PubMed Health⌕ Search

Biomedical subjects

Min Liu

Publications and source records attributed to Min Liu.

At least 91 records · Page 5Linked to original sources
PubMed2005

[Proliferation, differentiation, and gene expression profile of osteoblast of patient with spondyloepiphyseal dysplasia tarda with progressive arthropathy].

OBJECTIVE: To explore the proliferation, differentiation, and gene expression profile of the osteoblasts (OBs) of patient with spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA). METHODS: OBs from the head of femur of a SEDT-PA patient resected during operation were cultured. ELISA was used to examine the bone-specific alkaline phosphatase (BAP), osteocalcin (OC), and osteoprotegrin (OPC) in the lysate of OBs. The proliferation and survival of the OBs were evaluated with MTT method and (3)H-TDR incorporation. Flow cytometry was used to observe the cell cycle. Northern blotting was used to evaluate the mRNA expression of WISP3, a member of the CCN family, mRNA in the OBs. Gene differential expression microarray was used to determine the cDNA expression. Osteoblasts from the head of femur of a patient about the same age with fracture of femur neck was used as control. RESULTS: The cultured OBs from the SEDT-PA patient showed a higher survival capacity (0.86 +/- 0.04 vs 0.71 +/- 0.10) and more (3)H-TDR incorporation (1363 +/- 350 vs 867 +/- 128). The expressions of OC and OPG were down-regulated to the 1/4.3 and 1/4.69 of the control respectively. There was no significant difference in the expression of BAP. WISP3 was very lowly expressed in the OBs of the SEDT-PA patient. In comparison with the normal control, there were up-regulation of 22 genes, including those coding chemotactic factors and inflammatory factors, and down-regulation of 16 genes in the OBs of the SEDT-PA patient with a synthetic effect of more rapid proliferation of OBs and reduction of synthesis of extracellular matrix, resulting in osteopenia. CONCLUSION: Not significantly different between SEDT-PA patient and normal person, the WISP3 expression may not be a direct factor of SEDT-PA.

Alkaline Phosphatase↗
PubMed2005

CADASIL mutations impair Notch3 glycosylation by Fringe.

Mutations in the NOTCH3 gene trigger adult-onset stroke and vascular dementia in patients with CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). All CADASIL mutations described to date affect the epidermal growth factor-like (EGF-like) repeats located in the extracellular domain of the Notch3 receptor. These domains are also the target of sequential complex O-linked glycosylation mediated by protein O-fucosyltransferase 1 and Fringe. We investigated whether O-fucosylation or Fringe-mediated elongation of O-fucose on Notch3 is impaired by CADASIL mutations. Biochemical studies of a Notch3 fragment containing the first five EGF-like repeats of Notch3, including the mutational hot spot, showed that CADASIL mutations do not affect the addition of O-fucose but do impair carbohydrate chain elongation by Fringe. CADASIL changes also induced aberrant homodimerization of mutant Notch3 fragments and heterodimerization of mutant Notch3 with Lunatic Fringe itself. Together, these data suggest that Fringe plays a role in CADASIL pathophysiology.

Animals↗
PubMed2005

Small interfering RNA inhibits SARS-CoV nucleocapsid gene expression in cultured cells and mouse muscles.

SARS-CoV is a newly identified coronavirus that causes severe acute respiratory syndrome (SARS). Currently, there is no effective method available for prophylaxis and treatment of SARS-CoV infections. In the present study, the influence of small interfering RNA (siRNA) on SARS-CoV nucleocapsid (N) protein expression was detected in cultured cells and mouse muscles. Four siRNA expression cassettes driven by mouse U6 promoter targeting SARS-CoV N gene were prepared, and their inhibitory effects on expression of N and enhanced green fluorescence protein (EGFP) fusion protein were observed. A candidate siRNA was proved to down-regulate N and EGFP expression actively in a sequence-specific manner. The expression vector of this siRNA was constructed and confirmed to reduce N and EGFP expression efficiently in both cultured cells and adult mouse muscles. Our findings suggest that the siRNA should provide the basis for prophylaxis and therapy of SARS-CoV infection in human.

Animals↗
PubMed2005

Fluorescence quenching mechanism of a polyphenylene polyelectrolyte with other macromolecules: cytochrome c and dendrimers.

This study investigates the fluorescence quenching of a polyphenyl based polyelectrolyte by positively charged macromolecules (proteins and dendrimers). This work shows that the fluorescence quenching of the dendrimer materials does not involve energy transfer or electron transfer but is correlated to the overall charge on the dendrimer and its size. The quenching is hypothesized to result from conformational changes that occur upon binding the polyelectrolyte to the protein or dendrimer. This mechanism is qualitatively different from that invoked for small-molecule analytes.

Cytochromes c↗
PubMed2005

EM012, a microtubule-interfering agent, inhibits the progression of multidrug-resistant human ovarian cancer both in cultured cells and in athymic nude mice.

Drug resistance, in particular multidrug resistance, is a serious problem that impedes the effectiveness of chemotherapy. Multidrug resistance results mainly from an enhanced efflux of drugs by drug pumps located on the cell membrane such as P-glycoprotein. In the study reported here we showed that EM012, a microtubule-interfering agent, is a weak substrate for P-glycoprotein and inhibited the proliferation of A2780/ADR human ovarian cancer cells, which possess multidrug resistance due to P-glycoprotein overexpression. A2780/ADR cells treated with EM012 exhibited pronounced mitotic arrest, developed large multilobed nuclei, and eventually died through the initiation of apoptosis. Intraperitoneal treatment of A2780/ADR xenograft tumors in athymic nude mice with EM012 significantly inhibited tumor progression through triggering apoptosis and conferred an apparent survival advantage. Furthermore, EM012 treatment did not cause detectable toxicity to normal tissues. These findings suggest that EM012 may serve as a novel chemotherapeutic agent for the treatment of multidrug-resistant human ovarian cancer.

Animals↗
PubMed2005

GLP-1 reduces intestinal lymph flow, triglyceride absorption, and apolipoprotein production in rats.

Glucagon-like peptide 1 (GLP-1) is a gastrointestinal hormone secreted in response to meal ingestion by enteroendocrine L cells located predominantly in the lower small intestine and large intestine. GLP-1 inhibits the secretion and motility of the upper gut and has been suggested to play a role in the "ileal brake." In this study, we investigated the effect of recombinant GLP-1-(7-36) amide (rGLP-1) on lipid absorption in the small intestine in intestinal lymph duct-cannulated rats. In addition, the effects of rGLP-1 on intestinal production of apolipoprotein (apo) B and apo A-IV, two apolipoproteins closely related to lipid absorption, were evaluated. rGLP-1 was infused through the jugular vein, and lipids were infused simultaneously through a duodenal cannula. Our results showed that infusion of rGLP-1 at 20 pmol.kg(-1).min(-1) caused a dramatic and prompt decrease in lymph flow from 2.22 +/- 0.15 (SE) ml/h at baseline (n = 6) to 1.24 +/- 0.06 ml/h at 2 h (P < 0.001). In contrast, a significant increase in lymph flow was observed in the saline (control) group: 2.19 +/- 0.20 and 3.48 +/- 0.09 ml/h at baseline and at 6 h of lipid infusion, respectively (P < 0.001). rGLP-1 also inhibited intestinal triolein absorption (P < 0.05) and lymphatic apo B and apo A-IV output (P < 0.05) but did not affect cholesterol absorption. In conclusion, rGLP-1 dramatically decreases intestinal lymph flow and reduces triglyceride absorption and apo B and apo A-IV production. These findings suggest a novel role for GLP-1 in lipid absorption.

Animals↗
PubMed2005

Supramolecular aggregates constructed from gold nanoparticles and l-try-CD polypseudorotaxanes as captors for fullerenes.

A series of cyclodextrin-based polypseudorotaxanes (PPRs) were constructed by threading native beta-cyclodextrin or l-tryptophan-modified beta-cyclodextrin onto the amino-terminated PPG chains of different lengths. Subsequently, these PPRs were further assembled to form netlike supramolecular aggregates through the linkage of gold nanoparticles, and the resulting water-soluble Au-PPR aggregates were comprehensively characterized by FT-IR, UV, NMR, fluorescence spectroscopy, powder X-ray diffraction patterning, TG-DTA, and transmission electron microscopy. The results showed that the size and sedimentation rate of the Au-PPR aggregates were mainly dependent on the lengths of the PPG chains. Significantly, the Au-PPR aggregate 8, involving many l-tryptophan residues, showed not only a satisfactory water solubility but also a good capturing ability for fullerenes in aqueous solution. The 8-fullerene conjugate thus formed exhibited a good DNA cleavage ability under light irradiation.

DNA↗
PubMed2005

Bacterial expression and characterization of rat apolipoprotein E.

Apolipoprotein (apo) E is a protein involved in both lipid metabolism and neuroprotection. Recently, it has been suggested that apoE may play a role in the regulation of food intake and body weight in rodents. However, rodent plasma apoE is difficult to purify in reasonable amounts due to numerous time-consuming steps. To circumvent this, we created a bacterial expression system for the efficient production of large amounts of rat apoE. We inserted rat apoE DNA into the pET30 expression vector and overexpressed the proteins in Escherichia coli strain BL21 (DE3). A histidine tag present at the N-terminus allowed for easy purification of the recombinant protein. The tag was removed with an IgA protease (Igase) from Neisseria gonorrhoeae leaving the mature form of the protein. The use of Igase was important as several more common proteases routinely cleave apolipoproteins at undesired sites. The recombinant protein was then compared both structurally and functionally to rat plasma apoE. This expression system will be highly useful for probing the ability of rat apoE to mediate food intake in rats.

Animals↗
PubMed2005

Antagonism of ATP responses at P2X receptor subtypes by the pH indicator dye, Phenol red.

1 Many types of culture media contain a pH-sensitive dye. One commonly occurring dye, Phenol red sodium (Na(+)) salt, was tested for blocking activity at rat P2X(1-4) receptors (P2X(1-4)Rs) expressed in Xenopus oocytes. 2 Phenol red Na(+)-salt antagonised adenosine 5'-triphosphate (ATP) responses at P2X(1)R (IC(50), 3 microM) and, at higher concentrations, also blocked P2X(2)R and P2X(3)R. Phenol red Na(+)-salt, purified of lipophilic contaminants, blocked P2X(1)R and P2X(3)R by acting as an insurmountable antagonist. 3 Two lipophilic extracts of Phenol red antagonised ATP responses at P2XRs. Extract A was a potent antagonist at P2X(1)R (IC(50), 1.4 microM), whereas extract B was a potent antagonist at P2X(3)R (IC(50), 4.1 microM). A bisphenolic compound (RS151030) found in these extracts was a potent antagonist at P2X(1)R (IC(50), 0.3 microM) and at P2X(3)R (IC(50), 2.4 microM). 4 Phenolphthalein base was a potent irreversible antagonist at P2X(1)R (IC(50), 1 microM), whereas Phenolphthalein K(+)-salt was 25-fold less potent here. 5 Phenolphthalein base was a reversible antagonist of ATP responses at rat P2X(4)R (IC(50), 26 microM), whereas Phenolphthalein K(+)-salt was inactive. 6 Dimethyl sulphoxide (DMSO), used to dissolve lipophilic extracts, showed pharmacological activity by itself at rat P2X(1)R and P2X(4)R. 7 Thus, Phenol red and related compounds are antagonists at rat P2X(1)R, but are also active at other rat P2XRs. Phenolphthalein base is a newly identified, low potency antagonist of ATP responses at P2X(4)R. Culture media containing these red dyes should be used cautiously in future pharmacological studies of P2XRs. Also, wherever possible, the solvent DMSO should be used with caution.

Adenosine Triphosphate↗
PubMed2005

Construction of a eukaryotic expression system of HSP65 gene from Mycobacterium tuberculosis, and anti-HSP65 IgG produced in mice.

The purpose of this study was to express the HSP65 gene of Mycobacterium tuberculosis in eukaryotic cells and study its primary immune effect in animals. The HSP65 gene was amplified from the H37Rv strain of M. tuberculosis by PCR and then inserted into the expression plasmid pcDNA3.1(-). The recombinant plasmid pcHSP65 was transfected into HeLa cells by using the liposome transfection method and also injected into BALB/C mice to accomplish DNA immunization. The inserted gene was demonstrated to be identical to the reported HSP65 gene sequence. The transfected HeLa cells expressed HSP65 protein; Western blot showed the presence of a 65 kDa band of the inclusion body protein and immunofluorescence testing identified the protein expressed in cytoplasm. Specific IgG for the HSP65 protein could be identified in immunized mice. This study shows that recombinant eukaryotic expression plasmid pcHSP65 was constructed successfully, which lays a foundation for further study of gene therapy.

Animals↗
PubMed2005

[Expression of PDGF-B after fluid percussion brain injury in rats].

OBJECTIVE: To elucidate the changes of PDGF-B chain in the brain injured by fluid percussion. METHODS: The expression of PDGF-B protein was studied by immunohistochemistry and the results were assessed by image analysis system. RESULTS: Enhanced expression of PDGF-B protein induced by fluid percussion injury was seen at 1 h, and its marked up-regulation was noted at 4-7 days, and then the expression became decreased but it remained above the control levels till 14 days after injury. CONCLUSION: Fluid percussion brain injury induced expression of PDGF-B. The regular change pattern of PDGF-B level in time course seems to be of value in estimating the age of brain injury.

Animals↗
PubMed2005

[Methylation of hMLH1 gene promoter in gastric carcinoma with microsatellite instability].

BACKGROUND & OBJECTIVE: Mismatch repair (MMR) deficiency, characterized by microsatellite instability (MSI), is a major cause of hereditary nonpolyposis colorectal carcinoma (HNPCC). Our previous study showed that loss of MMR protein expression can also be seen in gastric carcinoma, but MMR gene mutation seldom occur. Promoter methylation, a main cause of suppressor gene inactivation, might also lead to defect of MMR gene function. This study was designed to investigate the relationship of hMLH1 gene promoter methylation status to MSI in gastric carcinoma, and analyze its action as a risk factor of carcinogenesis. METHODS: DNA was extracted from 52 samples of gastric carcinoma and their adjacent non-cancerous gastric mucosa. Polymerase chain reaction (PCR) was used to amplify microsatellite loci BAT-26, D17S261, D3S1283, D2S123, and D3S1611. MSI was studied by capillary electrophoresis. Methylation of hMLH1 gene promoter was detected by restrictive endonuclease digestion, expression of hMLH1 protein was detected by immunohistochemistry. RESULTS: Of the 52 specimens of gastric carcinoma, 13 with high MSI (MSI-H), 2 with low MSI (MSI-l), and 37 with microsatellite stability (MSS). Frequency of hMLH1 promoter methylation was significantly higher in the 13 specimens of gastric carcinoma with MSI-H than in the 39 specimens of gastric carcinoma with MSI-L or MSS (100% vs. 2.6%, P<0.01). Furthermore, frequency of hMLH1 promoter methylation was significantly higher in the 13 specimens of adjacent non-cancerous gastric mucosa of gastric carcinoma with MSI-H than in the 39 specimens of adjacent non-cancerous gastric mucosa of gastric carcinoma with MSI-L or MSS (46.2% vs. 2.6%, P<0.01). The methylation status was accordant with loss of hMLH1 protein expression. Methylation of hMLH1 gene promoter had no relation with differentiation and clinical stage of gastric carcinoma. CONCLUSION: Methylation of hMLH1 gene promoter exists in gastric carcinoma tissues with MSI-H, and their adjacent non-cancerous gastric mucosa, it may be a risk factor of carcinogenesis of gastric carcinoma.

Adaptor Proteins, Signal Transducing↗
PubMed2005

[Characterization of biologic behaviors and cDNA expression of articular chondrocytes in spondyloepiphyseal dysplasia tarda with progressive arthropathy].

OBJECTIVE: Spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA) is an autosomal-recessive hereditary disorder of cartilage homeostasis. The pathogenesis of SEDT-PA is unknown though it has been demonstrated that CCN6 is the SEDT-PA causing gene. The present study characterized the biologic behaviors and cDNA differential expression profile of articular chondrocytes in SEDT-PA. METHODS: The morphologic and functional features of growth, proliferation, differentiation and DNA synthesis of SEDT-PA chondrocytes were determined with cell growth curve, (3)H-TDR incorporation, MTT and flow cytometry. cDNA differential expression profile was carried out with gene microarray containing 8000 genes. Differentially expressed genes were verified by RT-PCR, Western blot and immunohistochemistry. RESULTS: As compared with normal control, the variant chondrocytes were much larger in size with an enhanced ability of proliferation and DNA synthesis and increased ratio of G(2)-M (10.72% vs 0.11%) to S phases (37.0% vs 15.8%). Matrix metalloproteinases (MMPs), which decompose the extra-cellular matrix of the cartilage, accumulated at the endochylema and failed in exocytosis, which lead to the negative feedback of the mRNA transcriptions. The mRNA expression of MMPs was down-regulated. At the same time, the mRNA expression of genes related to cell growth, proliferation and progression of cell cycles were up-regulated, while most of those associated with extracellular matrix, non-collagen proteins and poly-proteoglycans were down-regulated. CONCLUSIONS: The accumulation and failure in exocytosis of the MMPs decompose the extra-cellular matrix of the cartilage. The decreased expression of matrix proteins and polyproteoglycans is involved in the pathogenesis of arthropathy resulted from CCN6 mutation.

Adult↗
PubMed2005

[The expression of Fas after fluid percussion brain injury in rats].

OBJECTIVE: To inquire into the pathologic diagnosis and the dating of injuries of light closed encephalon injury. METHODS: Wistar rats were hurt by fluid percussion, and were killed respectively at 15 min, 30 min, 1 h, 3 h, 6 h, 12 h, 1 d, 4 d, 7 d, and 14 d after injury. The expression of Fas in the cerebral cortex, thalamus, and hippocampi was detected by immunohistochemistry and the results were assessed by image analysis system. RESULTS: The results showed that the expression of Fas could be detected in thirty minutes after injury, and then it increased significantly in three hours, reached apex in twelve hours after injury, decreased gradually in four days after injury, and returned to normal in 14 days after injury. CONCLUSION: This research demonstrated that Fas-mediated apoptosis appeared not only around brain trauma but also in the brain tissue far away from the traumatic area. It indicted that Fas expression is a useful target for diagnosis of early brain injury and the regularity of Fas expression could be used as one of indications in deducing the time of brain injury.

Animals↗
PubMed2005

[Screening of HBeAgTP interacting proteins in hepatocytes with yeast-two hybrid technique].

OBJECTIVE: To screen proteins in hepatocytes interacting with HBeAg transactivated protein (HBeAgTP) with yeast-two hybrid technique for investigating the biological functions of HBeAgTP. METHODS: Suppression subtractive hybridization (SSH) and bioinformatics techniques were used for screening and cloning of the target genes transactivated by HBeAg. The HBeAgTP gene was amplified by polymerase chain reaction (PCR) and HBeAgTP bait plasmid was constructed with yeast-two hybrid system 3, and then transformed into yeast AH109. The transformed yeast mated with yeast Y187 containing liver cDNA library plasmid in 2 x YPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing X-gal for selecting two times and screening. After extracting and sequencing of plasmid from blue colonies, the results were analyzed by bioinformatics. RESULTS: HBeAgTP gene was successfully cloned and expressed in yeast cells. Fifteen genes in twenty-four positive colonies were obtained using yeast-two hybrid technique. CONCLUSION: HBeAgTP conjugated protein genes were successfully cloned, along with the genes involved in transcription and translation of proteins, immunoloregulation, materials and energy metabolism in vivo.

Hepatitis B e Antigens↗
PubMed2005

[Random amplified polymorphic DNA analysis of tomato from seeds carried in Russian Mir space station].

OBJECTIVE: To identify the variation of hereditary substance of tomato offspring from seeds under long-duration spaceflight condition. METHOD: The tomato seeds carried in Russian MIR space station for six years, and the ground-based control were planted on the ground. The leaves of plants were used to do random amplified polymorphic DNA (RAPD) analysis. RESULT: Forty random primers were used in this study, among which 31 primers generated the same DNA band type, and 9 primers generated different DNA band types. Forty primers amplified 269 DNA bands, among which 29 DNA bands were polymorphic ones with a percentage of polymorphism of 10.8%. Compared with the control, plants from seeds carried in space station generated different band types. Band types were different among five plants from seeds carried in space station. The number of polymorphic bands generated by plant No. 5 compared with the control was the most, and that by plant No. 2 was the least. CONCLUSION: Long-duration spaceflight can cause variation of hereditary substance DNA of tomato.

DNA, Plant↗
PubMed2005

[Forensic applications of the sequencing of mitochondrial DNA cytochrome oxidase subunit I gene for sarcosaphagous flies (Diptera) in Huhhot and Dunhuang district].

OBJECTIVE: To solve the problems of identification of Sarcosaphagous flies and their larvae, pupas and eggs. METHODS: Sarcosaphagous Flies (Diptera) Samples were collected on the corpses of rabbits in the Huhhot district and a pig in the Dunhuang district. A 278bp region in the cytochrome oxidase subunit I (CO I) gene in mtDNA was analysed by DNA sequencing, A neighbour-joining tree using the Tamura and Nei model of nucleotide substitution was also constructed using the MEGA2.1 package. RESULTS: A 278 base pairs region of the gene for CO I encoding region of mtDNA of above all samples was showed less than 1% sequence divergence within species and about 3% divergence between species. CONCLUSION: It is an effective, easy and accurate method to be used for identification of these Sarcosaphagous Flies (Diptera) to species group by sequencing the 278 base pairs region of the CO I encoding gene of mtDNA.

Animals↗