Biomedical subjects

Juan Li

Publications and source records attributed to Juan Li.

At least 73 records · Page 4Linked to original sources

PubMed2006

[Effect of silencing survivin gene on sensitivity of myeloma cells to adriamycin].

BACKGROUND & OBJECTIVE: Survivin, a member of the inhibitors of apoptosis protein family (IAPs), is overexpressed in many cancers, but not in normally differentiated adult tissues. It is known to be involved in poor prognosis and resistance to chemotherapy and radiotherapy in many cancers. This study was designed to use RNA interference technique to down-regulate the expression of survivin gene in human myeloma cell line KM3, observe its effects on apoptosis of KM3 cells and sensitivity of KM3 cells to adriamycin (ADM). METHODS: Small interfering RNA (siRNA) targeting survivin mRNA was designed and in vitro chemosynthesized, and transfected into KM3 cells. Survivin mRNA and protein levels in KM3 cells were detected using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot 24, 48, and 72 h after transfection. The apoptosis of KM3 cells was observed under fluorescent microscope before and after transfection. The sensitivity of KM3 cells to ADM before and after transfection was assessed. RESULTS: The mRNA level of survivin was down-regulated by (47.0+/-4.3)%, (81.4+/-6.2)%, and (49.1+/-7.9)% of control at 24, 48, and 72 h after siRNA transfection, respectively; while the protein level of survivin was down-regulated by (39.6+/-3.8)%, (56.4+/-6.7)%, and (68.2+/-5.1)% of control, respectively. Under fluorescent microscope, the apoptosis rate of KM3 cells was (28+/-7)% at 48 h after transfection of survivin siRNA, which was significantly higher than that of control cells after transfection of negative siRNA (P<0.05). The 50% inhibition concentration (IC(50)) of ADM to KM3 cells was decreased from (1.12+/-0.14) micromol/L to (0.31+/-0.03) micromol/L. CONCLUSION: Down-regulation of survivin expression in KM3 cells by siRNA could effectively induce apoptosis of KM3 cells and increase their sensitivity to ADM.

Apoptosis↗

PubMed2006

[Apoptosis of K562 cells induced by nociceptin/orphanin FQ].

The study was to investigate the proliferation and apoptosis effect of nociceptin/orphanin FQ (OFQ) on 562 cells in vitro. Inhibition of K562 cells proliferation was measured by MTT assay. Morphological assessment of apoptosis was performed with Wright staining and transmission electron microscope. The apoptosis peak was measured by flow cytometry. DNA fragmentation was visualized by agarose gel electrophoresis. The results showed that OFQ time-dependently and no-dose-dependently inhibited the proliferation of K562 cells at concentrations of 10(-6) - 10(-13) mol/L. Discrete maximum of cytolytic activity was detected at concentrations of 10(-6) - 10(-7), 10(-9), 10(-12) mol/L. Compared with the control group K562 cells, the cells treated with OFQ at concentration of 10(-9) mol/L for 72 hours showed typical characteristics of apoptosis under transmission electron microscope. Apoptosis peak was found by FCM at concentration of 0, 10(-7), 10(-8), 10(-9) mol/L of OFQ for 72 hours, apoptosis rates were 0%, 22.8%, 23.8% and 26.5% respectively. DNA agarose gel electrophoresis revealed nuclear fragmentation (DNA ladder). It is concluded that OFQ can inhibit the proliferation of K562 cells and induce the apoptosis in K562 cells.

Apoptosis↗

PubMed2005

Differential effect of PMS777, a new type of acetylcholinesterase inhibitor, and galanthamine on oxidative injury induced in human neuroblastoma SK-N-SH cells.

In the search for highly selective and potent cholinesterase inhibitors (AChEI) being able to improve oxidative injury, PMS777, a tetrahydrofuran derivative, was designed as a novel dual PAF and acetylcholinesterase inhibitor. The aim of this study was to investigate the modulatory effects of PMS777 and galanthamine, another AChEI, on the oxidative injury induced in neuronal cells. The SK-N-SH cells stimulated with LPS+IL-(1beta) were selected to investigate the direct inhibitory effect of PMS777 and galanthamine. LPS+IL-(1beta) induced oxidative injury as assessed by ROS production (29%), GSH depletion (11%) and loss of mitochondrial activity (22%). GSH depletion was never decreased by either drug. In contrast, ROS production and mitochondrial activity were totally prevented by addition of PMS777 but not galanthamine. PMS777 also inhibits butylcholinesterase and it shows selectivity for acetylcholinesterase. Thus, this PAF antagonist inaugurates a new type of AChEI, able to fight oxidative injury. Therefore, PMS777 could be of interest on patients with cognitive impairments and inflammatory damage, as in AD.

Acetylcholinesterase↗

PubMed2005

Visual rating of medial temporal lobe metabolism in mild cognitive impairment and Alzheimer's disease using FDG-PET.

PURPOSE: This study was designed to examine the utility of visual inspection of medial temporal lobe (MTL) metabolism in the diagnosis of mild cognitive impairment (MCI) and Alzheimer's disease (AD) using FDG-PET scans. METHODS: Seventy-five subjects [27 normal controls (NL), 26 MCI, and 22 AD] with FDG-PET and MRI scans were included in this study. We developed a four-point visual rating scale to evaluate the presence and severity of MTL hypometabolism on FDG-PET scans. The visual MTL ratings were compared with quantitative glucose metabolic rate (MR(glc)) data extracted using regions of interest (ROIs) from the MRI-coregistered PET scans of all subjects. A standard rating evaluation of neocortical hypometabolism was also completed. Logistic regressions were used to determine and compare the diagnostic accuracy of the MTL and cortical ratings. RESULTS: For both MTL and cortical ratings, high intra- and inter-rater reliabilities were found (p values <0.001). The MTL rating was highly correlated with and yielded a diagnostic accuracy equivalent to the ROI MR(glc) measures (p values <0.001). The combination of MTL and cortical ratings significantly improved the diagnostic accuracy over the cortical rating alone, with 100% of AD, 77% of MCI, and 85% of NL cases being correctly identified. CONCLUSION: This study shows that the visual rating of MTL hypometabolism on PET is reliable, yields a diagnostic accuracy equal to the quantitative ROI measures, and is clinically useful and more sensitive than cortical ratings for patients with MCI. We suggest this method be further evaluated for its potential in the early diagnosis of AD.

Aged↗

PubMed2005

Sustained whole-body functional rescue in congestive heart failure and muscular dystrophy hamsters by systemic gene transfer.

BACKGROUND: The success of muscular dystrophy gene therapy requires widespread and stable gene delivery with minimal invasiveness. Here, we investigated the therapeutic effect of systemic delivery of adeno-associated virus (AAV) vectors carrying human delta-sarcoglycan (delta-SG) gene in TO-2 hamsters, a congestive heart failure and muscular dystrophy model with a delta-SG gene mutation. METHODS AND RESULTS: A single injection of double-stranded AAV serotype 8 vector carrying human delta-SG gene without the need of any physical or pharmaceutical interventions achieved nearly complete gene transfer and tissue-specific expression in the heart and skeletal muscles of the diseased hamsters. Broad and sustained (>12 months) restoration of the missing delta-SG gene in the TO-2 hamsters corrected muscle cell membrane leakiness throughout the body and normalized serum creatine kinase levels (a 50- to 100-fold drop). Histological examination revealed minimal or the absence of central nucleation, fibrosis, and calcification in the skeletal muscle and heart. Whole-body functional analysis such as treadmill running showed dramatic improvement, similar to the wild-type F1B hamsters. Furthermore, cardiac functional studies with echocardiography revealed significantly increased percent fractional shortening and decreased left ventricular end-diastolic and end-systolic dimensions in the treated TO-2 hamsters. The survival time of the animals was also dramatically extended. CONCLUSIONS: Systemic gene transfer of delta-SG by the AAV serotype 8 vector could effectively ameliorate cardiac and skeletal muscle pathology, profoundly improve cardiac and whole-body functions, and significantly prolong the lifespan of the treated TO-2 hamsters.

Animals↗

PubMed2005

Probing photophysical and photochemical processes of benzoic acid from ab initio calculations.

The CASSCF and DFT methods have been used to determine geometric and electronic structures of the benzoic acid monomer in the S(0), S(1), S(2), T(1), and T(2) electronic states. The S(1)/T(2)/T(1) three-surface intersection was found by the state-averaged CASSCF calculations, which, in combination with features of the five lowest electronic states, provides new insights into photophysical processes of the benzoic acid monomer. The potential energy profiles of the alpha C-C and C-O bond fissions as well as decarboxylation reaction in different electronic states have been determined for the benzoic acid monomer. The alpha C-O bond cleavage starts from the T(2) state and leads to the fragments of C(6)H(5)CO(X(2)A') and OH(X(2)Pi) in the ground state, which is predicted to be the most possible channel upon photoexcitation of the benzoic acid monomer at 270 nm or shorter wavelengths.

Journal Article↗

PubMed2005

Amelioration of laminin-alpha2-deficient congenital muscular dystrophy by somatic gene transfer of miniagrin.

Congenital muscular dystrophy (CMD) is characterized by severe muscle wasting, premature death in early childhood, and lack of effective treatment. Most of the CMD cases are caused by genetic mutations of laminin-alpha2, which is essential for the structural integrity of muscle extracellular matrix. Here, we report that somatic gene delivery of a structurally unrelated protein, a miniature version of agrin, functionally compensates for laminin-alpha2 deficiency in the murine models of CMD. Adeno-associated virus-mediated overexpression of miniagrin restored the structural integrity of myofiber basal lamina, inhibited interstitial fibrosis, and ameliorated dystrophic pathology. Furthermore, systemic gene delivery of miniagrin into multiple vital muscles significantly improved whole body growth and motility and quadrupled the lifespan (50% survival) of the dystrophic mice. Thus, our study demonstrated the efficacy of somatic gene therapy in a mouse model of CMD.

Agrin↗

PubMed2005

Inhibitory effect of genistein on mouse colon cancer MC-26 cells involved TGF-beta1/Smad pathway.

TGF-beta1/signaling has been shown to be associated with proapoptotic and antimitotic activities in epithelial tissues. Genistein, a major component of soybean isoflavone, has multiple functions resulting in anticancer proliferation. We herein showed that genistein dose-dependently increased TGF-beta1 mRNA expression in mouse colon cancer MC-26 cells. A mouse monoclonal anti-TGF-beta1 neutralizing antibody partially, but not completely, blocked the growth inhibition by genistein. By using adenoviral vector, we demonstrated that Smad7 overexpression attenuated genistein-induced growth inhibition and apoptosis as determined by MTT and apoptosis ELISA. Smad7 overexpression also inhibited upregulation of p21 and caspase-3 activity by geinistein. To further confirm inhibitory effect of genistein in MC-26 cells require TGF-beta1/Smad signaling, we employed Western blot and electrophoretic mobility shift assay to detect formation of Smad-DNA complexes and phosphorylation of Smad2 and Smad3, respectively. Data revealed that genistein induced an evident formation of Smad-DNA complexes and phosphorylation of Smad2 and Smad3, indicating increased TGF-beta1 signaling. Taken together, these findings first provided insights into possible molecular mechanisms of growth inhibition by genistein that required Smad signaling, which could aid in its evaluation for colon tumor prevention.

Animals↗

PubMed2005

Impact of simultaneous assay, the PCNA, cyclinD1, and DNA content with specimens before and after preoperative radiotherapy on prognosis of esophageal cancer-possible incorporation into clinical TNM staging system.

AIM: The aim of the present study is to use immunohistochemical methods to investigate the clinical implications of tumor markers in esophageal squamous cell carcinoma and evaluate their impact on prognosis. METHODS: From November 1990 to December 1996, 47 patients were treated with preoperative radiation followed by radical esophagectomy. All patients were confirmed pathologically as suffering from squamous cell carcinoma. Immunohistochemical stain was done for PCNA, cyclinD1 protein expression and DNA content analyzed by image cytometry. Kaplan-Meier method for single prognostic factor and log-rank test was used to test the significant difference. Cox stepwise regression model and prognosis index model were used for survival analysis with multiple prognostic factors. RESULTS: Radio-pathological change, T stage and N stage, as the traditional prognostic factors had statistical difference in 3-, 5- and 10-year survival rates. While, tumor cell proliferating marked PCNA, cyclinD1 and DNA content served as independent prognostic factors of esophageal carcinoma. There was definitely an identity between the single and multiple factor analyses. PI was more accurate to evaluate the prognosis of esophageal carcinoma. CONCLUSION: It is possible that tumor cell proliferating marked PCNA, cyclinD1 and DNA content would become the endpoints for evaluating the prognosis of esophageal carcinoma.

Adult↗

PubMed2005

Preparation and characterization of LiMn2-yCoyO4 spinels by low heating solid state coordination method.

Cathode material LiMn2-yCoyO4 spinels were prepared by annealing the mixed precursors, which were synthesized by a low heating solid state coordination method using lithium acetate, manganese acetate, cobalt acetate, and oxalic acid as original materials. The structures and morphologies of the LiMn2-yCoyO4 spinels were investigated as a function of annealing temperature and time. The results showed that all samples in different annealing temperature and time had the same spinel structure. There were some growth and agglomeration in the particles when annealing temperature increased from 450 to 650 degrees C. And the crystal structure was more perfect at the upper temperature. In addition, the electrochemical properties of LiMn2-yCoyO4 spinels used as cathode material for lithium-ion batteries were studied in detail in this paper.

Journal Article↗

PubMed2005

A combined zero electronic kinetic energy spectroscopy and ion-pair dissociation imaging study of the F2 + (X 2Pi g) structure.

Rotationally resolved pulsed field ionization and zero electronic kinetic energy photoelectron spectra for the transition F(2) (+)(X (2)Pi(g))<--F(2)(X (1)Sigma(g) (+)) have been recorded using the extreme ultraviolet coherence radiation. The vibrational energy spacings, rotational constants, and spin orbit coupling constants for the first three vibrational states of F(2) (+)(X (2)Pi(g)) have been determined accurately. The first adiabatic ionization potential (IP) of F(2) is determined as IP(F(2))=126 585.7+/-0.5 cm(-1). To determine the threshold E(tipp) for ion-pair production of F(2), the images of F(-)((1)S(0)) in the velocity mapping conditions have also been recorded at the photon energy of 126 751 cm(-1). Taking the Stark effect into account, the E(tipp) is determined as E(tipp)(F(2))=126 045+/-8 cm(-1) (15.628+/-0.001 eV). By combing the IP(F(2)) and the E(tipp)(F(2)) determined in this work and together with the reported ionization potential and electronic affinity of the F atom, the bond dissociation energies of F(2) and F(2) (+) are determined as D(0)(F(2))=1.606+/-0.001 eV and D(0)(F(2) (+))=3.334+/-0.001 eV, respectively.

Journal Article↗

PubMed2005

The adeno associated viral vector as a strategy for intradiscal gene transfer in immune competent and pre-exposed rabbits.

STUDY DESIGN: Experimental animal study. OBJECTIVES: This study evaluates the in vitro and in vivo transduction efficacy and transgene expression in immune competent and pre-exposed rabbits. SUMMARY OF BACKGROUND DATA: Degenerative disc disease (DDD) continues to pose a substantial clinical problem. Therapeutic options such as an interbody fusion are highly invasive and result in the loss of the intervertebral disc. In addition, interbody fusion puts the adjacent discs at an even higher risk for disc degeneration. A novel approach to slow DDD is to introduce high levels of growth factors into the degenerating disc by delivering the gene coding for the appropriate growth factor. The most efficient technique to do so to date uses viral vectors. However, viral vectors may be problematic because of their immunogenicity. The adeno-associated virus (AAV) viral vector is known to be less immunogenic than commonly used adenoviral vectors. METHODS: Human nucleus pulposus cells were transduced in vitro. Twenty-four Rabbits were injected with AAV viral vectors carrying different marker genes. Transgene expression and the humoral/cellular immune response to the vector was evaluated. RESULTS: We could show that the AAV viral vector transduces human as well as rabbit nucleus pulposus cells in vitro and in vivo. There is a significant humoral immune response against the AAV vector that decreases transgene expression over 10-fold in preimmunized animals. CONCLUSIONS: AAV is a valuable new vector to achieve transgene expression in the intervertebral disc. In preimmunized animals, its use needs to be further evaluated because of the significant reduction in transgene expression.

Animals↗

PubMed2005

Adeno-associated virus serotype 8 efficiently delivers genes to muscle and heart.

Systemic gene delivery into muscle has been a major challenge for muscular dystrophy gene therapy, with capillary blood vessels posing the principle barrier and limiting vector dissemination. Previous efforts to deliver genes into multiple muscles have relied on isolated vessel perfusion or pharmacological interventions to enforce broad vector distribution. We compared the efficiency of multiple adeno-associated virus (AAV) vectors after a single injection via intraperitoneal or intravenous routes without additional intervention. We show that AAV8 is the most efficient vector for crossing the blood vessel barrier to attain systemic gene transfer in both skeletal and cardiac muscles of mice and hamsters. Serotypes such as AAV1 and AAV6, which demonstrate robust infection in skeletal muscle cells, were less effective in crossing the blood vessel barrier. Gene expression persisted in muscle and heart, but diminished in tissues undergoing rapid cell division, such as neonatal liver. This technology should prove useful for muscle-directed systemic gene therapy.

Animals↗

PubMed2005

Management of infants with chronic lung disease of prematurity in China.

With improved survival of very low birth weight infants in China over the last decade, chronic lung disease of prematurity (CLD) is only now becoming prevalent. As a result the management of CLD in China is only now beginning. In this paper, we describe the practice of managing these infants with as much evidence base as possible but often the management is based on other published papers in China and elsewhere and other people's personal experience. It appears that oxygen therapy is important to the survival of CLD infants but blood oxygen concentrations must be monitored closely in infants needing oxygen supplementation. We aim for a target range for oxygen saturation range of between 90%-95% to prevent retinopathy of prematurity. Although dexamethasone is effective in the treatment of CLD particularly extubation of preterm infants from mechanical ventilation, we restrict its use in severe infant due to their side effects. We have little experience of home oxygen and are only now setting up management protocols for oxygen use for CLD in both hospital and at home. We hope that the survival and outlook for these infants with CLD will improve over the next few years.

Adrenal Cortex Hormones↗

PubMed2005

Prevention and reversal of lupus in NZB/NZW mice by costimulatory blockade with adeno-associated virus-mediated gene transfer.

OBJECTIVE: To investigate the potency of costimulatory blockade with adeno-associated virus (AAV)-mediated gene transfer in the prevention and reversal of lupus in a murine model. METHODS: AAV vectors expressing CTLA-4Ig or CD40Ig were injected into NZB/NZW mice. Serum levels of transgene expression and autoantibody titers were determined by enzyme-linked immunosorbent assay. The therapeutic effects on proteinuria, renal pathologic features, and survival rate were evaluated. Splenic T cell phenotypes were analyzed by flow cytometry. The humoral immune response to a foreign antigen was also examined in treated mice. RESULTS: A single injection of AAV serotype 8 (AAV8)-CTLA-4Ig in neonatal NZB/NZW mice before the onset of lupus effectively delayed and inhibited autoantibody production, proteinuria, and kidney damage and prolonged their lifespan. In addition, coinjection of AAV8-CTLA-4Ig and AAV8-CD40Ig vectors into neonatal mice achieved a synergistic effect and the best efficacy. The preventive effects were attributed to suppression of CD4+ T cell activation and the transition from naive to memory T cells. Moreover, coinjection of these 2 vectors in adult mice reversed the existing autoantibody levels, suppressed the development of proteinuria, and prolonged their lifespan. The therapeutic effects were found to be dependent on the vector dose. In addition, AAV-mediated long-term gene expression did not severely suppress the host humoral response to foreign antigen. CONCLUSION: Our findings show that delivery of costimulatory inhibitor transgenes by AAV vectors could prevent and reverse lupus in this murine model, suggesting the potential of AAV-mediated gene transfer as an alternative treatment for lupus.

Adenoviridae↗

PubMed2005

L3mbtl, the mouse orthologue of the imprinted L3MBTL, displays a complex pattern of alternative splicing and escapes genomic imprinting.

L3mbtl encodes a member of the Polycomb group of proteins, which function as transcriptional repressors in large protein complexes. The Drosophila D-l(3)mbt protein is considered a tumor suppressor since its inactivation results in brain tumors. The human L3MBTL gene lies in a region of chromosome 20 frequently deleted in patients with myeloid malignancies and has been proposed as a candidate 20q tumor suppressor gene. Recently we have shown that L3MBTL undergoes monoallelic methylation in hematopoietic tissues and is transcribed from the paternally derived allele. The mouse L3mbtl gene is located on chromosome 2, a region of syntenic homology with human chromosome 20, and in a region containing a number of genes subject to epigenetic regulation. Here we analyze the genomic structure and alternative splicing of L3mbtl and assess its imprinting status in mouse. L3mbtl displays a complex pattern of alternative splicing involving both 5' noncoding and coding exons and is transcribed from two promoters. Unlike its human counterpart, L3mbtl escapes imprinting and there is no differential methylation of its CpG island.

Alternative Splicing↗

PubMed2005

Identification and expression pattern of Bmlark, a homolog of the Drosophila gene lark in Bombyx mori.

Two Bombyx mori isoforms of the gene lark, which is shown to play an important role in Drosophila circadian rhythms, were identified and named Bmlark-PA and Bmlark-PB, respectively. Bmlark-PA consists of 5 exons and encodes a protein of 343 amino acid residues which contains 3 functional domains: two RRM (RNA recognization motif) domains and an RTZF (retroviral-type zinc finger) and shares 72% identity with the Drosophila gene lark at the amino acid level. Bmlark-PB lacks the sequence between 118 and 791 nt of Bmlark-PA and codes for a protein of 68 amino acid residues, which contains no distinct functional domains. Alignments of the cDNAs of Bmlark to the genomic draft sequence of B. mori showed that the gene Bmlark had a single copy in the genome, suggesting that an alternative splicing mechanism occurs in the gene Bmlark. RT-PCR analysis indicated that Bmlark-PA was expressed only in late pupae and adult but Bmlark-PB was broadly expressed in many tissues and throughout the developmental stages from embryo to adult.

Alternative Splicing↗

PubMed2005

Adrenomedullin gene delivery alleviates hypertension and its secondary injuries of cardiovascular system.

Adrenomedullin (AM) is a hypotensive peptide that functions as an important regulator in the cardiovascular and renal systems. The current study explored the potential therapeutic effects of delivering the human AM cDNA via a novel double-stranded adeno-associated virus vector (dsAAV) on hypertension and related complications in spontaneously hypertensive rats (SHR). A single dose of dsAAV-AM vector administered by tail vein injection into adult SHR resulted in significant reduction of systolic blood pressure at 2 weeks after gene delivery. This effect was observed through the entire duration of the experiment period (up to 16 weeks). Administration of dsAAV-AM also resulted in a decrease in total urine microalbumin content. Left ventricle and cardiomyocyte hypertrophy, fibrosis in the heart, glomerular sclerosis, and tubular injuries in the kidney were significantly reduced. Moreover, deterioration of hemodynamic variables was prevented in treated rats, as compared with the control groups. We conclude that AAV-mediated AM delivery can render a longterm and stable reduction of hypertension and protect against renal injury and cardiac remodeling in the spontaneously hypertensive rat model. Further preclinical studies are warranted for the development of a gene therapy strategy for human hypertension.

Adenoviridae↗