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Biomedical subjects

Ling Chen

Publications and source records attributed to Ling Chen.

At least 73 records · Page 4Linked to original sources
PubMed2005

Ocular manifestations of multiple sclerosis.

PURPOSE OF REVIEW: Multiple sclerosis is an autoimmune demyelinating disorder of the nervous system that is commonly manifested by visual system involvement and that may initially present with ophthalmologic symptoms. This paper reviews recent findings regarding the ocular manifestations in multiple sclerosis. RECENT FINDINGS: Manifestations of multiple sclerosis in the eye include both the afferent and efferent visual pathways. Optic neuritis, the most common ocular manifestation of multiple sclerosis, may be the initial clinical disease manifestation. Recent long-term follow-up data show that most patients with demyelinating optic neuritis have an excellent prognosis for recovery of central visual acuity. Evidence is emerging, however, for significant and broad reduction in both contrast sensitivity and color perception in multiple sclerosis patients despite near-normal visual acuities. Ocular motor deficits in multiple sclerosis include internuclear ophthalmoplegia and nystagmus, resulting in diplopia, oscillopsia, blurred visual, loss of stereopsis, and reading fatigue. Multiple sclerosis also may be associated with ocular inflammatory diseases, in particular pars planitis and retinal periphlebitis. SUMMARY: Ocular findings may be initial manifestations of multiple sclerosis and may predict additional demyelinating events. Recognizing these syndromes and signs will help clinicians to properly evaluate the patient, formulate an appropriate differential diagnosis, be able to discuss the prognosis with the patient, and help develop an effective therapeutic plan.

Eye Diseases↗
PubMed2005

Ataxia-telangiectasia-mutated dependent phosphorylation of Artemis in response to DNA damage.

Artemis plays a crucial role in the hairpin-opening step of antigen receptor VDJ gene recombination in the presence of catalytic subunit of deoxyribonucleic acid (DNA)-dependent protein kinase (DNA-PKcs). A defect in Artemis causes human radiosensitive-severe combined immunodeficiency. Cells from Artemis-deficient patients and mice display increased chromosomal instability, but the precise function of this factor in the response to DNA damage remains to be elucidate. In this study, we show that Artemis is hyperphosphorylated in an Ataxia-telangiectasia-mutated (ATM)- and Nijmegen breakage syndrome 1 (Nbs1)-dependent manner in response to ionizing radiation (IR), and that S645 is an SQ/TQ site that contributes to retarded mobility of Artemis upon IR. The hyperphosphorylation of Artemis is markedly reduced in ATM- and Nbs1-null cells. Reintroduction of wild-type ATM or Nbs1 reconstituted Artemis hyperphosphorylation in ATM- or Nbs1-deficient cells, respectively. In support of this functional link, hyperphosphorylated Artemis was found to physically associate with the Mre11/Rad50/Nbs1 complex in an ATM-dependent manner in response to IR-induced DNA double strand breaks (DSB). Since deficiency of either DNA-Pkcs or ATM leads to defective repair of IR-induced DSB, our finding places Artemis at the signaling crossroads downstream of DNA-PKcs and ATM in IR-induced DSB repair.

Ataxia Telangiectasia↗
PubMed2005

[Inhibition of CD40 expression on CA46 cell lines by hairpin siRNA eukaryotic expression vectors].

AIM: To construct human CD40 hairpin siRNA eukaryotic expression vectors and investigate their effects on CD40 expression, proliferation and apoptosis of CA46 cells. METHODS: Two DNA oligonucleotides encoding CD40 hairpin siRNAs were synthesized, and cloned into pSilenCircle to construct recombinant plasmid siCD40/pSilenCircle that expressed hairpin siRNAs under the control of pol III U6 promoter. At the same time, antiCD40/pSilenCircle encoding the antisense CD40 RNA and siFly/pSilenCircle encoding siRNA against luciferase were constructed as control vectors. The recombinants were identified by restriction enzyme digestion analysis and sequencing. The recombinant plasmids were transfected into CA46 cells. CD40 expression on CA46 cells and apoptosis were detected by flow cytometry. The proliferation of transfected CA46 cells was detected by MTS colorimetry. RESULTS: (1)siCD40/pSilenCircle, antiCD40/pSilenCircle and siFly/pSilenCircle had been constructed successfully. (2) CD40 expressions on siCD40/pSilenCircle- and antiCD40/pSilenCircle-transfected CA46 cells were significantly reduced, as compared with that on siFly/pSilenCircle-transfected CA46 cells (P<0.01 and P<0.05, respectively). Both hairpin siRNAs and antisense RNA had no influence on the proliferation and apoptosis of CA46 cells. CONCLUSION: Constructed siCD40/pSilenCircle and antiCD40/pSilenCircle can significantly inhibit CD40 expression, but have no significant influence on the proliferation and apoptosis of CA46 cells.

Animals↗
PubMed2005

[Study on multi-lineage potential of bone marrow mesenchymal stem cells derived from green fluorescent protein transgenic mice].

OBJECTIVE: To study the multi-lineage potential of bone marrow mesenchymal stem cells (MSCs) derived from transgenic mice with green fluorescent protein (GFP) gene in vitro. METHODS: A 6-week-old GFP transgenic mouse was executed by dislocation of cervical vertebra, and the marrow in tibia and thighbone was washed out with asepsis. The limited cell strains of MSCs derived from GFP transgenic mice (GFP-MSCs) were obtained with density gradient centrifugation. The passage 3 GFP-MSCs were induced to differentiate into osteoblast, adippcyte, neuron with solution of calcium induction medium, adipogenic medium and neural induction medium respectively. After being calcium-induced, the activity of alkaline phosphatase on GFP-MSCs was determined by micro-plate reader, and alizarin red staining was performed to test the formation of calcium concentration. The adipo-induced MSCs were detected with oil red O staining. Immunocytochemical staining was performed to detect the expression of NSE on neuron-induced MSCs. RESULTS: The ALP activity of GFP-MSCs heightened gradually along with being calcium-induced, and alizarin red staining showed positive. Oil red O staining of adipo-induced cells and NSE immunocytochemical staining of neuron-induced cells demonstrated positive. CONCLUSION: The limited cell strain of GFP-MSCs possesses multi-lineage potential, which can be used as an efficient tracking facility for studying the mechanism of multi-lineage potential on the MSCs.

Alkaline Phosphatase↗
PubMed2005

[Effect of the oil from ganoderma lucidum spores on pathological changes in the substantia nigra and behaviors of MPTP-treated mice].

OBJECTIVE: To investigate the oil from the spores of ganoderma lucidum, a rare Chinese herb, on the behaviors and pathological changes in the substantia nigra pars compacta (SNpc) in mouse models of Parkinson's disease (PD) induced by MPTP. METHODS: C57BL mice were divided into 3 groups, and the ganoderma spores oil + MPTP group were treated with ganoderma spores oil for 8 days, together with subcutaneous injection of MPTP (30 mg/kg) starting on the third day for 6 days; MPTP group were pretreated with normal saline before subcutaneous MPTP injection, and the normal control group received pretreatment with normal saline before subcutaneous normal saline injection. The behavioral changes of the mice in different groups were observed by pole test, dopamine and its metabolic products in the striatum determined by HPLC, tyrosine hydroxylase (TH) positive cells detected by immunofluorescence method, and expression of TH protein by Western blotting. RESULTS: The mice in the ganoderma spores oil + MPTP group presented significantly less involuntary movement of the limbs in the pole test than the mice in MPTP group. The levels of dopamine and DOPAC in the striatum of ganoderma spores oil-treated mice were increased as compared with those in MPTP group. The number of surviving TH-positive neurons in SNpc of mice in ganoderma spores oil + MPTP group was significantly greater than that in MPTP group, with also significantly increased TH protein expression. CONCLUSION: Ganoderma spores oil has neuroprotective effect for preventing doparminergic neuron from impairment by MPTP.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2005

Catalytic wet air oxidation for the treatment of emulsifying wastewater.

The wet air oxidation (WAO) and catalytic WAO (CWAO) of the high strength emulsifying wastewater containing nonionic surfactants have been investigated in terms of COD and TOC removal. The WAO and homogeneous CWAO processes were carried out at the temperature from 433 K to 513 K, with initial oxygen pressure 1.2 MPa. It was found that homogeneous catalyst copper(Cu(NO3)2) had an fairly good catalytic activity for the WAO process, and the oxidation was catalyzed when the temperature was higher than 473 K. Moreover, several heterogeneous catalysts were proved to be effective for the WAO process. At the temperature 473 K, after 2 h reaction, WAO process could achieve about 75% COD removal and 66% TOC removal, while catalysts Cu/Al2O3 and Mn-Ce/Al2O3 elevated the COD removal up to 86%--89% and that of TOC up to 82%. However, complete elimination of COD and TOC was proved to be difficult even the best non-noble catalyst was used. Therefore, the effluent from WAO or CWAO process need to be further disposed. The bioassay proved that the effluent from WAO process was amenable to the biochemical method.

Air↗
PubMed2005

[Clinical analysis of chronic suppurative otitis media in adults and children].

OBJECTIVE: To explore the differences and common features between adults and children with chronic suppurative otitis media in the course of disease, clinical characteristics and operation. METHOD: To compare and analyze the clinical information before the operation, the range of lesion and ossicular chain damage in adults group (85 cases) and children group (66 cases). RESULT: The morbidity of complications in children group was higher than that in adults group,with few intracranial otogenic complications in children group. The granuloma in external acoustic meatus was common in children group. The range of lesion in children group fixed with granuloma and cholesteatoma was more extensive than that in adults group. The complications in children group were more than those in adults group. CONCLUSION: There are more complications and more extensive lesion in children patients than those in adults patients with chronic suppurative otitis media. The operation of clearing lesion and retaining or reconstructing hearing are regarded as the first choice in the children patients.

Adolescent↗
PubMed2005

[Impact of preoperative lymphatic chemotherapy on relapse and metastasis of breast cancer and its mechanism].

BACKGROUND & OBJECTIVE: Although it is reported that lymphatic chemotherapy could raise drug concentrations in local lymph nodes and prolong survival time of patients with gastrointestinal tumors, its effect on breast cancer has not been explored. This study was to explore the impact of lymphatic chemotherapy on relapse and metastasis of breast cancer, and to investigate the mechanism. METHODS: Sixty patients with breast cancer of stage II-III were randomized into 2 groups: 40 patients in Epi-CH (carbon activated absorbing epirubicin) group were injected with 10 mg of Epi-CH in the tissue around primary tumor 72 h before modified radical resection; 20 patients in control group were injected with 10 mg of aqueous epirubicin in the same region. The stained nodes full of tumor cells in Epi-CH group and non-stained nodes in control group were selected. The apoptotic index (AI) of cancer cells in metastatic axillary lymph node was calculated by TUNEL method; the expression of Fas/Fas-L proteins was examined by SP immunohistochemistry; the relapse and metastatic rate was compared. RESULTS: The AI of cancer cells in metastatic axillary lymph node was significantly higher in Epi-CH group than in control group [(9.5+/-2.7)% vs. (3.8+/-1.4)%, P<0.01]. The expression of Fas protein was significantly higher in Epi-CH group than in control group (P<0.05), but the expression of Fas-L protein had no difference between the 2 groups (P>0.05). No chemotherapy-related local and whole body reaction occurred in both groups. The relapse and metastatic rate was significantly lower in Epi-CH group than in control group (P<0.05). CONCLUSION: Preoperative Epi-CH lymphatic chemotherapy could suppress relapse and metastasis of breast cancer, which might through up-regulating expression of Fas protein and inducing apoptosis of axillary metastasis cells.

Adult↗
PubMed2005

[Rapid and high-efficient composting process of municipal sewage sludge].

Based on the static composting process of the municipal sewage sludge (MSS), the paper demonstrates the dynamic composting process of the MSS from Shanghai Quyang Municipal Wastewater Treatment Plant. The dynamics of different operational and evaluating indices during the treatment process are discussed, such as water content, temperature, pH, dissolved organic carbon (DOC) and germination index (GI) and so on. It is concluded that the water content of materials, temperature,DOC and GI can be interpreted as the evaluating indices of the maturation of MSS. Under optimized condition, when the water content of initial materials was adjusted to 60 % +/- 2 % with appropriate sawdust and recycled materials, the results indicated that the temperature of composting materials could reach > 55 degrees C rapidly and last 4 days, thus 100% of the pathogens would be killed out. In the end of composting process, the water content of outputs was reduced exactly to about 35%, DOC could be decomposed by about 50%. T heincompact, odorless, and almost mature output could meet the land application control standard of MSS and the class A standard of US EPA.

Bacteria, Aerobic↗
PubMed2004

Synthesis of uniform Cu2S nanowires from copper-thiolate polymer precursors by a solventless thermolytic method.

Uniform hexagonal Cu2S nanowires with 2-6 nm diameters, 0.1 to several mum in length, were made by precipitation and thermolysis at 155 degrees C for 120 min from a Cu-thiolate colloid with a viscosity of 93.5 mPa/s. The morphologies of the final nanoproducts are governable through control of the coordination chemistry of Cu ions and thiols and the association of the Cu/S fragments. The evolution of nanowires, with the polymerization and heating temperature, and the parameters affecting the viscosity of the colloid precursor are reported.

Journal Article↗
PubMed2004

Modeling signal and background components of electrosensory scenes.

Weakly electric fish are able to detect and localize prey based on microvolt-level perturbations in the fish's self-generated electric field. In natural environments, weak prey-related signals are embedded in much stronger electrosensory background noise. To better characterize the signal and background components associated with natural electrolocation tasks, we recorded transdermal voltage modulations in restrained Apteronotus albifrons in response to moving spheres, tail bends, and large nonconducting boundaries. Spherical objects give rise to ipsilateral images with center-surround structure and contralateral images that are weak and diffuse. Tail bends and laterally placed nonconducting boundaries induce relatively strong ipsilateral and contralateral modulations of opposite polarity. We present a computational model of electric field generation and electrosensory image formation that is able to reproduce the key features of these empirically measured signal and background components in a unified framework. The model comprises an array of point sources and sinks distributed along the midline of the fish, which can conform to arbitrary body bends. The model is computationally fast and can be used to estimate the spatiotemporal pattern of activation across the entire electroreceptor array of the fish during natural behaviors.

Animals↗
PubMed2004

ERK1/2 and p38 pathways are required for P2Y receptor-mediated prostate cancer invasion.

The G protein-coupled P2Y purinoceptors have wide physiological functions, but their role(s) in tumor progression remain unclear. Here, we report that stimulation of P2Y receptors enhances prostate cancer cell invasion in two human prostate carcinoma cell lines, which is mediated by ERK1/2 and p38 signaling pathways. P2Y agonists stimulated prostate cancer cell invasion, and increased the activities of ERK1/2 and p38 protein kinases. The stimulated cancer cell invasion was inhibited by the presence of MEK1 inhibitor PD98059 or p38 inhibitor SB203580. Expression of dominant-negative mutant of MEK1 (KA-MEK1), or up-regulation of MKP-5 (a dual-specificity phosphatase of p38), both reduced the invasion of cultured prostate cancer cells. These results suggest that P2Y receptors and their down-stream ERK1/2 and p38 protein kinases are important regulators promoting prostate cancer invasion.

Enzyme Activation↗
PubMed2004

Effect of amino acid substitutions in the rad50 ATP binding domain on DNA double strand break repair in yeast.

The Saccharomyces cerevisiae Rad50-Mre11-Xrs2 complex plays a central role in the cellular response to DNA double strand breaks. Rad50 has a globular ATPase head domain with a long coiled-coil tail. DNA binding by Rad50 is ATP-dependent and the Rad50-Mre11-Xrs2 complex possesses DNA unwinding and endonuclease activities that are regulated by ATP. Here we have examined the role of the Rad50 Walker type A ATP binding motif in DNA double strand break repair by a combination of genetic and biochemical approaches. Replacement of the conserved lysine residue within the Walker A motif with alanine, glutamate, or arginine results in the same DNA damage sensitivity and homologous recombination defect as the rad50 deletion mutation. The Walker A mutations also cause a deficiency in non-homologous end-joining. As expected, complexes containing the rad50 Walker A mutant proteins are defective in ATPase, ATP-dependent DNA unwinding, and ATP-stimulated endonuclease activities. Although the DNA end-bridging activity of the Rad50-Mre11-Xrs2 complex is ATP-independent, the end-bridging activity of complexes containing the rad50 Walker A mutant proteins is salt-sensitive. These results provide a molecular explanation for the observed in vivo defects of the rad50 Walker mutant strains and reveal a novel ATP-independent function for Rad50 in DNA end-bridging.

Adenosine Triphosphatases↗
PubMed2004

A cost-related approach for evaluating drug development programs.

Most pharmaceutical statisticians make a contribution to drug development at the study level by designing and analysing clinical studies. There is less involvement at the drug project level, especially when it comes to making a strategic decision for a drug development program. Motivated by the assessment of drug safety, this paper presents a new decision rule on whether or not to continue developing a new drug based on a cost function. The cost function takes into account both type I and type II errors in a decision making problem. It also incorporates both the cost and benefit from a drug development program. This cost-benefit approach enables company senior management to evaluate a drug program objectively and make decisions in a quantitative and rational manner. The probabilities of making correct decisions are illustrated by using a real data example.

Clinical Trials as Topic↗
PubMed2004

Two 3D supramolecular polymers constructed from an amino acid and a high-nuclear Ln6Cu24 cluster node.

The first successful attempt to construct 3D supramolecular frameworks with high-nuclear 3d-4f heterometallic clusters as a node is reported. The self-assembly of Ln3+, Cu2+ and amino acid in solution leads to the formation of two polymers, 35-nuclear complex [Sm6Cu29] 1 with a primitive cubic net-like structure and 36-nuclear complex [Nd6Cu30] 2 with a face-centred cubic network type structure. Glycine and L-proline, respectively, were used as ligands. It should be noted that 2 has a chiral framework. X-ray structure analyses show that 1 crystallizes in the triclinic P1 space group (a=19.6451(8), b=20.4682(8), c=20.7046(8) A, alpha=89.453(1), beta=66.290(1), gamma=68.572(1) degrees, V=7003.0(5) A3 and Z=1) and 2 belongs to the cubic P2(1)3 space group (a=b=c=32.4341(3) A, V=34 119.7(5) A3 and Z=4). Both complexes utilize Ln6Cu24 octahedral clusters as nodes and trans-Cu(amino acid)2 groups as bridges. Electrical conductivity measurements reveal that both polymers behave as semiconductors.

Amino Acids↗