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Biomedical subjects

Yun Gao

Publications and source records attributed to Yun Gao.

28 records · Page 2Linked to original sources
PubMed2004

[Analysis of volatile fragrant components in hawthorn tincture by gas chromatography-mass spectrometry].

The volatile fragrant components in hawthorn tincture were analyzed by GC/MS. 38 components were identified. The relative content of these constituents were determined with area mormalizing method and the identification ratio was 97.19%. The main components were 3-Hexen-1-ol(370.59 micrograms/g), Eugenol(320.95 micrograms/g), Butanedioic acid hydroxy, diethyl ester(191.25 micrograms/g), 2-Methyl-pentenoic acid(164.83 micrograms/g) and citric acid(80.87 micrograms/g) etc. The method is simple, rapid and highly sensitive and suitable for routine analysis and quality control.

Crataegus↗
PubMed2004

[Chromosome aberration analysis of peripheral lymphocytes in workers exposed to benzene].

OBJECTIVE: To study the effects of benzene exposure on chromosome aberration of peripheral lymphocytes in workers. METHODS: Measure the benzene concentration with 3M passive dosimetry badges and analyze chromosome aberrations of peripheral lymphocytes using non-banding method. RESULTS: The numerically aberrated cell rate of the workers exposed by benzene [13.00% (2.50%-21.00%)] was significantly higher than that of the controls [10.50% (3.50%-18.00%)] (P < 0.05), and the aberrated cell rate (excluded gaps) [14.50% (5.00%-23.50%)] was significantly higher than that of the controls [11.75(3.50-18.00)] (P < 0.05), too; the P values of the dose-effect relationships between hyperploidy cell rate, numerically aberrated cell rate and aberrated cell rate (excluded gaps) and 8 h-TWA were 0.0008, 0.3741 and 0.2816, respectively, and the P values of the dose-effect relationships between those and the cumulative exposure were 0.0009, 0.0376 and 0.0486, respectively; the premature centromere division cell rate of the benzene-exposed workers [1.75% (0-19.50%)] was not significantly higher than that of the controls [1.00% (0-15.00%)] (P > 0.05). CONCLUSION: Benzene exposure resulted in an increase of chromosome aberrations of the peripheral lymphocytes, which was in a dose-effect relationship manner; whether benzene exposure could induce premature centromere division deserves further studies.

Adult↗
PubMed2004

[Construction of recombinant expression vector and prokaryotic expression of human epididymal sperm protein P34H].

OBJECTIVE: To acquire purified recombinant human epididymal sperm protein P34H for basic and clinical studies. METHODS: On the basis of cloning of P34H coding region, P34H fragment was subcloned into the pQE-30 expression vector. The recombinant expression vector designated pQE-30/P34H was transformed into E. coli to induce the expression of the recombinant protein P34H on the reduction of IPTG. After sonication, the recombinant protein P34H was purified from the supernatant with Ni-NTA resin under native conditions. It was identified by SDS-PAGE analysis and DNA sequencing. RESULTS: Recombinant expression vector pQE-30/P34H was correctly constructed, identified with PCR and double-enzyme digestion. And the results of SDS-PAGE analysis and DNA sequencing showed that the protein was what we had hoped to acquire. CONCLUSION: Purified recombinant P34H can be acquired successfully with the above mentioned prokaryotic expression method.

Cloning, Molecular↗
PubMed2003

[Molecular cloning of human sperm surface protein P34H gene and semi-quantitative analysis of its expression in testis and epididymidis].

OBJECTIVES: To identify, clone and sequence human sperm protein P34H gene and perform semi-quantitative analysis of its expression in testis and epididymidis. METHODS: Total RNA was prepared from human epididymidis tissue. cDNA fragment encoding human P34H was amplified by RT-PCR using specific primers, and then was cloned into pGEM-T vector. Inserted P34H gene was sequenced by ABI 377 DNA Sequencer. Meanwhile, semi-quantitative analysis of P34H expression in testis and caput, corpus, cauda epididymidis was done by RT-PCR based on beta-actin as an inner control. RESULTS: Human sperm protein P34H gene was successfully cloned and its cDNA sequence was submitted to GenBank(Accession No. AF515625). CONCLUSIONS: The cloning of P34H gene may be useful for the further basic and clinical studies on P34H.

Base Sequence↗
PubMed2003

[Cloning and eukaryotic expression of human lipocalin-type prostaglandin D synthase in Pichia Pastoris].

OBJECTIVES: To express human testis Lipocalin-type prostaglandin D synthase in Pichia Pastoris for further research on biological function and clinical applications. METHODS: Human testis L-PGDS gene coding region was amplified from plasmid pGEX-2T/htL-PGDS by PCR with a deletion of the signal peptide sequence. The DNA fragment was inserted into pPIC9 to construct yeast expression plasmid followed by transformation of the yeast GS115 strain with electroporation. The recombinant his-tag protein was induced to express by methanol. RESULTS: The sequence of the amplified DNA fragment was identical to that of human testis L-PGDS previously reported. The recombinant protein was found with a molecular mass of 27,000 on SDS-PAGE, which was identical to that of native L-PGDS. CONCLUSIONS: Secretory expression of human L-PGDS was obtained in Pichia Pastoris.

Cloning, Molecular↗
PubMed2002

Lack of synergy for inhibitors targeting a multi-drug-resistant HIV-1 protease.

The three-dimensional structures of indinavir and three newly synthesized indinavir analogs in complex with a multi-drug-resistant variant (L63P, V82T, I84V) of HIV-1 protease were determined to approximately 2.2 A resolution. Two of the three analogs have only a single modification of indinavir, and their binding affinities to the variant HIV-1 protease are enhanced over that of indinavir. However, when both modifications were combined into a single compound, the binding affinity to the protease variant was reduced. On close examination, the structural rearrangements in the protease that occur in the tightest binding inhibitor complex are mutually exclusive with the structural rearrangements seen in the second tightest inhibitor complex. This occurs as adaptations in the S1 pocket of one monomer propagate through the dimer and affect the conformation of the S1 loop near P81 of the other monomer. Therefore, structural rearrangements that occur within the protease when it binds to an inhibitor with a single modification must be accounted for in the design of inhibitors with multiple modifications. This consideration is necessary to develop inhibitors that bind sufficiently tightly to drug-resistant variants of HIV-1 protease to potentially become the next generation of therapeutic agents.

Anti-HIV Agents↗
PubMed2002

[Advances in eukaryotic expression systems].

The increasing popularity of eukaryotic expression systems can be attributed to their capability of performing many post-translational modifications. At present, There mainly are three expression systems including yeast expression system, insect cell expression system and mammalian cell expression system. The methylotropic yeast Pichia Pastoris usually utilizes alcohol oxidase promoter to drive the expression of foreign gene. Recently, a continuous fermentation has been developed in Pichia Pastoris with the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. The baculovirus-mediated insect cell expression system is considered to be safe, powerful, but cell-lytic. Baculovirus-S2 system uses the popular and genetically well understood Drosphila S2 cells which do not appear to be lysed after infection. In mammalian cell expression system, recombinant adenovirus are attracting a great deal of attention as a highly efficient gene transfer vehicle. The frequency of Ad vector rescue by homologous recombination in E. coli and Cre-mediated site-specific recombination is significantly higher than by homologous recombination in vivo. Tetracycline-regulatable system is a widely used mammalian cell inducible expression system due to its high efficiency and stringency.

Adenoviridae↗
PubMedDate not supplied

Molecularly imprinted polymer for monocrotophos and its binding characteristics for organophosphorus pesticides.

In this study, molecular imprinting was used to develop a method based on noncovalent interaction for the synthesis of a monocrotophos-specific polymer. The selective binding characteristics of the template polymer were evaluated by 1H NMR study. The result was consistent with the existence of multi-molecular complexes formed by hydrogen-bonding interactions. Batch rebinding studies in acetonitrile were undertaken to quantitatively evaluate the affinity of the polymer for monocrotophos. The experimental binding isotherms were fitted to the Freundlich isotherm and the total number of binding sites of the polymer can be calculated to be 4.046 micromol g(-1). The induced affinity and selectivity by imprinting were examined chromatographically. The polymer gave more than 15 times longer retention for monocrotophos than the nonimprinted polymer with the same chemical composition. Other organophosphorus pesticides under study were eluted close to the void volume on the polymer column.

Environmental Monitoring↗
PubMedDate not supplied

Two-step simultaneous distillation and solvent extraction for isolation both free and bound aroma in tobacco.

In this investigation, a novel two-step simultaneous distillation and solvent extraction (two-step SDE) method was developed to isolate both free and bound aroma in tobacco. Firstly, free aroma were extracted into dichloromethane by SDE for 4 h with SDE sample solution at pH 5.5. Then the SDE sample solution was adjusted to pH 2.5, bound aroma were hydrolyzed, and released as free aroma extracted by fresh dichloromethane. Following, both the free and bound aroma were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The whole isolation procedure of both free and bound aroma was carried out in one SDE apparatus and using one same sample. Especially, the procedure of isolation of bound aroma was greatly simplified. To apply and validate the proposed two-step SDE method, a traditional method were also used to isolate the bound aroma. The total bound aroma obtained by the proposed two-step SDE method and the traditional method were 119.83 mg kg(-1) and 88.9 mg kg(-1), respectively. For isolation of bound aroma, the proposed two-step SDE method was of better extraction recovery, less labourious, solvent and time consuming than the traditional method.

Chromatography, Gas↗