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Biomedical subjects

Li Zhang

Publications and source records attributed to Li Zhang.

At least 199 records · Page 11Linked to original sources
PubMed2006

Antitumor activities of D-glucosamine and its derivatives.

The growth inhibitory effects of D-glucosamine hydrochloride (GlcNH(2).HCl), D-glucosamine (GlcNH(2)) and N-acetyl glucosamine (NAG) on human hepatoma SMMC-7721 cells in vitro were investigated. The results showed that GlcNH(2).HCl and GlcNH(2) resulted in a concentration-dependent reduction in hepatoma cell growth as measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. This effect was accompanied by a marked increase in the proportion of S cells as analyzed by flow cytometry. In addition, human hepatoma SMMC-7721 cells treated with GlcNH(2).HCl resulted in the induction of apoptosis as assayed qualitatively by agarose gel electrophoresis. NAG could not inhibit the proliferation of SMMC-7721 cells. GlcNH(2).HCl exhibited antitumor activity against Sarcoma 180 in Kunming mice at dosage of 125-500 mg/kg, dose of 250 mg/kg being the best. GlcNH(2).HCl at dose of 250 mg/kg could enhance significantly the thymus index, and spleen index and could promote T lymphocyte proliferation induced by ConA. The antitumor effect of GlcNH(2).HCl is probably host-mediated and cytocidal.

Animals↗
PubMed2006

Mesenchymal stem cell-organized bone marrow elements: an alternative hematopoietic progenitor resource.

Bone marrow-derived mesenchymal stem cells (BMMSCs) are multipotent postnatal stem cells that have been used for the treatment of bone defects and graft-versus-host diseases in clinics. In this study, we found that subcutaneously transplanted human BMMSCs are capable of organizing hematopoietic progenitors of recipient origin. These hematopoietic cells expressed multiple lineages of hematopoietic cell associated markers and were able to rescue lethally irradiated mice, with successful engraftment in the recipient, suggesting a potential bone marrow (BM) resource for stem cell therapies. Furthermore, we found that platelet-derived growth factor (PDGF) promotes the formation of BMMSC-generated BM niches through upregulation of beta-catenin, implying that the PDGF pathway contributes to the formation of ectopic BM. These results indicate that the BMMSC-organized BM niche system represents a unique hematopoietic progenitor resource possessing potential clinical value.

Animals↗
PubMed2006

The co-existence of two growth hormone receptors in teleost fish and their differential signal transduction, tissue distribution and hormonal regulation of expression in seabream.

Two genomic contigs of putative growth hormone receptors (GHRs) were identified in fugu and zebrafish genomes by in silico analysis, suggesting the presence of two GHR subtypes in a single teleost species. We have tested this hypothesis by cloning the full-length cDNA sequence of a second GHR subtype from the black seabream in which the first GHR subtype had been previously reported by us. In addition, we had also cloned the sequences of both GHR subtypes from two other fish species, namely the Southern catfish and the Nile tilapia. Phylogenetic analysis of known GHR sequences from various vertebrates revealed that fish GHRs cluster into two distinct clades, viz. GHR1 and GHR2. One clade (GHR1), containing 6 to 7 extracellular cysteine residues, is structurally more akin to the non-teleost GHRs. The other clade (GHR2), containing only 4 to 5 extracellular cysteine residues, is unique to teleosts and is structurally more divergent from the non-teleost GHRs. In addition, we had examined the biological activities of both GHR subtypes from seabream using a number of reporter transcription assays in cultured eukaryotic cells and demonstrated that both of them were able to activate the Spi 2.1 and beta-casein promoters upon receptor stimulation in a ligand specific manner. In contrast, only GHR1 but not GHR2 in seabream could trigger the c-fos promoter activity, indicating that the two GHR subtypes possess some differences in their signal transduction mechanisms. Also, the expression of GHR2 is significantly higher than GHR1 in many tissues of the seabream including the gonad, kidney, muscle, pituitary and spleen. In vivo hormone treatment data indicated that cortisol upregulated hepatic GHR1 expression in seabream but not GHR2, whereas testosterone decreased hepatic GHR2 expression but not GHR1. On the other hand, hepatic expression of both GHR1 and GHR2 in seabream was decreased by estradiol treatment.

Amino Acid Sequence↗
PubMed2006

Alteration of dissolved cadmium and zinc uptake kinetics by metal pre-exposure in the Black Sea bream (Acanthopagrus schlegeli).

We first examined the uptake kinetics of Cd and Zn in the juvenile marine black sea bream (Acanthopagrus schlegeli) over a wide range of ambient Cd and Zn concentrations, and the relationships with metal accumulation (uptake rate and amount of nonexchangeable surface binding) were established for different fish tissues. Both Cd and Zn accumulation in the body increased linearly with exposure time after the initial metal surface binding. The dissolved Cd and Zn uptake rate constants were 2.64 and 6.50 L/kg/d, respectively, and the kinetics followed a first-order process. No evidence of biphasic transport was found, in contrast to the situation in freshwater fish. Viscera were the most important sites of metal uptake, and gills were the second most important sites. The black sea breams were then acclimated at different Cd or Zn concentrations from either waterborne or dietary source for one week, and the alteration of metal uptake kinetics or subcellular distribution and metallothionein (MT) induction were further quantified. The Cd body burden was enhanced up to 8.6- and 49-fold after waterborne and dietary Cd pre-exposure, respectively. Cadmium pre-exposure also altered the tissue-specific subcellular Cd distribution and significantly elevated tissue MT levels. In contrast, the black sea breams were able to regulate Zn accumulation, and waterborne or dietary Zn pre-exposure had only weak influences on Zn body burden and redistribution. Both Cd and Zn pre-exposures enhanced the metal uptake rate constants, whereas the nonexchangeable surface bindings were less impacted by these pre-exposures. We demonstrated a positive relationship between the Cd uptake rate and Cd or MT concentration in the fish. Pre-exposure to metals may substantially modify the kinetics of metal uptake.

Animals↗
PubMed2006

[Protective effect of rosiglitazone on myocardium in diabetic cardiomyopathy of rats].

OBJECTIVE: To investigate the protective effect of PPARgamma ligands rosiglitazone on myocardium in diabetic cardiomyopathy of rats. METHODS: The rat model of diabetes was induced by administration of streptozotocin (STZ) for 6 or 10 weeks. In the treatment group the STZ-induced diabetic rats were treated with rosiglitazone. The left ventricular muscle specimens were taken from treatment and control group; then were examined under transmission electron microscope. RESULT: Cardiac myofibrils of diabetic rats in control group were obviously fewer and broken. There were fewer and smaller dissolved mitochondria with incomplete membrane and mixed cristae and karyopyknosis. Myocardium of diabetic rats treated with rosiglitazone was markedly improved although their blood glucose levels were still high. CONCLUSION: Hyperglycemia can cause destruction of myocardial cell structure. Rosiglitazone has protective effect on myocardial cells of diabetic rats, which seems to be independent of blood glucose levels.

Animals↗
PubMed2006

[Correlation between integrin subunits alpha5 and beta1 expressions in prostate cancer and its clinical implication].

OBJECTIVE: To explore the correlation between the expression of integrin subunits alpha5 and beta1 in prostate cancer (PCa) and its clinicopathological data including tumor grade and clinical stage. METHODS: Expressions of integrin subunits alpha5 and beta1 were examined in 30 cases of PCa and 30 cases of normal prostatic tissues by immunohistochemical assay. RESULTS: Expressions of integrin subunits alpha5 and beta1 in PCa were lower than those in normal prostatic tissues (P <0.05) respectively. CONCLUSION: Compared with normal prostatic tissues, expressions of integrin subunits alpha5 and beta1 in PCa were rather weaker or even faded. Expressions of integrin subunits alpha5 and beta1 revealed an positive correlation with tumor's Gleason grade and negative with clinical TNM stage. The results indicate that integrin subunits alpha5 and beta1 have potential values in the diagnosis and are predictable indices in the proliferation of PCa.

Aged↗
PubMed2006

Treatment of embolic stroke in rats with bortezomib and recombinant human tissue plasminogen activator.

Stroke elicits a progressive vascular dysfunction, which contributes to the evolution of brain injury. Thrombolysis with tissue plasminogen activator (tPA) promotes adverse vascular events that limit the therapeutic window of stroke to three hours. Proteasome inhibitors reduce vascular thrombotic and inflammatory events, and consequently protect vascular function. The present study evaluated the neuroprotective effect of bortezomib, a potent and selective inhibitor of the proteasome, alone and in combination with delayed thrombolytic therapy on a rat model of embolic focal cerebral ischemia. Treatment with bortezomib reduces adverse cerebrovascular events including secondary thrombosis, inflammatory responses, and blood brain barrier (BBB) disruption, and hence reduces infarct volume and neurological functional deficit when administrated within 4 h after stroke onset. Combination of bortezomib and tPA extends the thrombolytic window for stroke to 6 h, which is associated with the improvement of vascular patency and integrity. Real time RT-PCR of endothelial cells isolated by laser-capture microdissection from brain tissue and Western blot analysis showed that bortezomib upregulates endothelial nitric oxide synthase (eNOS) expression and blocks NF-kappaB activation. These results demonstrate that bortezomib promotes eNOS dependent vascular protection, and reduces NF-kappaB dependent vascular disruption, all of which may contribute to neuroprotection after stroke.

Animals↗
PubMed2006

[The preotective effects of total glycosides Rubus parviflolius on cerebral ischemic in rat].

OBJECTIVE: To observe the protective effects of total glycosides Rubus parviflolius (TGRP) on local cerebral ischemic. METHOD: The local cerebral ischemia in rat was made by middle cerebral artery occlusion(MACO). The infraction weight was determined by TTC stain. SOD, MDA, GSH and apoptotis were determined with different method respectively. RESULT: TGRP 20, 10 mg x kg(-1) ig markedly improved the abnormal nervous symptoms, incredsed the SOD, GSH activity and reduced contentes of MDA in brain of MACO rat, TGRP 20 mg x kg(-1) ig significantly decreased the numbers of apoptotic cells in ischemic cortex. CONCLUSION: TGRP has protective effects against cerebral infraction, and its mechanism may be related to anti-apoptotis and free radical.

Animals↗
PubMed2006

[PCR-RFLP analysis on Roegneria, Elymus, Hystrix and Kengyilia in Triticeae (Poaceae)].

PCR-RFLP of Plasmon on 23 species of Roegneria, Elymus, Hystrix and Kengyilia and 1 outgroup (Triticum aestivum L.) was carried out. The segments amplified with 3 cpDNA and 3 mtDNA universal primers were digested by 15 restriction endonucleases. Among 329 bands produced, 304 were polymorphic (92.4%). PCR-RFLP results showed that polymorphisms existed between the four genera and between the species in Roegneria, Elymus, Hystrix and Kengyilia, and genetic similarity coefficient was high. Roegneria grandis, R. aristiglumis, R. elytrigioides, R. alashanica and R. magnicaespes were grouped, while R. caucasica, R. ciliaris, R. amurensis and R. japonensis clustered together. Species of Kengyilia clustered independently. Five species of Elymus, 3 of Hystrix and Roegneria kamoji grouped together. The results suggested Kengyilia was a valid genus. As more cytological and molecular data are available, the taxonomic status of Roegneria, Elymus and Hystrix will be recognized.

DNA Primers↗
PubMed2006

[The effects of glutathione S-transferase (GSTT1 and GSTM1) genes polymorphisms on treatment efficacy and prognosis of acute myeloid leukemia].

OBJECTIVE: To investigate the impact of GSTT1 and GSTM1 genotypes on response, drug side effects and prognosis of acute myeloid leukemia (AML). METHODS: GSTT1 and GSTM1 genotypes were analysed in 180 AML patients with PCR. Complete remission (CR) rate, drug side-effects, overall survival, relapse-free survival and relapse rate were compared in groups with or without GSTT1 and GSTM1 genes. RESULTS: (1) The CR rate (96.9%) in GSTT1 and GSTM1 genes double-present patients was significantly higher than that in patients of GSTT1 null or GSTM1 null (CR rate 78.0%) (P = 0.013). The risk of failure to achieve CR in patients with GSTT1 null/GSTM1 null is 8.736 times higher than that in patients with GSTT1 and GSTM1 genes double-present (odds ratio OR was 8.736, 95% CI was 1.146 - 66.574). The CR rate (88.4%) in GSTT1 present patients was also significantly higher than that in patients of GSTT1 null (CR rate 74.7%) (P = 0.021, OR = 2.572, 95% CI 1.136 - 5.826). (2) There was no significant relationship between GSTT1/GSTM1 genotypes and the lasting time of neutrophilic granulocyte (ANC) < 0.5 x 10(9)/L and PLT < 20 x 10(9)/L. The risk of ALT abnormality in patients with GSTM1 null is 2.593 times higher than that in patients with GSTM1 present (P = 0.016, 95% CI 1.176 - 5.717). (3) Overall survival and relapse-free survival of GSTT1 and GSTM1 double-present patients were significantly better than those in patients of GSTT1 null/GSTM1 null (mean overall survival was 68.4 months vs 38.5 months, P = 0.028, and mean relapse-free survival was 73.5 months vs 34.9 months, P = 0.014, respectively). Relapse-free survival in GSTT1 null patients was significantly shorter than that in patients with GSTT1 present (26.7 months vs 64.3 months, P = 0.038), but there was no significant difference of overall survival between the two groups. The relapse rate of double-present patients was significantly lower than that of GSTT1 null/GSTM1 null patients (13.3% vs 35.6%, P = 0.019). CONCLUSION: GSTT1 and GSTM1 genotypes were apparently related with response, drug side effects and prognosis of patients with AML. GSTT1 and GSTM1 genotype might be useful in selecting appropriate chemotherapy regimens for patients with AML.

Adolescent↗
PubMed2006

[Upregulated Rho-kinase and increased phosphorylation of myosin-binding subunit of myosin phosphates are key players in a porcine coronary artery spasm model with interleukin-1beta].

OBJECTIVE: Phosphorylation of myosin light chain (MLC) is one of the most important steps for vascular smooth muscle contraction and Rho-kinase is involved in this process. We investigated the role of Rho-kinase in a porcine coronary artery spasm model with interleukin-1beta. METHODS: Segments of left coronary artery adventitia were surrounded by normal saline (n = 8) or IL-1beta agarose microne (n = 8) for 2 weeks. Vasospastic responses to intracoronary serotonin or histamine then studied at the saline or IL-1beta-treated site. The Rho-kinase mRNA expression in the treated site was measured by reverse transcription-polymerase chain reaction analysis (RT-PCR). The extent of phosphorylation of myosin-binding subunit of myosin phosphates (MBS, one of the major substrates of Rho-kinase) were quantified by Western blot analysis. RESULTS: Intracoronary serotonin or histamine repeatedly induced coronary artery spasm and coronary arterial stenosis was evidenced at IL-1beta-treated site. Expression of Rho-kinase mRNA in IL-1beta-treated site was significantly increased compared to saline treated site (98.20% +/- 7.66% vs. 63.70% +/- 4.26%, P < 0.05). Western blot analysis showed that during the serotonin-induced contractions the extent of phosphorylation of MBS was also significantly increased in the spastic site (25,485 +/- 4745 vs. 6510 +/- 779, P < 0.05). CONCLUSION: Rho-kinase upregulation at the spastic site and increased phosphorylation of myosin-binding subunit of myosin phosphates are key players in inducing vascular smooth muscle hypercontraction in this porcine model.

Animals↗
PubMed2006

[Digital pulse wave analyzing method in evaluating arterial compliance based on population study in Chinese 415 adults].

OBJECTIVE: To explore the reliability and validity of digital pulse wave analyzing method in evaluating arterial compliance in population-based study. METHODS: All 415 adults (132 men and 283 women) aged 20 to 86 years old were selected from urban (220 persons) and rural (195 persons) areas, respectively by a stratified randomly sampling method. Arterial compliance, evaluated by stiffness index (SI), was measured by using digital pulse wave analyzing method from the Pulse trace machine (Micro medical, London), and the SI value was determined accordingly. RESULTS: In the study on both repeatability and stability, there was a perfect correlation between the frequent measurements for one individual either on one occasion or on two 40-days-apart occasions. The SI values were not significantly different between the urban and the rural, men and women. Multiple stepwise regressions showed that systolic blood pressure and age were positively correlated with SI value, respectively (both P values were less than 0.001). The correlation kept unchanged after taking account of gender, BMI and heart rate. The mean SI values for people aged 20 to 29, 30 to 39, 40 to 49, 50 to 59 and > or = 60 were 7.35, 8.84, 10.41, 10.95 and 12.01 m/s (P < 0.01), respectively. CONCLUSIONS: Both systolic blood pressure and age should be contributed as the main influencing factors of arterial compliance. Digital pulse wave analyzing method is a preferable measurement in evaluating arterial compliance in population-based study due to its better repeatability and stability.

Adult↗
PubMed2006

[Cloning of major outer membrane protein gene of Legionella pneumophila and detection of its expression in prokaryotic cell].

In this study, the ompS gene, a major outer membrane protein gene of Legionella pneumophila, was obtained from the DNA of Legionella pneumophila by PCR. The gene was cloned into prokaryotic expressional plasmid pUC18 to construct recombinant plasmid. The recombinant plasmid was transformed into E. coli strain BL21. The identification was made by means of restriction enzyme analysis, polymerase chain reaction, DNA sequencing analysis, SDS--polyacrylamine gel electrophoresis analysis and Western blot. The results showed that the ompS gene of 914 bp was amplified from Legionella pneumophila DNA, the recombinant plasmid pLPompS was constructed and its expression in prokaryotic cell was detected successfully.

Amino Acid Sequence↗
PubMed2006

[Significance of EGFR and p-ERK expression in nasopharyngeal carcinoma].

OBJECTIVE: To detect the expression of EGFR and p-ERK in nasopharyngeal carcinoma (NPC) and investigate their clinical significance. METHODS: Immunohistochemistry LSAB method was adopted to detect the expression of EGFR and p-ERK. Statistical analysis was performed using SPSS statistical software package (10.0) to correlate their expression with clinical characteristics and prognosis. RESULTS: Positive staining for EGFR was observed in 39 of 55 cases (70.9%). The EGFR expression was correlated with clinical stage and gender. EGFR expression was correlated with poorer overall survival (OS) and shorter time to progression (TTP). Positive staining for p-ERK was observed in 29 of 55 cases (52.7%). There was a statistically significant association between positive p-ERK expression and advanced clinical stage. Positive p-ERK expression was correlated with poorer OS, disease-free survival (DFS) and TTP. EGFR expression was correlated with the expression of p-ERK. On multivariate analysis, age over 50 years was an independent poor prognostic factor for NPC. Both EGFR and p-ERK were not independent prognostic factors for NPC. CONCLUSION: Expressions of EGFR and p-ERK are detected in NPC. Their abnormally high expression signifies poor prognosis in NPC patients.

Age Factors↗
PubMed2006

[Level of urocortin mRNA during labor and effect of urocortin on myometrial contractility in vitro].

OBJECTIVE: To examine the expression of urocortin mRNA during labor and the effect of urocortin on myometrial contractility, and to investigate its role in the onset and progress of labor. METHODS: (1) Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), using beta-actin as internal standard was applied to determine the levels of urocortin mRNA in human placenta and myometrium from the group of cesarean section before (10 cases) and during (10 cases in latent phase and 10 cases in active phase) labor. (2) The isolated myometrial strips of pregnant women (n = 24) were prepared. The effects of urocortin with or without prostaglandin F(2alpha) (PGF(2alpha)) and oxytocin on myometrial contractility were evaluated by areas under the curve. RESULTS: (1) Semi-quantitative RT-PCR showed that the expression level of urocortin mRNA in placenta and myometrium after the onset of labor were higher than before labor (1.23 +/- 0.52, 1.32 +/- 0.22; 0.83 +/- 0.38, 0.94 +/- 0.13, respectively, P < 0.05). (2) Urocortin itself did not affect myometrial tension development at all concentrations tested, but it markedly increased PGF(2alpha)-induced myometrial contractility. The average area under the curve of controls was (2.12 +/- 0.15) cm(2) and of study strips was (3.90 +/- 0.33) cm(2) (P < 0.05); urocortin did not increase the myometrial response to oxytocin compared with controls (P > 0.05). CONCLUSION: The study indicates urocortin may indirectly modulate myometrial contractility during labor.

Adult↗
PubMed2006

[Study on the association between estrogen receptor alpha gene polymorphism and intrahepatic cholestasis of pregnancy].

OBJECTIVE: To investigate the relationship between estrogen receptor alpha (ERalpha) gene polymorphism and intrahepatic cholestasis of pregnancy (ICP). METHODS: The Xba I and Pvu II polymorphisms in intron 1 of ER alpha gene were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in 100 pregnant women with ICP (ICP group) and 100 normal pregnant women (control group). RESULTS: (1) The frequencies of XX, Xx and xx genotypes of Xba I polymorphism were 6%, 33% and 61% respectively in control group, and were 2%, 33% and 65% respectively in ICP group. There was no significant difference in the distribution of Xba I genotypes between the two groups (P > 0.05). The frequencies of the two alleles X and x were 23% and 78% in control group, and were 19% and 82% in ICP group, respectively. There was also no significant difference in the frequency of Xba I alleles between the two groups (P > 0.05). (2) The frequencies of PP, Pp and pp genotypes of Pvu II polymorphism were 18%, 42% and 40% respectively in control group, and were 12%, 53% and 35% respectively in ICP group. There was no significant difference in the distribution of Pvu II genotypes between the two groups (P > 0.05). The frequencies of the two alleles P and p were 39% and 61% in control group, and were 39% and 62% in ICP group, respectively. There was also no significant difference in the frequency of Pvu II alleles between the two groups (P > 0.05). (3) There was also no significant difference in the distribution of Xba I and Pvu II combinative genotype between the two groups (P > 0.05). CONCLUSION: The ERalpha gene polymorphism is not associated with the risk of ICP.

Adult↗
PubMed2006

[Effects of rapamycin on Rho-kinase and p27 mRNA expressions in a porcine coronary intimal proliferation model induced by interleukin-1beta].

OBJECTIVE: To observe the effects of rapamycin on the expressions of Rho-kinase and p27 mRNA during vascular intimal proliferation in a porcine model of coronary stenosis induced by interleukin-1beta (IL-1beta). METHODS: The proximal segments of LAD and LCX were wrapped with cotton mesh that had absorbed sepharose bead solution with or without IL-1beta. Selective coronary angiography was performed two weeks later and the animals were killed for collecting the samples for histopathology and RT-PCR analyzing of Rho-kinase and p27 mRNA. RESULTS: The expressions of Rho-kinase and p27 mRNA could be visualized in normal coronary wall. The expression of Rho-kinase mRNA was significantly enhanced and the expression of p27 mRNA was significantly decreased during the process of intimal proliferation induced by IL-1beta. Rapamycin significantly inhibited the intimal proliferation, reduced the infiltration of inflammatory cells, reduced the expression of Rho-kinase mRNA and increased the expression of p27 mRNA. CONCLUSIONS: The expression of Rho-kinase mRNA is upregulated and p27 mRNA downregulated in coronary artery stenosis induced by IL-1beta and these effects could be abolished by cotreatment with rapamycin.

Animals↗