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Biomedical subjects

Min Liu

Publications and source records attributed to Min Liu.

At least 145 records · Page 8Linked to original sources
PubMed2004

[Expression of hMSH2 and hMLH1 in stomach cancer and their correlation with Helicobacter pylori infection].

BACKGROUND & OBJECTIVE: The carcinogenesis of gastric carcinoma is related to many factors. Helicobacter pylori (HP) infection is one of the factors causing gastric carcinoma, but the exact molecular mechanism is not clear. Mismatch repair genes are important in keeping the accuracy of DNA replication. They are associated with carcinogenesis of alimentary canal. In order to investigate the role of hMSH2 and hMLH1 in stomach cancer and the possible mechanism of carcinogenesis caused by HP infection, we tested cancer tissue, surrounding mucosa and chronic superficial gastritic mucosa with and without HP infection. METHODS: HP infection was determined with quick-ureolytase method. Immunohistochemistry staining was used to exam the expression of hMSH2 and hMLH1 in tumor tissue and their surrounding mucosa and gastric mucosa. Chi-square was used for statistic analysis. RESULTS: The positive rate (67.1%) of hMSH2 expression in cancer tissue was significantly higher than those of surrounding mucosa (35.5%) and gastritic mucosa (42.1%) (P< 0.05); the positive rate (81.1%) of hMSH2 expression in poor differentiation group was significantly higher than those in well middle differentiation group (54.5%) and mucoid carcinoma group (54.5%) (P< 0.05), but there was no significant difference between the latter two groups. There was no significant difference among the positive rates of hMLH1 expression in cancer tissue (81.6%), in surrounding mucosa (90.8%), and in gastritic mucosa (89.5%) (P>0.05). The positive rate (47.1%) of hMLH1 expression in mucoid carcinoma group was significantly higher than those in well middle differentiation group (81.8%) and poor differentiation group (97.3%) (P< 0.05), but there was no significant difference between the latter two groups (P>0.05). In cancer tissue, the positive rate (56.8%) of hMSH2 expression in HP infection group was significantly lower than that without HP infection group (81.3%) (P< 0.05); the positive rates of hMLH1 expression was 77.2% in HP infection group and 87.5% in without HP infection group, but there was no significant difference between two groups (P >0.05). In surrounding mucosa, the positive rate of hMSH2 expression was 29.5% in HP infection group and 43.8% in without HP infection group, as well as those of hMLH1 were 86.4% and 96.9%, there were no significant differences between the groups. In gastritic mucosa, the positive rate of hMSH2 expression was 38.5% in HP infection group and 50.5% in HP-negative group, as well as those of hMLH1 were 88.5% and 91.7%; there was no significant difference between the groups. CONCLUSION: The expression of hMSH2 is associated with carcinogenesis of stomach cancer, and its high expression may be a potential marker of stomach cancer; HP infection inducing low expression of hMSH2 and hMLH1 may be one of molecular mechanisms by which HP infection leads to stomach cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Production of human liver prolidase by Saccharomyces cerevisiae as host cells.

AIM: To clone and express the recombinant human liver prolidase in yeast and explore the activities of both dipeptidase and organophosphoric acid anhydrolase (OPAA). METHODS: The cDNA encoding human liver prolidase derived from healthy adult liver was cloned into the pYES2, an expression vector of S cerevisiae, and then transformed into S cerevisiae INVSc1 by electroporation. The transformant with the highest enzymatic activity was induced by galactose for expression. The optimal induction conditions (temperature, induction time, and the initial amount of inoculation cells) were estimated by orthogonal experimental design. The recombinant prolidase and OPAA activities were assayed by spectrocolorimetric methods. RESULTS: The recombinant enzyme catalyzed the hydrolysis of organophosphorous compound soman as well as the hydrolysis of dipeptide Gly-Pro. Under the optimal induction conditions (20 h, 25 degree, initial OD(600)=0.4), the maximum activities of prolidase and OPAA came to 226.5 and 578 micromol.min(-1).g(-1) protein in cell lysate supernatants, respectively. SDS-PAGE of the recombinant enzyme in disrupted cell supernatants showed a molecular weight of 56 kDa. Intensity scanning of the SDS-PAGE gel revealed that the enzyme accounted for 3.16 % of the total protein in the supernatant. One liter incubation medium produced 7 g of wet yeast cell containing 4.56 mg of the recombination protein. CONCLUSION: The recombinant human liver prolidase produced by yeast cell (S cerevisiae) exhibited both dipeptidase and OPAA activities.

Adult↗
PubMed2004

Conversion regular patterns of acetic acid, propionic acid and butyric acid in UASB reactor.

On the basis of continuous tests and batch tests, conversion regular patterns of acetate, propionate and butyrate in activated sludge at different heights of the UASB reactor were conducted. Results indicated that the conversion capacity of the microbe is decided by the substrate characteristic when sole VFA is used as the only substrate. But when mixed substrates are used, the conversion regulations would have changed accordingly. Relationships of different substrates vary according to their locations. In the whole reactor, propionate's conversion is restrained by acetate and butyrate of high concentration. On the top and at the bottom of the reactor, conversion of acetate, but butyrate, is restrained by propionate. And in the midst, acetate's conversion is accelerated by propionate while that of butyrate is restrained. It is proved, based on the analysis of specific conversion rate, that the space distribution of the microbe is the main factor that affects substrates' conversion. The ethanol-type fermentation of the acidogenic-phase is the optimal acid-type fermentation for the two-phase anaerobic process.

Acetic Acid↗
PubMed2004

[Effect of Fe and Fe2+ on hydrogen production capacity with mixed culture].

The effects of Fe and Fe2+ concentration in the external environment on hydrogen production capacity of ethanol-type fermentative microorganism flora were investigated. The optimum range of Fe and Fe2+ concentration enhanced hydrogen production were obtained and the characteristic of fermentation types at different concentration of Fe and Fe2+ were discussed. It was demonstrated that both Fe and Fe2+ were able to enhance the hydrogen production capacity of microorganism flora. The maximum hydrogen production yield of 143.7mL x g(-1) glucose and the maximum specific hydrogen production rate 21.2mL x (h x g)(-1) were obtained at Fe2+ concentration of 200mg x L(-1) and 50mg x L(-1). The maximum hydrogen production yield of 156.1mL x g(-1) glucose and the maximum specific hydrogen production rate 23.5mL x (h x g)(-1) were obtained at Fe concentration of 1000mg x L(-1) and 500mg x L(-1). At the same concentration, the enhancement of Fe is better than Fe2+ when the concentration is higher than 50 mg x L(-1). A sequential extraction technique was used to represent arbitrary divisions between different metal forms of Fe2+ in the mixed culture.

Bacteria↗
PubMed2004

[A study on expression of hsp70 mRNA in the early stage of diffuse brain injury in rats].

OBJECTIVE: To evaluate the changes of hsp70 mRNA in neuron and glia of rat suffering early diffuse brain injury. METHODS: SD rats were used in the replication of the animal pattern of diffuse brain injury. In situ hybridization technique and image analysis technique were applied in detecting the hsp70 mRNA in the rat's cerebral cortex, thalamus and brain stem. RESULTS: The signal intensity of hsp70 mRNA could be detected in 5 minutes after brain injury; subsequently, it attained to the summit at 6 hours and declined at 12 hours after brain injury. CONCLUSION: The above data suggest that hsp70 mRNA is useful for the diagnosis of early diffuse brain injury and for distinguishing the postmortem injury from antemortem injury.

Animals↗
PubMed2004

[Anaerobic fermentation biohydrogen production from molasses, starch and milk wastewaters].

Research of anaerobic fermentation biohydrogen production from molasses, starch and milk wastewater in CSTR was conducted. The theoretic possibility of biohydrogen production from three kinds of organic materials and the hydrogen producing stability was also discussed. The results indicated that molasses and starch wastewaters are preferable feeds for anaerobic biohydrogen fermentation. The hydrocarbon is the optimal feed in the main three kinds of organic materials at present time. The sugars which dissolving better are preferable materials for biohydogen production than starch at present, but the starch is better than sugars for biohydrogen production in the future if the conditions could been controlled good. The niches are variety along with the different of feeds. The optimal pH values of stability operational controlling is 4.5 +/- 0.3 for sugars wastewater and 4.0 +/- 0.2 for starch wastewater. The ORP value must lower than -220 mV and the optimal value is about -300 mV. The milk wastewater is not the suitable biohydrogen production material in CST reactor.

Animals↗
PubMed2004

[Differentially expressed genes in prostate cancer and benign prostatic hyperplasia].

OBJECTIVE: To detect and analyze the differentially expressed genes in prostate cancer (PCa) and benign prostatic hyperplasia (BPH). METHODS: Oligonucleotide microarray containing 465 genes was used to investigate the differentially expressed genes in PCa and BPH. RESULTS: There were 35 differentially expressed genes between PCa and BPH, of which 17 were up-regulated and 18 down-regulated in PCa. CONCLUSION: The study of the differentially expressed genes in PCa and BPH should help to understand the molecular mechanism of PCa and identify the markers for diagnostic and therapeutic use.

Down-Regulation↗
PubMed2004

[A study of the expression of Fas after fluid percussion brain injury in rats].

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

Animals↗
PubMed2004

[Effect of nutrient on sludge settling property and bulking controls].

The effect of nutrient (N and P) deficiency on activated sludge settleability and characteristics of activated sludge flocs in Sequencing Batch Reactor (SBR) fed with brewery wastewater were investigated. The results showed that the activated sludge had good settling properties at influent BOD5/N/P was 100/5/1,100/5/0.8 and 100/4/0.8 respectively. When BOD5/N/P was 100/0.94/0.31,100/2/0.4,100/3/0.6 respectively, the sludge settleability became worse due to excessive growth of filamentous. When BOD5/N/P was 100/0.94/1,100/5/0.31,100/5/0.4,100/5/0.6 respectively, non-filamentous activated sludge bulking occurred. Adding sufficient nutrient to the influent, the sludge bulking was controlled effectively and the low SVI was recovered. When increasing COD loading rate, the duration of recovery could be diminished. When nitrogen and phosphorus were insufficient synchronously, aerobic granular sludge was formed which was averagely 2mm-6mm in diameter.

Bacteria, Aerobic↗
PubMed2004

[Polychlorinated biphenyls and organochlorine pesticides in animals from the Yangtze River Estuary and coastal areas].

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the animals of the Yangtze estuarine and coastal areas were determined with GC-ECD. The results showed that the concentration distribution of PCBs ranged from 43.7 to 1260.4 ng/g, with an average value of 342.5 ng/g; 1.5-159.4 ng/g and 33.7 ng/g for DDTs; 0.9-77.0 ng/g and 13.0 ng/g for HCHs. The spatial distribution patterns of different contaminants in the same animal species and the same pollutant in the different animal species didn't follow obvious laws. Whereas, animals of the same species were characterized by higher contamination levels for males than females, and the small individuals than large ones. Compared with other areas at home and abroad and low-high level limits, a preliminary assessment was presented. As a result, it was shown that there existed a moderate level, to some extent, with the contamination in the animals from the study area.

Animals↗
PubMed2004

[Influence of different doxorubicin-salt aggregates on the leakage of liposomal doxorubicin in vitro and long circulation in vivo].

AIM: To develop liposomes containing doxorubicin with different salts and to investigate their influence on the stability of liposomal doxorubicin in vitro and in vivo. METHODS: Liposomes were prepared by the film method, treated further by extruded through nuclear membrane. The entrapment efficiency was determined by column chromatography. In vitro drug release experiments were carried out with a dialysis bag (Mw cut-off 12000 - 14000). Reverse-phase HPLC was used to study the pharmacokinetics of liposomal doxorubicin. RESULTS: The particle size of liposomes with glycinate buffer, citrate buffer and ammonium sulfate as the inner water phase were (103 +/- 8), (102 +/- 12) and (97 +/- 8) nm. The zeta potential and the encapsulation ratio were (-21.3 +/- 0.5), (-21.7 +/- 0.4), (-20.9 +/- 0.7) mV and 47.8%, 96.7%, 98.6%, respectively. The leaking rate of doxorubicin from liposomes was related to the pH value of the release medium. The leaking rate increased at lowered pH. Pharmacokinetic study showed that the MRT (mean retention time) of liposomes with glycinate buffer, citrate buffer and ammonium sulfate as the inner water phase were 12.13, 23.31 and 29.79 h, respectively. CONCLUSION: Doxorubicin showed different stability in liposomes with different inner water phases, the weaker the acid in the inner water phase, the stabler the liposome.

Ammonium Sulfate↗
PubMed2003

Hole transfer in a C-shaped molecule: conformational freedom versus solvent-mediated coupling.

The electronic coupling matrix elements attending the charge separation reactions of a C-shaped molecule containing an excited pyrene as the electron acceptor and a dimethylaniline as the donor are determined in aromatic, ether, and ester solvents. Band shape analyses of the charge-transfer emission spectra (CT --> S(0)) provide values of the reaction free energy, the solvent reorganization energy, and the vibrational reorganization energy in each solvent. The free energy for charge separation in benzene and toluene solvents is independently determined from the excited state equilibrium established between the locally excited pyrene S(1) state and the charge-transfer state. Analyses of the charge separation kinetics using the spectroscopically determined reorganization energies and reaction free energies indicate that the electronic coupling is solvent independent, despite the presence of a cleft between the donor and acceptor. Hence, solvent molecules are not involved in the coupling pathway. The orientations of the donor and acceptor units, relative to the spacer, are not rigidly constrained, and their torsional motions decrease solvent access to the cleft. Generalized Mulliken-Hush calculations show that rotation of the pyrene group about the bond connecting it to the spacer greatly modulates the magnitude of through-space coupling between the S(1) and CT states. The relationship between the torsional dynamics and the electron-transfer dynamics is discussed.

Journal Article↗
PubMed2003

Biochemical heterogeneity, migration, and pre-fertilization release of mouse oocyte cortical granules.

BACKGROUND: Oocyte cortical granules are important in the fertilization of numerous species including mammals. Relatively little is known about the composition, migration, and pre-fertilization release of mammalian oocyte cortical granules. RESULTS: Results obtained with confocal scanning laser microscopy indicated that mouse oocytes have at least two populations of cortical granules, one that bound both the lectin LCA and the antibody ABL2 and one that bound only LCA. Both types of granules were synthesized at the same time during oocyte maturation suggesting that the ABL2 antigen is targeted to specific granules by a sorting sequence. The distribution of both populations of cortical granules was then studied during the germinal vesicle to metaphase II transition. As the oocytes entered metaphase I, the first cortical granule free domain, which was devoid of both populations of cortical granules, formed over the spindle. During first polar body extrusion, a subpopulation of LCA-binding granules became concentrated in the cleavage furrow and underwent exocytosis prior to fertilization. Granules that bound ABL2 were not exocytosed at this time. Much of the LCA-binding exudate from the release at the cleavage furrow was retained in the perivitelline space near the region of exocytosis and was deduced to contain at least three polypeptides with approximate molecular weights of 90, 62, and 56 kDa. A second cortical granule free domain developed following pre-fertilization exocytosis and subsequently continued to increase in area as both, LCA and LCA/ ABL2-binding granules near the spindle became redistributed toward the equator of the oocyte. The pre-fertilization release of cortical granules did not affect binding of sperm to the overlying zona pellucida. CONCLUSIONS: Our data show that mouse oocytes contain at least two populations of cortical granules and that a subset of LCA-binding cortical granules is released at a specific time (during extrusion of the first polar body) and place (around the cleavage furrow) prior to fertilization. The observations indicate that the functions of the cortical granules are more complex than previously realized and include events occurring prior to gamete membrane fusion.

Animals↗
PubMed2003

Neuropeptide Y and lipid increase apolipoprotein AIV gene expression in rat hypothalamus.

Apolipoprotein AIV (apo AIV) is a circulating signal released from intestinal cells in response to lipid feeding and contributes to the anorectic effect of a lipid meal. We have demonstrated that apo AIV is also synthesized in the hypothalamus, and that hypothalamic apo AIV gene expression is regulated physiologically. Neuropeptide Y (NPY) is a hypothalamic neuropeptide with broad regulatory actions in the central nervous system. In the present studies, the effects of intracerebroventricular (i.v.t.) administration of NPY and of intraduodenal lipid infusion on hypothalamic apo AIV gene expression were determined using competitive RT-PCR in fasted rats. I.v.t. injection of NPY alone significantly increased apo AIV mRNA levels in the hypothalamus in a dose-dependent manner. Intraduodenal infusion of lipid also stimulated the gene expression of hypothalamic apo AIV, but no further significant increment occurred when i.v.t. injection of NPY was combined with lipid infusion. These results suggest that NPY and lipid may regulate apo AIV gene expression in the rat hypothalamus.

Analysis of Variance↗
PubMed2003

Synthesis of twist-twist pi-conjugated di-sec-alkylstilbenes and stilbene polymers.

Twist-twist pi-conjugated (TTPC) pi systems promise unique properties with their 90 degrees twist angles. Di-sec-alkyl substituted stilbenes, 5, were prepared by low-valent titanium coupling of phenyl ketones, 4. Long alkyl chains stopped the coupling reaction. Stilbenes 5 were shown to be approximately 90% TTPC. Inserting TTPC units into poly(p-phenylene) polymers created highly fluorescent, soluble, TTPC pi systems with weak electronic segmentation for organic light emitting diode (OLED) studies.

Journal Article↗
PubMed2003

Systematic development and validation of stability indicating micellar electrokinetic chromatography methods for early stage drug candidates.

Suitable methods for assessment of purity, potency and stability of new drug substances and drug products are required to be rapidly developed and validated to provide appropriate data for early project development decisions. In order to routinely provide methods of consistent and suitable quality to meet increasingly aggressive timelines, systematic approaches to both develop and validate analytical technologies have been developed. Systematic approaches to evaluate separation parameters such as buffer pH, buffer ionic strength, surfactant concentration, organic modifiers, organic modifier concentration, applied voltage and temperature were evaluated for an early stage drug candidate. Techniques to improve method precision and ruggedness were also examined. Finally, the validation results from the micellar electrokinetic chromatography method utilizing an internal standard were compared against the simultaneously developed high-performance liquid chromatography method.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2003

Peptide-bond modification for metal coordination: peptides containing two hydroxamate groups.

Peptide-bond modification via N-hydroxylation has been explored as a strategy for metal coordination to induce conformational rigidity and orient side chains for specific molecular recognition. N-Hydroxyamides were prepared by reacting N-benzyloxyamino acid esters or amides with Fmoc-AA-Cl/AgCN (Fmoc: 9-fluorenylmethoxycarbonyl; AA: amino acid) in toluene or Fmoc-AA/HATU/DIEA in DMF (HATU: O-(7-azabenzotriazol-lyl)-1,1,3,3-tetramethyluronium hexafluorophosphate; DIEA: N,N-diisopropylethylamine; DMF: N,N-dimethylformamide), followed by deblocking of benzyl protecting groups. Novel linear and cyclic N,N'-dihydroxypeptides were efficiently assembled using Fmoc chemistry in solution and/or on a solid support. As screened by electrospray ionization-mass spectroscopy (ESI-MS), high iron-binding selectivity and affinity were attainable. Compounds having a spacer of two alpha-amino acids between the amino acids bearing the two hydroxamates, i.e., a spacer of 8 atoms, generated 1:1 iron complex species in the gas phase. Moreover, high performance liquid chromatography (HPLC), uv/vis, and (1)H-NMR analyses provided direct evidence for complex formations in solution. Significantly, the representative compound cyclo(Leu-Psi[CON(OH)]-Phe-Ala-Pro)(2) (P8) may serve as a robust metal-binding scaffold in construction of a metal-binding library for versatile metal-mediated molecular recognition.

Chromatography, High Pressure Liquid↗