAV2/hFIX injected mice could efficiently express hFIX and peaked at three weeks after injection, then slowly decreased but low level hFIX antigen was still detectable till 10 weeks after injection. There were significant differences between the high, middle and low dose groups of rAAV2/hFIX and the control group (P < 0.01), the plasma FIX clotting activities in the model mice were improved remarkably, bleeding time was greatly shortened and bleeding in 5 min was decreased. The hFIX expression level and FIX clotting activity of the high dose of rAAV2/hFIX group (1.6 x 10(13) v.g./kg) reached about (387.0 +/- 12.5) ng/ml plasma in contrast with the normal levels of (30.0 +/- 5.5)% at the third week after injection. No rAAV2 vector DNA was detected in the organs except for injected muscle tissue. CONCLUSION: The rAAV2/hFIX transfected BHK-21 and C2C12 cells could efficiently express hFIX antigen and was of therapeutic effects for the hemophilia B model mice by intramuscularly injection.The results provide the basis for clinical trial of rAAV2 gene therapy for hemophilia B.

Animals↗
PubMed2004

[Sodium butyrate induces rat hepatic oval cells differentiating into mature hepatocytes in vitro].

OBJECTIVE: To elucidate the effects of sodium butyrate on rat hepatic oval cell differentiation in vitro. METHODS: Hepatic oval cells were isolated from rats fed with a choline-deficient diet supplemented with 0.1% (w/w) ethonine for 4 to 6 weeks. The cultured hepatic oval cells were identified by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). After hepatic oval cells were treated with sodium butyrate, the morphological changes were studied through Giemsa staining and the albumin expression level was tested by Western blot. RESULTS: Immunohistochemical results showed the isolated cells were positive for both mature hepatocyte marker albumin and bile duct cell marker cytokeratin-19. Furthermore, RT-PCR results showed that the cells expressed stem cell marker c-kit, but not hematopoietic stem cell marker CD34. In short, the isolated cells were rat hepatic oval cells. 0.75 mmol/L sodium butyrate induced obvious phenotype changes of hepatic oval cells, including enlargement of the oval cells, a decrease in nucleus to cytoplasm ratio, and a 50% increase in the number of binucleated cells. Western blot results showed that 0.75 mmol/L sodium butyrate markedly raised the expression of albumin. CONCLUSION: Sodium butyrate, a differentiation promoting agent, can induce rat hepatic oval cells (liver progenitor cells) to differentiate into mature hepatocytes in vitro.

Animals↗
PubMed2004

[Detection of differentially expressed genes in hepatocellularcarcinoma cells SMMC-7721 treated with Typhonium giganteum extract by mRNA differential display].

OBJECTIVE: To screen and identify the differentially expressed genes in hepatocellular carcinoma cells SMMC-7721 responsing to the aqueous extract from dried powdered rhizomes of Typhonium giganteum (AEoTGE). METHOD: The response of hepatocellular carcinoma cells SMMC-7721 to AEoTGE was explored with the technique of mRNA differential display. RESULT: After hepatocarcinoma cells SMMC-7721 were treated by AEoTGE for 36 hours, 1 gene expression was upgrade and 1 gene expression was downgrade induced by AEoTGE. CONCLUSION: The research has provided important clues for the molecular mechanism of how hepatocarcinoma cells responseing to T. giganteum.

Araceae↗
PubMed2004

[Combined gene therapy enhances collateral vascularization in coronary artery occlusion swine model].

OBJECTIVE: To investigate the efficacy of combined gene transfer of vascular endothelial growth factor (VEGF) and angiotensin-1 (Ang-1) in swine coronary artery occlusion. METHODS: Swine underwent left thoracotomy followed by ligation of left anterior descending coronary artery. Constructed PCD(2)/VEGF and/or PCD(2)/Ang-1 eukaryotic expression plasmid was directly injected into the swine myocardium. RT-PCR, immunohistochemistry, capillary density and arteriole density were used to detect gene expression and biological effect. Coronary angiography was done to evaluate collateral circulation of the occluded artery. RESULTS: High levels of VEGF and Ang-1 mRNA and protein expression were detected. There was a significant increase in the number of capillaries and arterioles as compared with a control group (P < 0.05). Capillary density and arteriole density of the combination therapy group were higher than those of the swing receiving either therapy alone. Coronary angiography showed better collateral circulation in the combination therapy group. CONCLUSIONS: Direct injection of PCD(2)/VEGF and PCD(2)/Ang-1 can transfect the myocardium and express VEGF and Ang-1 protein. Combined gene transfer of VEGF and Ang-1 can increase capillary and arteriole number and enhance collateral circulation of the occluded coronary artery more effectively.

Angiotensin I↗
PubMed2003

Insect antifeedants from Munronia henryi: structure of munroniamide.

A novel A,B-seco-tetranortriterpenoid lactam, named munroniamide (1), along with three known ceramides (2-4), was isolated from the methanolic extract of the whole bodies of Munronia henryi. The structure of 1 was established using spectroscopic methods. Compound 2 exhibited significant antifeeding activity, and 1 exhibited moderate activity, whereas 3 and 4 showed negative activity against Pieris brassicae L.

Animals↗
PubMed2003

Insulin resistance of gluconeogenic pathways in neonatal rats after prenatal ethanol exposure.

Alcohol exposure during pregnancy is associated with fetal growth restriction and programs the offspring to insulin resistance later in life. The underlying mechanisms are still uncertain, but a dysregulation of gluconeogenesis and adipose hormones may be contributory. Newborn rats from dams that had been given ethanol (EtOH) or water (controls) during pregnancy were studied. Adiponectin mRNA was determined in subcutaneous fat by RT-PCR, and serum adiponectin was measured by RIA. Subsets of rats were killed before and after intraperitoneal administration of insulin, to determine, by RT-PCR, the hepatic expression of gluconeogenic enzymes and that of the transcription factor peroxisome proliferator-activated receptor-coactivator (PGC)-1, which promotes gluconeogenesis. EtOH offspring had delayed hypoglycemic response to insulin but normal adiponectin mRNA and serum levels compared with controls. The inhibitory response of the gluconeogenic enzyme phosphoenol- pyruvate carboxykinase (PEPCK) and PGC-1 mRNAs to insulin was blunted in EtOH offspring compared with controls. The data suggest that intrauterine EtOH exposure causes insulin resistance of genes for PGC-1 and PEPCK early in life.

Adiponectin↗
PubMed2003

Posttranscriptional control of the competence factor betaFTZ-F1 by juvenile hormone in the mosquito Aedes aegypti.

In anautogenous mosquitoes, vitellogenesis, which includes production of yolk protein precursors, requires blood feeding. Consequently, mosquitoes transmit many diseases. Understanding the molecular mechanisms of vitellogenesis regulation will contribute significantly to vector control strategies. Newly emerged Aedes aegypti females require 3 days before becoming competent to activate vitellogenesis in response to a blood-meal-initiated, elevated titer of 20-hydroxyecdysone (20E). An orphan nuclear receptor gene betaFTZ-F1 is transcribed in the fat body of newly emerged mosquito females; however, the betaFTZ-F1 protein is only found 3 days later. Dramatically increased titer of the juvenile hormone III (JH III) is essential for the acquisition of 20E competence. In vitro fat body culture experiments have shown that betaFTZ-F1 protein appears after exposure to JH III. Injection of double-stranded RNA complementary to betaFTZ-F1 into newly emerged females attenuated expression of the early genes EcR-B, E74B, and E75A and the target YPP gene Vg, in response to a blood meal. Thus, betaFTZ-F1 is indeed the factor defining the acquisition of competence to 20E in the mosquito fat body. Moreover, this is achieved through JH III-mediated posttranscriptional control of betaFTZ-F1.

Aedes↗
PubMed2003

Whole body insulin resistance in rat offspring of mothers consuming alcohol during pregnancy or lactation: comparing prenatal and postnatal exposure.

This study examined the effects of maternal ethanol (EtOH) consumption during pregnancy or lactation on glucose homeostasis in the adult rat offspring. Glucose disposal was determined by minimal model during an intravenous glucose tolerance test in rats that had a small or normal birth weight after EtOH exposure in utero and in rats whose mothers were given EtOH during lactation only. All three EtOH groups had decreased glucose tolerance index and insulin sensitivity index, but their glucose effectiveness was not different from that of controls. In addition, EtOH rat offspring that were small at birth had elevated plasma, liver, and muscle triglyceride levels. The data show that EtOH exposure during pregnancy programs the body to insulin resistance later in life, regardless of birth weight, but that this effect also results in dyslipidemia in growth-restricted rats. In addition, insulin resistance is also evident after EtOH exposure during lactation.

Animals↗
PubMed2003

Effect of culture media on the chemical and physical characteristics of polysaccharides isolated from Poria cocos mycelia.

Mycelia of a wild strain Poria cocos were cultured in two media differing in one constituent: bran extract or corn steep liquor, and are designated as wb and wc, respectively. Six polysaccharide fractions were isolated sequentially from the two mycelia by 0.9% NaCl (PCM1), hot water (PCM2), 0.5 M NaOH (PCM3-I and -II) and 88% formic acid (PCM4-I and -II). Their chemical and physical characteristics were determined by infrared spectroscopy (IR), gas chromatography (GC), 13C NMR, light scattering (LS) and viscometry. The results indicated that wb-, wc-PCM1, and PCM2 were heteropolysaccharides mainly composed of alpha-D-glucose, mannose, and galactose, whereas wb-PCM3-I and wc-PCM3-I were mainly (1-->3)-alpha-D-glucans, and wb- and wc-PCM3-II, PCM4-I and PCM4-II were (1-->3)-beta-D-glucans. Interestingly, (1-->3) alpha- and (1-->3)-beta-D-glucans co-existed in the 0.5 M NaOH fraction and were separated individually into the two fractions (PCM3-I and PCM3-II) after neutralizing with acetic acid. The polysaccharides from wc-PCM cultured in media containing corn steep liquor contained relatively more protein. The polysaccharide fractions also existed in conformations including random coil (as in PCM0 and PCM1) and expanded chain (as in PCM3), and differed molecular mass. In addition, two exo-polysaccharides isolated from the two culture media by methanol precipitation (wb- and wc-PCM0) also differed in their monosaccharide composition.

Chemical Phenomena↗
PubMed2003

Antitumor activities of heteropolysaccharides of Poria cocos mycelia from different strains and culture media.

Ten water-soluble heteropolysaccharide fractions were isolated from Poria cocos mycelia cultured from one wild and one cultivated strain in two identical culture media differing only in one component: either corn steep liquor or bran extract. The chemical compositions, including monosaccharide profile, protein content, and molecular mass M(w) of the mycelial polysaccharides were determined. Both the in vitro and in vivo antitumor activities of the heteropolysaccharides were evaluated and compared. The heteropolysaccharides from Poria cocos mycelia cultured with the wild strain in a medium containing corn steep liquor exhibited the highest antitumor activities against Sarcoma 180 in vivo.

Animals↗
PubMed2003

Tools for the automatic identification and classification of RNA base pairs.

Three programs have been developed to aid in the classification and visualization of RNA structure. BPViewer provides a web interface for displaying three-dimensional (3D) coordinates of individual base pairs or base pair collections. A web server, RNAview, automatically identifies and classifies the types of base pairs that are formed in nucleic acid structures by various combinations of the three edges, Watson-Crick, Hoogsteen and the Sugar edge. RNAView produces two-dimensional (2D) diagrams of secondary and tertiary structure in either Postscript, VRML or RNAML formats. The application RNAMLview can be used to rearrange various parts of the RNAView 2D diagram to generate a standard representation (like the cloverleaf structure of tRNAs) or any layout desired by the user. A 2D diagram can be rapidly reformatted using RNAMLview since all the parts of RNA (like helices and single strands) are dynamically linked while moving the selected parts. With the base pair annotation and the 2D graphic display, RNA motifs are rapidly identified and classified. A survey has been carried out for 41 unique structures selected from the NDB database. The statistics for the occurrence of each edge and of each of the 12 bp families are given for the combinations of the four bases: A, G, U and C. The program also allows for visualization of the base pair interactions by using a symbolic convention previously proposed for base pairs. The web servers for BPViewer and RNAview are available at http://ndbserver.rutgers.edu/services/. The application RNAMLview can also be downloaded from this site. The 2D diagrams produced by RNAview are available for RNA structures in the Nucleic Acid Database (NDB) at http://ndbserver.rutgers.edu/atlas/.

Algorithms↗
PubMed2003

Asymmetric transfer hydrogenation of prochiral ketones in aqueous media with new water-soluble chiral vicinal diamine as ligand.

[reaction: see text] An easily accessible water-soluble chiral o-sulfonated 1,2-diphenylethlenediamine 2 and its mono-N-tosylated derivative 3 were synthesized for the first time. The ruthenium-complex-catalyzed reduction of prochiral ketones in aqueous media has been examined by using 3 as ligand and sodium formate as the source of hydrogen. The asymmetric transfer hydrogenation of omega-bromo acetophenones was achieved, in which only formate displacement occurred when formic acid/triethylamine azeotrope was used as the hydrogen donor.

Journal Article↗
PubMed2003

Inducible expression of keratinocyte growth factor (KGF) in mice inhibits lung epithelial cell death induced by hyperoxia.

Oxidant-induced injury to the lung is associated with extensive damage to the lung epithelium. Instillation of keratinocyte growth factor (KGF) in the lungs of animals protects animals from oxidant-induced injury but the mechanism of protection is not well understood. An inherent problem in studying KGF function in vivo has been that constitutive overexpression of KGF in the lung causes embryonic lethality with extensive pulmonary malformation. Here we report the development of a stringently regulated, tetracycline-inducible, lung-specific transgenic system that allows regulated expression of KGF in the lung without causing developmental abnormalities from leaky KGF expression. By using this system, we show that exposure of KGF-expressing mice to hyperoxia protects the lung epithelium but not the endothelium from cell death in accordance with the selective expression of KGF receptor on epithelial and not on endothelial cells. Investigations of KGF-induced cell survival pathways revealed KGF-induced activation of the multifunctional pro-survival Akt signaling axis both in vitro and in vivo. Inhibition of KGF-induced Akt activation by a dominant-negative mutant of Akt blocked the KGF-mediated protection of epithelial cells exposed to hyperoxia. KGF-induced Akt activation may play an important role in inhibiting lung alveolar cell death thereby preserving the lung architecture and function during oxidative stress.

Animals↗