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Biomedical subjects

Lei Zhao

Publications and source records attributed to Lei Zhao.

At least 73 records · Page 4Linked to original sources

Resveratrol and estradiol rapidly activate MAPK signaling through estrogen receptors alpha and beta in endothelial cells.

Vascular endothelial cells (EC) are an important target of estrogen action through both the classical genomic (i.e. nuclear-initiated) activities of estrogen receptors alpha and beta (ERalpha and ERbeta) and the rapid "non-genomic" (i.e. membrane-initiated) activation of ER that stimulates intracellular phosphorylation pathways. We tested the hypothesis that the red wine polyphenol trans-resveratrol activates MAPK signaling via rapid ER activation in bovine aortic EC, human umbilical vein EC, and human microvascular EC. We report that bovine aortic EC, human umbilical vein EC, and human microvascular EC express ERalpha and ERbeta. We demonstrate that resveratrol and estradiol (E(2)) rapidly activated MAPK in a MEK-1, Src, matrix metalloproteinase, and epidermal growth factor receptor-dependent manner. Importantly, resveratrol activated MAPK and endothelial nitric-oxide synthase (eNOS) at nm concentrations (i.e. an order of magnitude less than that required for ER genomic activity) and concentrations possibly achieved transiently in serum following oral red wine consumption. Co-treatment with ER antagonists ICI 182,780 or 4-hydroxytamoxifen blocked resveratrol- or E(2)-induced MAPK and eNOS activation, indicating ER dependence. We demonstrate for the first time that ERalpha-and ERbeta-selective agonists propylpyrazole triol and diarylpropionitrile, respectively, stimulate MAPK and eNOS activity. A red but not a white wine extract also activated MAPK, and activity was directly correlated with the resveratrol concentration. These data suggest that ER may play a role in the rapid effects of resveratrol in EC and that some of the atheroprotective effects of resveratrol may be mediated through rapid activation of ER signaling in EC.

Angiogenesis Inhibitors↗

Critical role of macrophage 12/15-lipoxygenase for atherosclerosis in apolipoprotein E-deficient mice.

BACKGROUND: Mice lacking leukocyte type 12/15-lipoxygenase (12/15-LO) show reduced atherosclerosis in several models. 12/15-LO is expressed in a variety of cells, including vascular cells, adipocytes, macrophages, and cardiomyocytes. The purpose of this study was to determine which cellular source of 12/15-LO is important for atherosclerosis. METHODS AND RESULTS: Bone marrow from 12/15-LO-/-/apoE-/- mice was transplanted into apoE-/- mice and vice versa. Deficiency of 12/15-LO in bone marrow cells protected apoE-/- mice fed a Western diet from atherosclerosis to the same extent as complete absence of 12/15-LO, although plasma 8,12-iso-iPF2alpha-IV, a measure of lipid peroxidation, remained elevated. 12/15-LO-/-/apoE-/- mice regained the severity of atherosclerotic lesion typical of apoE-/- mice after replacement of their bone marrow cells with bone marrow from apoE-/- mice. Peritoneal macrophages obtained from wild-type but not 12/15-LO-/- mice caused endothelial activation in the presence of native LDL. Absence of 12/15-LO decreased the ability of macrophages to form foam cells when exposed to LDL. CONCLUSIONS: We conclude that macrophage 12/15-LO plays a dominant role in the development of atherosclerosis by promoting endothelial inflammation and foam cell formation.

Animals↗

KIAA0008 gene is associated with invasive phenotype of human hepatocellular carcinoma--a functional analysis.

PURPOSE: To investigate the function of the KIAA0008 gene, one of the leading genes in the signature associated with hepatocellular carcinoma (HCC) metastasis selected by cDNA microarray, and especially its possible roles in invasion and metastasis of hepatocellular carcinoma. METHODS: Expression levels of KIAA0008 in 27 primary tumors and 23 matched non-tumor liver tissues from HCC patients, and four HCC cell lines with different metastatic potentials were detected by semi-quantitative RT-PCR and real-time RT-PCR. Recombinant expression plasmid vectors of the KIAA0008 gene were constructed and transfected into HCC cells. The subcellular localization of the KIAA0008 gene product and in vitro effects of KIAA0008 overexpression on proliferation and invasion of HCC cell line were also investigated. RESULTS: Expression levels of KIAA0008 in HCC tissues were statistically higher than those of paired non-tumorous liver tissues (P < 0.001, paired Wilcoxon test), and in HCCs with high invasiveness these were statistically higher than those with low invasiveness (P = 0.002, Mann-Whitney test). In the four HCC cell lines with an identical genetic background and stepwise higher invasiveness potentials, its expression was consistent with their invasiveness potential. The KIAA0008 gene product was concentrated on the nucleus and cell membrane of HCC cells, without any distribution in the cytoplasm. Overexpression of KIAA0008 in the MHCC97L cell line resulted in increased cell proliferation, colony formation, and invasion. CONCLUSIONS: KIAA0008 expression is associated with invasiveness of HCC; overexpression of KIAA0008 leads to a more invasive phenotype of HCC cell lines.

Adult↗

The 5-lipoxygenase pathway promotes pathogenesis of hyperlipidemia-dependent aortic aneurysm.

Activation of the 5-lipoxygenase (5-LO) pathway leads to the biosynthesis of proinflammatory leukotriene lipid mediators. Genetic studies have associated 5-LO and its accessory protein, 5-LO-activating protein, with cardiovascular disease, myocardial infarction and stroke. Here we show that 5-LO-positive macrophages localize to the adventitia of diseased mouse and human arteries in areas of neoangiogenesis and that these cells constitute a main component of aortic aneurysms induced by an atherogenic diet containing cholate in mice deficient in apolipoprotein E. 5-LO deficiency markedly attenuates the formation of these aneurysms and is associated with reduced matrix metalloproteinase-2 activity and diminished plasma macrophage inflammatory protein-1alpha (MIP-1alpha; also called CCL3), but only minimally affects the formation of lipid-rich lesions. The leukotriene LTD(4) strongly stimulates expression of MIP-1alpha in macrophages and MIP-2 (also called CXCL2) in endothelial cells. These data link the 5-LO pathway to hyperlipidemia-dependent inflammation of the arterial wall and to pathogenesis of aortic aneurysms through a potential chemokine intermediary route.

5-Lipoxygenase-Activating Proteins↗

Epidural anesthesia can protect fibrinolytic function after surgery.

OBJECTIVE: To study the influences of different anesthesia techniques on stress response, coagulation and fibrinolytic function. METHODS: Thirty patients undergoing hysterectomy were randomized into three groups: Group E (continuous epidural anesthesia, n=10), Group G+E (epidural anesthesia combined general anesthesia, n=10) and Group G (general anesthesia, n=10). The blocking level with epidural anesthesia was maintained between T(6)-L(3) with 0.75% bupivacaine followed by Patient Controlled Epidural Analgesia (PCEA). General anesthesia was finished with convention followed by Patient-Controlled Analgesia (PCA). Blood samples were taken at pre-anesthesia (T(0)), the end of operation (T(1)) and postoperative 24 h (T(2)), 72 h (T(3)) to determine catecholamine concentration, coagulation and fibrinolysis variables. RESULTS: The nonepinephrine (NE) levels in Group E and Group G+E were not changed throughout the procedure, but obviously elevated in Group G (P<0.01) as compared with the baseline and those in the other Groups (P<0.05). The epinephrine (E) levels at T(1) in all groups were markedly increased as compared with those at T(0) and peaked (P<0.01), and then returned to the baseline at T(3). Fibrinogen (FIB) levels in all groups were obviously decreased at T(1), postoperatively elevated rapidly and peaked at T(3) (P<0.01). FIB levels at T(3) in groups G+E and G were much higher than that in Group E (P<0.05). The thrombin-anti-thrombin III complex (TAT) levels at T(1) in Group G+E and G were significantly increased as compared with those at Group E (P<0.01), and subsequently recovered to pre-anesthesia following surgery. TAT level in Group E was more decreased postoperatively than the baseline and those in the other groups (P<0.05). The D-dimer level in Group E over time was remarkably increased as compared with the baseline (P<0.05), and the D-dimer levels peaked at T(2) in all groups (P<0.01). The tissue-type plasminogen activator (t-PA) was more elevated than T(0) at T(1) (P<0.01) in all groups, and then returned to normal in Group E. But the marked decrease of t-PA in Groups G+E and G was revealed 72 h after surgery and became much lower than that in Group E (P<0.01). The plasminogen activating inhibitor-1(PAI-1) in Group G and Group G+E was more elevated perioperatively and became higher than that in Group E (P<0.01). CONCLUSION: Epidural anesthesia can preserve fibrinolytic function after lower-abdomen surgery by the inhibitory effects on surgical stress, PAI-1 and other mechanisms. The thromboprophylactic effects are revealed only following epidural anesthesia.

Adult↗

Selenium distribution in a Se-enriched mushroom species of the genus Ganoderma.

Data reported here show that Ganoderma lucidum could biotransform inorganic selenite in the substrate into organic forms by intergrating Se into proteins (56-61%) and polysaccharides (11-18%) and other components. Furthermore, water- and alkaline-soluble protein components were mainly responsible for the storage of organic Se, and Se-Met accounts for only a minor (8.2-18.3%) amount of the selenocompounds present in proteins. The molecular mass of most proteins or protein subunits containing Se was no more than 16 kDa. A low concentration of Se (<100 microg/g) in the substrate facilitated the synthesis of total protein and amino acids in G. lucidum, but a high concentration of Se (>150 microg/g) played a reverse role. Additionally, Se concentration in the culture had no significant effect on the distribution of the amino acids and proteins.

Amino Acids↗

Stepwise metastatic human hepatocellular carcinoma cell model system with multiple metastatic potentials established through consecutive in vivo selection and studies on metastatic characteristics.

PURPOSE: To establish a "stepwise metastatic human hepatocellular carcinoma (HCC) cell model system" for in-depth study of the underlying mechanisms of HCC metastasis. METHODS: Using MHCC97- a metastatic human hepatocellular carcinoma (HCC) cell line reported in 1999-as the parent cells, we subsequently established three cell lines (MHCC97-L, HMCC97-H, and HCCLM3) with increasing spontaneous metastatic potential. Now, the fourth cell line with unique multiple metastatic characteristics has been established by six rounds of in vivo selection. RESULTS: This cell line, designated as HCCLM6, is a polygonal epithelial cell with hypotriploid karyotype, the modal chromosomes are 55-58, and marker chromosomal abnormalities include i(1) (q10), i(8)(q10), der (4) t(4;8)(q31;q22), i(X)(q10). The cell population doubling time was 32 h. Fluorescent PCR showed HBV DNA integration in the cellular genome. Thirty-five days after HCCLM6 was injected subcutaneously into BALB/c nude mice, prominent lung metastases occurred in 100% of the recipient animals. When tumor tissue was orthotopically implanted into the liver of nude mouse, widespread loco-regional and pulmonary metastases occurred. Inoculation of this cell into the footpad of nude mice also produced 75% regional lymph node metastasis. Compared with MHCC97-L which was not metastastatic via subcutaneous or footpad inoculation and 40% metastatic via orthotopic inoculation, HCCLM6 had increased expression of matrix metalloproteinase (MMP-2 and MMP-9) and cytokeratin 19 (CK19), and decreased expression of Rb2/p130. The establishment of this new cell line has completed our stepwise metastatic HCC cell mode system, which was characterized by a similar genetic background but with significant differences in spontaneous metastasis behavior. CONCLUSIONS: The study supports the theory that cancer metastasis is a highly selective dynamic process and the cell model system could be a useful platform for the study of HCC metastasis.

Animals↗

Lipoxygenase pathways in atherogenesis.

15-lipoxygenase-1 (also known as 12/15-LO in mice) and 5-LO/5-LO-activating protein (FLAP) cascades play central roles in low-density lipoprotein oxidation and leukotriene biosynthesis, respectively. Several genetic and expression studies unraveling an association of the 5-LO/FLAP pathway to human cardiovascular disease have surfaced recently. Experimental studies in 12/15-LO knockout, 15-LO-1 transgenic, and 5-LO knockout mice on atherosclerotic backgrounds combined with gene expression data in human coronary artery disease have created compelling links that these pathways participate in the etiologic progression. However, a few conflicting studies and several unexplained mechanistic issues need to be resolved prior to assigning firm roles for LOs in cardiovascular disease. Development of novel pharmacologic tools to dissect the individual enzymes and receptors in the LO pathways should improve understanding of the individual components in the inflammatory aspects of atherosclerosis disease progression.

Animals↗

Modulation of nuclear factor-kappa B activity by indomethacin influences A beta levels but not A beta precursor protein metabolism in a model of Alzheimer's disease.

Epidemiological studies show that some nonsteroidal anti-inflammatory drugs, nonspecific inhibitors of the cyclooxygenase enzyme, reduce the incidence of Alzheimer's disease (AD). We determined the impact of two nonsteroidal anti-inflammatory drugs on A beta levels, deposition, and metabolism in a mouse model (the Tg2576) of AD-like amyloidosis. To this end, mice were treated with indomethacin and nimesulide continuously from 8 months of age until they were 15 months old. At the end of the study, indomethacin significantly reduced A beta(1-40) and A beta(1-42) levels in both cortex and hippocampus. This decrease was coincidental with a significant reduction of the nuclear factor (NF)-kappa B activity. By contrast, nimesulide had no effect on both A beta peptides and NF-kappa B. Consistently, mice receiving indomethacin, but no nimesulide, showed a significant reduction in the amyloid burden compared with placebo. Neither drug had an effect on plasma levels of A beta peptides or the A beta precursor protein metabolism. In vitro studies confirmed that genetic absence of this factor reduces the anti-amyloidogenic effect of indomethacin. These findings indicate that chronic administration of indomethacin by blocking the activation of the NF-kappa B significantly reduces the amyloid pathology in Tg2576 mice, and provide insights into the mechanisms by which this drug could slow progression of AD.

Alzheimer Disease↗

Effect of Zn(II) on the structure and biological activity of natural beta-NGF.

Only beta-NGF, the subunit of the 7S NGF complex, exhibits NGF activity, but the function of the zinc ion in native beta-NGF has received little attention. Flameless atomic absorption spectroscopy (FAAS) measurements reveal that native beta-NGF contains Zn(II) with a Zn(II)/beta-NGF stoichiometry of 1:14.6. The presence of Zn(II) in the native molecule results in significant changes of the secondary structure and local tertiary structure around Trp(s) with respect to those of apo beta-NGF, as suggested by spectra of fluorescence and circular dichrosim. Stopped-flow studies show that there are at least two steps during the interaction of Zn(II) with the apo form. In comparison with its apo form, the native beta-NGF shows a higher ability to trigger the proliferation of TF1 cells and mediate the survival of PC12. Thus it is most likely that the structural changes caused by the presence of Zn(II) directly lead to the increase in the biological activity of beta-NGF. All results indicate that Zn(II) in native beta-NGF plays an important role in the structure and the biological activity of the protein.

Animals↗

[A survey on knowledge and habits of oral health in freshmen of Sichuan University].

OBJECTIVE: To investigate the oral health knowledge and habits of freshmen of Sichuan University and promote the prophylactic therapy of dental diseases in the university. METHODS: The table and the standard on oral health survey authorized by WHO were employed in this study. RESULTS: Only 13.1% of all the investigated freshmen had periodic oral health examination. 74.4% brush teeth twice per day, only 7.7% brush teeth over 3 minutes, 16.6% insist in fluoridated toothpaste, and only 6% had applied dental floss. 51.9% do not often take snack food and 94.7% are non-smokers; (4) Tests of prophylactic therapy of dental caries and periodontal diseases and oral health knowledge have poor results. CONCLUSION: The freshmen have limited knowledge of oral health and lack serious attitude toward oral cleaning behaviors.

Health Knowledge, Attitudes, Practice↗

[Study on extraction process of Radix Bupleuri].

The orthogonal design was used to optimize extraction process of Radix Bupleuri with content of total saponin and yield of the extract as markers. Factors that have been chosen were ethanol concentration, ethanol consumption, extraction times and extraction time. Each factor had three levels. The result showed that the optimum extraction condition was 80% ethanol, 4 times the amount of material, refluxing for 4 times, 60 minutes each time. The optimized process was stable and workable.

Analysis of Variance↗

Mutations in the substrate binding site of thrombin-activatable fibrinolysis inhibitor (TAFI) alter its substrate specificity.

Thrombin-activable fibrinolysis inhibitor (TAFI) is a zymogen that inhibits the amplification of plasmin production when converted to its active form (TAFIa). TAFI is structurally very similar to pancreatic procarboxypeptidase B. TAFI also shares high homology in zinc binding and catalytic sites with the second basic carboxypeptidase present in plasma, carboxypeptidase N. We investigated the effects of altering residues involved in substrate specificity to understand how they contribute to the enzymatic differences between TAFI and carboxypeptidase N. We expressed wild type TAFI and binding site mutants in 293 cells. Recombinant proteins were purified and characterized for their activation and enzymatic activity as well as functional activity. Although the thrombin/thrombomodulin complex activated all the mutants, carboxypeptidase B activity of the activated mutants against hippuryl-arginine was reduced. Potato carboxypeptidase inhibitor inhibited the residual activity of the mutants. The functional activity of the mutants in a plasma clot lysis assay correlated with their chromogenic activity. The effect of the mutations on other substrates depended on the particular mutation, with some of the mutants possessing more activity against hippuryl-His-leucine than wild type TAFIa. Thus mutations in residues around the substrate binding site of TAFI resulted in altered C-terminal substrate specificity.

Amino Acid Sequence↗

Interfacial peptide inhibitors of HIV-1 integrase activity and dimerization.

Peptides derived from the interfacial region of dimeric HIV-1 integrase were evaluated as inhibitors of integrase's 3'-endonuclease activity. Three peptides were found to be moderately potent inhibitors with IC(50) values in the low micromolar range. The mode of inhibition was probed through protein crosslinking experiments. Active interfacial peptides were found to inhibit crosslinking of the dimeric form of integrase. Interfacial peptides that were poor inhibitors had no effect on integrase crosslinking.

Chromatography, High Pressure Liquid↗

Coronary MR angiography: respiratory motion correction with BACSPIN.

PURPOSE: To improve the signal-to-noise ratio (SNR) of breath-held coronary magnetic resonance angiography (CMRA) without increasing the number or duration of breath holds. MATERIALS AND METHODS: In this BACSPIN (Breathing AutoCorrection with SPiral INterleaves) technique, a single breath-held electrocardiogram (ECG)-gated multi-slice interleaved-spiral data set is acquired, followed by repeated imaging of the same slices during free breathing. Each spiral interleaf from the breath-held data set is used as a standard for comparison with corresponding acquisitions at the same interleaf angle during free breathing. The most closely matched acquisitions are incorporated into a multi-slice, multi-average data set with increasing SNR over time. In-plane translations of the coronary artery can be measured and compensated for each accepted acquisition before combination with the other acquisitions. RESULTS: CMRA was performed on six volunteers, with improved SNR and minimal motional blurring. In some cases, breath holding could be dispensed with completely and the average respiratory position used as a reference. CONCLUSION: BACSPIN provides a promising method for CMRA with improved SNR and limited breath-holding requirements.

Coronary Vessels↗

[Comparative study of differentially expressed genes in mouse bone marrow and fetal liver cells].

Hematopoiesis undergoes several migrations from yolk sac to liver and spleen, and finally bone marrow until the end of life. A number of investigations have demonstrated that the hematopoietic microenvironment plays very important role in this process. However, the exact mechanisms remain unknown. In order to systematically analyze and understand the role of hematopoietic microenvironment in the regulation and control of hematopoiesis, a microarray containing 588 complementary DNAs was used to compare the gene expressions between those in murine fetal liver and bone marrow cells. The results obtained from array hybridization were analyzed and reconfirmed by using bioinformatics and RT-PCR as well as Northern blot. The results showed that 65 and 131 genes were relatively high expressed in bone marrow and fetal liver cells respectively among 588 known genes in the array-membrane. According to the survey in the PubMed, 39 out of bone-marrow-expressed genes and 71 in fetal-liver-expressed genes were closely related to the hematopoiesis. Further reconfirmation by RT-PCR or Northern blot has demonstrated that CD18, CD44 an d PSGL-1 genes chosen for analysis were highly expressed in adult bone marrow, but unexpressed or lower expressed in fetal liver cells, resulting in high similarity to the array results. Moreover, the expressions of CD18 and CD44 in fetal liver were down-regulated with the increment of gestational age. In conclusion, the gene expressions in bone marrow and fetal liver cells are obviously different, some of the genes are down-regulated at the different stages of ontogeny. The different gene expression levels between bone marrow and fetal liver, especially those genes closely related to the hematopoiesis, may be the molecular basis for the explanation of why hematopoietic stem cells derived from different tissues have different characterizations as well as the differences from the beginning and terminating of fetal liver hematopoiesis, and why hematopoietic stem cells derived from fetal liver is tremendously difficult to be grafted in bone marrow.

Animals↗