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Biomedical subjects

Feng Li

Publications and source records attributed to Feng Li.

At least 217 records · Page 12Linked to original sources
PubMed2003

MASSIS: a mass spectrum simulation system. 2: Procedures and performance.

The use of the mass spectral simulation system, MASSIS, is reported and its performance has been evaluated. The search for substructures matching with fragments stored in four pivot databases was realised using the Ullmann algorithm. Special cleavage rules, such as the McLafferty rearrangement, the retro-Diels-Alder reaction, elimination of a neutral small molecule and oxygen migration, are processed through shortest path and depth-first search algorithms. For a search in the database of small fragments, the key step is to determine the tautomeric fragments; then a match can be obtained using a subgraph isomorphism algorithm. A string match is used to determine peak intensity. If the limited environment of an atom is the same as that found in the database of relationships between fragment and intensity, this intensity value is assigned to the query atom. Performance in a set of tests is very important in evaluating the system performance. A comparison of peaks with an intensity greater than 5% (relative) shows that our system has a very high performance figure (> 90% ) for routine organic compounds.

Algorithms↗
PubMed2003

Small solitary pulmonary nodules (< or =1 cm) detected at population-based CT screening for lung cancer: Reliable high-resolution CT features of benign lesions.

OBJECTIVE: We assessed thin-section CT features specific to benignity in solitary pulmonary nodules of 1 cm or smaller that were detected at population-based CT screening for lung cancer. MATERIALS AND METHODS: Two reviewers independently made qualitative (presence or absence of lobulation, spiculation, air bronchogram, cavity, satellite lesions, pleural tag, concave margins, polygonal shape, and peripheral subpleural lesion) and quantitative (lesion size, percentage of ground-glass opacity areas, and two- and three-dimensional ratios of lesion) assessments in CT images of 72 nodules (25 lung cancers, seven atypical adenomatous hyperplasias, and 40 benign lesions). Optimal criteria specific to benignity were studied. RESULTS: The prevalence of polygonal shape (p = 0.005 and p = 0.019, reviewer 1 and reviewer 2), peripheral subpleural lesion (p = 0.011 and p = 0.033), a predominantly solid lesion (p < 0.001 and p < 0.001), and three-dimensional ratios (p < 0.001 and p < 0.001) were greater in benign lesions than in malignancies. The prevalence of a predominantly solid lesion (p < 0.001 and p < 0.001) was greater in benign lesions than in atypical adenomatous hyperplasias, and the prevalence of a peripheral subpleural lesion (p = 0.004 and p = 0.012) was greater in atypical adenomatous hyperplasias than in malignancies. Using a single CT feature, polygonal shape and a three-dimensional ratio of greater than 1.78 showed 100% specificity for both reviewers. Among all combinations of CT findings specific to benignity, a combined criterion of a predominantly solid lesion and peripheral subpleural lesion or polygonal shape or the three-dimensional ratio attained the highest sensitivity (63% and 60%) for both reviewers. CONCLUSION: A combined criterion of CT features was optimal for predicting benign pulmonary lesions.

Adenocarcinoma↗
PubMed2003

Indeterminate solitary pulmonary nodules revealed at population-based CT screening of the lung: using first follow-up diagnostic CT to differentiate benign and malignant lesions.

OBJECTIVE: We studied the role of the first follow-up diagnostic CT for differentiating benign and malignant lesions in indeterminate solitary pulmonary nodules revealed at CT screening for lung cancer in which a total of 13,786 CT examinations (46% in women and 54% in men; 46% were smokers; mean age, 62 years) were performed. MATERIALS AND METHODS: We reviewed thin-section CT findings on the initial diagnostic CT (lesion size; percentages of ground-glass-opacity areas of lesion; and presence or absence of lobulation, spiculation, air bronchogram, cavity, satellite lesions, pleural tag, concave margins, polygonal shape, and peripheral subpleural lesion) in 80 pulmonary nodules (36 malignancies and 44 benign lesions) of 80 patients. We evaluated changes in size (regression, no change, or growth) on the first follow-up CT performed 42-120 days (mean, 93 days) after the initial CT. RESULTS: The greatest accuracy (81%) with 89% sensitivity and 75% specificity for determining malignancy was attained with a combined criterion of growth of lesions or predominantly ground-glass-opacity lesions. Of all criteria that were specific to malignancy, the greatest sensitivity (50%) was achieved with a combination of growth or no change in size of lesions and predominantly ground-glass opacity and no concave margins. Of all criteria that were specific to benign lesions, the greatest sensitivity (45%) was attained with a combination of lesion regression or polygonal shape. CONCLUSION: Follow-up CT findings were useful, and a combination of findings on initial CT and follow-up CT was optimal for differentiating benign and malignant pulmonary nodules.

Adult↗
PubMed2003

[Identification of down-regulated expressed sequence tag at chromosome 3p21 in nasopharyngeal carcinoma].

BACKGROUND & OBJECTIVE: It was reported that a locus of high frequency loss of heterozygosity was found at 3p14-25 of nasopharyngeal carcinoma (NPC) cells. This study was designed to identify the expressed sequence tags (ESTs) associated with NPC at chromosome 3p21 in order to clone new candidate NPC-associated genes at the locus. METHODS: The expression of relative ESTs at 3p21 was determined in nasopharyngeal carcinoma tissues and normal nasopharyngeal epithelia using ESTs homology analysis with bioinformatics in computer network combined with reverse transcription-polymerase chain reaction (RT-PCR). The expression of EST was detected in other normal tissues and tumor cell lines using Northern blot analysis. RESULTS: Comparing with expression of normal nasopharyngeal epithelia, EST (N31985) was down-regulated in 60.00% (3/5) nasopharyngeal carcinoma cell lines and 47.06% (16/34) nasopharyngeal carcinoma tissues (P < 0.05). CONCLUSION: N31985 is down-regulated in NPC, suggesting it may play a role in NPC carcinogenesis.

Carcinoma, Squamous Cell↗
PubMed2003

[In vitro culture of murine fetal epidermal stem cell and its relationship with the regeneration of follicle].

OBJECTIVE: To isolate and culture the murine fetal epidermal stem cells (ESCs) and folliculus pili cells (FPCs) in vitro, and to observe the regeneration of hair follicle and epidermis after cografting of ESCs and FPCs. METHODS: The ESCs were isolated by adhering to murine type IV collagen and were cultured in conditional medium. The expression level of beta1-integrin and keratin 15 in ESCs was detected. At the same time, the cell cycle and clony forming eficiency (CFE) in ESCs were also determined. The FPCs were isolated and cultured and inoculated in fibrin-gel to form FPCs-gel. A full skin equivalent was prepared by combining ESCs with FPCs-gel and was grafted onto total skin loss wounds on the back of BALB/C nude mice. The histological changes of the wounds and the hair follicles were observed at 8 - 10 weeks after the grafting. RESULTS: There were high level expressions of beta1-integrin and keratin 15 in murine fetal ESCs. It was indicated by cell cycle analysis that cells in G1 stage accounted for 94.9% of the cells, while that in S stage, 3.5%, suggesting slow cell cycle. Nevertheless, the keratinocytes in G1 stage accounted for 74.1% and that in S stage, 17.5% of cells in control group. The CFE of ESCs was 15.3%, and it was much higher than that in control group (6.7%). The newly formed hair follicles could be found in the grafted rats but not in the control group 8 - 10 weeks after the wound healing in nude rats. CONCLUSION: The ESCs could be successfully isolated and cultured in vitro and might participate in the formation of hair follicle structure under the induction of FPCs.

Animals↗
PubMed2003

Coagulation and fibrinolytic activity in patients with acute cerebral infarction.

OBJECTIVE: To measure the concentration of D-dimer (DD), tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and plasminogen (PLG) activity in plasma and cerebrospinal fluid in patients with acute cerebral infarction and to investigate their clinical significance. METHODS: The concentrations of D-dimer, t-PA, and PAI-1 in plasma and cerebrospinal fluid in patients were measured by enzyme-linked immunosorbent assay (ELISA). The PLG biological activity was detected using the chromophore method. The results were compared with those of the controls. RESULTS: The concentrations of D-dimer, t-PA and PAI-1 in cerebrospinal fluid and plasma in patients with acute cerebral infarction were much higher than those of normal subjects (P < 0.01). Conversely, the level of PLG activity was significantly lower in the patients than in the controls (P < 0.01). CONCLUSION: Hypercoagulability and secondary hyperfibrinolysis exist in patients with acute cerebral infarction.

Acute Disease↗
PubMed2003

The effects of inhibiting P18(INK4C) expression on the invasion of gastric adenocarcinoma cell line.

Using cDNA microarray with double dots of 4096 human genes, P18(INK4C), a member of CKI, was found down-regulated in a gastric adenocarcinoma metastatic cell line (RF-48), compared with the corresponding primary cancer cell line (RF-1), which implied that P18(INK4C) might be involved in cell invasion and metastatic progression of human gastric adenocarcinoma. Antisense RNA expression plasmid was applied to inhibit P18(INK4C) expression to study the effect of decreased P18(INK4C) expression on cell migration, invasion and proliferation ability and cell cycle of RF-1. Results showed that inhibition of P18(INK4C) expression could obviously enhance cell invasion ability of RF-1, but had little effect on its cell cycle and cell migration and proliferation ability. These results implied that P18(INK4C) might play a pivotal role in regulating cell invasion, rather than regulating cell cycle and proliferation in the progression of human gastric adenocarcinoma as expected before.

Adenocarcinoma↗
PubMed2003

[Cbfa1 induces the expression of the mineral-related proteins in human dental papilla cells].

OBJECTIVE: To explicit whether the expression of the mineral-related proteins is regulated by cbfa1 in human dental papilla cells. METHODS: Human dental papilla cells were cultured in vitro and transfected with pcDNA3-cbfa1 recombinant plasmids. After selected with G418 sulfate, a cell clone named PC-3, which could stably express the cbfa1 mRNA and protein, was proved by PCR and western blot. Then the amount of ALP and OC and the expression of OPN, BSP, ON, DMP1, DSP and DSPP were detected by immunohistochemistry, Western blot and PCR methods. RESULTS: We established the human dental papilla cells model PC-3 which could stably express the cbfa1 mRNA and protein. Compared with normal cells, a lot of mineral-related proteins such as ALP, OC, OPN, BSP, ON, DMP1 were upregulated in PC-3 cells. CONCLUSIONS: In human dental papilla cells, cbfa1 can induce the expression of most mineral-related genes and proteins. It may implicate that cbfa1 must play a key role during tooth development and mineralization.

Alkaline Phosphatase↗
PubMed2003

[Purification and characterization of trichokirin-S1, a novel ribosome-inactivating peptide from seeds of Trichosanthes kirilowii].

A novel peptide from the seeds of Trichosanthes kirilowii, trichokirin-S1, was purified by extraction of protein body, ammonia sulfate precipitation, Blue-gel affinity chromatography, FPLC Mono S ion exchange chromatography and Superose12 gel filtration chromatography. Its molecular weight was determined to be 11,426 by MALDI-TOF MS analysis. Its reaction mechanism to inactive ribosome was the same as that of the ribosome-inactivating protein trichosanthin, a rRNA N-glycosidase. The purified trichokirin-S1 showed a strong inhibitory activity on protein synthesis in cell-free rabbit reticulocyte lysate system, with IC(50) of 0.7 nmol/L. Therefore, trichokirin-S1 may be a promising and efficient toxin moiety of immunotoxins.

Amino Acid Sequence↗
PubMed2003

[Purification and partial characterization of luffin P1, a peptide with translational inhibitory activity and trypsin inhibitory activity, from seeds of Luffa cylindrica].

A peptide, luffin P1, from seeds of Luffa cylindrica, was purified by ammonia sulfate precipitation, CM-52 ion exchange chromatography, Blue-gel affinity chromatography and FPLC Mono S ion exchange chromatography. Its molecular weight was 5226.5 as determined by MALDI-TOF-MS analysis. The sequence of N-terminal 11 amino acids of luffin P1 was identical with the partial N-terminal sequence (from G3 to R13) of 6.5K Arg/Glu rich peptide, which was also isolated from the seeds of Luffa cylindrica. Besides, luffin P1 had a very high homology with a trypsin inhibitor, named C2 peptide, from pumpkin seeds. Interestingly, the purified luffin P1 not only showed a strong inhibitory activity on protein synthesis in rabbit reticulocyte lysate cell-free translation system with IC(50) of 0.6 nmol/L, but also had trypsin inhibitory activity with IC(50) of 22 micromol/L.

Animals↗
PubMed2003

[Comparative study on safety and immunogenicity between influenza subunit vaccine and split vaccine].

OBJECTIVE: To compare the reactogenicity and serology between influenza subunit vaccine and split vaccine. METHODS: A randomized, double-blind study was carried out among children (age 6 - 12 years) in order to compare the safety and immunogenicity of an influenza inactivated subunit vaccine (Agrippal, Chiron Vaccines) with that of a split vaccine (Flurix, GSK). RESULTS: A total of 499 subjects were vaccinated and included in the safety analysis. A total of 249 subjects received Agrippal and 250 received Flurix. All subjects were kept under medical observation for 30 minutes in order to check the evidence of having any immediate local and systemic reaction. Daily observation records were collected during the 3-day follow-up after vaccination. 6.4% of the cases with fever >or= 37.5 degrees C was reported in the Flurix group, but 2.4% in Agrippal group which was significantly less than the former group (P > 0.05). Blood samples (the D0 pre- and D23 post-vaccination sera) were collected from 224 of Agrippal group and 223 of Flurix group and analysed by the haemagglutination inhibition (HI) assay. Agrippal and Flurix induced similar seroprotection (HI titer >or= 1:40, H1N1 99.6% vs 100.0%; H3N2 99.1% vs 99.1%) and seroconversion (4-fold increase, 95.1% vs 97.8%; H3N2 74.5% vs 79.8%) rates and geometric mean titer (GMT) increase (16.0 vs 21.0; 5.4 vs 6.4) against the two A subtypes. A similar seroprotection rate (94.2% vs 96.4%) and GMT increase (21.2 vs 18.2) against the influenza B strain were also noticed in both vaccines. No significant difference was found in the results of immunological assay between the two vaccines (P < 0.05). A lower seroconversion rate against B strain was observed in Agrippal group than in Flurix group (91.1% vs 97.3%). CONCLUSION: In terms of safety, both vaccines were generally well tolerated. The fever reaction was less frequently seen in the Agrippal group. Both vaccines induced an effective immune response in the vaccines.

Antibodies, Viral↗
PubMed2003

[Effects of escharectomy during shock stage on the plasma lipid and serum free fatty acid levels in scalded rats].

OBJECTIVE: To investigate the influence of escharectomy during shock stage on plasma lipid and free fatty acid levels in scalded rats. METHODS: Thirty-two adult Wistar rats inflicted with 30% TBSA III degree scalding were employed as the model and were divided into normal control (NC), scalding control (SC) and treatment groups (T), and the latter was further divided into three sub groups according to the time of escharectomy, i.e. 8 postburn hour (PBHs) (T8), 24 PBHs (T24) and 96 PBHs (T96) groups. The rats were sacrificed at 168 PBHs. The postburn changes in the rat plasma lipid and free fatty acid levels were determined. RESULTS: 1) There was significant increase in serum triglyceride (TG), cholesterol (CHO), high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), apolipoprotein A (ApoA), apolipoprotein B (ApoB) and all the free fatty acids (FFAs) in the total serum FFAs excluding myristic acid (P < 0.05) at 168 PBHs in rats of all the T groups. 2) The serum levels of TG, CHO, ApoB, total FFA, lauric acid, palmitic acid, zoomaric acid, oleic acid and linoleic acid in T8 and T24 groups were evidently lower than those in SC group (P < 0.05). The plasma levels of VLDL, stearic acid and arachidonic acid in T8 were obviously lower than those in SC group (P < 0.05); 3) In T96 group, the serum levels of ApoB and lauric acid were significantly lower than those in SC group (P < 0.05), but all the other indices remained higher than those before injury. CONCLUSION: There was enhanced fat mobilization after severe burn injury. Escharectomy during shock stage might decrease fat mobilization, which was beneficial to the restoration of normal lipid metabolism.

Animals↗
PubMed2003

[Purification of recombinant Schistosoma japonicum signaling protein 14-3-3 and antibody preparation].

OBJECTIVE: To prepare and characterize the polyclonal and monoclonal antibodies(McAbs) against Schistosoma japonicum(Sj) signaling protein 14-3-3. METHODS: Recombinant Sj14-3-3 protein was expressed and the gel slices were lyophilized. Rabbits were immunized with the ground gel powder to prepare polyclonal antibodies against Sj14-3-3. BALB/c mice were immunized with recombinant Sj14-3-3 purified by electroelution. The anti-rSj14-3-3 monoclonal antibody was obtained by using hybridoma technique. Characterization of the antibodies was performed by enzyme linked immunosorbent assay (ELISA) and Western blotting analysis. RESULTS: Purified recombinant Sj14-3-3 protein was obtained. The titers of immune sera from the animals were 1:8-1:64. The monoclonal antibody(McAb) against 14-3-3 antigen was obtained and its subclass was found to be IgG1. The McAb reacted strongly and specifically with the expressed Sj14-3-3 protein. CONCLUSION: The anti-14-3-3 sera were obtained and the hybridoma cell lines which secreted stable monoclonal antibodies against Sj14-3-3 were established, which provides a new approach to study the role of Sj14-3-3 in the signal transduction of S. japonicum.

14-3-3 Proteins↗
PubMed2003

[Detection of COL1A1/PDGFB fusion transcripts in dermatofibroscoma protuberans by revers transcriptase-polymerase chain reaction using paraffin-embedded tissues].

OBJECTIVE: To detect the COL1A1/PDGFB fusion transcripts and discuss its clinicopathological significance in dermatofibroscoma protuberans. METHODS: Formalin fixed, paraffin-embedded tumor specimens from 12 patients with DFSP were reviewed by light microscope and the expression of COL1A1/PDGFB mRNA resulting from the reciprocal translocation t(17;22) (q22;q13.1) was detected by one-step revers transcriptase-polymerase chain reaction. The following tumor specimens were included as controls: 2 fibrosarcoma, 2 malignant fibrous histocytoma, 3 leiomyosarcoma, 1 dermarofibroma and 1 nerve shealth tumor. RESULTS: The COL1A1/PDGFB fusion transcripts were detected in 8 (67%) of 12 samples from patients with DFSP. Nucleotide sequence analysis using the PCR products confirmed that different regions of the COL1A1 gene, respectively, were fused with of PDGFB gene. No COL1A1/PDGFB fusion transcripts were detected in the control tumors. CONCLUSION: Detection of specific COL1A1/PDGFB fusion transcripts in DFSP will help to diagnose the nature of DFSP and research the mechanism of its molecular histogenesis.

Adolescent↗
PubMed2003

[Study on the diagnostic significance of detecting the expression of AChR-gamma mRNA in rhabdomyosarcoma tissues].

OBJECTIVE: To detect over-expression of AChR-gamma mRNA in rhabdomyosarcoma tissues by duplex RT-PCR and discuss its potential in diagnosis of rhabdomyosarcoma. METHODS: Duplex RT-PCR was applied to the simultaneous detection of AChR-alpha and gamma subunit messenger RNA in 17 cases of rhabdomyosarcoma (9 ERMS, 6 ARMS, 2 PRMS). 20 cases of non-rhabdomyosarcomous small round cell tumors (6 poorly differentiated synovial sarcomas, 6 ES/PNET, 6 lymphomas, 2 neuroblastomas) and three normal muscle samples were also detected for AChR-alpha and gamma mRNA by the same method. RESULTS: AChR-alpha and AChR-gamma mRNA were expressed in all the cases of rhabdomyosarcoma. The rate of quantity in both transcripts was AChR-gamma/AChR-alpha >or= 1, but the rate for three normal muscle samples was < 1. Cases of non-rhabdomyosarcomous small round cell tumors were all negative for AChR-gamma. CONCLUSION: AChR-gamma mRNA expression detected by molecular genetic methods is useful in diagnosis and differential diagnosis of rhabdomyosarcoma.

Diagnosis, Differential↗
PubMed2003

Factors contributing to the incompatibility between simplified-step adhesives and self-cured or dual-cured composites. Part II. Single-bottle, total-etch adhesive.

PURPOSE: As adhesives containing hydrophilic/acidic resin components are vulnerable to water movement after polymerization, this study tested the hypothesis that coupling of a single-bottle adhesive (OptiBond Solo Plus) to self/dual-cured composites is compromised by adhesive permeability, even with the adjunctive use of chemical co-initiators. MATERIALS AND METHODS: Two versions of chemical co-initiators (activators) were investigated: the proprietary resin-containing OptiBond Solo Plus Activator (A), and a resin-free solution of 2% benzene sulphinic acid sodium salt in ethanol (B). For microtensile bond testing, hydrated (H) or dehydrated (D) bonded human dentin were coupled to a dual-cured composite (Bis-Core) under light- (L) or self-activation (C) mode. A delayed light-activation mode (DL) was also employed to simulate the slower rate of polymerization of self-cured composites but without the influence from adverse chemical interaction. Nine groups were tested: 1) L-H (control); 2) DL-H; 3) DL-D; 4) C-H; 5) C-D; 6) CA-H; 7) CA-D; 8) CB-H; and 9) CB-D. For transmission electron microscopy, a light-cured and an experimental self-cured composite of the same composition were used for the nine groups. RESULTS: Only the bond strength results of the experimental groups DL-D (Group 3) and CB-D (Group 9) were not significantly different from the control group L-H (p > 0.05). TEM revealed the presence of discrete silver-filled water blisters along the adhesive-composite interface in groups 2, 6, and 8, and within the composite in group 4. Adverse chemical interaction in groups 4 and 5 resulted in the observation of a line of silver deposits along the adhesive composite interface. CONCLUSION: The coupling of composites after prolonged contact with hydrated dentin bonded with OptiBond Solo Plus is affected by the intrinsic permeability of the adhesive. The adjunctive use of the Activator is only slightly effective in improving the coupling of this adhesive with self/dual-cured composites. Although the use of resin-free benzene sulphinic acid sodium salt solution completely eliminates the adverse chemical interaction, the inherent permeability of the polymerized adhesive precludes optimal coupling of self/dual-cured composites to bonded hydrated dentin.

Acid Etching, Dental↗