Biomedical subjects

Li Yang

Publications and source records attributed to Li Yang.

At least 271 records · Page 15Linked to original sources

PubMed2002

Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection.

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.

Aluminum↗

PubMed2002

Structure of the Lrp-regulated serA promoter of Escherichia coli K-12.

Expression of the Escherichia coli serA gene is activated in vivo by the product of the lrp gene, leucine-responsive regulatory protein (Lrp), an effect partially reversed by L-leucine. We show here that serA is transcribed from two promoters, P1 45 bp upstream of the translation start site, and P2 92 bp further upstream. Lrp binds to a long AT-rich sequence from -158 to -82 from the start of the coding region, i.e. upstream of P1 and overlapping P2. It activates transcription from P1 and represses expression from P2. A second regulator, cAMP/CRP, activates P2, an effect that is largely inhibited by Lrp, such that catabolite repressor protein (Crp) and Lrp are rival activators of serA transcription.

Base Sequence↗

PubMed2002

Immunogene therapy of tumors with a vaccine based on the ligand-binding domain of chicken homologous integrin beta3.

The breaking of immune tolerance against angiogenesis-associated molecules should be a useful approach for cancer therapy by active immunity. We used chicken integrin beta3 as a model antigen to explore the feasibility of immunogene therapy of the tumors with a vaccine based on a single xenogeneic homologous gene, targeting the molecules associated with angiogenesis. To test this concept we constructed a plasmid DNA encoding the ligand-binding domain of chicken integrin beta3 (P-BD-C) and control vectors. We found that immunogene therapy of tumors with a vaccine based on the ligand-binding domain of chicken integrin beta3 (P-BD-C) was effective in both protective and therapeutic anti-tumor immunity in several tumor models in mice. Autoantibodies against integrin beta3 in sera of mice immunized with the ligand-binding domain of chicken integrin beta3 could be found by Western blot analysis and ELISA assay. The purified immunoglobulins were effective in the inhibition of endothelial cell proliferation in vitro, and in anti-tumor activity as well as in the inhibition of angiogenesis by adoptive transfer in vivo. The anti-tumor activity and the production of integrin beta3-specific autoantibodies (manifested by significantly elevated Ig G1 and Ig G2b) could be abrogated by the depletion of CD4+ T lymphocytes. These observations may provide a vaccine strategy for cancer therapy through the induction of the autoimmunity against the molecules associated with tumor growth in a cross-reaction with a single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Animals↗

PubMed2002

Antioxidative and free radical scavenging effects of ecdysteroids from Serratula strangulata.

The antioxidative and free radical scavenging effects of four ecdysteroids, 20-hydroxyecdysone (E1), 25-deoxy-11,20-dihydroxyecdysone (E2), 24-(2-hydroxyethyl)-20-hydroxyecdysone (E3), and 20-hydroxyecdysone-20,22-monoacetonide (E4), isolated from the Chinese herb Serratula strangulata have been investigated in vitro. These ecdysteroids could protect human erythrocytes against oxidative hemolysis induced by a water-soluble azo initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). They could also inhibit the peroxidation of rat liver microsomes induced by hydroxyl radicals, as monitored by the formation of thiobarbituric acid reactive substances (TBARS), and prevent radical-induced decrease of membrane fluidity as determined by fluorescence polarization. They reacted with galvinoxyl radicals in homogeneous solution, and the pseudo-first-order rate constants were determined spectrophotometrically by following the disappearance of galvinoxyl radicals. Compounds E1 and (or) E3 were the most active in both antioxidative and radical-scavenging reactions.

Animals↗

PubMed2002

Acute hypertension provokes internalization of proximal tubule NHE3 without inhibition of transport activity.

Acute hypertension rapidly decreases proximal tubule (PT) Na(+) reabsorption, facilitated by a redistribution of PT Na(+)/H(+) exchangers (NHE3) out of the apical brush border, increasing NaCl at the macula densa, the signal for autoregulation of renal blood flow and GFR. This study aimed to determine whether NHE3 activity per transporter decreases during acute hypertension and the time dependence of the response. Blood pressure was elevated by 50-60 mmHg in male Sprague-Dawley rats for 5 or 30 min by constricting arteries. Renal cortical membranes were fractionated by density gradient centrifugation. NHE3 transport activity was assayed as the rate of appearance of acridine orange (AO) from AO-loaded vesicles in response to an inwardly directed Na(+) gradient. After 5-min hypertension, 20% of total NHE3 protein, assayed by immunoblot, redistributed from low-density apical membranes to middensity membranes enriched in intermicrovillar cleft markers; by 30 min, a similar percentage shifted to heavier density membranes containing markers of endosomes. NHE3 activity shifted to higher density membranes along with NHE3 protein, that is, no change in activity/transporter during acute hypertension. Confocal analysis of NHE3 distribution also verified removal from apical microvilli and appearance in subapical vesicles. We conclude that the decrease in renal PT Na(+) transport during acute hypertension is mediated by removal of transport-competent NHE3 from the apical brush border to subapical and internal reserves.

Amiloride↗

PubMed2002

Application of dopamine as an electroactive ligand for the determination of aluminum in biological fluids.

Dopamine (3,4-dihydroxyphenylethylamine, DA) is applied as an electroactive chelant for indirect determination of aluminum (Al) in biological fluids. It is observed that the decrease of the differential pulse voltammetric (DPV) anodic peak current of DA is linear with the increase of Al concentration. Under optimum experimental conditions (pH 8.6, 2.0 x 10(-4) M DA, and 0.03 M NH4Ac-NH3 x H2O buffer solution), two linear ranges, 5.0 x 10(-8) - 4.0 x 10(-7) M and 4.0 x 10(-7) - 7.2 x 10(-6) M Al(III), are obtained. The detection limit of Al is 1.9 x 10(-8) M and the relative standard deviation for 4 x 10(-6) M Al(III) is 3.1% (N = 8). Many biologically active foreign species have been selected for interference. Excellent recoveries and accuracy have been obtained in the measurements of Al in biological samples such as synthetic renal dialysate, Ringer's solution, human whole blood, cerebrospinal fluid of demented patient, and urine of diabetic patient. The methodological principle that Al complexes with DA on the electroactive position result in the depression of electrochemical activities of DA has been verified by comparing both the electrochemical behaviors and the spectroscopic responses like UV-vis and Raman of DA in the presence and in the absence of Al.

Aluminum↗

PubMed2002

Apoptosis of rat hepatic stellate cells induced by anti-focal adhesion kinase antibody.

AIM: To explore the role of focal adhesion kinase (FAK) in the apoptosis in culture-activated rat hepatic stellate cells (HSCs) using a specific anti-FAK antibody. METHODS: Rat HSCs were prepared from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenze gradient. Culture-activated HSCs were serum-starved and treated with the anti-FAK antibodies for 24, 48 or 72 h. The apoptosis of HSC was detected by DNA-fragment assay, flow cytometry and caspase-3 activity determination. The expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA was assessed by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: The experiment showed that anti-FAK antibodies induced apoptosis of culture-activated rat HSCs. This phenomenon displayed the classical features of apoptotic cell death (DNA fragmentation, cell cycle analysis) after treated with 30 mg.L(-1) FAK antibody for 72 h, and accompanied by a significant increase of caspase-3 activity(1208+/-76) vs (309+/-28) nmol.min(-1).g(-1), t=208.5, P<0.05. Meanwhile, treatment with the FAK antibody in HSCs could markedly decrease the TIMP-1 mRNA expression (0.07+/-0.01 vs 0.38+/-0.03, t=2.72, P<0.05). CONCLUSION: FAK plays an important role in the survival of HSCs and the specific anti-FAK antibody could induce the apoptosis in rat HSCs.

Animals↗

PubMed2002

Effects of the tyrosine protein kinase inhibitor genistein on the proliferation, activation of cultured rat hepatic stellate cells.

AIM: Hepatic stellate cell (HSC) plays a pivotal role in liver fibrosis and is considered as the therapeutic target for the treatment of hepatic fibrosis. Tyrosine protein kinase plays an important role in the proliferation, activation of HSC. The purpose of the study is to investigate the effects of the tyrosine protein kinase inhibitor genistein on the proliferation and activation of cultured rat HSC. METHODS: Rat HSC were isolated from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient. Culture-activated HSC were serum-starved and incubated with 10(-9) to 10(-5) mol/L concentration of genistein for 24, 48 or 72 h. In PDGF-induced HSC proliferation, HSC were stimulated with 10 microg.L(-1) PDGF-BB for 15 min, and then treated with genistein for the same time. Cell proliferation was measured by MTT assay and based on flow cytometric analysis of cell cycle. The a-smooth muscle actin (alpha-SMA) expression in HSC was studied with confocal laser microscopy and flow cytometry. c-fos, c-jun and cyclin D(1) expression in HSC was also detected by flow cytometry. RESULTS: Genistein inhibited basal and PDGF-induced proliferation of HSC at the concentration of 10(-8) to 10(-5)mol/L, and treatment with 10(-7) mol/L concentration of genistein for 48 h inhibited the HSC proliferation significantly (the inhibition rate was 70.3 %, P<0.05). Immunofluorescence detected by confocal laser microscopy and flow cytometry showed that treatment with 10(-7) mol/L genistein for 48 h suppressed the expression of alpha-SMA significantly in HSC (the specific fluorescence intensity were 60.2+/-21.5 vs 35.3+/-11.6 and 12.8+/-10.4 vs 9.54+/-6.39, respectively, both P<0.05). The intensity of c-fos, c-jun and cyclin D(1) expression of HSCs treated with 10(-7)mol/L genistein for 48 h was also significantly decreased compared with the controls. CONCLUSION: Genistein influences proliferation of HSC, suppresses the expression of alpha-SMA in HSC and t inhibits the intensity of c-fos, c-jun and cyclin D(1) expression of HSCs. Genistein has therapeutic potential against liver fibrosis.

Actins↗

PubMed2002

[Progress in molecular genetics of correlating genes of breast cancer].

Good progress has been made in the researches on correlating genes of breast cancer in recent years. Quite a few kinds of genes such as susceptibility gene, oncogene and tumor suppressor genes have been found with implications for diagnosis, therapy and prognosis. Abnormality of breast cancer susceptibility gene (BRCA) is of great significance, especially in the development of breast cancer.

BRCA1 Protein↗

PubMed2002

Two new components from Serratula strangulata Iljin.

From the alcoholic extract of the whole plants of Serratula strangulata, two new compounds have been isolated and their structures established by spetroscopic methods as strangusin-A (1) and strangusin-B (2).

Asteraceae↗

PubMed2002

[Reconstruction of partial nose defects with retroauricular free flap transplantation].

OBJECTIVE: To present the operation for nose defect reconstruction using a retroauricular free flap and the auricle cartilage. METHODS: Based on the anatomy and blood supply of the retroauricular region, a flap was designed and harvested with the posterior auricular vessels as its pedicle. The flap was used to repair nose defects in five patients. Of them, three had unilateral subtotal alinasal defects, one had nasal apex defect, and one had defects on nasal apex and bilateral ala. The size of the defect ranged from 2.5 cm x 1.5 cm to 3.0 cm x 4.0 cm. The flap varied between 3.0 cm x 2.0 cm and 4.5 cm x 3.5 cm. In 4 cases, the auricular cartilage of 2.0 cm x 1.5 cm to 1.5 cm x 1.0 cm was taken along with the flap. The posterior auricular vessels were anastomosed with the facial vessels. The donor site was covered with full-thickness skin graft. RESULTS: Postoperatively, the blood supply to the flaps was fairly good in 3 cases, while there was various venous stasis in 2 cases during the first 4 days. However, the postoperative results of the 5 cases were satisfactory. CONCLUSIONS: The retroauricular free flap is a good choice for partial nose reconstruction, which had the merits of well-hidden donor site, good color match, and one-stage operation.

Humans↗

PubMed2002

[Construction of fetal mesenchymal stem cell cDNA subtractive library].

UNLABELLED: To identify differentially expressed genes between fetal mesenchymal stem cell (MSC) and adult MSC, especially specified genes expressed in fetal MSC, a cDNA subtractive library of fetal MSC was constructed using suppression subtractive hybridization (SSH) technique. At first, total RNA was isolated from fetal and adult MSC. Using SMART PCR synthesis method, single-strand and double-strand cDNAs were synthesized. After Rsa I digestion, fetal MSC cDNAs were divided into two groups and ligated to adaptor 1 and adaptor 2 respectively. Results showed that the amplified library contains 890 clones. Analysis of 890 clones with PCR demonstrated that 768 clones were positive. The positive rate is 86.3%. The size of inserted fragments in these positive clones was between 0.2 - 1 kb, with an average of 400 - 600 bp. CONCLUSION: SSH is a convenient and effective method for screening differentially expressed genes. The constructed cDNA subtractive library of fetal MSC cDNA lays solid foundation for screening and cloning new and specific function related genes of fetal MSC.

Cloning, Molecular↗

PubMed2002

[The influence of Matrine on apoptosis of fibroblasts and the expression of apoptotic modulation related protein in hypertrophic scar of rabbit ear].

OBJECTIVE: To investigate the effects of Matrine on apoptosis of fibroblasts and the expression of apoptotic modulation related protein in the hypertrophic scar. METHODS: Hypertrophic scar was produced on the ear of 24 New Zealand white rabbits, which were employed as the model, and were randomly and equally divided into control (CC) and Matrine (M) groups (12 in each group). Matrine (50 g/L) was injected into the ear scar in M group and with normal saline in C group once every four days. At 2, 4, 6, 8 and 12 weeks after the injection, the apoptotic fibroblast count in the scar was determined by TUNEL method, and the expressions of apoptosis related modulation proteins p53, bcl-2, bax were detected by immunohistochemistry method. RESULTS: The apoptotic fibroblast count was much larger in M group than that in C group at all test time points (P < 0.05). Furthermore, the bax expression was increased and that of p53 and bcl-2 was decreased significantly in M group. In adding, the scar became flat in M group. CONCLUSION: Matrine might obviously enhance the fibroblast apoptosis in rabbit ear hypertrophic scar, and up-regulate the expression of apoptosis related modulation protein bax and down-regulate the expression of p53 and Bcl-2.

Alkaloids↗

PubMed2002

[Influence of endothelial cells on the proliferation of scar-derived fibroblast in hypertropic scar tissue].

OBJECTIVE: To investigate the influence of the endothelial cells on the scar-derived fibroblasts in the hypertropic scar tissue. METHODS: The endothelial cell from the human umbilical vein was cultured and its supernatant was then collected. Thereafter, it was mixed with the pre-cultured scar-derived fibroblasts from the hypertropic scar tissue. The fibroblasts were analyzed with a flow cytometer in a MTT-assay method to evaluate the cell proliferation and its division cycle. RESULTS: The endothelial cells were significantly increasing the scar-derived fibroblast proliferation (P < 0.05), compared with the control. The proportion of the fibroblasts in the S-stage of cell cycle was also quite high. CONCLUSION: The endothelial cells may secrete some active products, which may enhance the proliferation of the scar-derived fibroblasts and stimulate the fibroblasts into the S-stage of cell generation cycle.

Cell Cycle↗

PubMed1999

Fusion Expression, Immunogenicity and Applications of C-terminally Truncated HCV Core Proteins.

Clones expressing full-length(aa 1-191) or C-terminally truncated forms (aa 1-69 and aa 1-40) of hepatitis C virus core(HCc) protein fused to the C-terminal of glutathione S-transferase(GST) were constructed and their expressions in different strains of Escherichia coli were compared. The expressed proteins were soluble. ELISA and Western blot analyses showed that GSTC191 was poorly expressed and had poor stability, whereas GSTC69 and GSTC40 were stable and could be purified to 90% purity in a single step on glutathione-Sepharose 4B. Mice immunized with these purified proteins produced high-titre antibodies. As an application, purified GSTC69 and GSTC40 were used in a preliminary assay of anti-HCc antibodies in patients'sera, and results showed that they had high specificity in the assay.

Journal Article↗

PubMedDate not supplied

Anxiolytic agent, dihydrohonokiol-B, recovers amyloid beta protein-induced neurotoxicity in cultured rat hippocampal neurons.

The effects of anxiolytic honokiol derivative, dihydrohonokiol-B (DHH-B), on amyloid beta protein (Abeta(25-35), 10 nM)-induced changes in Cl(-)-ATPase activity, intracellular Cl- concentration ([Cl-]i) and glutamate neurotoxicity were examined in cultured rat hippocampal neurons. DHH-B (10 ng/ml) recovered Abeta-induced decrease in neuronal Cl(-)-ATPase activity without any changes in the activities of Na+/K+-ATPase and anion-insensitive Mg2+-ATPase. A GABA(C) receptor antagonist (1,2,5,6,-tetrahydropyridin-4-yl) methyl-phosphinic acid (TPMPA, 15 microM), inhibited the protective effects of DHH-B on Cl(-)-ATPase activity. DHH-B reduced Abeta-induced elevation of [Cl-]i as assayed using a Cl(-)-sensitive fluorescent dye, and prevented Abeta-induced aggravation of glutamate neurotoxicity. These data suggest that DHH-B exerts the neuroprotective action against Abeta through GABA(C) receptor stimulation.

Adenosine Triphosphatases↗

PubMedDate not supplied

Conditioned medium from Listeria innocua stimulates emergence from a resting state: not a response to E. coli quorum sensing autoinducer AI-2.

The lag phase of the bacterial growth curve is an important determinant in speeding the detection of pathogens. It is affected by many factors including the prevailing growth environment and inoculum size, as well as specific signal molecules. The elucidation of growth-regulating signal molecules is further facilitated by culturing cells in defined growth media. In this study, a defined medium capable of supporting growth of Listeria innocua at similar levels as obtained using a complex brain heart infusion (BHI) media was developed. Further, the effects of conditioned medium (CM) on population lag time of L. innocua was investigated using a rapid parallel approach (with an automated microtiter plate reader). Importantly, the lag phase was shortened by up to approximately 50% by the addition of CM from L. innocua cultures obtained late in the exponential phase. Finally, while L. innocua were found to secrete bacterial signaling autoinducer, AI-2, tests using Escherichia coli based CM having a 90-fold difference in AI-2 level suggested that the observed decrease in lag phase was not due to E. coli-derived AI-2 and was instead due to elements specific to L. innocua. These findings indicate secreted signal molecules may be found in CM that speed detection of L. innocua.

Cell Division↗

PubMedDate not supplied

Giant cell arteritis in China: a prospective investigation.

The objective of this prospective study was to investigate further the clinical features of patients with giant cell (temporal) arteritis (GCA). All patients diagnosed from July 1999 to March 2001 at the Department of Neurology of the Second Xiangya Hospital in China were included. The final diagnosis was based on clinical manifestations, a temporal artery biopsy, response to steroid, and follow-up. The American College of Rheumatology (ACR) criteria for the classification of GCA were tested in the patients identified. Sixteen patients with GCA were identified; 13 (81.25%) patients fulfilled the 1990 ACR criteria for the classification of GCA. Clinical findings included the following: mean age at disease onset 43.13 years (range 28-60) and 81.25% of the patients under the age of 50 when the disease began; men 93.75%; the common initial symptoms including new headache 62.50% and.visual symptoms 18.75%; the common clinical findings at presentation including new headache 93.75%, temporal artery abnormality 81.25%, visual abnormality 56.25%, and fever 25.00%; raised erythrocyte sedimentation rate (ESR) 68.75%; and uncommon findings including jaw claudication, ptosis, fatigue, syncope, hemiparesis; all 16 patients underwent a temporal artery biopsy; inflammatory cell infiltration 68.75% in arterial wall, fragmented internal elastica 100.00%, fibrinoid necrosis 18.75%, smooth muscle cell changes 62.50%, and thrombosis in the lumen 31.25%. The mean time from symptom onset to suspicion of GCA or biopsy was 5.52 months (range 0.25-24.33); the initial diagnosis was wrong in 87.50% of patients. These examples are too small a number to permit definite conclusion. But the results suggest that GCA may not be a rare disorder in China, mean age at disease onset was relatively young, males may be more susceptible, the clinical features of GCA have not been widely appreciated yet, there was a delay between diagnosis and treatment, and initial diagnosis was wrong in many patients.

Adult↗