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Biomedical subjects

Ming Li

Publications and source records attributed to Ming Li.

At least 109 records · Page 6Linked to original sources

PRIMA: peptide robust identification from MS/MS spectra.

In proteomics, tandem mass spectrometry is the key technology for peptide sequencing. However, partially due to the deficiency of peptide identification software, a large portion of the tandem mass spectra are discarded in almost all proteomics centers because they are not interpretable. The problem is more acute with the lower quality data from low end but more popular devices such as the ion trap instruments. In order to deal with the noisy and low quality data, this paper develops a systematic machine learning approach to construct a robust linear scoring function, whose coefficients are determined by a linear programming. A prototype, PRIMA, was implemented. When tested with large benchmarks of varying qualities, PRIMA consistently has higher accuracy than commonly used software MASCOT, SEQUEST and X! Tandem.

Amino Acid Sequence↗

von Hippel-Lindau gene mutation in non-syndromic familial pheochromocytomas.

Approximately 50% of patients with non-syndromic familial pheochromocytomas had germline von Hippel-Lindau (VHL) gene mutations, but no reports on the subject were available in China. A total of five unrelated Chinese families with non-syndromic familial pheochromocytomas were screened for VHL gene mutation by polymerase chain reaction (PCR) and subsequent direct sequencing. Missense germline mutations of VHL gene were detected in four of the five families. Arg161Gln (695G-A) mutation was found in two families, and the other two families had Leu163Phe (700C-T) and Arg167Trp (712C-T) mutation, respectively. In conclusion, VHL gene may have frequent mutation in Chinese patients with non-syndromic familial pheochromocytomas.

Adrenal Gland Neoplasms↗

Expression and effect of transforming growth factor-alpha and tumor necrosis factor-alpha in human pheochromocytoma.

This study observed the expression of transforming growth factor-alpha (TGF-alpha) and tumor necrosis factor-alpha (TNF-alpha) in pheochromocytoma (PHEO) tissue and examined their effects on the proliferation and apoptosis of human PHEO cells. The mRNA and protein expressions of TGF-alpha and TNF-alpha were higher in PHEO tissues than in normal adrenal medullary tissues, and their expressions varied with pathological features. TGF-alpha and TNF-alpha stimulated the proliferation of primary human PHEO cells, but had no effect on the cell apoptosis. Both TGF-alpha and TNF-alpha might be involved in the pathogenesis of human PHEO. TNF-alpha needs to be further investigated before its treatment of PHEO can be realized in clinical practice.

Adrenal Gland Neoplasms↗

Effect of delta-elemene on Hela cell lines by apoptosis induction.

This study was designed to investigate the apoptosis-inducing activity of delta-elemene on Hela cells in vitro. MTT assay and Hoechst 33258/PI fluorescence microscopy were used for this investigation. Apoptosis was further confirmed and quantified by DNA fragmentation ELISA, Annexin V (AnV) binding of externalized phosphatidylserine and the mitochondrial probe JC-1 using flow cytometry. Generation of reactive oxygen species (ROS) was detected using CM-H2DCFDA. Western blots analysis was performed using antibodies against the pro-caspase-3, or PRAP (Poly (ADP-ribose) polymerase). The results showed that delta-elemene exhibited a marked antiproliferative effect on Hela cells in dose- and time-dependent manners, and had little inhibition to normal human liver cell line WRL-68. It was demonstrated that delta-elemene was capable of inducing DNA fragmentation in a dose- and time-dependent manner. AnV positivity and the disturbance of the polarized mitochondrial transmembrane potential (Deltapsim) suggested that delta-elemene induced apoptotic death of Hela cells. Western blot analysis demonstrated that delta-elemene activated the caspase-signaling pathway, leading to the proteolysis conversion of pro-caspase-3 to activate caspase-3, and the subsequent cleavage of the caspase substrate PARP. Further, it was noted that the apoptotic effect of delta-elemene could be attenuated by L-Glutathione (GSH) or z-DEVD-fmk. It suggested that the increase in ROS generation might be involved in the mechanism of delta-elemene induced cell apoptosis.

Apoptosis↗

Factors associated with adolescents' physical inactivity in Xi'an City, China.

PURPOSE: To explore the sociodemographic and environmental factors at community, school, and household levels associated with physical inactivity. METHODS: In a cross-sectional study in 2004, physical activity level was assessed using a validated questionnaire in 1787 students. Physical inactivity was defined as less than 150 min.wk of moderate activity (4-6 METs) or less than 60 min.wk of vigorous activity (> 6 METs). Sociodemographic and environmental information was recorded on self-administered questionnaires. Hierarchical multiple logistic models were developed based on a conceptual framework of factors related to physical activity. RESULTS: Overall, girls were twice as likely to be inactive. Adolescents aged 14 yr were 30% less likely to be inactive compared with those younger than 13 yr (95% CI: 0.5-0.9). Paternal education was inversely associated with inactivity (OR: 0.6, 95% CI: 0.4-0.9). Adolescents living in neighborhoods without sidewalks were 1.3 times more likely to be inactive (95% CI: 1.0-1.6). At the school level, lack of extracurricular exercise (OR: 1.3, 95% CI: 1.1-1.6) and fewer sports meetings (OR: 2.0, 95% CI: 1.4-2.9) were associated with physical inactivity. Difficult access to community recreational facilities (moderate OR: 1.4, 95% CI: 1.0-1.9; difficult OR: 1.7, 95% CI: 1.2-2.4) and concerns about safety in the neighborhood (OR: 2.1, 95% CI: 1.1-4.1) were associated with inactivity. There were some differences associated with physical inactivity between boys and girls. CONCLUSION: Strategies to promote physical activity in Chinese adolescents should integrate associated factors at household, school, and community levels and address the important gender differences in factors associated with physical inactivity in youth.

Adolescent↗

[Time-resolved fluoroimmunoassay of carcino-embryonic antigen and preparation of its diagnostic reagent].

AIM: To establish a two-site time-resolved fluoroimmunoassay (TRFIA) for detection of carcino-embryonic antigen(CEA) based on the direct sandwich technique(One monoclonal antibody(mAb) is immobilized on the surface of microtiter plate strip wells, another mAb is labelled with Eu(3+)) and prepare its diagnostic reagent. METHODS: The sandwich TRFIA for detection of serum CEA level using anti-CEA mAbs was used. RESULTS: The measure range of CEA-TRFIA was (1-560) microg/L. The analytical sensitivity was 0.28 mug/L. The intra- and inter-assay coefficients of variation (CV) were 7.2%-8.6% and 8.9%-13.2%, respectively. There was no cross-reaction to AFP, CA12-5, CA19-9 and albumin. Cross reactivity to CA15-3 was 1.62 microg/L. The correlation coefficient of blood samples detected by CEA-TRFIA and commercially available CEA CLIA (chemiluminescent immunoassay) kit (Roche) was 0.946. CONCLUSION: CEA-TRFIA is a new immunoassay which has several advantages including high sensitivity, specificity and a wide working range. It is suitable for routine clinical use.

Carcinoembryonic Antigen↗

[Colocalized expression of Fas and Fas-ligand in acute pancreatitis and its correlation with cell apoptosis].

OBJECTIVE: To study the expressions of Fas and Fas-Ligand (FasL) genes in rats with acute pancreatitis (AP) and their relation to apoptosis of pancreatic acinar cells. METHODS: Rat models of acute pancreatitis with varied severity were established by retrograde injection of sodium taurocholate at different concentrations via the apancreatobiliary duct. The expressions of Fas and FasL mRNAs and proteins were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. The apoptosis of acinar cells was quantified by in situ nick ending-labeling technique. RESULTS: of expressions fas, FasL mRNA and protein were colocalized in normal pancreatic acinar cells. In pancreatic tissue with less severe inflammation, the expressions of Fas and FasL mRNA increased significantly, and the apoptosis index of the acinar cells was also elevated; with the increase in the severity of the pancreatitis, the expression of Fas and FasL mRNAs were gradually lowered and apoptosis index of the acinar cells was increased. CONCLUSION: Fas/FasL system might be involved in the renewal and homeostasis of normal pancreatic tissue, and constitute an important pathway mediating the apoptosis of pancreatic acinar cells in AP.

Acute Disease↗

[Preparation and identification of monoclonal antibodies against Helicobacter pylori].

OBJECTIVE: To prepare and identify monoclonal antibodies (mAbs) against Helicobacter pylori (Hp). METHODS: BALB/c mice were immunized with the supernatant and precipitation of cultured Hp after ultrasonication and mAbs were obtained by means of hybridoma technique. The resultant mAbs was evaluated for subtype, titer, affinity, and further identified with Lpp20, HspA, urease A, CagA, urease B, and catalase prepared by recombinant expression. RESULTS: Totally 34 hybridoma cell lines were established which secreted specific mAbs, including 31 against the supernatant and 3 against the precipitation of Hp, and the prepared mAbs showed specific reaction against Lpp20 (3 strains), HspA (2 strains), urease A (4 strains), CagA (1 strain), urease B (5 strains), and catalase (2 strains) antigens, respectively. The mAbs was all identified as immunoglobulin G1 (IgG1) and theirs titer in the culture supernatant and ascites was 1:16 to 1:32 and 1:32000 to 1:64000 respectively with affinity constants (K(aff)) ranging from 1 x 10(-10) to 5.2 x 10(-12) mol/L. CONCLUSION: The mAbs specially against Hp have been obtained, which may facilitate further study of detection and vaccine development of Hp.

Animals↗

[Clinical analysis of bronchopulmonary infection with hypermastigotes: a report of two cases and review of the Chinese literature].

OBJECTIVE: To describe the clinical features of bronchopulmonary infection with hypermastigotes. METHODS: Two cases of bronchopulmonary infection with hypermastigotes were reported. The clinical features of another six cases from the Chinese literature were reviewed. RESULTS: Bronchopulmonary infection with hypermastigotes mostly occurs in the hot and humid southern area. The symptoms are severe, with different manifestations such as chronic cough, asthma, pneumonia, and even lung abscess. Final diagnosis is made by the presence of hypermastigotes in smears of secretions from the respiratory tract. An antiprotozoal such as metronidazole is always effective. CONCLUSION: In patients with unexplained cough, asthma, and pneumonia or lung abscess which do not respond to ordinary therapy, rare pathogens such as hypermastigotes need to be considered.

Bronchopneumonia↗

[Prevalence of overweight and obesity and its associated risk factors in students aged 11-17 in Xi'an in 2004].

OBJECTIVE: To assess the magnitude of overweight and obesity and its associated sociodemographic factors in adolescents attending junior high schools in Xi'an, Shanxi province. METHODS: A total of 1 804 adolescents attending junior high schools in Xi'an (age: 11-17 years) were enrolled randomly from 30 schools in 6 districts in Xi'an. Overweight and obesity was categorized with body mass index (BMI) cutoffs from Working Group of Obesity in China (WGOC). Underweight was defined by BMI-Z < or = -2 s. Sociodemographic information was collected from the parents of the survey participants using self-administered, structured and precoded questionnaires. RESULTS: Overall 17.4% of adolescents were overweight or obese (overweight 11.2%; obesity 6.2%), but there was a marked gender difference in the prevalence with 20.2% of boys versus 14.4% of the girls being overweight or obese. The prevalence of underweight was 2.7%. In a multivariate model, age, residence, household wealth, and parents' BMI were significantly associated with overweight and obesity (P < 0.05). After having been adjusted for age and gender, the odds ratio of an adolescent being overweight and obese was 2.7 (95% CI: 1.8-4.0) folds higher in urban areas than in rural areas, and was 1.6 (95% CI: 1.04-2.5) folds higher for adolescents from rich families than those from poor families. An adolescent with one or both parents overweight was 1.8 (95% CI: 1.3-2.5) more likely to be overweight themselves compared to those with normal weight parents. CONCLUSIONS: Overweight and obesity is a major public health problem in adolescents in Xi'an. Overweight and obesity is more prevalent in younger boys from richer families living in urban districts and those whose parents were either overweight or obese.

Adolescent↗

[Cloning, expression and identification of catalase of Helicobacter pylori].

AIM: To construct the recombinant plasmid containing catalase (KatA) of Helicobacter pylori (Hp), analyze its nucleic acid sequence, express it in E. coli and study its antigenicity. METHODS: KatA fragments were amplified from Hp chromosomal DNA by PCR. Its T-A was cloned, sequenced and compared with other HP strains on the GenBank. Then the gene cloned into pGEX-4T-1 fusion expression vector was expressed in E. coli and purified by GST-affinity chromatography. The purified product was used to identify 29 stains of mouse anti Hp monoclonal antibodies and analyze antigenicity with serum of Hp-infected patients by Western blot. RESULTS: KatA fragments were composed of 1,515 bp (GenBank No. DQ333889) and the nucleotide homology with other Hp strains on the GenBank was 96%-97%. 85 kDa of the recombinant KatA-pGEX-4T-1 was expressed in E. coli. 4 of 29 anti-Hp mouse monoclonal antibodies were against KatA. Western blot analysis proved that KatA was specifically recognized in the serum of Hp-infected patients. CONCLUSION: The recombinant KatA has original antigenicity. It is of great value to clinical sero-diagnosis and vaccine study of Hp.

Antibodies, Monoclonal↗

[Effects of tributyltin chloride (TBT) and triphenyltin chloride (TPT) on rat testicular Leydig cells].

OBJECTIVE: To investigate the effects of tributyltin chloride (TBT) and triphenyltin chloride (TPT) on rat testicular Leydig cells. METHODS: The rat Leydig cells (LC-540) were incubated with 0 to 80 nmol/L TBT and TPT for 24 to approximately 96 h, and then the cell viability was determined by MTT. DNA fragmentation ladder formation of cell apoptosis was examined by agarose electrophoresis. Effects of chelator of intracellular Ca2+ (BAPTA) and the inhibitors of PKA, PKC and TPK on cell apoptosis induced by TBT were observed. Effects of TBT on testosterone production in primary cultured rat Leydig cells treated with or without hCG were detected. RESULTS: TBT and TPT suppressed Leydig cell survival in a time- and dose-dependent manner. The suppressive effects of TBT and TPT on the cell survival was caused by apoptosis which was determined by DNA ladder formation. The apoptotic effect of TBT was possibly mediated by the rise in intracellular Ca2+ because it could be blocked by BAPTA, the chelator of intracellular Ca2+; PKA, PKC and TPK inhibitors did not prevent the apoptotic effects induced by TBT. TBT markedly suppressed testosterone production of primary cultured rat Leydig cells with or without hCG stimulation. CONCLUSION: TBT and TPT induced apoptosis in rat testicular Leydig cells possibly through increasing intracellular Ca2+. TBT reduced the testosterone production of rat Leydig cells.

Animals↗

[Comparison of distribution of cholinergic nerves and M2 receptors between rat atria and ventricles].

OBJECTIVE: To investigate the general pattern of cholinergic nerve distribution and M(2) receptors in adult rat heart. METHODS: Karnovsky-Roots histochemical staining combining point counting method and immunochemical SABC method with image analysis were used to identify the cholinergic nerves and M(2) receptors, respectively, in adult rat heart. RESULTS: Positive staining of cholinergic nerves and M(2) receptors was found in all regions of the rat heart, and the point count of cholinergic nerves in the atria was 4.6 times as much as that in ventricles, and the area of immunoreactive substance for M(2) receptors two-fold higher in the atria than in the ventricles. The point counts of the cholinergic nerves in the medial-layer myocardium were fewer than that in subepicardial and endocardial tissues of the left ventricular free wall. However, M(2) receptors were comparable among the 3 layers of the left free ventricular wall. CONCLUSION: Cholinergic nerves and M(2) receptors are located in both rat atria and ventricles, but their density is much higher in the atria than in the ventricles. Transmural heterogeneity characterizes cholinergic nerve innervation in the left ventricular free wall without significant differences in M(2) receptor density.

Animals↗

[Immunocytochemical study of phospholipase C-gamma1 expression in mouse embryonic tissue].

To investigate the expression of phospholipase C-gamma1 (PLC-gamma1) in mouse embryonic tissues, serial tissue sections were prepared routinely for immunocytochemistry for PLC-gamma1. The results showed that PLC-gamma1 was expressed in the cartilage, skeletal muscles, myocardium, the collecting tubule of the kidney, connective tissues and the brain, suggesting the important role PLC-gamma1 and the related signal pathway may play in the development of mouse embryonic tissues.

Animals↗

[Analysis of the concentration of plasma copper and collagen in fetal membrane of the preterm's mothers].

OBJECTIVE: The purpose of the study is to determine primarily the concentration of plasma copper and collagen in fetal membrane of the preterm's mothers, and explore the relation of copper status and fetal membrane collagen of preterm's mothers. METHODS: The general situations were collected both in neonatos and their mothers. The plasma copper concentrations of mother venous blood and cord blood were analyzed by ICP-OES. Sirius Red dyeing was first used in fetal membrane to detect the thickness and collagen in preterm's and full-term's mothers. RESULTS: The prevalence of premature rupture of membrane (PROM) was 40.00% in preterm's mothers, and 9.09% in the full-term's mothers. The mothers' preconceptual weight, infant body length and body weight at birth were lower in preterm group than those of the full-term group. The cord blood plasma copper was significantly lower in preterms than in full-terms. Both the thickness and the concentration of collagen I and II of non-split fetal membrane of preterm's mothers were significantly less than those of the full-term's mothers. CONCLUSION: Both the concentration of plasma copper and fetal membrane collagen of preterm's mothers were lower than that of the full-term's. It can confer that the deficient copper status could lead to immature collagen in fetal membrane which induce PROM and have preterm birth finally. More work need to be done in this field.

Adult↗

[Cloning and expression of lumbrokinase gene in Pichia pastoris].

Lumbrokinase gene F238 was amplified by RT-PCR from the total RNA of earthworm (Eisenia fetida). The gene including signal peptide sequence was inserted into pUCm-T vector to construct pUCm-T-F238. The product was sequenced. The GenBank accession number was DQ202401. Lumbrokinase F238 comprised 738bp and included an open reading frame that encoded a polypeptide of 245 amino acid residues, containing a signal peptide of 7 amino acid residues and a mature peptide of 238 amino acid residues. Both nucleotide and amino acid sequences homologies were 99% after the sequence was compared with Lumbricus rubellus F-III-2. There were two base pair mutations, which subsequently caused two amino acid mutations. The characteristics and structure of F238 was analysed and predicted with biology softwares and databases. The pl of F238 was 4.61. It had eleven Cysteines, which formed three disulfide bonds. Its secondary structure mainly consisted of beta-sheet. Lumbrokinase F238 had serine active center. It was a protease in trypsin family of serine protease superfamily. Lumbrokinase gene F238-m without signal peptide sequence was obtained by PCR using pUCm-T-F238 as template. The expression vector pPIC9-F238-m was constructed by inserting gene F238-m into yeast expression and secretion plasmid pPIC9. Plasmid pPIC9-F238-m was linearized with BgIII and then transformed into Pichia pastoris strain GS115 cell by electroporation method. Phenotypes of transformants were screened in MM and MD plates to ensure the integration of lumbrokinase gene F238-m into yeast chromosome DNA. Methanol was added to a final concentration of 0.5% for the expression of recombination protein every 24h to maintain induction. The result of SDS-PAGE showed that the molecular weight of the expression product was about 28 kDa, in correspondence with the theoretical molecular weight. After the induction of expression, the fibrinolytic activity of the supernatant was measured using artificial fibrin plates. Then the engineering strain of high activity was obtained, and the fibrinolytic activity was up to 100 U/mL.

Animals↗

[Transgenic mice produced by intracytoplasmic sperm injection].

In our previous study, normal and fertile mice were successful produced from oocytes following intracytoplasmic sperm injection (ICSI). In the present study, the possibility of producing transgenic embryos and offspring with this procedure was evaluated. After freezing-thawed once using HEPES-CZB medium without cryoprotectants, the cauda sperm from KM fertile male were exposed to the circular or linear pEGFP-N1 DNA for 1 min and then co-injected into metaphase II oocytes of B6D2F1 strain. When the zygotes with two pronuclei were cultured in CZB medium to day 3.5, 39.1% (9/23) of them, derived from oocytes co-injected with sperm head and pEGFP-N1 plasmid DNA, were expressed GFP protein. After transfer of the ICSI embryos with two pronuclei from co-injection of sperm head and foreign DNA, seven recipients delivered 30 pups (23.8%, 30/126). Southern blot results revealed that three of sixteen offspring integrated with GFP and neomycin genes together (18.8 %). Interestingly, all of them were produced from oocytes co-injected sperm head and linear DNA (33.3%, 3/9), while none of seven ICSI offspring integrated either GFP or neomycin gene in the group of co-injection of sperm head and circular plasmid DNA. These results indicated that the high efficiency of transgenic mouse could be produced by ICSI. It may be shown that linear DNA is more easily to integrate into host genome than circular DNA when ICSI was used to produce transgenic animals.

Animals↗

[Establishment of protein expression profile of human normal colonic epithelia].

OBJECTIVE: To establish a protein expression profile of human normal colonic epithelia. METHODS: Two-dimensional gel electrophoresis (2-DE) was applied to separate the total proteins of 20 human normal colonic epithelial tissues. The expression proteins in the human normal colonic epithelia were identified by both matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization tandem mass spectrometry (ESI-Q-TOF), and the biological function and subcellular locations of the identified proteins were analyzed by bioinformatics. RESULTS: A 2-DE reference map of human normal colonic epithelium was established. On the 2-DE map, 1020+/-50 protein spots were detected, 204 protein spots representing 162 non-redundant proteins were identified, and 37 proteins had posttranslational modification. The identified proteins were categorized into several protein groups according to their functions or subcellular locations, whose data were available at our website (http://www.xyproteomics.org). CONCLUSION: A protein expression profile of human normal colonic epithelia is established for the first time, which provides useful information for investigating the physiological functions and pathologic process of colonic epithelia.

Adult↗