Biomedical subjects

Jie Li

Publications and source records attributed to Jie Li.

At least 55 records · Page 3Linked to original sources

PubMed2006

Dynamics of a discotic liquid crystal in the isotropic phase.

Optically heterodyne-detected optical Kerr effect (OHD-OKE) experiments are conducted to study the orientational dynamics of a discotic liquid crystal 2,3,6,7,10,11-hexakis(pentyloxy)triphenylene (HPT) in the isotropic phase near the columnar-isotropic (C-I) phase transition. The OHD-OKE signal of HPT is characterized by an intermediate power law t(-0.76+/-0.02) at short times (a few picoseconds), a von Schweidler power law t(-0.26+/-0.01) at intermediate times (hundreds of picoseconds), and an exponential decay at long times (tens of nanoseconds). The exponential decay has Arrhenius temperature dependence. The functional form of the total time dependent decay is identical to the one observed previously for a large number of molecular supercooled liquids. The mode coupling theory schematic model based on the Sjogren [Phys. Rev. A 33, 1254 (1986)] model is able to reproduce the HPT data over a wide range of times from <1 ps to tens of nanoseconds. The studies indicate that the HPT C-I phase transition is a strong first order transition, and the dynamics in the isotropic phase display a complex time dependent profile that is common to other molecular liquids that lack mesoscopic structure.

Journal Article↗

PubMed2006

Enhanced antitumor effect against human telomerase reverse transcriptase (hTERT) by vaccination with chemotactic-hTERT gene-modified tumor cell and the combination with anti-4-1BB monoclonal antibodies.

Human telomerase reverse transcriptase (hTERT) represents an attractive target for cancer immunotherapy because hTERT is reactivated in most human tumors. In an attempt to develop an effective vaccine against most human cancers, we constructed chemotactic-hTERT vaccine. Two hTERT fragments encoding multiple cytotoxic T lymphocyte and T helper cell epitopes were fused as a tumor antigen (named Te). The plasmid based DNA vaccine (pCCL21-Te-Fc) was constructed by linking human CCL21 and IgG Fc gene sequences to each end of Te. In poorly immunogenic B16F10 mouse melanoma model, DNA (pCCL21-Te-Fc) vaccination significantly inhibited tumor growth and all of the mice were dead by day 52. The immunization with pCCL21-Te-Fc-modified tumor cells (B16/CCL21-Te-Fc) resulted in a higher antitumor effect than DNA vaccination and 25% of tumor-bearing mice achieved long-term survival (> 120 days). The combined therapy of B16/CCL21-Te-Fc plus anti-4-1BB MAbs further enhanced the immune response, resulting in 75% of tumor-bearing mice achieved long-term survival (> 120 days) in subcutaneous model and few lung nodules in pulmonary metastasis model. Rechallenge experiment showed that a persistent memory response was successfully induced by the combined therapy. In vivo depletion of lymphocytes indicated that CD8+ T cells were essential in the antitumor activity induced by B16/CCL21-Te-Fc plus anti-4-1BB MAbs, whereas NK cells and CD4+ T cells played substantial roles. The CTL activity induced by pCCL21-Te-Fc-transfected PBMCs specifically lysed a variety of human leukocyte antigen-matched and hTERT-positive human tumor cells, suggesting pCCL21-Te-Fc could serve as a vaccine against most human cancers.

4-1BB Ligand↗

PubMed2006

Comparative proteomic profiles of meningioma subtypes.

Meningiomas are classified into three groups (benign, atypical, and anaplastic) based on morphologic characteristics. Atypical meningiomas, which are WHO grade 2 tumors, and anaplastic meningiomas, which are WHO grade 3 tumors, exhibit an increased risk of recurrence and premature death compared with benign WHO grade 1 tumors. Although atypical and anaplastic meningiomas account for <10% of all of meningiomas, it can be difficult to distinguish them from benign meningiomas by morphologic criteria alone. We used selective tissue microdissection to examine 24 human meningiomas and did two-dimensional gel electrophoresis to determine protein expression patterns. Proteins expressed differentially by meningiomas of each WHO grade were identified and sequenced. Proteomic analysis revealed protein expression patterns unique to WHO grade 1, 2, and 3 meningiomas and identified 24 proteins that distinguish each subtype. Fifteen proteins showed significant changes in expression level between benign and atypical meningiomas, whereas nine distinguished atypical from anaplastic meningiomas. Differential protein expression was confirmed by Western blotting and immunohistochemistry. We established differential proteomic profiles that characterize and distinguish meningiomas of increasing grades. The proteins and proteomic profiles enhance understanding of the pathogenesis of meningiomas and have implications for diagnosis, prognosis, and treatment.

Electrophoresis, Gel, Two-Dimensional↗

PubMed2006

Regulation of CD95 (Fas) expression and Fas-mediated apoptotic signaling in HLE B-3 cells by 4-hydroxynonenal.

The Fas (apo/CD95) receptor which belongs to the TNF-alpha family is a transmembrane protein involved in the signaling for apoptosis through the extrinsic pathway. During this study, we have examined a correlation between intracellular levels of 4-HNE and expression of Fas in human lens epithelial (HLE B-3) cells. Our results show that in HLE B-3 cells, Fas is induced by 4-HNE in a concentration- and time-dependent manner, and it is accompanied by the activation of JNK, caspase 3, and the onset of apoptosis. Fas induction and activation of JNK are also observed in various tissues of mGsta4 null mice which have elevated levels of 4-HNE. Conversely, when 4-HNE is depleted in HLE B-3 cells by a transient transfection with hGSTA4, Fas expression is suppressed. However, upon the cessation of hGSTA4 expression in these transiently transfected cells, Fas and 4-HNE return to their basal levels. Fas-deficient transformed HLE B-3 cells stably transfected with hGSTA4 show remarkable resistance to apoptosis. Also, the wild-type HLE B-3 cells in which Fas is partially depleted by siRNA acquire resistance to 4-HNE-induced apoptosis, suggesting an at least partial role of Fas in 4-HNE-induced apoptosis in HLE B-3 cells. We also demonstrate that during 4-HNE-induced apoptosis of HLE B-3 cells, Daxx is induced and it binds to Fas. Together, these results show an important role of 4-HNE in regulation of the expression and functions of Fas.

Aldehydes↗

PubMed2006

PRL-3 initiates tumor angiogenesis by recruiting endothelial cells in vitro and in vivo.

We show here that PRL-3 protein is expressed in fetal heart, developing blood vessels, and pre-erythrocytes but not in their mature counterparts. These observations imply that PRL-3 may be involved in the early development of the circulatory system. Because PRL-3 mRNA had been reported to be consistently elevated in metastatic samples derived from colorectal cancers, we attempted to investigate if PRL-3 might be involved in tumor angiogenesis and if PRL-3-expressing cells could cross-talk to human umbilical vascular endothelial cells (HUVEC) by using an in vitro coculture system. HUVECs were grown with fibroblasts, which were later overlaid with PRL-3-expressing cells. We observed that both PRL-3-expressing Chinese hamster ovary (CHO) cells and PRL-3-expressing DLD-1 human colon cancer cells could redirect the migration of HUVECs toward them; in addition, PRL-3-expressing DLD-1 cells could enhance HUVEC vascular formation. In vivo injection of PRL-3-expressing CHO cells into nude mice to form local tumors resulted in the recruitment of host endothelial cells into the tumors and initiation of angiogenesis. We further showed that PRL-3-expressing cells reduced interleukin-4 (IL-4) expression levels and thus attenuated IL-4 inhibitory effects on the HUVEC vasculature. Our findings provide direct evidence that PRL-3 may be involved in triggering angiogenesis and establishing microvasculature and it may serve as an attractive therapeutic target with respect to both angiogenesis and cancer metastasis.

Animals↗

PubMed2006

Identification of a novel human lysophosphatidic acid acyltransferase, LPAAT-theta, which activates mTOR pathway.

Lysophosphatidic acid acyltransferase (LPAAT) is an intrinsic membrane protein that catalyzes the synthesis of phosphatidic acid (PA) from lysophosphatidic acid (LPA). It is well known that LPAAT is involved in lipid biosynthesis, while its role in tumour progression has been of emerging interest in the last few years. To date, seven members of the LPAAT gene family have been found in human. Here we report a novel LPAAT member, designated as LPAAT-theta, which was 2728 base pairs in length and contained an open reading frame (ORF) encoding 434 amino acids. The LPAAT-theta gene consisted of 12 exons and 11 introns, and mapped to chromosome 4q21.23. LPAAT-theta was ubiquitously expressed in 18 human tissues by RT-PCR analysis. Subcellular localization of LPAAT-theta-EGFP fusion protein revealed that LPAAT-theta was distributed primarily in the endoplasmic reticulum (ER) of COS-7 cells. Furthermore, we found that the overexpression of LPAAT-theta can induce mTOR-dependent p70S6K phosphorylation on Thr389 and 4EBP1 phosphorylation on Ser65 in HEK293T cells.

Acyltransferases↗

PubMed2006

Dynamics in supercooled ionic organic liquids and mode coupling theory analysis.

Optically heterodyne-detected optical Kerr effect experiments are applied to study the orientational dynamics of the supercooled ionic organic liquids N-propyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide (PMPIm) and 1-ethyl-3-methylimidazolium tosylate (EMImTOS). The orientational dynamics are complex with relaxation involving several power law decays followed by a final exponential decay. A mode coupling theory (MCT) schematic model, the Sjögren model, was able to reproduce the PMPIm data very successfully over a wide range of times from 1 ps to hundreds of ns for all temperatures studied. Over the temperature range from room temperature down to the critical temperature Tc of 231 K, the OHD-OKE signal of PMPIm is characterized by the intermediate power law t(-1.00+/-0.04) at short times, a von Schweidler power law t(-0.51+/-0.03) at intermediate times, and a highly temperature-dependent exponential (alpha relaxation) at long times. This form of the decay is identical to the form observed previously for a large number of organic van der Waals liquids. MCT analysis indicates that the theory can explain the experimental data very well for a range of temperatures above Tc, but as might be expected, there are some deviations from the theoretical modeling at temperatures close to Tc. For EMImTOS, the orientational dynamics were studied on the ps time scale in the deeply supercooled region near its glass transition temperature. The orientational relaxation of EMImTOS clearly displays the feature associated with the boson peak at approximately 2 ps, which is the first time domain evidence of the boson peak in ionic organic liquids. Overall, all the dynamical features observed earlier for organic van der Waals liquids using the same experimental technique are also observed for organic ionic liquids.

Journal Article↗

PubMed2006

Involvement of Na+/K+-ATPase in hydrogen peroxide-induced hypertrophy in cardiac myocytes.

We have shown that increased production of reactive oxygen species (ROS) was required for ouabain-induced hypertrophy in cultured cardiac myocytes. In the present study we assessed whether long-term exposure of myocytes to nontoxic ROS stress alone is sufficient to induce hypertrophy. A moderate amount of H2O2 was continuously generated in culture media by glucose oxidase. This resulted in a steady increase in intracellular ROS in cultured cardiac myocytes for at least 12 h. Such sustained, but not transient, increase in intracellular ROS at a level comparable to that induced by ouabain was sufficient to stimulate protein synthesis, increase cell size, and change the expression of several hypertrophic marker genes. Like ouabain, glucose oxidase increased intracellular Ca2+ and activated extracellular signal-regulated kinases 1 and 2 (ERK1/2). These effects of glucose oxidase were additive to ouabain-induced cellular changes. Furthermore, glucose oxidase stimulated endocytosis of the plasma membrane Na+/K+-ATPase, resulting in significant inhibition of sodium pump activity. While inhibition of ERK1/2 abolished glucose oxidase-induced increases in protein synthesis, chelating intracellular Ca2+ by BAPTA-AM showed no effect. These results, taken together with our prior observations, suggest that ROS may cross talk with Na+/K+-ATPase, leading to the activation of hypertrophic pathways in cardiac myocytes.

Animals↗

PubMed2006

Mouse lymphomas caused by an intron-splicing donor site deletion of the FasL gene.

A spontaneous lymphoma was detected in mice, which was caused by a recessive autosomal mutation. The genetic basis was revealed to be a 5-bp deletion at the splicing donor site of the first intron of the FasL gene, resulting in aberrant transcripts coding for non-functional proteins. This mutation of the FasL gene caused development of lymphoma in all four mouse genetic backgrounds tested and the lymphoma was characterized by an expansion of leucocytes that were TCR+CD3+B220+CD19-CD4-CD8-. Accordingly, severe splenomegaly developed in the mutant mice. Interestingly, thymic hyperplasia was observed in mutant mice at later stages. These results underscore the functional importance of the splicing donor site in the function of the FasL gene and provide an independent evidence for a role of FasL in normal development of lymophocytes. The mutant mice offer another genetically defined mouse model for further studies of the role and mechanism of action of FasL.

Alternative Splicing↗

PubMed2006

Quantitative structure-retention relationship studies using immobilized artificial membrane chromatography I: amended linear solvation energy relationships with the introduction of a molecular electronic factor.

Linear solvation energy relationships (LSERs) amended by the introduction of a molecular electronic factor were employed to establish quantitative structure-retention relationships using immobilized artificial membrane (IAM) chromatography, in particular ionizable solutes. The chromatographic indices, log k(IAM), were determined by HPLC on an IAM.PC.DD2 column for 53 structurally diverse compounds, including neutral, acidic and basic compounds. Unlike neutral compounds, the IAM chromatographic retention of ionizable compounds was affected by their molecular charge state. When the mean net charge per molecule (delta) was introduced into the amended LSER as the sixth variable, the LSER regression coefficient was significantly improved for the test set including ionizable solutes. The delta coefficients of acidic and basic compounds were quite different indicating that the molecular electronic factor had a markedly different impact on the retention of acidic and basic compounds on IAM column. Ionization of acidic compounds containing a carboxylic group tended to impair their retention on IAM, while the ionization of basic compounds did not have such a marked effect. In addition, the extra-interaction with the polar head of phospholipids might cause a certain change in the retention of basic compounds. A comparison of calculated and experimental retention indices suggested that the semi-empirical LSER amended by the addition of a molecular electronic factor was able to reproduce adequately the experimental retention factors of the structurally diverse solutes investigated.

Algorithms↗

PubMed2006

Inhibitory effects of lanthanum chloride on extracellular matrix in injury tissues of rats.

The propose of the present study is to investigate the effects of lanthanum chloride (LaCl(3)), a rare earth compound, on extracellular matrix molecules in rat wound tissues, hoping to provide a clue for further study in reducing excessive extracellular matrix formation in trauma and burn, as well as in fibrous disorders. In order to elucidate its action mechanism, we investigated its effects on fibroblast apoptosis, intracellular calcium, collagen synthesis and expression, and fibronectin mRNA expression. We found that treatment with 0.25 ml of 50 mM (1.5mg/injection) LaCl(3) for three consecutive days induced fibroblast apoptosis and inhibited collagen synthesis and expression. Comparing to control, at day 14 after wounding, apoptosis and the level of intracellular calcium in wound tissues were significantly increased, but at day 28 after wounding, apoptosis was not continually increased and gradually became normal. In contrast, the amount of (3)H-proline incorporation and the expression of type I and III collagen decreased at days 14 and 28 after wounding by LaCl(3)-treatment. The expression of fibronectin mRNA was not significant changed at days 14 and 28 after-wounding by LaCl(3)-treatment as compared to the control. The results suggest that LaCl(3) may reduce the extracellular matrix formation at certain concentrations during wound healing and be worth further study as an anti-fibrous agent. Because lanthanides have been used to clinical treatment with antibacterial agents in burn, it may be more suitable for the treatment of severe burn.

Animals↗

PubMed2006

PKC inhibition is involved in trichosanthin-induced apoptosis in human chronic myeloid leukemia cell line K562.

Trichosanthin (TCS), a type I ribosome-inactivating protein, induces cell death in various cell types including several tumor cell lines. However, the mechanism remains largely uncharacterized. In this study, we investigated the possible mechanism underlying its cytotoxicity by using human chronic myeloid leukemia cell line K562. We found that TCS induced apoptosis in K562 cells in a time- and concentration-dependent manner and can be blocked by caspase-3 inhibitors. Interestingly, TCS treatment induced a transient elevation in intracellular calcium concentration and a slow increase in reactive oxygen species production, while calcium chelators and antioxidants had no obvious effect on TCS-induced apoptosis, suggesting that calcium changes and reactive oxygen species may not be involved in TCS-mediated apoptosis in K562 cells. Instead we found that TCS partly inhibited PKC activity. Indeed, the PKC activator, PMA, inhibited while the PKC inhibitor, calphostin c, enhanced TCS-induced apoptosis. These PKC modulators had similar effects on TCS-induced cleavage of caspase-3, and caspase-3 inhibitors prevented calphostin c-enhanced apoptosis induced by TCS. In summary, we conclude that TCS induces apoptosis in K562 cells partly via PKC inhibition and caspase-3 activation.

Apoptosis↗

PubMed2006

Formation of hydrogen peroxide and degradation of phenol in synergistic system of pulsed corona discharge combined with TiO2 photocatalysis.

In the present work, a synergistic system of pulsed corona discharge combined with TiO(2) photocatalysis has been developed to investigate the degradation rate of phenol solutions by varying experimental conditions of gas bubbling varieties (air, O(2), and Ar), solution pH values, and radical scavenger additives. The hydrogen peroxide (H(2)O(2)) concentration, which indicated the amount of hydroxyl radicals (OH) in the reaction system under different conditions of gas bubbling varieties and scavenger species, was also reviewed. The obtained results revealed that degradation efficiency of phenol could be increased by the addition of TiO(2) in pulsed discharge system. The gas of Ar and O(2) bubbled into the reaction system was found to be favorable for phenol degradation and H(2)O(2) formation. Both in air bubbling and in O(2) bubbling reaction system, the higher degradation rate of phenol occurred in the case of acidic solution. The addition of sodium carbonate or n-butanol in the solution displayed a negative effect for phenol removal, while the H(2)O(2) concentration showed different changing trend by adding different radical scavengers. The most effective degradation of the three main intermediates of catechol, 1,4-hydroquinone, and 1,4-benzoquinone formed during phenol decomposition existed in the synergistic system of pulsed corona discharge and TiO(2) photocatalysis bubbled with O(2).

1-Butanol↗

PubMed2006

Investigation on correlation between expression of CD58 molecule and severity of hepatitis B.

AIM: To investigate the correlation between expression of CD58 and severity of hepatitis B. METHODS: The level of soluble CD58 (sCD58) in serum of patients with hepatitis B was detected by enzyme-linked immunosorbent assay. The level of expression of membrane CD58 molecule in PBMC was detected by direct immunofluorescence. The levels of serumal TBIL, DBIL, IBIL, ALT and AST were detected by the automated biochemistry analyzer as well. RESULTS: The levels of sCD58 in serum and membrane CD58 molecule in PBMC of patients with hepatitis B were significantly higher than that in normal controls (P < 0.05). Level of CD58 was related to the levels of serumal TBIL, DBIL, IBIL, ALT and AST. CONCLUSION: The level of CD58 molecule (in both serum and PBMC form) of patients with hepatitis B is related to the degree of liver damage.

CD58 Antigens↗

PubMed2006

Controlled proteolysis and the properties of milk gels.

Milk gels induced by partial proteolysis of the kappa-casein followed by acidification were studied, and their gelation behavior was compared to that of milk gels induced by simultaneous acidification and renneting, using dynamic rheology. There were generally two stages (at pH values below and above 5.0) in the gelation of the milk whose kappa-casein had been partially proteolyzed and acidified. The onset of gelation was at higher pH as the degree of kappa-casein proteolysis increased. The development of G' immediately after the onset of gelation was faster in the milk gels induced by simultaneous acidification and renneting, because of the continuing kappa-casein proteolysis. Preheat treatment caused the onset of gelation to occur at higher pH than for unheated milk. However, the maximum tan delta during gelation always occurred at the same pH (for a given concentration of acidulant), and its value and position were independent of the extent of renneting and whether the milks had been heat treated. The results are discussed in terms of the interactions between casein micelles occurring during gelation.

Animals↗

PubMed2006

Eradication of H pylori infection in a rural population: one-day quadruple therapy versus 7-day triple therapy.

AIM: To compare the one-day quadruple therapy with a standard 7-d triple therapy for H pylori eradication in a rural population of China. METHODS: A total of 396 patients with (13)C-urea breath test positive for H pylori were assigned into two groups: 239 patients received one-day quadruple therapy (amoxicillin 2000 mg qid; metronidazole 500 mg qid; bismuth citrate 900 mg qid and lansoprazole 60 mg once daily) and 157 patients received 7-d standard triple therapy (amoxicillin 1000 mg bid; clarithromycin 500 mg bid and lansoprazole 30 mg bid). All the patients underwent a (13)C-UBT to assess the eradication of H pylori infection six weeks after treatment. RESULTS: Two hundred and twenty-nine patients completed the one-day therapy (95.8%) and 148 patients completed the 7-d therapy (94.2%). The one-day therapy eradicated H pylori infection in 64 patients (27.95%). In contrast, 103 patients (69.59%) were H pylori negative after the 7-d therapy (P < 0.01). CONCLUSION: This pilot study suggests there is no beneficial effect of the one-day therapy in treatment of H pylori infection compared with the 7-d standard therapy.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2006

Potential bridges for HIV infection to men who have sex with men in Guangzhou, China.

To assess the potential for HIV acquisition among men who have sex with men (MSM) in Guangzhou, China, we conducted a cross-sectional, anonymous, face-to-face survey of MSM in the metropolitan area of Guangzhou, China. As a pilot recruitment for a cohort study, participants were recruited by convenience sampling through newspaper and television advertising, website information, and respondent referral. Blood samples were tested for HIV, hepatitis B (HBV), hepatitis C (HCV), and syphilis. Client-centered HIV and STD counseling was provided.A total of 201 MSM were interviewed and 200 blood samples were tested. The prevalence of HIV antibody was 0% (97.5% CI 0-1.8%); 17.5% of MSM were HBV surface antigen positive; 1.0% had HCV antibodies; 10.5% had antibodies to syphilis. Syphilis seropositivity was associated with sex with a foreign MSM in the last six months and 10.4% reported sex with a foreign MSM overall. The majority (54.7%) reported unprotected anal sex with other men. Nearly one-third (31.8%) had regular female partners; 25.9% were currently married to a woman; 6% had casual female partners; 4.5% had sex with a female sex worker; 4.5% had sex with a male sex worker; and 12.9% had unprotected vaginal sex and unprotected anal sex with a man in the past six months. Only one MSM reported injection drug use (0.5%). The currently low prevalence of HIV but high level of unprotected anal sex, high prevalence of syphilis infection, and sexual networks that include foreign MSM point to a transient window for HIV prevention among MSM in Guangzhou. We recognize challenges to recruiting a representative sample of MSM and retaining them in longitudinal cohort studies.

Adolescent↗

PubMed2006

An investigation of the surface enhanced Raman scattering (SERS) from a new substrate of silver-modified silver electrode by magnetron sputtering.

'Pure' silver nanoparticles on silver electrode were prepared by magnetron sputtering. The silver-modified silver electrode has good stability and the silver nanoparticles on silver electrode have homogeneous size distribution. Compared with the silver colloid modified silver electrode, there were no any extraneous component ions on the electrode, for the modified silver nanoparticles are prepared by magnetron sputtering. Synchronously, we obtained much higher quality SERS spectra of adenine molecules on the silver electrode modified by magnetron sputtering (SEMMS), and the study of the adsorption behavior of adenine on the silver-modified silver electrode by surface enhanced Raman scattering (SERS) indicated that the silver-modified silver electrode was highly efficient substrates for SERS investigation. From the rich information on the SEMMS obtained from high-quality potential-dependent SERS, we may deduce the adsorption behavior of adenine and the probable SERS mechanism in the process. The probable reasons are given.

Adenine↗