PubMed Health⌕ Search

Biomedical subjects

Cheng He

Publications and source records attributed to Cheng He.

At least 37 records · Page 2Linked to original sources
PubMed2005

DNA prime followed by protein boost enhances neutralization and Th1 type immunity against FMDV.

Prime-boost strategy has been exhibited its potency to enhance immune responses, which would be important to the success to develop a vaccine against the foot-and-mouth disease virus (FMDV). An eukaryotic expression construct encoding the FMDV capsid VP1 protein with a recombinant VP1 protein or a commercial FMDV vaccine were tested in the prime-boost strategy in mice and cattle trials. The levels of induced specific antibodies, T cell proliferations, and DTH activities were significantly higher in the prime-boost groups than in those vaccinated with DNA, protein or FMDV vaccine alone. More importantly, the levels of neutralizing antibodies in the former groups were significantly higher than others and could last for at least four months in cattle trials. This study suggests that the prime-boost strategy significantly improves the effective immunity and may provide a longer protection against FMDV infection.

Animals↗
PubMed2004

Molecular basis of distinct interactions between Dok1 PTB domain and tyrosine-phosphorylated EGF receptor.

Phosphotyrosine binding (PTB) domains of the adaptor proteins Doks (downstream of tyrosine kinases) play an important role in regulating signal transduction of cell-surface receptors in cell growth, proliferation and differentiation; however, ligand specificity of the Dok PTB domains has until now remained elusive. In this study, we have investigated the molecular basis of specific association between the Dok1 PTB domain and the tyrosine-phosphorylated EGFR. Using yeast two-hybrid and biochemical binding assays, we show that only the PTB domain from Dok1 but not Dok4 or Dok5 can selectively bind to two known tyrosine phosphorylation sites at Y1086 and Y1148 in EGFR. Our structure-based mutational analyses define the molecular determinants for the two distinct Dok1 PTB domain/EGFR interactions and provide the structural understanding of the specific interactions between EGFR and PTB domains in the divergent Dok homologues.

Animals↗
PubMed2004

The effects of ciliary neurotrophic factor on neurological function and glial activity following contusive spinal cord injury in the rats.

Ciliary neurotrophic factor (CNTF) has been implicated in the pathophysiology of injury to the central nervous system. The rapid increase in CNTF production following spinal cord injury (SCI) in rats is thought to serve a role in the neuronal survival and functional recovery. In this study, 40 SD rats were divided into four groups: sham-operated group, saline-treated group, 5- and 10-microg CNTF group. Saline and CNTF were given through lumbar intrathecal catheter for 10 days after T10 segment of spinal cord were injured by modified Allen contusion method. Animals were behaviorally tested for 6 weeks using the Basso, Beattie, Bresnahan locomotor rating scale and inclined plane test. At the end of 6 week, rubrospinal neurons of five rats in each group were labeled by retrograde transport of the horseradish peroxidase (HRP) from the lesion site, and then the labeled red nucleus neuron (RN) numbers were counted. Additional rats were histologically assessed for tissue sparing and neuronal loss and reactive gliosis at the injury site and adjacent areas. Rats treated with CNTF regained greater improvements in hindlimb function than controls. The amount of spared tissue was significantly higher in CNTF-treated animals than in controls. After CNTF treatment, the number of HRP-labeled RN neurons were significantly increased. Astrocytes and microglia reactivity was more pronounced in CNTF-treated animals than in controls. These results indicate that intrathecal infusion of exogenous CNTF following SCI may significantly reduce tissue damage and protect the rubrospinal descending tracks and enhances functional recovery, and may also induce more gliosis.

Animals↗
PubMed2003

Olfactory ensheathing cells genetically modified to secrete GDNF to promote spinal cord repair.

Olfactory ensheathing cell (OEC) transplantation has emerged as a very promising therapy for spinal cord repair. In this study, we tested the ability of genetically modified OECs to secrete high levels of glial cell line-derived neurotrophic factor (GDNF) to promote spinal cord repair. The GDNF gene was transduced into OECs using a retroviral-based system. The engineered OECs were first characterized by their ability to express and secrete biologically active GDNF in vitro. After implantation into the spinal cord of adult rats with complete spinal cord transection, OEC survival and GDNF production were examined. The locomotor functions of animals were assessed and axon regeneration was evaluated at the morphological level. To our knowledge, we report for the first time that the genetically modified OECs are capable of producing GDNF in vivo to significantly improve recovery after spinal cord injury (SCI). This work combined the outgrowth-promoting property of OECs with the neuroprotective effects of the additionally overexpressed neurotrophic factors and opens new avenues for the treatment of SCI.

Animals↗
PubMed2003

Identification of the key amino acids of glial cell line-derived neurotrophic factor family receptor alpha1 involved in its biological function.

Glial cell line-derived neurotrophic factor (GDNF) plays a critical role in neurodevelopment and survival of midbrain dopaminergic and spinal motor neurons in vitro and in vivo. The biological actions of GDNF are mediated by a two-receptor complex consisting of a glycosylphosphatidylinositol-linked cell surface molecule, the GDNF family receptor alpha1 (GFRalpha1), and receptor protein tyrosine kinase Ret. Although structural analysis of GDNF has been extensively examined, less is known about the structural basis of GFRalpha1 function. In this study, based on evolutionary trace method and relative solvent accessibility prediction of residues, a set of trace residues that are solvent-accessible was selected for site-directed mutagenesis. A series of GFRalpha1 mutations was made, and PC12 cell lines stably expressing different GFRalpha1 mutants were generated. According to the survival and differentiation responses of these stable PC12 cells upon GDNF stimulation and the GDNF-GFRalpha1-Ret interaction assay, residues 152NN153, Arg259, and 316SNS318 in the GFRalpha1 central region were found to be critical for GFRalpha1 binding to GDNF and eliciting downstream signal transduction. The single mutation R259A in the GFRalpha1 molecule simultaneously lost its binding ability to GDNF and Ret. However N152A/N153A or S316A/N317A/S318A mutation in the GFRalpha1 molecule still retained the ability to bind with Ret. These findings suggest that distinct structural elements in GFRalpha1 may be involved in binding to GDNF and Ret.

Amino Acid Substitution↗
PubMed2003

Monofunctional platinum complexes showing potent cytotoxicity against human liver carcinoma cell line BEL-7402.

Three novel Pt(II) complexes [PtL(1)'Cl] I (L(1)' = glycine-N'-8-quinolylamide), [PtL(2)'Cl] II (L(2)' = l-alanine-N'-8-quinolylamide), and [PtL(3)Cl] III [L(3) = N-(tert-butoxycarbonyl)-l-methionine-N'-8-quinolylamide] have been synthesized and characterized. The crystal structure of complexes II and III showed that the ligands are three-coordinated with only one Cl(-) as the leaving group. Complex II crystallized in the monoclinic system with space group P2(1), a = 9.502(2) A, b = 4.724(1) A, c = 14.800(3) A, while complex III crystallized in the orthorhombic system with space group P2(1)2(1)2(1), a = 5.441(1) A, b = 12.978(3) A, c = 29.438(6) A. These complexes have been tested against a wide range of tumor cell lines including BEL-7402, HCT-116, SPC-A4, MOLT-4, P388, HL-60, A-549, SGC-7901, MKN-28, and HO-8910. Complex III is highly cytotoxic against the HCT-116 (IC(50) = 0.38 microM), SPC-A4 (IC(50) = 0.43 microM), BEL-7402 (IC(50) = 0.43 microM), and MOLT-4 (IC(50) = 0.61 microM) cell lines. The cell line most sensitive to III is human liver carcinoma cell line BEL-7402, which has a response rate of 75.1% at 6.6 x 10(-7) M, nearly 6 times higher than that of cisplatin.

Antineoplastic Agents↗
PubMed2003

[Effect of tumor necrosis factor-alpha on differentiation of mesencephalic neural stem cells and proliferation of oligodendrocytes in the rat].

To observe the influence of tumor necrosis factor-alpha (TNF-alpha) on differentiation of rat mesencephalic neural stem cells (NSCs), the numbers of neurons, astrocytes and oligodendrocytes generated from NSCs were analyzed after differentiation for 3 days by using immunocytochemistry technique. The results show that: (1) TNF-alpha enhanced the proportions of neurons and oligodendrocytes in progeny of NSCs; and (2) TNF-alpha induced the proliferation of oligodendrocytes derived from NSCs, but the proliferation of astrocytes was not influenced by TNF-alpha. We conclude that the TNF-alpha could influence the application of NSCs.

Animals↗
PubMed2003

Lanthanide-transition heterometallic extended structures with novel orthogonal metalloligand as building block.

One-dimensional lanthanide-transition heterometallic chains of squares, [LnNi(2)L(3)(HL)(DMF)(4)(ClO(4))(4).S]( infinity ) (Ln = Gd and Tb; HL is the Schiff base obtained by the condensation of 2-pyridylaldehyde with isonicotinic hydrazide N-oxide; S = solvent) and [LnNi(2)L(4)(DMF)(4)(ClO(4))(3).S]( infinity ) (Ln = Dy; S = solvent), were synthesized by self-assembly between well-designed orthogonal metalloligands [Ni(HL)L](+) and the Ln(III) ions, which act as the bridging units and nodes, respectively.

Journal Article↗
PubMed2003

The effect of bone marrow stromal cells on neuronal differentiation of mesencephalic neural stem cells in Sprague-Dawley rats.

There are numerous parallels between the heamatolymphopoietic and nervous systems in terms of the mechanisms regulating their development. We proposed that neural stem cells (NSCs) may respond to the microenvironmental signals provided by bone marrow stromal cells (BMSCs) which regulate the differentiation and maturation of hematolymphopoietic stem cells. First, we isolated and proliferated BMSCs from the femur and tibia, and NSCs from the midbrain of Sprague-Dawley (SD) rats, and then investigated the effects of BMSCs on the differentiation of NSCs into neurons, astrocytes and oligodendrocytes by directly plating neurospheres on BMSC monolayers in serum-free conditions. The results confirmed that BMSCs induced NSCs to differentiate selectively into neurons. The percentage of neurons significantly increased in 7 days in vitro co-cultures of NSCs and BMSCs as compared to NSCs cultures alone. When the duration of the cultures was extended to 12 days in vitro, BMSCs enhanced the survival of neurons derived from these NSCs; our investigation then focused on the underlying mechanism for this effect of BMSCs. NSCs were cultured with BMSC conditioned-medium and co-cultured with membrane fragments of live BMSCs or paraformaldehyde fixed BMSCs, the inducing activity of BMSCs was solely detectable in BMSC conditioned-medium, indicating that soluble factors secreted by BMSCs were responsible for its effect on the neuronal differentiation of NSCs. Therefore, BMSCs may provide a powerful tool for therapeutic neurological applications.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed2003

Activation of delta opioid receptors induces receptor insertion and neuropeptide secretion.

Here we describe a novel mechanism for plasma membrane insertion of the delta opioid receptor (DOR). In small dorsal root ganglion neurons, only low levels of DORs are present on the cell surface, in contrast to high levels of intracellular DORs mainly associated with vesicles containing calcitonin gene-related peptide (CGRP). Activation of surface DORs caused Ca(2+) release from IP(3)-sensitive stores and Ca(2+) entry, resulting in a slow and long-lasting exocytosis, DOR insertion, and CGRP release. In contrast, membrane depolarization or activation of vanilloid and P2Y(1) receptors induced a rapid DOR insertion. Thus, DOR activation induces a Ca(2+)-dependent insertion of DORs that is coupled to a release of excitatory neuropeptides, suggesting that treatment of inflammatory pain should include blockade of DORs.

Animals↗
PubMed2003

Selective degradation of AU-rich mRNAs promoted by the p37 AUF1 protein isoform.

An AU-rich element (ARE) consisting of repeated canonical AUUUA motifs confers rapid degradation to many cytokine mRNAs when present in the 3' untranslated region. Destabilization of mRNAs with AREs (ARE-mRNAs) is consistent with the interaction of ARE-binding proteins such as tristetraprolin and the four AUF1 isoforms. However, the association of the AUF1-mRNA interaction with decreased ARE-mRNA stability is correlative and has not been directly tested. We therefore determined whether overexpression of AUF1 isoforms promotes ARE-mRNA destabilization and whether AUF1 isoforms are limiting components for ARE-mRNA decay. We show that the p37 AUF1 isoform and, to a lesser extent, the p40 isoform possess ARE-mRNA-destabilizing activity when overexpressed. Surprisingly, overexpressed p37 AUF1 also destabilized reporter mRNAs containing a noncanonical but AU-rich 3' untranslated region. Since overexpressed p37 AUF1 could interact in vivo with the AU-rich reporter mRNA, AUF1 may be involved in rapid turnover of mRNAs that lack canonical AREs. Moreover, overexpression of p37 AUF1 restored the ability of cells to rapidly degrade ARE-mRNAs when that ability was saturated and inhibited by overexpression of ARE-mRNAs. Finally, activation of ARE-mRNA decay often involves a translation-dependent step, which was eliminated by overexpression of p37 AUF1. These data indicate that the p37 AUF1 isoform and, to some extent, the p40 isoform are limiting factors that facilitate rapid decay of AU-rich mRNAs.

Animals↗
PubMed2003

A structure-function analysis of glial cell-line-derived neurotrophic factor receptor alpha1.

The GFRalpha1 cDNA was amplified by RT-PCR from fetal rat hippocampus. The soluble recombinant GFRalpha1 and its mutants were obtained from an Escherichia coli expression system. The biological activity of soluble GFRalpha1 and its mutants were evaluated in PC12 cells. The results suggest that the central domain of GFRalpha1 is a crucial determinant for ligand binding. This established a solid basis for further study to find the key amino acid mediating the binding of GDNF and GFRalpha1.

Amino Acid Sequence↗
PubMed2002

The epidermal growth factor receptor juxtamembrane domain has multiple basolateral plasma membrane localization determinants, including a dominant signal with a polyproline core.

The epidermal growth factor (EGF) receptor is located predominantly in the basolateral membrane of polarized epithelia, where it plays a pivotal role during organogenesis and tissue homeostasis. We have shown previously that a 22-amino acid sequence in the EGF receptor juxtamembrane domain contains autonomous sorting information necessary for basolateral localization using the Madin-Darby canine kidney epithelial cell model. The goal of this study was to determine the molecular basis of EGF receptor basolateral membrane expression using site-directed mutagenesis to modify specific residues in this region. We now show that this sequence has two different, functionally redundant basolateral sorting signals with distinct amino acid requirements: one dependent on residues (658)LL(659) conforming to well-characterized leucine-based sorting signals, and a second containing a polyproline core comprising residues Pro(667) and Pro(670) ((667)PXXP(670)). Our data also suggest that Arg(662) contributes to the function of the proline-based signal. (667)PXXP(670) was the dominant signal when both motifs were present and was more effective than (658)LL(659) at overriding strong apical sorting signals located in the same molecule. Site-directed mutations at Arg(662), Pro(667), and Pro(670) were also associated with increased apical expression of full-length EGF receptors, demonstrating for the first time that the juxtamembrane region is necessary for accurate polarized expression of the native molecule.

Amino Acid Sequence↗
PubMed2002

[Progress of monoaminergic receptor investigation on depression].

It is widely accepted that monoamine transmitters are playing an important role in the progress of depression. The functions of monoamine transmitters and their receptors change profoundly during depression and its treatment. This paper is attempted to review the new progress of investigation into serotonin receptors, adrenoceptors and dopamine receptors related with depression mechanism respectively.

Biogenic Monoamines↗
PubMed2002

[Effects of different frequency electromagnetic fields on the differentiation of midbrain neural stem cells].

Objective. To examine the effect of electromagnetic fields (EMF) (20 Hz, 8 mT; 5 Hz, 8 mT) on the neuron-orientated differentiation of neural stem cells (NSCs) from midbrains of new-bom rats. Method. Differentiated NSCs were exposed to EMF for 2 x 15 min per day lasting for I d, 5 d, or 10 d. The sham-exposure controls were correspondingly established. Cells were fixed and processed for immunofluorescent staining using the antibody against neuron-specific marker MAP2, then the percentage of MAP2+ cells was calculated. Result. The two EMFs promoted the differentiation of a neuronal fate in different ways. Both of them came into effect even after 1 d exposure. When cells exposed to the 20 Hz EMF, the percentage of neuron-orientated cells gradually increased with longer-term exposure and the most significant effect appeared in 10 d group while that happened in 5 d group under the condition of 5 Hz EMF. The effect contrasted horizontally, significant differences between the two EMFs were observed only at 10 d groups, 20 Hz EMF having more favorable effect than 5 Hz EMF. Conclusion. 20 Hz and 5 Hz EMF could promote the differentiation of midbrain NSCs to a neuronal phenotype in different ways, suggesting that the physical induction might be another strategy to manipulate the differentiation of NSCs.

Animals↗
PubMed2002

[The neuroattract growth effect of ciliary neurotrophic factor on recurrent laryngeal nerve regeneration].

OBJECTIVE: To investigate the neuroattract growth effect of Ciliary neurotrophic factor (CNTF) on recurrent laryngeal nerve (RLN) regeneration. METHODS: 28 canines were divided into 4 groups (n = 7). RLN was severed and sutured in silicone chamber. CNTF or saline were injected into silicone chambers during nerve repair and injected subcutaneously every day after surgery in group A and B respectively. In group C and D, end to end anastomosis of RLN was performed, and CNTF or saline was used respectively for one month. The nerve regeneration and neuroattract growth effect were evaluated with electrophysiological, morphological examination and horseradish peroxidase(HRP) retrograde tracing 2, 3 and 4 months postoperatively. RESULTS: Physiological adductory and adductory motion was observed in all 7 cases in group A and C respectively, and in 3 cases in group B. No motion in group D. Misdirected electrical activity by misdirected nerve regeneration was found in 3 cases in group B and 6 cases in group D. On average, the potential of misdirected electrical activity in group D was significantly greater than that in group B (P < 0.05). Compared with group B, the number of HRP retro-gradely labeled motoneuron increased significantly in group A in ambiguous nucleus, but in nodosity shape ganglia the number of the labeled neurons were not significantly different between group A and B. The average number and diameter of myelinated axons in the group A and C were significantly greater than those in group B and D, but no significant difference was found between group A and B, D and C respectively. CONCLUSION: The results suggested that exogenous CNTF can enhance motor axon regeneration and have neuroattract growth effect on recurrent laryngeal nerve regeneration.

Animals↗