Biomedical subjects

Jie Li

Publications and source records attributed to Jie Li.

At least 127 records · Page 7Linked to original sources

PubMed2006

[Hypersensitization of alpha-adrenoreceptor of artery smooth muscle in hypertensive rats and hypertensive patients].

AIM: To investigate the hypersensitization of alpha-adrenoreceptor of artery smooth muscle in hypertensive patients and rats and the mechanisms concerned. METHODS: Isometric tension of artery ring segments was recorded by a sensitive myograph system in vitro and the relative amount of alpha-adrenoreceptor mRNA was quantified by a real-time PCR. RESULTS: Noradrenaline (NA)-induced concentration-contraction curve of mesenteric artery segments in spontaneously hypertensive rats (SHR) was more potent than that in Wistar-Kyoto (WKY) rats. The E(max) of NA in SHR was 1.82 times of that of WKY. The concentration-contractile curve induced by NA in great omental arteries of hypertensives significantly shifted toward left and the pD2 value of NA was larger than that of normotensives. After organ culture, the concentration-contractile curves of SD rat mesenteric artery induced by NA shifted toward left with significantly increased E(max). The relative amounts of mRNA for alpha1-adrenoreceptor was increased, but mRNA level for alpha2-adrenoreceptor did not change. CONCLUSION: The sensitivity of alpha1-adrenoreceptor of artery smooth muscle in hypertensive man and rat is enhanced, suggesting alpha1-adrenoreceptor is upregulated.

Adrenergic alpha-Agonists↗

PubMed2006

[A comparison study for differentiation between human fetal retinal progenitor cells and brain neural stem cells in vitro].

OBJECTIVE: Investigating the potential of differentiation of human fetal retinal progenitor cells (hRPCs) and brain neural stem cells (hBNSCs) in vitro. METHODS: hRPCs and hBNSCs were isolated from human fetuses (8-12 weeks of gestation) and cultured in serum-free DMEM/F12 culture medium with N2 supplement, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) or culture medium with 10% fetal bovine serum (FBS) but without EGF and bFGF. Immunocytochemical and immunofluorescence studies were conducted for identification of neural stem cells, retinal progenitors or the subtypes of neurons, astrocytes, retinal ganglion cells and rod photoreceptors with the specific antibodies for Nestin, Pax6, Map2, GFAP, Thy-1 and Rhodopsin, respectively. RESULTS: Both hRPCs and hBNSCs could proliferate and differentiate in DMEM/F12 + N2 with or without 10% FBS and expressed specific markers of immature neuroepithelial cells, retinal progenitors, mature neurons, astrocytes, retinal ganglion cells and rod photoreceptors. hBNSCs easily attached, spread out longer neurites and to form a network when cultured with serum contained medium. hRPCs were more difficult to attach and had only short dendrites. CONCLUSIONS: Both hRPCs and hBNSCs can differentiate into retinal specific cell types in vitro. The adherent, migration and differential capacity of hRPCs and hBNSCs are different when these cells are induced by the serum-contained culture medium.

Brain↗

PubMed2005

Activation of transcriptional activities of AP1 and SRE by a novel zinc finger protein ZNF445.

Zinc finger proteins play important roles in various cellular functions, including cell proliferation, differentiation, and apoptosis. Mitogen-activated protein kinase (MAPK) signal transduction pathways are one of the most common mechanisms in eukaryotic cell regulation. Many transcription factors are important targets of MAPKs. In this study, we identified a novel gene encoding a zinc finger protein named ZNF445. The ZNF445 mRNA consists of 9105 nucleotides and has a 1031-amino acid open reading frame. The predicted 119-kDa protein contains a leucine-rich region (LER or SCAN domain) at the N-terminus, followed by a well-conserved Krüppel-associated box (KRAB) domain. At the C-terminus of the protein, there are 14 C2H2 (Cys2-His2) zinc finger motifs. ZNF445 gene is mapped to chromosome 3p21.32. Northern blot analysis indicates that a 9.1 kb transcript specific for ZNF445 is expressed in uterus, thymus, small intestine, colon, pancreas, peripheral blood leukocyte, and especially at a higher level in the testis and skeletal muscle in human adult tissues. ZNF445 protein was located in the nucleus when overexpressed in cultured cells. Reporter gene assays showed that ZNF445 is a transcriptional repressor, and overexpression of ZNF445 in the HEK 293T cells activates the transcriptional activities of AP1 and SRE. Deletion studies showed that the SCAN domain of ZNF445 may be involved in this activation. Furthermore, we found that expression of ZNF445 can increase p42/44 MAPK, MEK and Raf-1 phosphorylation. These results clearly indicate that ZNF445 is a member of the zinc finger transcription factor family and may function in MAPK pathway through Raf-1/MEK/p42/44 MAPK signals.

Amino Acid Sequence↗

PubMed2005

Study on the relationship between level of CD58 expression in peripheral blood mononuclear cell and severity of HBV infection.

BACKGROUND: As one of the intercellular adhesion molecules, CD58 plays important roles in promotion of the adhesion between T cells and target cells, hyperplasia, activation of T cells and natural killer cells, and balance between Th1 and Th2. We studied the relationship between the levels of CD58 expression in peripheral blood mononuclear cells (PBMCs) and severity of HBV infection. METHODS: The levels of CD58 mRNA in PBMCs were detected using quantitative reverse transcription PCR. The percentage of CD58 positive cells was detected by flow cytometry in patients and healthy controls. RESULTS: The levels of CD58 mRNA and the percentage of CD58 positive cells in patients infected with HBV were significantly higher than that in the control. Based on severity of HBV infection, the patients were classified into four groups. The expression of CD58 increased significantly in an order from mild chronic, moderate chronic, severe chronic to severe hepatitis groups. The levels of CD58 mRNA and the percentage of CD58 positive cells in PBMCs from patients with HBV infection were both positively correlated with serum levels of ALT and AST. CONCLUSION: The level of CD58 expression is related with the severity of HBV infection and the degree of liver damage.

Alanine Transaminase↗

PubMed2005

5-Aza-2'-deoxycytidine induces retinoic acid receptor-beta(2) demethylation and growth inhibition in esophageal squamous carcinoma cells.

Esophageal squamous cell carcinoma (ESCC) is one of the most common tumors in human. Previous studies showed that multiple genetic and epigenetic alterations involved in carcinogenesis of esophagus, whereas the molecular mechanisms are poorly understood. So far, more and more ESCC-related genes have been found and retinoic acid receptor beta(2) (RARbeta(2)) is such a gene which was recognized as a putative tumor suppressor gene since reduced RARbeta(2) mRNA expression has been observed in several solid tumors, including ESCC. A growing evidence indicated that RARbeta(2) was required for the growth inhibitory effect of retinoic acid (RA). However, the molecular mechanism of its inactivation remained obscure in ESCC. The RARbeta2 methylation status was assessed by methylation-specific PCR (MSP) in 12 ESCC cell lines and compared with their mRNA and protein expression level. Bisulfite sequencing of RARbeta(2) promoter region was performed to confirm the MSP results. After 5-aza-2'-deoxycytidine (5-aza-dc) treatment the expression of RARbeta(2) was reversed in two RARbeta(2)-downregulated cell lines. Therefore, hypermethylation of the promoter regions of RARbeta2 gene is a major mechanism of transcriptional inactivation and might be involved in tumor development of esophagus in some ESCC cell lines suggesting that multiple mechanisms contribute to the loss of RARbeta(2) expression in ESCC cell lines. Furthermore, the methylation status of RARbeta(2) promoter region and its expression was analyzed in 51 ESCC tissue samples with their adjacent normal epithelia and two normal esophageal epithelia. The results showed that there was a statistically significant correlation between methylation status of RARbeta(2) and tumor grade; Moreover, a relationship between methylation status and decreased RARbeta(2) expression was found only in G(2) stage tumors. After 5-aza-dc treatment, RARbeta(2) restoration was accompanied by growth inhibition and this might be one of the mechanisms but not the only mechanism for the tumor cell growth inhibition by 5-aza-dc. This study may have clinical applications for ESCC therapy and prevention.

Adult↗

PubMed2005

Individual adult human neurons display aneuploidy: detection by fluorescence in situ hybridization and single neuron PCR.

Neurons, once committed, exit the cell cycle and undergo maturation that promote specialized activity and are believed to operate upon a stable genome. We used fluorescence in situ hybridization, selective cell microdissection, and loss of heterozygosity analysis to assess degree of aneuploidy in patients with a neurodegenerative disease and in normal controls. We found that aneuploidy occurs in approximately 40% of mature, adult human neurons in health or disease and may be a physiological mechanism that maintains neuronal fate and function; it does not appear to be an unstable state. The fact that neuronal stem cells can be identified in adult humans and that somatic mosaicism may be found in neuronal precursor cells deserves further investigation before using adult neural stem cells to treat human disease.

Adult↗

PubMed2005

Alterations in degradative pathways and protein aggregation in a neuropathy model based on PMP22 overexpression.

Charcot-Marie-Tooth disease type 1A (CMT1A) is commonly associated with duplication of the peripheral myelin protein 22 (PMP22) gene. Mice expressing seven copies of the human PMP22, termed C22, suffer from a demyelinating neuropathy and display phenotypic traits of CMT1A. In this article, we investigate whether protein aggregates play a role in the CMT1A-like pathology of C22 mice. Utilizing biochemical and immunochemical tools, we found slowed turnover rate of the newly-synthesized PMP22 and the presence of cytoplasmic protein aggregates in affected nerves. The formation of these aggregates correlates with reduced proteasome activity and the accumulation of detergent-insoluble ubiquitinated substrates. A fraction of the aggregates associates with autophagosomes and lysosomes. Together, these data indicate that as a result of missorting and inefficient proteasomal degradation, the aggregation of PMP22 and recruitment of autophagosomes and lysosomes are key factors in the subcellular pathogenesis of CMT1A neuropathies.

Animals↗

PubMed2005

Lysine carboxylation in proteins: OXA-10 beta-lactamase.

An increasing number of proteins are being shown to have an N(zeta)-carboxylated lysine in their structures, a posttranslational modification of proteins that proceeds without the intervention of a specific enzyme. The role of the carboxylated lysine in these proteins is typically structural (hydrogen bonding or metal coordination). However, carboxylated lysines in the active sites of OXA-10 and OXA-1 beta-lactamases and the sensor domain of BlaR signal-transducer protein serve in proton transfer events required for the functions of these proteins. These examples demonstrate the utility of this unusual amino acid in acid-base chemistry, in expansion of function beyond those of the 20 standard amino acids. In this study, the ONIOM quantum-mechanical/molecular-mechanical (QM/MM) method is used to study the carboxylation of lysine in the OXA-10 beta-lactamase. Lys-70 and the active site of the OXA-10 beta-lactamase were treated with B3LYP/6-31G(d,p) density functional calculations and the remainder of the enzyme with the AMBER molecular mechanics force field. The barriers for unassisted carboxylation of neutral lysine by carbon dioxide or bicarbonate are high. However, when the reaction with CO2 is catalyzed by a molecule of water in the active site, it is exothermic by about 13 kcal/mol, with a barrier of approximately 14 kcal/mol. The calculations show that the carboxylation and decarboxylation of Lys-70 are likely to be accompanied by deprotonation and protonation of the carbamate, respectively. The analysis may also be relevant for other proteins with carboxylated lysines, a feature that may be more common in nature than previously appreciated.

Computational Biology↗

PubMed2005

Development of a functional cDNA array for evaluation of the Th1/Th2 balance.

The immune balance controlled by CD4(+) helper T cell subsets (T helper 1 (Th1) and T helper 2 (Th2)) is crucial for immunoregulation and its imbalance causes various immune diseases including infections, allergic disorders and autoimmune diseases. Therefore, it is of great importance to develop a system of diagnosing Th1/Th2 imbalances for curing immune diseases. Here we developed a functional cDNA array filter useful for assessing the Th1/Th2 balance in mice. To overcome the disadvantages of conventional microarrays carrying thousands of genes, we prepared an array filter containing 40 Th1-specific and 32 Th2-specific genes, which were selected from over 8700 genes based on (i) the specificity of expression in Th1 or Th2 cells and (ii) an expression level which is high enough for detection using a DNA array. This array filter provided a prompt and precise evaluation for the skewing of the Th1/Th2 balance combined with our calculation algorithm. The bias toward Th1 or Th2 was evaluated visually at a glance by aligning the genes on the filter. Moreover, we succeeded in evaluating the skewing of the Th1/Th2 balance in vivo during acute graft versus host disease (GVHD). Thus, this array filter will provide a novel tool for evaluation of the Th1/Th2 balance in a variety of immune diseases.

Acute Disease↗

PubMed2005

Proteome analysis of microdissected tumor tissue using a capillary isoelectric focusing-based multidimensional separation platform coupled with ESI-tandem MS.

This study demonstrates the ability to perform sensitive proteome analysis on the limited protein quantities available through tissue microdissection. Capillary isoelectric focusing combined with nano-reversed-phase liquid chromatography in an automated and integrated platform not only provides systematic resolution of complex peptide mixtures based on their differences in isoelectric point and hydrophobicity but also eliminates peptide loss and analyte dilution. In comparison with strong cation exchange chromatography, the significant advantages of electrokinetic focusing-based separations include high resolving power, high concentration and narrow analyte bands, and effective usage of electrospray ionization-tandem MS toward peptide identifications. Through the use of capillary isoelectric focusing-based multidimensional peptide separations, a total of 6866 fully tryptic peptides were detected, leading to the identification of 1820 distinct proteins. Each distinct protein was identified by at least one distinct peptide sequence. These high mass accuracy and high-confidence identifications were generated from three proteome runs of a single glioblastoma multiforme tissue sample, each run consuming only 10 microg of total protein, an amount corresponding to 20,000 selectively isolated cells. Instead of performing multiple runs of multidimensional separations, the overall peak capacity can be greatly enhanced for mining deeper into tissue proteomics by increasing the number of CIEF fractions without an accompanying increase in sample consumption.

Brain Neoplasms↗

PubMed2005

Ribosomal protein L10a, a bridge between trichosanthin and the ribosome.

Trichosanthin is a type I ribosome-inactivating protein with many pharmacological activities. The trichosanthin-coupled Sepharose affinity purification revealed a protein, which was identified by mass spectrometry as the ribosomal protein L10a. The interaction between trichosanthin and recombinant L10a was further confirmed by in vitro binding assay. Kinetic analysis by surface plasmon resonance technology revealed that L10a had a high affinity to trichosanthin with a K(D) of 7.78nM. The study with mutated forms of trichosanthin demonstrated that this specific association correlates with the ribosome-inactivating activity of trichosanthin. This finding might provide insight into the mechanisms by which trichosanthin inactivates ribosome and that underlies its pharmacological effect.

Chromatography, Affinity↗

PubMed2005

[Successful preimplantation genetic diagnosis for alpha-thalassemia using fluorescent polymerase chain reaction].

OBJECTIVE: To develop single-cell fluorescent gap polymerase chain reaction (PCR) assay for preimplantation genetic diagnosis (PGD) in couples at risk of having child with alpha-thalassemia. METHODS: Single cell fluorescent gap PCR which can detect the alpha-thalassemia Southeast Asia deletion (-SEA deletion), was applied to single lymphocytes and blastomeres which coming from four clinical PGD cycles. RESULTS: The Single cell fluorescent gap PCR can detect the alpha-thalassemia -SEA deletion, which account for 94% of hydrop fetalis in Chinese population with an amplification efficiency of 90.0% (72/80) and allele drop-out (ADO) rate of 8.3% (6/72) in lymphocytes. In four clinical PGD cycles, a total 38 embryos were detected and 38 blastomeres were obtained. Thirty-four blastomeres were amplified with the amplification efficiency of 89.5% (34/38) and ADO rate of 5.9% (2/34). Eleven embryos were shown to be normal homozygous, eight embryos were shown to be heterozygous and 15 embryos were shown to be affected homozygous. Eleven embryos were transferred back to the uterus of the patients. Two pregnancy achieved, resulting in two live healthy births, which confirmed the results of PGD. CONCLUSION: This first reported unaffected pregnancy resulting from PGD using fluorescent gap PCR for alpha-thalassemia demonstrates that this technique, as an alternative to prenatal diagnosis, is a reliable and effective way to help those carrier couples to get a healthy baby.

Adult↗

PubMed2005

Gene therapy restores vision-dependent behavior as well as retinal structure and function in a mouse model of RPE65 Leber congenital amaurosis.

Retinal pigment epithelium-specific protein 65 kDa (RPE65) is a protein responsible for isomerization of all-trans-retinaldehyde to its photoactive 11-cis-retinaldehyde and is essential for the visual cycle. RPE65 mutations can cause severe, early onset retinal diseases such as Leber congenital amaurosis (LCA). A naturally occurring rodent model of LCA with a recessive nonsense Rpe65 mutation, the rd12 mouse, displays a profoundly diminished rod electroretinogram (ERG), an absence of 11-cis-retinaldehyde and rhodopsin, an overaccumulation of retinyl esters in retinal pigmented epithelial (RPE) cells, and photoreceptor degeneration. rd12 mice were injected subretinally at postnatal day 14 with rAAV5-CBA-hRPE65 vector. RPE65 expression was found over large areas of RPE soon after treatment. This led to improved rhodopsin levels with ERG signals restored to near normal. Retinyl ester levels were maintained at near normal, and fundus and retinal morphology remained normal. All parameters of restored retinal health remained stable for at least 7 months. The Morris water maze behavioral test was modified to test rod function under very dim light; rd12 mice treated in one eye performed similar to normally sighted C57BL/6J mice, while untreated rd12 mice performed very poorly, demonstrating that gene therapy can restore normal vision-dependent behavior in a congenitally blind animal.

Animals↗

PubMed2005

Increased astrocyte proliferation in rats after running exercise.

The aim in this study was to investigate whether physical exercise could induce astroglial proliferation in the frontoparietal cortex and dorsolateral striatum where extensive angiogenesis had been found after exercise in previous studies. Adult male Sprague Dawley rats (n=48) were used in four experimental groups. Animals were exercised 30 min each day on a treadmill on which repetitive locomotor movement was required, for 0 (n=12), 3 (n=12) or 6 (n=12) weeks, as well as 3-week exercise plus 3-week rest (n=12). Brain tissues of the exercised and non-exercised rats were processed for glial fibrillary acidic protein (GFAP) immunocytochemistry (n=6 x 4) and Western blotting (n=6 x 4) to evaluate regional astrocyte proliferation in the frontoparietal cortex and dorsolateral striatum. By using GFAP immunocytochemistry and stereological methods, we compared the density of astrocytes in the animals with or without exercise. In comparison to non-exercised animals, a significant (p<0.01) increase in the number of astrocytes was observed in both cortex and striatum of rats exercised for 3 or 6 weeks. Our data also indicated that astrocytic density continued to increase up to 6 weeks either with an additional 3 weeks of exercise (p<0.01) or 3 weeks of rest (p<0.01). In addition, Western blotting analysis showed an obvious increase in GFAP protein from cortex and striatum of exercised animals. Astrocytosis after exercise, coupled with angiogenesis, is thought to provide strength to the neurovascular unit (a construct consisting of microvascular endothelium, astroglia, neurons and the extracellular matrix). Strengthening of this unit by exercise may protect blood-brain-barrier function following brain injury, such as that occurring after stroke.

Animals↗

PubMed2005

Glycodiversification for the optimization of the kanamycin class aminoglycosides.

In an effort to optimize the antibacterial activity of kanamycin class aminoglycoside antibiotics, we have accomplished the synthesis and antibacterial assay of new kanamycin B analogues. A rationale-based glycodiversification strategy was employed. The activity of the lead is comparable to that of commercially available kanamycin. These new members, however, were found to be inactive against aminoglycoside resistant bacteria. Molecular modeling was used to provide the explanation. Thus, a new strategy for structural modifications of kanamycin class aminoglycosides is suggested.

Anti-Bacterial Agents↗

PubMed2005

Intrasarcoplasmic amyloidosis impairs proteolytic function of proteasomes in cardiomyocytes by compromising substrate uptake.

The presence of increased ubiquitinated proteins and amyloid oligomers in failing human hearts strikingly resembles the characteristic pathology in the brain of many neurodegenerative diseases. The ubiquitin-proteasome system (UPS) is responsible for degradation of most cellular proteins and plays essential roles in virtually all cellular processes. UPS impairment by aberrant protein aggregation was previously shown in cell culture but remains to be demonstrated in intact animals. Mechanisms underlying the impairment are poorly understood. We report here that UPS proteolytic function is severely impaired in the heart of a mouse model of intrasarcoplasmic amyloidosis caused by cardiac-restricted expression of a human desmin-related myopathy-linked missense mutation of alphaB-crystallin (CryAB(R120G)). The UPS impairment was detected before cardiac hypertrophy, and failure became discernible, suggesting that defective protein turnover likely contributes to cardiac remodeling and failure in this model. Further analyses reveal that the impairment is likely attributable to insufficient delivery of substrate proteins into the 20S proteasomes, and depletion of key components of the 19S subcomplex may be responsible. The derangement is likely caused by aberrant protein aggregation rather than loss of function of the CryAB gene because UPS malfunction was not evident in CryAB-null hearts and inhibition of aberrant protein aggregation by Congo red or a heat shock protein significantly attenuated CryAB(R120G)-induced UPS malfunction in cultured cardiomyocytes. Because of the central role of the UPS in cell regulation and the high intrasarcoplasmic amyloidosis prevalence in failing human hearts, our data suggest a novel pathogenic process in cardiac disorders with abnormal protein aggregation.

Amyloidosis↗

PubMed2005

A novel transgenic mouse model reveals deregulation of the ubiquitin-proteasome system in the heart by doxorubicin.

Ubiquitin-proteasome system (UPS) mediated proteolysis is responsible for the degradation of majority of cellular proteins, thereby playing essential roles in maintaining cellular homeostasis and regulating a number of cellular functions. UPS dysfunction was implicated in the pathogenesis of numerous disorders, including neurodegenerative disease, muscular dystrophy, and a subset of cardiomyopathies. However, monitoring in vivo functional changes of the UPS remains a challenge, which hinders the elucidation of UPS pathophysiology. We have recently created a novel transgenic mouse model that ubiquitously expresses a surrogate protein substrate for the UPS. The present study validates its suitability to monitor in vivo changes of UPS proteolytic function in virtually all major organs. Primary culture of cells derived from the adult transgenic mice was also developed and tested for their applications in probing UPS involvement in pathogenesis. Applying these newly established in vivo and in vitro approaches, we have proven in the present study that doxorubicin enhances UPS function in the heart and in cultured cardiomyocytes, suggesting that UPS hyper-function may play an important role in the acute cardiotoxicity of doxorubicin therapy.

Animals↗

PubMed2005

Differential effects of human neuromelanin and synthetic dopamine melanin on neuronal and glial cells.

We investigated the effects of neuromelanin (NM) isolated from the human substantia nigra and synthetic dopamine melanin (DAM) on neuronal and glial cell lines and on primary rat mesencephalic cultures. Lactate dehydrogenase (LDH) activity and lipid peroxidation were significantly increased in SK-N-SH cells by DAM but not by NM. In contrast, iron-saturated NM significantly increased LDH activity in SK-N-SH cells, compared with 100 mg/mL ETDA-treated NM containing a low concentration of bound iron. DAM, but not NM, stimulated hydroxyl radical production and increased SK-N-SH cell death via apoptotic-like mechanisms. Neither DAM nor NM induced any changes in the glial cell line U373. 3H-dopamine uptake in primary rat mesencephalic cultures was significantly reduced in DAM-compared with NM-treated cultures, accompanied by increased cell death via an apoptosis-like mechanism. Interestingly, Fenton-induced cell death was significantly decreased in cultures treated with both Fenton reagent and NM, an effect not seen in cultures treated with Fenton reagent plus DAM. These data are suggestive of a protective role for neuromelanin under conditions of high oxidative load. Our findings provide new evidence for a physiological role for neuromelanin in vivo and highlights the caution with which data based upon model systems should be interpreted.

Animals↗