Search PubMed⌕ Search

Biomedical subjects

Lei Chen

Publications and source records attributed to Lei Chen.

At least 145 records · Page 8Linked to original sources
PubMed2004

[Effects of autologous hematopoietic stem cell transplantation on immune function in patient with systemic lupus erythematosus].

To investigate the effects of autologous hematopoietic stem cell transplantation (AHSCT) on immune index in patient with systemic lupus erythematosus (SLE), and evaluate its treatment outcome, the flow cytometry (FCM) and enzyme linked immunosorbent assay (ELISA) were used to detect the leukocyte differentiation antigen, sIL-2R, IL-6, C3, C4, autoantibodies, immunoglobulin for 33 case of SLE before transplantation and at 1, 3, 6, 12 months after transplantation. The results showed that the ratio of CD4(+), CD19(+) cell, the level of sIL-2R, IL-6 and the positive rate of autoantibodies were significantly lower, CD8(+), CD16(+)CD56(+) cell and C3, C4 were higher than those before transplantation. Out of the 33 patients, 26 achieved CR, 3 reached PR and 4 relapsed at 4 - 6 months after transplantation. It is concluded that the immune indexes of patients with SLE changed significantly following AHSCT. These immune indexes may be indications to predict the status of remission in patient with SLE.

Adolescent↗
PubMed2004

[Relationship between the prevalence of microalbuminuria and components of metabolic syndrome in Shanghai].

OBJECTIVE: To study the relationship between the prevalence of microalbuminuria and components of metabolic syndrome in Shanghai. METHODS: A total of 3532 Shanghai Chinese (men 1622, women 1910) aged over 20 years were included. Body mass index (BMI), blood pressure, fasting plasma glucose, lipid profile and plasma insulin concentrations were measured in all subjects. Oral glucose tolerance test was performed in those subjects without knowing the diabetic history. Urinary albumin-to-creatinine ratio (ACR) was measured in an early morning spot urine sample. Microalbuminuria was diagnosed when ACR was between 30 and 300 mg/g. RESULTS: (1) The prevalence of microalbuminuria was increasing with aging (P < 0.001). When compared with subjects having normal ACR, the waist-hip ratio, systolic and diastolic pressure, serum triglyceride level, fasting plasma glucose and homeostasis model assessment-insulin resistance (HOMA-IR) were all significantly increased in those subjects with microalbuminuria. (2) Along with the increment of number of items on metabolic disorders, the prevalence of microalbuminuria was significantly increased (P for trend < 0.001). (3) Multiple logistic regression analyses revealed that hypertension and hyperglycemia were independent factors associated with microalbuminuria (OR = 2.15, P < 0.001 and OR = 1.64, P = 0.01 respectively). Those subjects with two or more items on metabolic disorders had higher odd ratio for the development of microalbuminuria (OR = 3.93 and 4.77, both P < 0.001) when compared with the subjects without metabolic disorder. CONCLUSION: The prevalence of microalbuminuria was independently associated with hypertension and hyperglycemia. The subjects with multiple metabolic abnormalities had higher risk for the development of microalbuminuria, especially in metabolic syndrome.

Adult↗
PubMed2004

[Coculture of dendritic cell with cytokine-induced killer results in a significant increase in cytotoxic activity of CIK to tumor cells in vitro and in vivo].

OBJECTIVE: To explore whether coculture of dendritic cells (DC) with cytokine-induced killer (CIK) lead to an increase of cytotoxicity against tumor cells in vitro and in vivo. METHODS: DC and CIK were prepared from human peripheral blood mononuclear cells (PBMC) by conventional methods, the DC pulsed with or without NB4 leukemia cell lyses (LCL) was cocultured with the CIK (LCL-DC + CIK and DC + CIK), CIK was used as control. Cells phenotypes were analyzed by flow cytometry, secretion of IFN-gamma was determined by ELISPOT assay, and cytotoxicity was assayed in vitro with (51)Cr-release assay. A human leukemia cell NB4-bearing nude mice model was established to test in vivo antitumor efficacy and cell homing. RESULTS: Compared with CIK, LCL-DC + CIK got a significant increasing of proliferation rate [(18.2 +/- 2.1) times vs (11.6 +/- 2.3) times, P < 0.05] and CD(3)(+)CD(56)(+) expression rate [(51.05 +/- 2.63)% vs (30.18 +/- 1.45)%, P < 0.05], and the number of IFN-gamma secreting cells was increased significantly [(13.86 +/- 3.28)/10(4) cells vs (8.74 +/- 2.53)/10(4) cells, n = 12, P < 0.05]. Meanwhile, LCL-DC + CIK led to an increase of cytotoxic activity to NB4, K562, and KG1a cells, and showed significant inhibition of the growth of transplanted tumor cells and increased tumor free survival rate of nude mice (100% vs 66.7%, P < 0.05), DiI labeled LCL-DC + CIK were detected in spleen, lymph node and tumor within a week after injection. There was no significant different in antitumor activity between LCL-DC + CIK cell and DC + CIK cell. CONCLUSION: Coculture of CIK with DCs can promote the effect of CIK against tumor in vitro and in vivo. DC-CIK is promising as an immuno-therapeutic strategy for patients with leukemia.

Animals↗
PubMed2004

[Construction and functional study of truncated beta catenin genes].

AIM: To observe the subcellular location and the change of the transcriptional activity of truncated beta catenins in mammalian cells. METHODS: The full length wild type beta catenin gene was cloned by RT-PCR. The truncated beta catenins were constructed by deleting the N terminal, the C terminal or the Armadillo domain sequences, and were inserted into the EGFP expression vector. After they were transfected into 293 cells, the transcriptional activity of truncated beta catenins in 293 cells was detected by dual luciferase reporter system. The subcellular location of truncated beta catenin in transfected COS7 cells was observed under fluorescence microscope. RESULTS: The eukaryotic expression vector containing truncated beta catenin gene and expression vector of truncated beta catenin gene fused with EGFP gene were constructed successfully. C terminus-deleted beta catenin localized mainly in the cytoplasm of transfected COS7 cells, and the transcriptional activity of the N terminus- and the C terminus- deleted beta catenins was lower than that of the wild type beta catenin in transfected 293 cells. CONCLUSION: The different locations of truncated beta catenins in transfected COS7 cells suggest that the truncated ones play different roles in the transcriptional activity.

Animals↗
PubMed2004

[Cerebrospinal rhinorrhen of 5 cases].

OBJECTIVE: To investigate the approaches of diagnosis and therapy to cerebrospinal rhinorrhea and to improve the effects of diagnosis and therapy. METHOD: Five cases of cerebrospinal rhinorrhea were analyzed retrospectively. Four were performed repair assisted by operation navigation instrument and endoscopy, 1 was performed forehead craniotomy with coronal incision and reconstruction with pedicled galeal flaps. RESULT: Followed up half a year, all the patients were healed. CONCLUSION: The patient of cerebrospinal rhinorrhea can be repaired by endoscopy if the opening is small. The navigation instrument is evidently helpful to find the opening more quickly and exactly. The patients with wider opening had better to accept reconstruction with appropriate materials after undergoing craniotomy to ensure the effects of the therapy.

Adult↗
PubMed2004

Identification of differentially expressed genes from spinal cord after firearm injury to rabbit sciatic nerves.

OBJECTIVE: Peripheral nerve regeneration depends on gene regulation by central neurons. To search for more effective treatment methods to improve the regeneration of wounded peripheral nerves, gene expression profile of spinal cord after firearm injury to rabbit sciatic nerves are studied with DNA micro-array technique. METHODS: A total of 54 rabbits were randomly divided into 4 groups: Groups d1, d3, d7 and normal control group. Lumbar spinal cords were sampled. RNA and mRNA were extracted, labeled by Cy3 and Cy5, and analyzed by mouse_8192S gene chips. RESULTS: A total of 1367, 923, and 61 genes with differential expression were found on day 1, day 3, and day 7 after trauma respectively. Five expressed sequence tag (EST) sequences demonstrated differential expression during 7 days after trauma. CONCLUSIONS: There is complex gene profile with differential expression after firearm nerve injury, among which AW701496, U84291, W13926, X04017 and AW822394 EST sequences may be important regulation factors that involved in regeneration of peripheral nerve injury.

Animals↗
PubMed2004

[Analysis on intraspecific variation of Cnidium monnieri by RAPD].

OBJECTIVE: To study the genetic variation of Cnidium monnieri from different regions. METHODS: Random amplified polymophic DNA technique was used to analyze genetic polymorphy of Cnidium monnieri from 9 different regions, and dendrogram was constructed by UPGMA. RESULTS: 20 random primers were used for polymorphic selection. A total of 75 bands were amplified, 64 of which were polymorphism. CONCLUSION: The smaller the geographic distances between two Cnidium monnieri, the smaller genetic differences. However, it should not be overlooked that natural environment, especially the local ecological conditions may also show some influences on the genetic variations among different C. monnieri samples.

Cluster Analysis↗
PubMed2003

Activation of apoptosis signal-regulating kinase 1 by reactive oxygen species through dephosphorylation at serine 967 and 14-3-3 dissociation.

Oxidative stress has been indicated in a variety of pathological processes such as atherosclerosis, diabetes, and neurodegenerative diseases. Understanding how intracellular signaling pathways respond to oxidative insults such as hydrogen peroxide (H(2)O(2)) would have significant therapeutic implications. Recent genetic studies have placed apoptosis signal-regulating kinase 1 (ASK1) in a pivotal position in transmitting H(2)O(2)-initiated signals. How ASK1 is activated by H(2)O(2), though, remains a subject of intense investigation. Here we report a mechanism by which H(2)O(2) induces ASK1 activation through dynamic control of its phosphorylation at serine 967. We found that treatment of COS7 cells with H(2)O(2) triggers dephosphorylation of Ser-967 through an okadaic acid-sensitive phosphatase, resulting in dissociation of the ASK1.14-3-3 complex with concomitant increase of ASK1 catalytic activity and ASK1-mediated activation of JNK and p38 pathways.

14-3-3 Proteins↗
PubMed2003

Pathogenesis of X-linked Charcot-Marie-Tooth disease: differential effects of two mutations in connexin 32.

X-linked Charcot-Marie-Tooth disease is an inherited peripheral neuropathy arising in patients with mutations in the gene encoding connexin 32 (Cx32). Cx32 is expressed at the paranodes and Schmidt-Lantermann incisures of myelinating Schwann cells in which it is believed to form a reflexive pathway between the abaxonal and adaxonal cytoplasmic domains. Patients with the Val181Ala (V181A) mutation have a severe peripheral neuropathy. Experiments using a nude mouse xenograft system show that Schwann cells expressing only this mutant form of Cx32 are profoundly impaired in their ability to support the earliest stages of regeneration of myelinated fibers. Coupling between paired Xenopus oocytes expressing V181A is reduced compared with the coupling between oocytes expressing wild-type human Cx32 (32WT), and protein levels assayed by Western blot are substantially lower. Immunocytochemisty shows that Neuro2a cells expressing the V181A mutant have very few gap junction plaques compared with cells expressing 32WT; Cx32 protein levels are lower in these cells than in those expressing 32WT. Because failure of normal regeneration is evident before formation of myelin, loss of function of Cx32 may impact on the function of precursors of the myelinating Schwann cell before the formation of the hypothesized reflexive pathway. The Glu102Gly (E102G) mutation leads to a milder phenotype. Early regeneration is normal in grafts with Schwann cells expressing the E102G mutant. The only abnormality detected in the behavior of its channel is increased sensitivity to acidification-induced closure, a property that may lead to reduced gap junction coupling during periods of metabolic stress. This restricted functional abnormality may explain the relatively mild phenotype seen in the xenograft model and in E102G patients.

Acids↗
PubMed2003

Increased retention of functional fusions to toxic genes in new two-hybrid libraries of the E. coli strain MG1655 and B. subtilis strain 168 genomes, prepared without passaging through E. coli.

BACKGROUND: Cloning of genes in expression libraries, such as the yeast two-hybrid system (Y2H), is based on the assumption that the loss of target genes is minimal, or at worst, managable. However, the expression of genes or gene fragments that are capable of interacting with E. coli or yeast gene products in these systems has been shown to be growth inhibitory, and therefore these clones are underrepresented (or completely lost) in the amplified library. RESULTS: Analysis of candidate genes as Y2H fusion constructs has shown that, while stable in E. coli and yeast for genetic studies, they are rapidly lost in growth conditions for genomic libraries. This includes the rapid loss of a fragment of the E. coli cell division gene ftsZ which encodes the binding site for ZipA and FtsA. Expression of this clone causes slower growth in E. coli. This clone is also rapidly lost in yeast, when expressed from a GAL1 promoter, relative to a vector control, but is stable when the promoter is repressed. We have demonstrated in this report that the construction of libraries for the E. coli and B. subtilis genomes without passaging through E. coli is practical, but the number of transformants is less than for libraries cloned using E. coli as a host. Analysis of several clones in the libraries that are strongly growth inhibitory in E. coli include genes for many essential cellular processes, such as transcription, translation, cell division, and transport. CONCLUSION: Expression of Y2H clones capable of interacting with E. coli and yeast targets are rapidly lost, causing a loss of complexity. The strategy for preparing Y2H libraries described here allows the retention of genes that are toxic when inappropriately expressed in E. coli, or yeast, including many genes that represent potential antibacterial targets. While these methods are generally applicable to the generation of Y2H libraries from any source, including mammalian and plant genomes, the potential of functional clones interacting with host proteins to inhibit growth would make this approach most relevant for the study of prokaryotic genomes.

Bacillus subtilis↗
PubMed2003

Preparation of mesoporous ZrO2 with the middle phase formed in a trioctyl (or alkyl) phosphinic oxide-kerosene/HCl-ZrOCl2 extraction system.

The extraction behavior and phase behavior of TOPO (or TRPO)-kerosene/HCl-ZrOCl(2) systems have been investigated. The middle phase with bicontinuous structure is first used as both the Zr(IV) source and the template to prepare mesoporous material just by precipitation with aqua ammonia under low temperature. By this method, crystal mesoporous ZrO(2) powders with average d-values of 6.3 and 7.48 nm, respectively, have been obtained. TG-DTA, TEM, and XRD are adopted for the characterization of the synthesized sample.

Journal Article↗
PubMed2003

Effects of the GABA-uptake inhibitor tiagabine in rat globus pallidus.

To elucidate the cellular action of tiagabine, an inhibitor of GAT-1 GABA transporter, in the globus pallidus, whole-cell patch-clamp recordings were made from rat globus pallidus neurons in the acutely prepared brain slice. Superfusion of tiagabine significantly prolonged the decay kinetics of both action potential-dependent and -independent (tetrodotoxin-resistant) inhibitory postsynaptic currents (IPSCs) that were mediated by GABA(A) receptors. Furthermore, it decreased the frequency of these IPSCs. The latter effect was reversed by the GABA(B) receptor antagonist CGP55845, which alone had no effect, suggesting the involvement of presynaptic GABA(B) receptors. Thus, tiagabine could inhibit or disinhibit globus pallidus neurons by increasing the activation of the GABA(A) receptors and presynaptic GABA(B) receptors, respectively. In the behaving animal, tiagabine when injected unilaterally into the globus pallidus caused consistent ipsilateral rotation of the rats indicative of increased inhibition of globus pallidus activity. This finding could be explained by the proposition that in the presence of tiagabine, prolonged action of GABA on GABA receptors would dominate over the inhibitory effect of tiagabine on GABA release. Our findings on the electrophysiological and behavioral effects of tiagabine in globus pallidus suggest that this basal ganglia nucleus is one of the sites of action of tiagabine and provides a rationale for investigating its involvement in epilepsy.

Animals↗
PubMed2003

NIK is a component of the EGF/heregulin receptor signaling complexes.

Nuclear factor kappaB-inducing kinase (NIK) is a member of the MAP kinase kinase kinase family that was first identified as a component of the TNF-R1-induced NF-kappaB activation pathway (TNF, tumor necrosis factor; nuclear factor kappaB, NF-kappaB). Gene knockout study, however, suggests that NIK is dispensable for TNF-R1- but required for lymphotoxin-beta receptor-induced NF-kappaB activation. A NIK kinase inactive mutant is a potent inhibitor of NF-kappaB activation triggered by various stimuli, suggesting that NIK is involved in a broad range of NF-kappaB activation pathways. To unambiguously identify signaling pathways that NIK participates in, we screened antibody arrays for proteins that are associated with NIK. This effort identified ErbB4, one of the EGF/heregulin receptors, and Grb7, an adapter protein associated with ErbB4 (ErbB, epidermal growth factor receptor family protein; EGF, epidermal growth factor; Grb, growth factor receptor bound). Coimmunoprecipitation experiments demonstrated that NIK interacted with Grb7, as well as Grb10 and Grb14, but not Grb2. Domain mapping experiments indicated that the central GM domain of Grb7 was sufficient for its interaction with NIK. Coimmunoprecipitation experiments also indicated that Grb7 and NIK could be simultaneously recruited into signaling complexes of all known EGF/heregulin receptors, including EGFR, ErbB2, ErbB3, and ErbB4. In reporter gene assays, NIK could potentiate Grb7, ErbB2/ErbB4, and EGF-induced NF-kappaB activation. A NIK kinase inactive mutant could block ErbB2/ErbB4 and EGF-induced NF-kappaB activation. Moreover, EGF/heregulin receptors activated NF-kappaB in wild-type, but not NIK-/- embryonic fibroblasts. Our findings suggest that NIK is a component of the EGF/heregulin receptor signaling complexes and involved in NF-kappaB activation triggered by these receptors.

ErbB Receptors↗
PubMed2003

Sexually dimorphic roles of steroid hormone receptor signaling in gonadal tumorigenesis.

Sex steroids control cellular phenotypes by binding to receptor proteins that in turn regulate downstream gene expression. They are important tropic factors in hormonally responsive tissues and have been implicated in the pathogenesis of both benign proliferations and malignancies at some of these sites. Knockout mice lacking inhibins, alpha:beta heterodimeric peptide hormones of the TGFbeta superfamily, develop gonadal tumors that produce sex steroids and depend on pituitary gonadotropin hormones. To better appreciate how sex steroid receptor signaling pathways contribute to the loss of granulosa/Sertoli cell proliferation in the ovary and testis of inhibin alpha (Inhalpha) knockout mice, we are using both pharmacologic and genetic approaches. Roles of androgens in testicular tumor development have been investigated in our previous studies using double-mutant mice lacking inhibins and carrying the null testicular feminization (tfm) mutation of the androgen receptor. Herein, we report that androgens also participate in the development of ovarian tumors, as tumor development is forestalled in mice treated with flutamide, a nonsteroidal inhibitor of androgen actions. Additionally, we generated double-mutant mice lacking estrogen receptor alpha (ERalpha) and Inhalpha or ERbeta and Inhalpha, as well as triple-mutant mice lacking ERalpha, ERbeta, and Inhalpha to determine the effects of individual and combined ER signaling pathways on tumor development. Although estrogens may have proliferative effects during follicle development and are important in specifying the granulosa cell phenotype, ERalpha and ERbeta signaling are not essential for timely granulosa cell tumor development or granulosa cell-like morphological features in ovarian tumors. However, redundant ER signaling through ERalpha and ERbeta in males is critical for testicular tumor formation, as triple-knockout, but not double-knockout, males are protected from early Sertoli cell tumorigenesis and death. Together, these studies indicate important and sexually dimorphic functions of estrogens and androgens in tumor development in this mouse model and indicate, for the first time, overlapping functions of ERalpha and ERbeta in Sertoli cell pathophysiology.

Androgens↗
PubMed2003

Neurotrophins and netrins require calcineurin/NFAT signaling to stimulate outgrowth of embryonic axons.

Axon outgrowth is the first step in the formation of neuronal connections, but the pathways that regulate axon extension are still poorly understood. We find that mice deficient in calcineurin-NFAT signaling have dramatic defects in axonal outgrowth, yet have little or no defect in neuronal differentiation or survival. In vitro, sensory and commissural neurons lacking calcineurin function or NFATc2, c3, and c4 are unable to respond to neurotrophins or netrin-1 with efficient axonal outgrowth. Neurotrophins and netrins stimulate calcineurin-dependent nuclear localization of NFATc4 and activation of NFAT-mediated gene transcription in cultured primary neurons. These data indicate that the ability of these embryonic axons to respond to growth factors with rapid outgrowth requires activation of calcineurin/NFAT signaling by these factors. The precise parsing of signals for elongation turning and survival could allow independent control of these processes during development.

Active Transport, Cell Nucleus↗
PubMed2003

NMR and parity violation: low-temperature dependence in 1H CRAMPS and 13C CP/MAS ssNMR spectra of alanine enantiomer.

Life is based on L-amino acids and D-sugars rather than the enantiomeric D-amino acids and L-sugars. This broken symmetry is now believed to be a feature of fundamental physics-a result of symmetry-breaking induced by the weak force, which makes one enantiomer slightly more stable than the other. An amplification mechanism based on quantum mechanical tunneling could give rise to a second-order phase transition. In order to understand the transition mechanism, we measured the temperature dependence of 1H CRAMPS solid state NMR and 13C CP/MAS spectra of D- and L-alanine crystals from 295 K through to 220 K. Obvious difference of NMR behaviors between two enantiomers was observed in the phase transition which may be related to one suggested by Salam, caused biochirality among twenty amino acids.

Alanine↗
PubMed2003

Packing structure and self-heating in capillary electrochromatography.

The origin of bubble formation during operation of capillary electrochromatography (CEC) has been an issue of debate. Ohmic heating resulted from current passed through a packed column was proposed as the primary cause. However, this explanation has been questioned on the ground that the current measured in CEC is much lower than that measured with open-tubular separation systems where no bubble formation occurs. To resolve this issue, we carried out a theoretical study correlating self-heating of the electrolyte with packing structure of the column. We used a bundle of capillary tubes, a bundle of two types of capillary tubes and two bundles of capillary tubes connected serially to model, respectively, the flow channels in the column of non-porous particles, in the column of porous particles and in the column of various packing densities. The results from this study indicate that, for columns of homogeneous packing density, the heat output is indeed smaller than that in open-tubular columns of the same dimensions. In this case, the self-heating cannot be a key factor responsible for the bubble formation in CEC. However, for columns of heterogeneous packing density, a large excess of heat release may be produced in column sections of high packing density and, in turn, over-heating in such sections may become the primary cause for the formation of bubbles. It follows from this study that preparation of columns of homogeneous packing structure is essential to obtain reproducible and bubble-free CEC systems.

Chromatography, Micellar Electrokinetic Capillary↗