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Biomedical subjects

Jun Liu

Publications and source records attributed to Jun Liu.

At least 325 records · Page 18Linked to original sources
PubMed2003

Isolation of resistance related-genes to Phytophthora infestans with suppression subtractive hybridization in the R-gene-free potato.

Suppression subtractive hybridization (SSH) was applied in the search of the genes induced during the interaction between Phytophthora infestans and horizontal resistance potato (R-gene-free). A subtractive library of potato, which highly enriches for resistance-related genes to P. infestans, was constructed. The potato leaves after inoculating 48 h with mixture of P. infestans races were used as "tester" and uninoculated leaves as "control" in the experiments. Total 150 of 840 randomly chosen cDNA clones were identified with the reveres Northern dot-blot screening method. The sequencing results of 26 clones indicated that several fragments were previously shown to be activated during resistance responses. Seven differentially expressed fragments had significant homologous with EST of potato leaves inoculated with P. infestans. The sequences of nucleotide or amino acids of partial cDNA fragments shared identity with tomato, tobacco and Arabidopsis while four cDNA fragments that had no significant homology with EST in GenBank were expected to be new genes involved in the disease response.

Blotting, Northern↗
PubMed2003

[An experimental study of the effects of profenofos on antioxidase in rabbits].

In order to explore the effects of superoxide dismutase(SOD), catalase(CAT), glutathione-peroxidase (GSH-Px) in rabbits exposed by profenofos and its meaning. 18 rabbits were divided into three groups randomly: A group (high-dose group), B group(low-dose group), C group(control group), each group including 6 rabbits. The activities of SOD, CAT, GSH-Px in plasma, and cholinesterase(ChE) in blood were measured in different exposure period. The results showed that activities of SOD, CAT and GSH-Px increased, ChE decreased markedly compared with those in the same group before experiment and control group (P < 0.05, P < 0.01). The increase of antioxidase activities was earlier than the decease of ChE activity. It suggests that profenofos can result in the increases of the activities of SOD, CAT and GSH-Px, which may be earlier diagnostic index in profenofos poisoning.

Animals↗
PubMed2003

[Synthesis and in vitro antibacterial activities of new 3,5-disubstituted oxazolidinone compounds].

AIM: To design and synthesize new oxazolidinone antibacterial agents. METHODS: The synthetic method reported in literature has been modified and new 3,5-disubstituted oxazolidinone compounds were synthesized on the basis of SAR reported in the literature and their antibacterial activities in vitro were determined. RESULTS: Eighteen new objective compounds were synthesized, and their structures were determined by IR, 1HNMR and FAB-MS. Within the eighteen new objective compounds, sixteen compounds showed antibacterial activity in vitro and compound 9, 10 and 10b showed better antibacterial activities in vitro than ciprofloxacin (CIP), sultamicillin (Sul) and vancomycin (VCO). Compounds 9a and 11c have no antibacterial activity in vitro at all. CONCLUSION: Compounds 9, 10 and 10b are worthy to be intensively studied.

Ampicillin↗
PubMed2003

[Reproductive biology of Macrobrachium nipponensis in Lake Wuhu].

Macrobrachium nipponensis is a key species of freshwater shrimps in China. To know its reproductive biology is very important for its protection and rational use. Studies from September 1998 to September 1999 in LakeWuhu showed that the spawning ground of M. nipponensis was situated in the littoral zone of the whole lake. The main spawning period of overwintering shrimps was from mid-April to mid-July (water temperature 20.5-31 degrees C), and that of non-overwintering shrimps was from mid-July to mid-September (water temperature 31-23 degrees C). The sex ratio (female:male) increased gradually during the spawning period, and the absolute fecundity of overwintering shrimps was higher than that of non-overwintering ones. The relationship between absolute fecundity and body length and between absolute fecundity and body weight could be expressed as cubic equation and simple linear equation, respectively. The relative fecundity (RW) of M. nipponnensis could regard as a constant, and its 95% confidence limits was 1067.76 +/- 16.94 eggs.g-1.

Animals↗
PubMed2003

[Relationship between the patients' knowledge on hypertension prevention and control and the rate on blood pressure control].

OBJECTIVE: To study the relationship between blood pressure control status and patients' knowledge on hypertension prevention and control among hypertensive patients. METHODS: A total of 726 hypertensives were selected from four community health service centers (2 urban and 2 rural) in Beijing. All subjects were investigated by questionnaires and their blood pressures were measured at the same time. RESULTS: The rate for blood pressure under control (< 140/90 mm Hg, 1 mm Hg = 0.133 kPa) in the rural and urban patients were 46.4% and 23.9% respectively. The control rate increased with the increase of patients' knowledge on prevention and control of hypertension in both urban and rural patients. The cumulative effect of knowledge on hypertension control status could contribute 30.0% to the difference in hypertension control rate between rural and urban patients. CONCLUSION: Patients' knowledge on hypertension control was significantly related to the rate on hypertension control. Health education should be helpful to improve the rate on hypertension control.

Aged↗
PubMed2003

[Mitochondrial DNA large deletions associated with presbycusis].

OBJECTIVE: By observing the relationship between the fragment deletion of mitochondrial DNA (mt DNA) of inner ear in rat and the hearing loss to investigate the possible role of mt DNA deletion in presbycusis. METHOD: Thirty wistar rats were divided into group A (young rat, 4 months, n = 15) and group B (old rat, 24-30 months, n = 15) according to the age. The threshold of the auditory brainstem response (ABR) was tested. The inner ear membranous labyrinth tissue was harvested and the mtDNA was amplified to identify 4,834 bp deletion by PCR technique. RESULT: The mean of ABR thresholds in group B (64.79 +/- 10.88 dB peSPL) was significantly higher than that in group A (40.00 +/- 4.66 dB peSPL) (P < 0.01). In group B, 9 of the 15 rats demonstrates the mtDNA 4,834 bp deletion, while no deletion was detected in group A. CONCLUSION: Deletion of mtDNA of inner ear tissue in old rat is found. The mtDNA deletion is associated with the presbycusis and may be one of the causes of presbycusis.

Aging↗
PubMed2003

[Studies on organ phytomorphology of leaves from Rehmannia glutinosa].

OBJECTIVE: To set up the fittest medium and optimum condition for leaves from Rehmannia glutinosa to form regenerated plantlets directly and to induce microtubers. METHOD: Leaves of different phases obtained from the virus-free plantlets were incubated in some kinds of media on the back side. RESULT AND CONCLUSION: The fittest medium for the formation of regenerated plantlet was MS + 6-BA 2.0 mg.L-1 and the fittest medium for the induction of microtuber was MS + 6-BA 1.0 mg.L-1 + NAA 0.5 mg.L-1. The optimum incubation temperaue was 25 degrees C and the light length was (2,000-3,000 lx) 12 h.d-1.

Culture Media↗
PubMed2003

[Construction and expression of prokaryotic expression vector for pTAT-HBV targeted ribonuclease fusion protein].

AIM: To construct Tat-HBV targeted ribonuclease fusion protein prokaryotic expression vector and express it in E.coli. METHODS: The cDNAs encoding HBV targeted ribonuclease, human eosinophil-derived neurotoxin and HBV core protein were respectively cloned into prokaryotic expression vector pTAT-HA. Recombinant plasmids were transformed into E.coli BL21(DE3) LysS, then the transformed cells were induced with IPTG. The expression of the fusion proteins were analyzed by SDS-PAGE and Western blot. RESULTS: The three recombinant plasmids were constructed and expressed after IPTG induction successfully. CONCLUSION: The obtained Tat-HBV targeted ribonuclease fusion protein has laid the foundation for using TR in therapy of HBV infection.

Eosinophil-Derived Neurotoxin↗
PubMed2003

[Progress on research of tissue culture of Rehmannia glutinosa].

OBJECTIVE: To review the development of tissue culture on Rehmannia glutinosa. METHOD: Documentaries at home and abroad were consulted. RESULT AND CONCLUSION: The tissue culture conditions of R. glutinosa were summarized and the problems of tissue culture in R. glutinosa were also pointed out.

Culture Media↗
PubMed2002

Identification and characterization of P15RS, a novel P15(INK4b) related gene on G1/S progression.

To screen genes involved in P15(INK4b) regulation during cell cycle, differential display method was applied to compare mRNAs from G(1) synchronized cells of MLIK6, which overexpressed P15(INK4b) gene, and its control MLC2. By using this approach, 15 cDNA fragments that were preferentially expressed in MLIK6 cells, but not in MLC2 cells, were screened out. A novel gene named P15RS was identified with further analysis. Combining the sequence from DD-PCR, homology analysis against EST database and RACE, a 4,404 bp complete cDNA sequence of P15RS was generated. Sequence analysis revealed that P15RS cDNA encoded a 312-amino-acid peptide containing a RAR domain that is involved in regulation of nuclear pre-mRNA, which suggests that P15RS may be a nuclear regulation protein. Genomic sequence analysis demonstrated that human P15RS gene was localized on chromosome 18q12 with seven exons and six introns. Expressing antisense P15RS in MLIK6 cells can up-regulate the expression of cyclinD1 and cyclinE. These data indicate that P15RS may act as a negative regulator in G(1) phase.

Amino Acid Sequence↗
PubMed2002

Chemical reaction in binary mixtures near the critical region: thermal decomposition of 2,2'-azobis(isobutyronitrile) in CO2/ethanol.

The effects of pressure and of the composition of the CO2/ethanol mixed solvent in the critical region on the kinetics of the decomposition of 2,2'-azobis(isobutyronitrile) (AIBN) were studied at 333.15 K. The rate constants (kd) in the mixed solvent far from the critical point and in liquid n-hexane and ethanol were also determined for comparison. It was found that kd is very sensitive to pressure in the mixed solvent near the critical point. However, in the mixed solvent outside the critical region kd is nearly independent of pressure. Interestingly, kd in the mixed solvent in the critical region can be higher than that in ethanol at the same temperature, suggesting that no significant enhancement in the reaction rate by a small pressure change in the critical region of the mixed solvent can be achieved by changing the composition of the liquid solvent in the traditional way. Transition-state theory can predict kd in the mixed solvent far from the critical point and in the liquid solvents well. However, it cannot predict kd in the mixed solvent in the critical region. The special intermolecular interaction between the solvent and the reaction species may contribute to this interesting phenomenon. This work also shows that if pure CO2 or ethanol are used as solvents, the reaction cannot be carried out in the critical region of the solvents at the desired temperature, while it can be conducted in the critical region of the mixed solvent of suitable composition, where the solvent is highly compressible.

Journal Article↗
PubMed2002

Transient mechanoactivation of neutral sphingomyelinase in caveolae to generate ceramide.

The vascular endothelium acutely autoregulates blood flow in vivo in part through unknown mechanosensing mechanisms. Here, we report the discovery of a new acute mechanotransduction pathway. Hemodynamic stressors from increased vascular flow and pressure in situ rapidly and transiently induce the activity of neutral sphingomyelinase but not that acid sphingomyelinase in a time- and flow rate-dependent manner, followed by the generation of ceramides. This acute mechanoactivation occurs directly at the luminal endothelial cell surface primarily in caveolae enriched in sphingomyelin and neutral sphingomyelinase, but not acid sphingomyelinase. Scyphostatin, which specifically blocks neutral but not acid sphingomyelinase, inhibits mechano-induced neutral sphingomyelinase activity as well as downstream activation of extracellular signal-regulated kinase 1 and 2 (ERK1 and ERK2) by increased flow in situ. We postulate a novel physiological function for neutral sphingomyelinase as a new mechanosensor initiating the ERK cascade and possibly other mechanotransduction pathways.

Animals↗
PubMed2002

Biomimetic arrays of oriented helical ZnO nanorods and columns.

Extended helical or chiral nanostructures are usually associated with biomolecules but are mostly absent in synthetic materials. Here we report the first synthesis of unusual oriented and extended helical nanostructures in synthetic ceramics. Large arrays of oriented helical ZnO nanorods and columns are formed using simple citrate ions to control the growth habits of the ZnO crystal. This novel mechanism could lead to new approaches to control the orientation, the surface area, and the defect structure of synthetic materials that are critical for practical applications. The morphology generated in the helical ZnO nanostructure shows remarkable resemblance to the growth morphology of nacreous calcium carbonate and thus may shed new light on morphology and orientation control of biominerals.

Molecular Mimicry↗
PubMed2002

Entrapping enzyme in a functionalized nanoporous support.

The enzyme organophosphorus hydrolase (OPH) was spontaneously entrapped in carboxylethyl- or aminopropyl-functionalized mesoporous silica with rigid, uniform open-pore geometry (30 nm). This approach yielded larger amounts of protein loading and much higher specific activity of the enzyme when compared to the unfunctionalized mesoporous silica and normal porous silica with the same pore size. When OPH was incubated with the functionalized mesoporous silica, protein molecules were sequestered in or excluded from the porous material, depending on electrostatic interaction with the charged functional groups. OPH entrapped in the organically functionalized nanopores showed an exceptional high immobilization efficiency of more than 200% and enhanced stability far exceeding that of the free enzyme in solution. The combination of high protein loading, high immobilization efficiency and stability is attributed to the large and uniform pore structure, and to the optimum environment introduced by the functional groups.

Aryldialkylphosphatase↗