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Biomedical subjects

Feng Li

Publications and source records attributed to Feng Li.

At least 55 records · Page 3Linked to original sources
PubMed2006

[Clinical evaluation of the heart function early after repair of tetralogy of Fallot: follow-up of 43 patients].

OBJECTIVE: To evaluate the heart function of the patients early after the repair of tetralogy of Fallot (TOF). METHODS: Forty-three patients with TOF, 25 males and 18 females, underwent operation at the age of 2.5 - 52 years (16.7 years on average) and were followed up for 1 - 3.5 years. Twenty-one age-matched healthy persons were used as controls. Tissue Doppler imaging (TDI) was used to measure the values of the peak tricuspid ring velocity during early diastole (Ea), late diastole (Aa), systole, and isovolumic contraction, and isovolumetric contraction acceleration (IVA); and isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), and isovolumetric contraction velocity (IVV) of the right ventricle. Tei index was calculated using the formula: (ICT + IRT)/ET. Treadmill test was used on the patients aged > 17 to measure the maximal heart rate maximal blood pressure, maximal exercise tolerance (MET), and movement time. RESULTS: The peak tricuspid ring velocity during Ea of the repaired TOF group (rTOF group) was 11.5 +/- 2.6 cm/s, significantly lower than that of the control group (17.1 +/- 2.4 cm/s, P < 0.0001), the peak tricuspid ring velocity during Aa of the rTOF group was 9.6 +/- 1.7 cm/s, significantly lower than that of the control group (12.9 +/- 2.9 cm/s, P < 0.001), the E/A of the rTOF group was 1.16 +/- 0.36, significantly lower than that of the control group (1.36 +/- 0.26, P < 0.05). The IVV of the rTOF group was 7.7 +/- 1.8 cm/s, significantly lower than that of the control group (9.9 +/- 1.4 cm/s, P = 0.0030, and the IVA of the rTOF group was 131.7 +/- 37.6 cm/s(2), significantly lower than that of the control group (222.5 +/- 39.2 cm/s(2), P < 0.001). The Tei index of the rTOF group was 0.58 +/- 0.11, significantly higher than that of the control group (0.52 +/- 0.04, P = 0.029). The maximal heart rate maximal blood pressure, MET, and movement time of the rTOF group were all significantly lower than those of the control group (P < 0.05 or P < 0.01). CONCLUSION: The heart function of the patients undergoing repair of TOF fails to recover to the normal level during a short time after the surgery.

Adolescent↗
PubMed2006

Construction of a nasopharyngeal carcinoma 2D/MS repository with Open Source XML database--Xindice.

BACKGROUND: Many proteomics initiatives require integration of all information with uniformcriteria from collection of samples and data display to publication of experimental results. The integration and exchanging of these data of different formats and structure imposes a great challenge to us. The XML technology presents a promise in handling this task due to its simplicity and flexibility. Nasopharyngeal carcinoma (NPC) is one of the most common cancers in southern China and Southeast Asia, which has marked geographic and racial differences in incidence. Although there are some cancer proteome databases now, there is still no NPC proteome database. RESULTS: The raw NPC proteome experiment data were captured into one XML document with Human Proteome Markup Language (HUP-ML) editor and imported into native XML database Xindice. The 2D/MS repository of NPC proteome was constructed with Apache, PHP and Xindice to provide access to the database via Internet. On our website, two methods, keyword query and click query, were provided at the same time to access the entries of the NPC proteome database. CONCLUSION: Our 2D/MS repository can be used to share the raw NPC proteomics data that are generated from gel-based proteomics experiments. The database, as well as the PHP source codes for constructing users' own proteome repository, can be accessed at http://www.xyproteomics.org/.

Carcinoma↗
PubMed2006

17beta-estradiol (betaE2) protects human retinal Müller cell against oxidative stress in vitro: evaluation of its effects on gene expression by cDNA microarray.

17beta-estradiol (betaE(2)) is an effective neuroprotectant against hydrogen peroxide (H(2)O(2))-induced retinal neuronal cell death and light-induced photoreceptor degeneration. Müller cells are the principal macroglia responsible for supporting retinal neuronal survival, information processing and removing metabolic waste. However, the role of betaE(2) on human Müller cells is unclear. In this study, the effects of betaE(2) on human Müller cell survival and gene expression were examined. Our data revealed that betaE(2) is able to increase human Müller cell viability after exposure to H(2)O(2) through inhibition of apoptosis. Microarray analysis revealed significant changes in the expression of 69 genes (total of 21,324 genes screened) in cultured human Müller cells 6 h after betaE(2) treatment. Four of the betaE(2)-responsive genes [thrombospondin 1 (TSP1), mitogen-activated protein kinase kinase kinase 3 (MAP3K3), large conductance calcium-activated potassium channel beta2 subunit (KCNMB2), and SRY (sex-determining region Y)-box 11 (SOX11)] were validated by both real-time qRT-PCR and semi-quantitative RT-PCR. Interestingly, exposure of human Müller cells to betaE(2) increased pigment epithelium-derived factor (PEDF) gene expression as measured by both RT-PCR and real time qRT-PCR. Our data demonstrate, for the first time, that betaE(2) protects cultured human Müller cells against H(2)O(2)-induced cell death through the inhibition of apoptosis. This protective effect may operate through regulation of genes, such as TSP1, MAP3K3, SOX11, TSP1, and PEDF, and may in turn exert an important role in protecting retinal neurons.

Antioxidants↗
PubMed2006

Incorporation of a nanosplitter interface into an LC-MS-RD system to facilitate drug metabolism studies.

In the work reported here, a novel interface, the nanosplitter, is incorporated into the drug metabolism laboratory in order to enhance the analytical capabilities of detecting and identifying drug-related metabolites to support drug metabolism studies during the drug development process. When an existing LC-MS-radiometric detector (RD) system is coupled with this nanosplitter, the system becomes capable of performing dynamic microspray under a typical analytical LC method. With the superior MS sensitivity offered by this system, most of the analytical LC methods developed for metabolite profiling can then be easily adopted for metabolite identification work. The improvement of these analytical capabilities can streamline the entire process of the drug metabolism study. In the experiments presented here, the nanosplitter interface coupled with analytical HPLC systems (e.g. 4.6 x 250 mm column @ 1 ml/min) demonstrated significant increases in MS signal (2x to 40x peak area) when compared to the standard LC-MS interface for both in vitro and in vivo metabolism studies. Furthermore, this signal gain facilitated the MS detection of additional metabolites (observed in the radiometric trace) that were below the MS level of detection when using the standard interface.

Animals↗
PubMed2006

Study on interaction between microtubule associated protein tau and prion protein.

Microtubule-associated protein tau is considered to play roles in many neurodegenerative diseases including some transmissible spongiform encephalopathies. To address the possible molecular linkage of prion protein (PrP) and tau, a GST-fusion segment of human tau covering the three-repeat region and various PrP segments was used in the tests of GST pull-down and immunoprecipitation. We found tau protein interacted with various style prion proteins such as native prion protein (PrPc) or protease-resistant isoform (PrPSc). Co-localization signals of tau and PrP were found in the CHO cell tranfected with both PrP and tau gene. The domain of interaction with tau was located at N-terminal of PrP (residues 23 to 91). The evidence of molecular interactions between PrP and tau protein highlights a potential role of tau in the biological function of PrP and the pathogenesis of TSEs.

Animals↗
PubMed2006

Computer-aided diagnosis for the detection and classification of lung cancers on chest radiographs ROC analysis of radiologists' performance.

RATIONALE AND OBJECTIVES: The aim of the study is to investigate the effect of a computer-aided diagnostic (CAD) scheme on radiologist performance in the detection of lung cancers on chest radiographs. MATERIALS AND METHODS: We combined two independent CAD schemes for the detection and classification of lung nodules into one new CAD scheme by use of a database of 150 chest images, including 108 cases with solitary pulmonary nodules and 42 cases without nodules. For the observer study, we selected 48 chest images, including 24 lung cancers, 12 benign nodules, and 12 cases without nodules, from the database to investigate radiologist performance in the detection of lung cancers. Nine radiologists participated in a receiver operating characteristic (ROC) study in which cases were interpreted first without and then with computer output, which indicated locations of possible lung nodules, together with a five-color scale illustrating the computer-estimated likelihood of malignancy of the detected nodules. RESULTS: Performance of the CAD scheme indicated that sensitivity in detecting lung nodules was 80.6%, with 1.2 false-positive results per image, and sensitivity and specificity for classification of nodules by use of the same database for training and testing the CAD scheme were 87.7% and 66.7%, respectively. Average area under the ROC curve value for detection of lung cancers improved significantly (P = .008) from without (0.724) to with CAD (0.778). CONCLUSION: This type of CAD scheme, which includes two functions, namely detection and classification, can improve radiologist accuracy in the diagnosis of lung cancer.

Clinical Competence↗
PubMed2006

Improving radiologists' recommendations with computer-aided diagnosis for management of small nodules detected by CT.

RATIONALE AND OBJECTIVES: To evaluate how computer-aided diagnosis (CAD) can improve radiologists' recommendations for management of possible early lung cancers on CT. MATERIALS AND METHODS: Twenty-eight lung cancers and 28 benign lesions were employed. Each group of 28 lesions was classified into subgroups of two sizes (9 between 6 and 10 mm and 19 between 11 and 20 mm) and three patterns (8 with pure ground glass opacity [GGO], 12 with mixed GGO and 8 solid lesions). Sixteen radiologists participated in the observer study, first without and then with CAD. Radiologists' recommendations, including (1) follow-up in 12 months, (2) in 6 months, (3) in 3 months, or (4) biopsy, were compared at three levels of their malignancy probability ratings (low: 1%-33%; medium: 34%-66%; high: 67%-99%) for 896 observations (56 lesions by the 16 radiologists) in the two size subgroups and three patterns. RESULTS: The number of recommendations changed by radiologists by use of CAD was 163 (18%) among all 896 observations. Among these changed recommendations, the fraction showing a beneficial effect from CAD was 68% (111/163), and the fraction showing a beneficial effect regarding biopsy recommendations was 69% (48/70). With CAD, the radiologists' performance regarding biopsy recommendations was significantly improved for 43 lung cancers (31 changed to biopsy versus 12 changed away from biopsy; P = .003) and was also improved for 27 benign lesions (10 changed to biopsy versus 17 changed away from biopsy; P = .18). Most of the cancers with improved recommendations were solid lesions or mixed GGO and relatively large. CONCLUSION: CAD has the potential to improve the appropriateness of radiologists' recommendations for small malignant and benign lesions on CT scans.

Aged↗
PubMed2006

Photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide.

GOAL, SCOPE AND BACKGROUND: The polynitramines, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are important military explosives and regulated toxic hazardous compounds. Production, testing and use of the compounds has resulted in numerous acres of contaminated soils and groundwater near many munitions facilities. Economical and efficient methods for treatment of wastewater and cleanup of soils or groundwater containing RDX and HMX are needed. This study focuses on the photocatalytic treatment of RDX wastewater with nano-sized titanium dioxide (nano-TiO2) under simulated sunlight, whose intensity and wavelength are similar to that of the real sunlight in Xi'an at noon. The objective is to determine the potential for RDX destruction with nano-TiO2 in aqueous solution. METHODS: An activated carbon fiber (ACF) cloth-loaded with nano-TiO2 was put into the RDX containing solution, and the concentration of RDX was measured (by HPLC-UV) at regular time intervals under simulated sunlight. RESULTS: The RDX degradation percentage of the photocatalytic process is higher than that of Fenton oxidation before 80 min, equivalent after 80 min, and it reaches 95% or above after 120 min. The nano-TiO2 catalyst can be used repeatedly. DISCUSSION: The photocatalytic degradation kinetics of RDX under simulated sunlight can be described by a first-order reaction kinetics equation. The possible degradation mechanism of RDX was presented and the degradation performance was compared with that of biological method. CONCLUSIONS: It was demonstrated that the degradation of RDX wastewater is very effective with nano-TiO2 as the photocatalytic catalyst under simulated sunlight. The efficiency of the nano-TiO2 catalyst for RDX degradation under simulated sunlight is nearly identical to that of Fenton oxidation. RECOMMENDATIONS AND PERSPECTIVES: To date, a number of catalysts show poor absorption and utilization of sunlight, and still need ultraviolet light irradiation during wastewater degradation. The nano-TiO2 used in the described experiments features very good degradation of RDX under simulated sunlight, and the manufacturing costs are rather low (around 10 Euro/m2). Moreover, the degradation efficiency is higher compared to that of the biological method. This method exhibits great potential for practical applications owing to its easiness and low cost. If it can be applied extensively, the efficiency of wastewater treatment will be enhanced greatly.

Azocines↗
PubMed2006

The spleen as a target in severe acute respiratory syndrome.

It has been proposed that immune injury is the central mechanism of pathogenesis of the infectious disease, severe acute respiratory syndrome (SARS). To gain a better understanding of immune injury in the spleen, we investigated the number and distribution of various immune cell types in the spleens of SARS patients. We performed autopsies on six confirmed SARS cases, with six normal subjects as controls; spleen samples from these autopsies were examined with hematoxylin and eosin (H&E) sections, in situ hybridization for SARS virus genomic sequences, and immunohistochemistry with seven monoclonal antibodies to five cell types. The number and distribution of these cells were measured and analyzed using an image analysis system. SARS genomic sequences were detected in all SARS spleens. The SARS spleens all had severe damage to the white pulp and showed an alteration of the normal distribution of various cell types. Immunocytes in the red pulp were decreased by 68.0-90.7% except for CD68+ macrophages and human leukocyte antigen (HLA)-DR positive antigen-presenting cells (APC), which were decreased to a lesser degree. On average, CD68+ macrophages were increased in size by 2.21-fold. We hypothesize that the collapse of the splenic immune system plays a key role in the clinical outcome of these patients.

Adult↗
PubMed2006

3-O-(3',3'-dimethysuccinyl) betulinic acid inhibits maturation of the human immunodeficiency virus type 1 Gag precursor assembled in vitro.

3-O-(3',3'-Dimethysuccinyl) betulinic acid (PA-457) has been shown to potently inhibit human immunodeficiency virus (HIV) replication in culture. In contrast to inhibitors that act upon the viral proteinase, PA-457 appears to block only the final maturational cleavage of p25CA-p2 to p24CA. However, attempts to replicate this effect in vitro using recombinant Gag have failed, leading to the hypothesis that activity is dependent upon the assembly state of Gag. Using a synthesis/assembly system for chimeric HIV type 1 Gag proteins, we have replicated the activity of PA-457 in vitro. The processing of assembled chimeric Gag can be inhibited by the addition of drug with only the final cleavage of p25CA-p2 to p24CA blocked. Consistent with our hypothesis and with previous findings, inhibition appears specific to Gag assembled into an immature capsid-like structure, since synthetic Gag that remains unassembled is properly processed in the presence of the compound. To further analyze the authenticity of the assay, PA-457 was tested in parallel with its inactive parental compound, betulinic acid. Betulinic acid had no effect upon p25 processing in this system. Analysis of a PA-457-resistant mutant, A1V, in this system pointed to more rapid cleavage as a possible mechanism for resistance. However, characterization of additional mutations at the cleavage site and in p2 suggests that resistance does not strictly correlate with the rate of cleavage. With the establishment of an in vitro assay for the detection of PA-457 activity, a more detailed characterization of its mechanism of action will be possible.

Capsid Proteins↗
PubMed2006

Virus counterdefense: diverse strategies for evading the RNA-silencing immunity.

Viruses are obligate, intracellular pathogens that must manipulate and exploit host molecular mechanisms to prosper in the hostile cellular environment. Here we review the strategies used by viruses to evade the immunity controlled by 21- to 26-nt small RNAs. Viral suppressors of RNA silencing (VSRs) are encoded by genetically diverse viruses infecting plants, invertebrates, and vertebrates. VSRs target key steps in the small RNA pathways by inhibiting small RNA production, sequestering small RNAs, or preventing short- and long-distance spread of RNA silencing. However, although VSRs are required for infection, explicit data demonstrating a role of silencing suppression in virus infection are available only for a few VSRs. A subset of VSRs bind double-stranded RNA, but a distinct protein fold is revealed for each of the four VSRs examined. We propose that VSR families are evolved independently as a viral adaptation to immunity. Unresolved issues on the role of RNA silencing in virus-host interactions are highlighted.

Gene Amplification↗
PubMed2006

Preparation of high purity ZnO nanobelts by thermal evaporation of ZnS.

High purity one-dimensional ZnO nanobelts were synthesized by thermally evaporating commercial ZnS powders in a hydrogen-oxygen mixture gas at 1050 degrees C. It was found that these ZnO nanobelts had a single crystal hexagonal wurtzite structure growing along the [0001] direction. They had a rectangle-shaped cross-section with typical widths of 20 to 100 nanometers and lengths of up to hundreds of micrometers with lattice constants of a = 0.325 nm and c = 0.520 nm. The self-catalytic hydrogen-oxygen assisted growth of ZnO nanobelt is discussed. The photoluminescence (PL) characterization of the ZnO nanobelts shows strong near-band UV emission (about 383 nm) and one broad peak at 501 nm, which indicates that the ZnO nanobelts have good potential application in optoelectronic devices.

Crystallization↗
PubMed2006

The effect of sulfur on the structure of carbon nanotubes produced by a floating catalyst method.

The effect of sulfur on the structures (shell number and diameter distribution) of carbon nanotubes (CNTs) was investigated in detail using high resolution transmission electronic microscopy (HRTEM) and Raman spectroscopy. Single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs) with different diameter distributions were obtained only by increasing the sulfur addition amount with methane as carbon source. A similar structure change was found for ethanol as carbon source with changing the sulfur addition amount. These results indicate that addition of sulfur is necessary to enhance the growth of SWNTs and DWNTs, independent of the carbon source for our method. Based on the growth parameter study, HRTEM observations and kinetic considerations, the role of sulfur in the nucleation and growth of CNTs was discussed.

Catalysis↗
PubMed2006

[The expression of pseudogene HMGA1L2 in thyroid lesions].

Pseudogene HMGA1L2 mRNA level was detected using RT-PCR in 50 cases of thyroid lesions. The results show that HMGA1L2 mRNA was found in all 12 cases of nodular goiter, all 9 cases of thyroid adenoma and all 15 cases of papillary carcinoma. In 14 cases of thyroid follicular carcinoma, However, the frequency of HMGA1L2 mRNA expression was 35.7%, which was significantly different from that in other types of thyroid lesions (P < 0.05). This is the first report of mRNA expression of pseudogene HMGA1L2 in nodular goiter and thyroid tumors. It indicate that pseudogene HMGA1L2 expression analysis could be helpful in differentiation between follicular carcinoma and adenoma.

Base Sequence↗
PubMed2006

[Relationship between serum interleukin-10 and insulin resistance in metabolic syndrome].

OBJECTIVE: To investigate the relationship between serum interleukin-10 (IL-10) level and insulin resistance (IR) in patients with metabolic syndrome (MS). METHODS: Eighteen MS subjects and 18 age-matched normal subjects were enrolled. IR was evaluated by hyperinsulinemic-euglycemic clamp technique and serum IL-10 level measured by ELISA. Pearson's correlation analysis was used to investigate the relationship between serum IL-10 level and IR. RESULTS: Serum IL-10 levels were significantly higher in patients with MS than in the controls [1.3 (0.8/3.1) pg/ml vs 2.4 (1.1/4.5) pg/ml, P<0.05], and glucose metabolic rate (M value) derived from hyperinsulinemic-euglycemic clamp technique was lower in MS subjects than in controls [(5.76+/-1.81) mg/kg.min vs (8.39+/-1.25) mg/kg.min], P<0.05]. Serum IL-10 levels showed a positive correlation with M value (P<0.05). CONCLUSION: Patients with MS have greater IR and lower serum IL-10 levels than normal subjects, and lowered IL-10 levels might be involved in the pathogenesis of IR in MS.

Adult↗
PubMed2006

[Effects of cordyceps sinensis alcohol extractive on serum interferon-gamma level and splenic T lymphocyte subset in mice with viral myocarditis].

AIM: To investigate the effects of early application of cordyceps sinensis alcohol extractive (CSAE) on myocardial injury, level of serum IFN-gamma and splenic T lymphocyte subset in murine viral myocarditis (VMC). METHODS: 100 male BALB/c mice were divided randomly into control group (CG), infectious group (IG) and CSAE therapy group (CTG). Mice in IG and CTG were infected with Coxsackie virus B3 (CVB3). The 14-day survival rates and myocardial histopathology were observed. Serum IFN-gamma level was detected by ELISA and splenic CD3+, CD4+, CD8+ T lymphocytes were detected by flow cytometry. RESULTS: Serum IFN-gamma level and the percentage of splenic T lymphocyte subset in IG were decreased significantly, and CD4+/CD8+ T cell ratio increased significantly as compared with those of CG. Myocardial lesions in CIG were attenuated, while the 14-day survival of mice 85% (vs IG 55%, P<0.05), serum IFN-gamma and the percentage of splenic CD3+, CD8+ T lymphocytes in CTG were significantly higher than those in IG. There were no significant differences of the percentage of T lymphocyte subset and CD4+/CD8+ T cell ratio between CTG and CG. CONCLUSION: CSAE plays an important protective role against viral-induced murine myocarditis by inducing IFN-gamma and regulating T lymphocyte.

Animals↗