Biomedical subjects

Yang Li

Publications and source records attributed to Yang Li.

At least 163 records · Page 9Linked to original sources

PubMed2004

Effect of autonomic nervous system on the transmural dispersion of ventricular repolarization in intact canine.

The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization in intact canine was investigated. By using the monophasic action potential (MAP) recording technique, monophasic action potentials (MAPs) of the epicardium (Epi), midmyocardium (Mid) and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes at the left ventricular free wall in 12 open-chest dogs. MAPD90 and transmural dispersion of repolarization among three myocardial layers as well as the incidence of the EAD before autonomic nervous stimulation and during autonomic nervous stimulation were compared. The results showed that the MAPD90 of Epi, Mid and Endo before autonomic nervous stimulation were 278 +/- 11 ms, 316 +/- 16 ms and 270 +/- 12 ms respectively, the MAPD90 of Mid was significantly longer than that of Epi or Endo (P<0.01). MAPD90 of Epi, Mid and Endo were shortened by 19 +/- 4 ms, 45 +/- 6 ms, 18 +/- 3 ms respectively during sympathetic stimulation. Compared with that of the control, the transmural dispersion of repolarization during sympathetic stimulation was shortened from 44 +/- 4 ms to 15 +/- 3 ms (P<0.01), but early afterdepolarizations were elicited in the Mid of 5 dogs (41%) during sympathetic stimulation. Parasympathetic stimulation did not significantly affect the MAPD90 in the three layers. It is concluded that there is the transmural dispersion of ventricular repolarization in intact canine. Sympathetic stimulation can reduce transmural dispersion of repolarization, but it can produce early afterdepolarizations in the Mid. Parasympathetic stimulation does not significantly affect the transmural dispersion of ventricular repolarization.

Action Potentials↗

PubMed2004

Protective effect of carvedilol on abnormality of L-type calcium current induced by oxygen free radical in cardiomyocytes.

The protective effect of carvedilol on abnormality of L-type calcium current induced by oxygen free radical in single guinea pig ventricular myocytes was studied. Whole-cell patch clamp technique was used to study the effect of H2O2 (0.5 mmol/L) on L-type calcium current in single guinea pig ventricular myocytes and the action of pretreatment with carvedilol (0.5 micromol/L). 0.5 micromol/L carvedilol had no significant effect on ICa,L and its channel dynamics. In the presence of 0.5 mmol/L H2O2, peak current of ICa,L was reduced significantly (P<0.001), the I-V curve of ICa,L was shifted upward, steady-state activation curve and steady-state deactivation curve of ICa,L were shifted left and recovery time of ICa,L was delayed significantly (P<0.001). 0.5 micromol/L carvedilol significantly alleviated the inhibitory effect of H2O2 on ICa,L as compared with that in H2O2 group (P<0.01). In addition, carvedilol reversed the changes of dynamics of ICa,L induced by H2O2. It was concluded that carvedilol could alleviate the abnormality of L-type calcium current induced by oxygen free radical in cardiomyocytes. It shows partly the possible mechanism of the special availability of carvedilol in chronic heart failure.

Adrenergic beta-Antagonists↗

PubMed2004

Effects of volsartan on transmural heterogeneous changes of transient outward potassium currents in hypertrophic cardiomyocytes in rabbits.

The transmural heterogeneous changes of transient outward potassium currents (Ito) in rabbit hypertrophic cardiaomyocytes and the effects of long-term prophylactic treatment with volsartan were investigated. Rabbits were divided into hypertrophy group (left ventricular hypertrophy induced by partial ligation of abdominal aorta), vol-treated group (volsartan was administrated after the ligation), and control group (sham operated). Myocytes were isolated by a two-step enzymatical method. The sub-endocardial (Endo) and sub-epicardium (Epi) tissues were separated from midmyocardium (Mid) with a razor. Whole-cell patch-clamp technique was used to record potassium currents. The results showed that membrane capacitance was larger in hypertrophic cells than those in control and vol-treated cells (P<0.01 vs control cells, n=30). The densities of Ito in hypertrophic cells were reduced by sub-epicardium (Epi) (27.8 +/- 2.9) %, midmyocardium (Mid) (41.0+/-4.7) %, and sub-endocardium (Endo) (20.3 +/- 3.4) % compared with those in control cells. The decrease of Ito density was more pronounced in Mid than in Epi and Endo (P<0.01 vs Epi or Endo). There were no significant differences in Ito densities between vol-treated group and control group in three layers separately. In conclusion, volsartan can inhibit the transmural heterogeneous changes of Ito in left ventricular hypertrophic cardiomyocytes in rabbit.

Animals↗

PubMed2004

The changes of potassium currents in rabbit ventricle with healed myocardial infarction.

To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (Ito), delayed rectifier potassium current (IK) and inward rectifier potassium current (IK1) of left ventricular myocytes in non-infarcted zone of HMI were investigated. Rabbits were randomly assigned into two groups: HMI group, in which animals were subjected to thoracotomy and ligation of the circumflex coronary and sham-operated group, in which rabbits underwent thoracotomy but no conorary ligation. 3 months after the operation, the whole myocyte patch clamp technique was used to record APD, Ito, IK, and IK1 of ventricular myocytes in non-infarcted zone. Our results showed that the membrane capacitance was larger in HMI group than in sham-operated group. Action potential duration was significantly lengthened in HMI group and early afterdepolarization (EAD) appeared in HMI group. The densities of Ito, I(K, tail), and IK1 were reduced significantly in HMI group, from 6.72 +/- 0.42 pA/pF, 1.54 +/- 0.13 pA/pF and 25.6 +/- 2.6 pA/pF in sham-operated group to 4.03 +/- 0.33 pA/pF, 1.14 +/- 0.11 pA/pF and 17.6 +/- 2.3 pA/pF, respectively. It is concluded that the reduced densities of Ito, I(K, tail) and IK1 in ventricular myocytes of non-infarcted zone in HMI were responsible for the prolongation of APD and the presentation of EAD which played important roles in the development of malignant arrhythmia in HMI.

Action Potentials↗

PubMed2004

Concurrent analysis of loss of heterozygosity (LOH) and copy number abnormality (CNA) for oral premalignancy progression using the Affymetrix 10K SNP mapping array.

Like most human cancers, oral squamous cell carcinoma (SCC) is characterized by genetic instabilities. In this study, a single platform (Affymetrix 10K SNP mapping array) was used to generate both loss of heterozygosity (LOH) and DNA copy number abnormality (CNA) read-outs for precise and high-resolution genetic alteration profiles. As a proof of principle, we performed this concordant analysis on a panel of deletion and trisomy cell lines with known chromosomal alterations and the precise LOH and CNA regions were detected as expected. Using a previously described oral SCC progression model system, we identified a set of genomic regions that may be associated with the malignancy progression, including chromosome regions 3pter-3p35.3, 3p14.1-3p13, 11p, 11q14.3-11q22.2, and 11q13.5-11q14.1. These data show that it is feasible to utilize high-density SNP arrays to generate concordant LOH and CNA profiles at high resolution.

Carcinoma, Squamous Cell↗

PubMed2004

Cathepsin L is crucial for a Th1-type immune response during Leishmania major infection.

Prior to the activation of CD4+ T cells, exogenous proteins are digested by endo/lysosomal enzymes in antigen-presenting cells (APCs) to produce antigenic peptides that are presented on MHC class II molecules. In the studies described here, the functional significance of cathepsin L for antigen processing and Th1/Th2 differentiation in experimental leishmaniasis was investigated. We first demonstrated that cathepsin L is one of the candidates for endo/lysosomal enzymes in the processing of soluble Leishmania antigen (SLA) by using CLIK148, a specific inhibitor of cathepsin L. Treatment of BALB/c or DBA/2 mice with CLIK148 exacerbated the disease by enhancing an SLA-specific Th2-type response such as IL-4 production. CLIK148 did not exert any direct influence on Leishmania major promastigotes themselves or on the course of L. major infection in SCID mice. Taken together, these findings suggest that treatment of host mice with CLIK148 affects the processing of SLA in APCs, resulting in the potentiation of Th2-type immune responses and thus leading to exacerbation of the disease. Furthermore, endo/lysosomal cathepsin L was found to be functionally distinct from previously described cathepsins B and D.

Animals↗

PubMed2004

Pre-eclampsia is associated with the failure of melanoma cell adhesion molecule (MCAM/CD146) expression by intermediate trophoblast.

The purpose of this study was to determine whether the expression of melanoma cell adhesion molecule (MCAM/CD146), like most other endothelial adhesion molecules, is reduced in the pregnancy disorder pre-eclampsia, and whether it is associated with the invasiveness of trophoblast. We used immunohistochemical approaches and analyzed 42 placentas from control and pre-eclamptic patients using an anti-CD146 monoclonal antibody. Our data show that in normal placentas, CD146 staining was specifically detected in intermediate trophoblasts that are most invasive and migratory, but not detected in noninvasive cytotrophoblasts or syncytiotrophoblasts. However in pre-eclampsia, CD146 was no longer present in the intermediate trophoblasts, although it was detectable in the blood vessels. At the same time, we tested CD31/PECAM-1, another endothelial adhesion molecule, and found its negative staining for all kinds of trophoblasts in both normal and pre-eclamptic placentas. The different staining patterns of CD146 in the normal and pre-eclamptic placentas provide the first evidence that in pre-eclampsia, intermediate trophoblasts fail to express CD146, implicating that CD146 plays an important role in trophoblast invasion.

Adult↗

PubMed2004

A novel RDS/peripherin gene mutation associated with diverse macular phenotypes.

Pattern dystrophy is a heterogeneous group of retinal dystrophies of which butterfly-shaped pattern dystrophy (BPD) and adult-onset foveomacular dystrophy (AOFMD) are the two most common forms. BPD is characterized by a butterfly-shaped, irregular, depigmented lesion at the level of the retinal pigment epithelium. In contrast, AOFMD is characterized by the presence of slightly elevated, symmetric, solitary, round to oval, yellow lesions at the level of the retinal pigment epithelium. We identified three independent kindreds with pattern dystrophy, one with four patients affected with BPD and the other two with 14 affected patients with AOFMD. We performed complete ophthalmic examination, fluorescein angiography, linkage mapping, and mutational screening in the RDS/peripherin gene in the affected patients. Patients affected with BPD had a best-corrected vision of 20/20 to 20/25, whereas vision in the eyes of patients with AOFMD ranged from 20/20 to 20/400. In all three kindreds, sequence analysis identified an A-to-G change at nucleotide position 422 of the RDS/peripherin gene, predicting a novel Tyr-141-Cys substitution. A haplotype analysis revealed that these three kindreds shared an identical disease haplotype at the RDS/peripherin locus, indicating that the mutation reflects a founder effect. The sequence change that segregated with the disease phenotype was not observed in 200 control chromosomes. Our results identified a novel mutation in the RDS/ peripherin gene that can cause diverse macular phenotypes. Genetic and clinical investigation of pattern dystrophy may provide useful diagnostic tools and new treatment strategies for this disorder.

Adult↗

PubMed2004

Umbilical cord blood transplantation in Chinese children with beta-thalassemia.

To evaluate factors affecting outcome of sibling umbilical cord blood transplantation in Chinese children with thalassemia. The authors conducted a retrospective review of all patients undergoing such transplants in a single institution. Nine children with thalassemia major were diagnosed at a median age of 12 months. They received irregular blood transfusions and suboptimal iron chelation therapy before transplant. Sibling cord blood transplant was performed at a median of 5.5 years (range 3.5-10 years). Six donors were HLA-identical; three were one- to three-antigen mismatched. The mean number of nucleated cells infused was 6.6 x 10(7)/kg (range 3.4-12.7); the mean number of CD34+ cells infused was 3.8 x 10(5)kg (range 0.6-11.7). Seven patients had engraftment of donor cells. The median number of days to achieve a neutrophil count of > 0.5 x 10(9)/L was 19 days (range 10-25); the median number of days to achieve a platelet count of > 20 x 10(9)/L was 33 days (range 19-63). Of the six patients who received HLA-identical transplants, one developed grade 2 and two developed grade 1 acute graft-versus-host disease. Two of the three patients receiving mismatched cord blood did not achieve engraftment, and the other one engrafted but developed grade 4 acute graft-versus-host disease. Two patients subsequently developed secondary graft rejection and had autologous marrow regeneration before day 60 posttransplantation. With a median follow-up of 49 months (range 38-64), eight patients survived but only four were transfusion-independent. Umbilical cord blood transplant appears to have a higher chance of nonengraftment and secondary rejection. A more intensive immunosuppressive conditioning regimen may be required.

Adolescent↗

PubMed2004

Ubiquitin-fusion degradation pathway plays an indispensable role in naked DNA vaccination with a chimeric gene encoding a syngeneic cytotoxic T lymphocyte epitope of melanocyte and green fluorescent protein.

Antitumour immunity against murine melanoma B16 was achieved by genetic immunization with a naked chimeric DNA encoding a fusion protein linking green fluorescent protein (GFP) to the N-terminus of a major CD8(+) cytotoxic T lymphocyte (CTL) epitope of tyrosinase-related protein 2 (TRP-2(181-188)) of murine melanoma, designated as pGFP-TRP-2. Tumour growth was profoundly suppressed in C57BL/6 mice immunized with pGFP-TRP-2, while mice vaccinated with pTRP-2 showed rapid tumour growth and died within 40 days after tumour challenge. Splenocytes of mice immunized with pGFP-TRP-2 showed high CTL activity specific for TRP-2(181-188). GFP-TRP-2 expressed in COS-7 cells was rapidly degradated in vitro and the degradation was almost completely prevented by adding a proteasome inhibitor, MG-132, in the culture. Furthermore, the antimelanoma immunity induced by genetic immunization with pGFP-TRP-2 was completely cancelled in mice deficient in proteasome activator PA28alpha/beta. Taken together, GFP-TRP-2 processed by cytosolic proteasome played a central role in breaking peripheral tolerance to a melanoma/melanocyte antigen, TRP-2(181-188), by activating CD8(+) CTL specific for TRP-2(181-188). TRP-2(181-188) fused to GFP may be readily cut off from GFP by the ubiquitin-fusion degradation (UFD) pathway and efficiently presented to major histocompatibility complex class I molecules, resulting in effective induction of CD8(+) T cells specific for the CTL epitope. Furthermore, CD4(+) T cells specific for GFP were shown to play a crucial role in the antimelanoma immunity, probably potentiating activity of TRP-2-specific CTL and/or the "ubiquitin-proteasome pathway". It is noteworthy to document that genetic immunization with pGFP plus pTRP-2(181-188) failed to exert the antitumour immunity.

Animals↗

PubMed2004

Identification of specific peptide ligands for B-lymphoma cell and its effect on tyrosine phosphorylation and cell apoptosis.

OBJECTIVE: To search novel method for diagnosis and therapy of B-lymphoma, specific small molecular peptide ligands against binding site of tumor cells were screened and its effects on signal transduction and cell apoptosis were tested. METHODS: Specific peptide ligands were screened by binding with site of human B lymphoma cell (OC1LY8) using peptide-bead libraries. The identified peptides were characterized with responsible cells by rebinding test. The role of tyrosine phosphorylation of peptide ligand was tested by Western blot; and its apoptosispromoting role was observed by confocal fluorescent microscope. RESULTS: Specific peptide ligand was able to bind specifically to site on cell surface and enter into cytoplasm. Tetrameric peptide ligand was able to strongly trigger signal transduction resulting in tyrosine phosphorylation and cellular apoptosis in OC1LY8 cell line. CONCLUSION: Screened peptide ligand can effectively bind with OC1LY8 cell, stimulate cellular tyrosine phosphorylation and induce cellular apoptosis.

Amino Acid Sequence↗

PubMed2004

Experimental study on the mechanism of sex difference in the risk of torsade de pointes.

BACKGROUND: Torsade de pointes (TdP) is a form of polymorphic ventricular tachycardia featuring prolonged QT intervals. Female gender is associated with an increased risk of TdP. However, the causes of the sex difference in risk are poorly understood. Recently, transmural dispersion of repolarization (TDR) has been implicated in the genesis of TdP. Consequently, we compared TdP incidence and TDR between male and female rabbit hearts in order to investigate the mechanism of sex difference in TdP risk in rabbits in vitro. METHODS: By means of monophasic action potential recording techniques, the monophasic action potential of the epicardium, midmyocardium, and endocardium were simultaneously recorded using specially designed plunge-needle electrodes placed across the left ventricular free wall of both female (n = 8) and male (n = 8) rabbit hearts purfused by the Langendorff method. TdP was induced by bradycardia, d-sotalol, and low-K+, Mg2+ Tyrode solution. RESULTS: TDR measurements in all three myocardial layers of male and female rabbit hearts were (18 +/- 2) ms and (21 +/- 2) ms, respectively (n = 8, P > 0.05). After perfusion with d-sotalol, the 90% monophasic action potential duration was prolonged in both male and female rabbits. TDR in male and female rabbit hearts increased to (29 +/- 2) ms and (61 +/- 2) ms, respectively, a difference that is significant. Eight female rabbit hearts had early afterdepolarization and 7 of them developed TdP. Seven male rabbit hearts had early after depolarization, but only one of these hearts developed TdP. CONCLUSION: Greater TDR may play an important role in the higher incidence of TdP in female rabbit hearts.

Action Potentials↗

PubMed2004

[Effects of TGF beta 1 on the cell cycle of irradiated human lung fibroblasts and its signal transduction mechanism].

AIM: To investigate the effects of TGF beta 1 on the proliferative activity and cell cycle of normal and gamma ray-irradiated human lung fibroblasts (HLFs). METHODS: HLFs were cultured and irradiated with 3Gy gamma rays and then stimulated by TGF beta 1 at 0.01, 0.1, 1 and 10 microg/L. The proliferative activity and cell cycle were detected by MTT colorimetry and FACS. Furthermore, the expressions of signal proteins Smad3/4 in HLFs were observed by immunohistochemical staining and FACS. RESULTS: TGF beta 1 of 10 microg/L could promote the proliferation of HLFs, with the number of cells in S phase increased. It also could enhance the expression of Smad3 protein and promote the nuclear translocation of Smad4 protein. CONCLUSION: A given dose of TGF beta 1 can promote the proliferation of gamma rays-irradiated HLFs by regulating their cell cycle in which the activation of Smad pathway may play a role.

Cell Cycle↗

PubMed2004

[Expansion of CIK/NK cells from cord blood by using different combinations of stem cell factor, FLT3 ligand and interleukin 2, 7, 15 in vitro].

To explore the efficacy of the different combinations of stem cell factor (SCF), FLT3 ligand (FL) and interleukin (IL) 2, 7, 15 on the induction and expansion of cord blood (CB) derived CIK/ NK cells in vitro, according to the different combinations of cytokines, combinations of cytokines were divided into 3 groups: group A (SCF + IL2 + IL7 + IL15), group B (SCF + FL + IL2 + IL7 + IL15) and group C (IL2 + IL7 + IL15 as control group). At 21 days of culture, the proportion and the expansion rate of CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells were measured. The results showed that at 21 days in culture, the percentages of CD3(+)CD56(+) CIK cells derived from CB-MNC in group A, B and C were (19.84 +/- 2.93)%, (26.20 +/- 4.05)%, (24.03 +/- 4.99%) and that of NK cells were (49.60 +/- 1.40)%, (51.16 +/- 6.45)% and (30.85 +/- 8.12)%, respectively. The proliferation of CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells was the most effective in group B (SCF + FL + IL2 + IL7 + IL15). Expansion multiple of CIK cell number increased from 575.81 +/- 221.72 (control) to 796.09 +/- 278.47 with peak value of 1 313, and that of NK cells increased from 30.39 +/- 14.47 (control) to 65.85 +/- 30.83 with peak value of 121.06. In conclusion, a proper cytokines (SCF + FL + IL2 + IL7 + IL15) culture system can effectively induce and expand CB CD3(+)CD56(+) CIK cells and CD3(-)CD56(+) NK cells simultaneously.

CD3 Complex↗

PubMed2004

Analysis of human transforming growth factor beta-induced gene mutation in corneal dystrophy.

BACKGROUND: Corneal dystrophy is a group of inherited blinding diseases of the cornea. This study was to identify the mutations of the keratoepithelin (KE) gene for proper diagnosis of corneal dystrophy. METHODS: Three families with corneal dystrophy were analysed. Thirteen individuals at risk for corneal dystrophy in family A, the proband and her son in family B, and the proband in family C were examined after their blood samples were obtained. Mutation screening of human transforming growth factor beta-induced gene (BIGH3 gene) was performed. RESULTS: Five individuals in family A were found by clinical evaluation to be affected with granular corneal dystrophy and carried the BIGH3 mutation W555R. However, both probands in families B and C, also diagnosed with granular corneal dystrophy, harboured the BIGH3 mutation R124H. CONCLUSION: Molecular genetic analysis can improve accurate diagnosis of corneal dystrophy.

Adolescent↗

PubMed2004

Differentially expressed protein markers in human submandibular and sublingual secretions.

Proteome analysis of secretions from individual salivary glands is important for understanding the health of the oral cavity and pathogenesis of certain diseases. However, cross-contamination of submandibular (SM) and sublingual (SL) glandular secretions can occur. The close anatomic relationship of the SM and SL ductal orifices can lead to such contamination. Additionally, these glands may share common ducts. To insure the purity of SM/SL secretions for proteomic analysis, it is important to develop unique biomarkers which could be used to verify the integrity of the individual glandular saliva. In this study, a proteomics approach based on mass spectrometry and gel electrophoresis techniques was utilized to identify and verify a set of proteins (cystatin C, calgranulin B and MUC5B mucin), which are differentially expressed in SM/SL secretions. SM/SL fluids were obtained from nine healthy subjects. Cystatin C was found to be an SM-selective protein as it was found in all SM fluids but not detected in two SL fluids. MUC5B mucin and calgranulin B, on the other hand, were found to be SL-selective proteins. All SL samples contained MUC5B mucin, whereas MUC5B mucin was not detected in four SM samples. Eight of the SL samples contained calgranulin B; however, calgranulin B was absent in eight SM samples. This set of protein markers, especially calgranulin B, can be used to determine the purity of SM/SL samples, and therefore identify potential individuals who do not exhibit cross-contaminated SM/SL secretions, an important requirement for subsequent proteome analysis of pure SM and SL secretions.

Adult↗

PubMed2004

[Progress in researches on A-kinase anchor proteins in sperm].

This article reviews the advances in the studies of A-kinase anchor proteins (AKAPs) in sperm, including their classification, structure and mechanism. The influence of AKAPs that are involved on sperm mobility and acrosome reaction is emphasized. We hope it could play a directive role in the studies of AKAPs that are involved in regulating sperm mobility and acrosome reaction.

A Kinase Anchor Proteins↗

PubMed2004

Effects of imidapril on heterogeneity of action potential and calcium current of ventricular myocytes in infarcted rabbits.

AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique. RESULTS: The action potential duration of repolarization 90 % (APD90) was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of I(Ca-L) [was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measured. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

Action Potentials↗