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Biomedical subjects

L Q Huang

Publications and source records attributed to L Q Huang.

At least 19 recordsLinked to original sources
PubMed2001

Microgravimetric DNA sensor based on quartz crystal microbalance: comparison of oligonucleotide immobilization methods and the application in genetic diagnosis.

We report on the study of immobilization DNA probes onto quartz crystal oscillators by self-assembly technique to form variety types of mono- and multi-layered sensing films towards the realization of DNA diagnostic devices. A 18-mer DNA probe complementary to the site of genetic beta-thalassaemia mutations was immobilized on the electrodes of QCM by covalent bonding or electrostatic adsorption on polyelectrolyte films to form mono- or multi-layered sensing films by self-assembled process. Hybridization was induced by exposure of the QCMs immobilized with DNA probe to a test solution containing the target nucleic acid sequences. The kinetics of DNA probe immobilization and hybridization with the fabricated DNA sensors were studied via in-situ frequency changes. The characteristics of QCM sensors containing mono- or multi-layered DNA probe constructed by direct chemical bonding, avidin-biotin interaction or electrostatic adsorption on polyelectrolyte films were compared. Results indicated that the DNA sensing films fabricated by immobilization of biotinylated DNA probe to avidin provide fast sensor response and high hybridization efficiencies. The effects of ionic strength of the buffer solution and the concentration of target nucleic acid used in hybridization were also studied. The fabricated DNA biosensor was used to detect a set of real samples. We conclude that the microgravimetric DNA sensor with its direct detection of amplified products provide a rapid, low cost and convenient diagnostic method for genetic disease.

Biosensing Techniques↗
PubMed2001

[A preliminary study on relationship between Atractylodes lancea and A. chinensis as analyzed by RAPD].

OBJECTIVE: To study the relationship between A. lancea and A. chinensis by RAPD analysis. METHOD: Using 10 random primers, RAPD of seven Atractylodes samples was performed. The result was analyzed by RAPDistance Package Version 1.04. RESULT: A total of 60 polymerphic loci were amplified. It appears that the Atractylodes samples tend to cluster in relation to their habitats, and A. lancea has close phylogenetic relationship with A. japonica. CONCLUSION: A certain correlation among the chemical composition, genetic diversity and geographic distribution has been revealed. It is reasonable to separate A. lancea from A. chinensis according to their habitats.

Atractylodes↗
PubMed2001

[Studies on quality specification standards for Saposhnicovia divaricata (Turcz.) Schischk].

OBJECTIVE: To work out a qualitative-quantitative standard for Saposhnikovia divaricata. METHOD: TLC and HPLC were adopted. RESULT: Four chromone compounds were identified by TLC, and the contents of two chromone compounds were determined by HPLC. CONCLUSION: Prim-O-glucosylcimifugin, 4'-O-beta-D-glucosyl-5-O-methylvisamminol, sec-O-glucosylhamaudol and cimifugin should be present simultaneously in S. divaricata. The contents of prim-O-glucosylcimifugin and 4'-O-beta-D-glucosyl-5-O-methylvisamminol in S. divaricata should not be lower than 0.12% respectively.

Apiaceae↗
PubMed2001

[Determination of acyclovir in mouse plasma and tissues by reversed-phase high performance liquid chromatography].

The aim of this study was to establish an high performance liquid chromatographic method for determining acyclovir (ACV) concentration in mouse plasma and tissues. A solution of 0.25 mL 60 g/L perchloric acid and 0.25 mL acetonitrile was added into 0.2 mL plasma or 0.2 g tissues to precipitate proteins. Following centrifugation, the supernatant obtained was injected into a reversed-phase column. Operating conditions were Hypersil ODS column(250 mm x 4.6 mm i.d., 5 microns), methanol-water-acetic acid(1:99:0.5, volume ratio) solution as mobile phase at a flow rate of 1.5 mL/min, UV detection at 252 nm. The detection limit of ACV concentration in plasma was 20 micrograms/L and that in tissues was 50 ng/g. The standard curves for ACV were linear in plasma and homogenate of tissues (r > 0.99). The precision of the method was good and the recoveries of ACV were higher than 97.5%. So this method is rapid, accurate and convenient for determination of ACV concentrations in plasma and tissues.

Acyclovir↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. III. Comparison of coumarins of "bai zhi" with those of closely related wild plants].

OBJECTIVE: To provide chemical data for confirming the original plant of traditional Chinese drug "Bai Zhi". METHOD: Coumarins of 4 cultivated breeds of "Bai Zhi" and 3 closely related wild plants, together with other 2 Angelica plants were compared by HPLC. RESULT: According to coumarin patterns, 4 cultivated breeds of "Bai Zhi" and 3 closely related wild plants could be divided into 3 groups: 1. 4 cultivated breeds of "Bai Zhi" ("Chuan Bai Zhi", "Hang Bai Zhi", "Qi Bai Zhi" and "Yu Bai Zhi") and Angelica dahurica var. formosana; 2. A. dahurica; 3. A. porphyrocaulis. CONCLUSION: In point of the coumarin components, A. dahurica var. formosana is closer to traditional Chinese drug "Bai Zhi" than the others.

Angelica↗
PubMed2001

[Induction of callus of Hypericum perforatum L. and qualitative identification of active constituents of its callus].

OBJECTIVE: To induce the callus of H. perforatum and identify hypericin and pseudohypericin of its callus. METHOD: The callus was induced in different culture conditions, and active constituents were determined by HPLC. RESULT AND CONCLUSION: The inductions of callus from different parts were discussed, the induction rate of the leaf axil being the highest. The MS basic medium with 4 micrograms.L-1 2,4-D and 0.2 microgram.L-1 6-BA was the best of all screened media. Hypericin in the callus is determined by HPLC.

Anthracenes↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. IV. Discussion on original plant and cultivation history of traditional Chinese drug "bai zhi" and evolution of its closely related wild plants].

OBJECTIVE: To confirm the original plant of traditional Chinese drug "Bai Zhi" and to inquire into the cultivation history of "Bai Zhi" and evolution of closely related wild plants of "Bai Zhi". METHOD: Various research results obtained were synthesized and discussed according to historical and current data. RESULT: Obtained research results, historical and current data showed almost no difference. CONCLUSION: 1. Angelica dahurica var. formosana must be the original plant of traditional Chinese drug "Bai Zhi". 2. A. porphyrocaulis should be treated as a variety of A. dahurica, named as A. dahurica var. porphyrocaulis. 3. 4 sorts of Chinese traditional drug "Bai Zhi" (Chuang Bai Zhi, Hang Bai Zhi, Qi Bai Zhi and Yu Bai Zhi) should not be taxonomically distinguished. The history of utilization and cultivation of "Bai Zhi", and the evolutional relation of the closely related wild plants of "Bai Zhi" (A. dahurica, A. dahurica var. formosana, and A. dahurica var. porphyrocaulis) were also discussed.

Angelica↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. I. Morphological and anatomical studies on "bai zhi" and closely related wild plants].

OBJECTIVE: To supplement morphological and anatomical data for confirming the original plant of traditional Chinese drug "Bai Zhi" (Radix Angelicae Dahuricae). METHOD: Morphologocal observation and anatomical study were made on 4 cultivated breeds and closely related wild plants of "Bai Zhi". RESULT: According to morphological and anatomical characteristics discovered in this paper, 7 samples noted above could be divided into 3 groups: 1. 4 breeds ("Chuan Bai Zhi", "Hang Bai Zhi", "Qi Bai Zhi" and "Yu Bai Zhi") and Angelica dahurica var. formosana; 2. A. dahurica; 3. A. porphyrocaulis. CONCLUSION: In the morphological and anatomical point of view, A. dahurica var. formosana is closer to traditional Chinese drug "Bai Zhi" than others.

Angelica↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. II. Karyological and pollen morphological studies on "bai zhi" and closely related wild plants].

OBJECTIVE: To supplement cytobiological and pollen morphological data for confirming the original plant of traditional Chinese drug "Bai Zhi". METHOD: Karyological study and pollen observation were made on "Bai Zhi" and its closely related wild plants. RESULT: Similarities and differences of "Bai Zhi" and its closely related wild plants were found. CONCLUSION: 1. 4 cultivated breeds of "Bai Zhi", Angelica dahurica, A. dahurica var. formosana, A. porphyrocaulis are really closely related plants. 2. A. dahurica var. formosana is closer to traditional Chinese drug "Bai Zhi" than others.

Angelica↗
PubMed2001

[Isolation of a kind of endophytic fungus which can produce taxol compounds].

OBJECTIVE: To isolate a kind of endophytic fungus which can produce taxol compounds from the bark of Taxus Cuspidata Sieb et Zucc. METHODS: Endophytic fungus was isolated from the bark of Taxus Cuspidata Sieb et Zucc by aseptic techniques and the analysis of the culture fluid from the fermentation of fungus was carried out by high performance liquid chromatography (HPLC). RESULTS: Endophytic fungus was obtained from the bark of Taxus Cuspidata Sieb et Zucc and the chemical analysis showed that the culture of fungus contain taxol compounds. CONCLUSION: Endophytic fungus which can produce taxol compounds exists in the bark of Taxus Cuspidata Sieb et Zucc.

Chromatography, High Pressure Liquid↗
PubMed2000

Identification of a novel HLA-Cw*05 allele, Cw*0503.

HLA-Cw*05 is one of the least polymorphic subgroups of HLA-C; so far only two alleles, namely Cw*0501 and Cw*0502, have been reported. We report here the identification of a third allele, Cw*0503, in a Caucasian individual. Cw*0503 is closely related to Cw*0501 with only six nucleotide substitutions clustering over a fragment of 48 nucleotides at the beginning of exon 4. All these six substitutions at the same positions have been found only in HLA-B*44 alleles, suggesting that Cw*0503 is a result of recombination between Cw*0501 and one of B*44 alleles.

Alleles↗
PubMed2000

[A review of development of pharmacognosy].

OBJECTIVE: To Review the development of pharmacognosy in China. METHODS: Based on relevant materials. RESULTS: The characteristics of the development of pharmacognosy in China have been summarized. CONCLUSION: With the passage of time, the science of pharmacognosy will take up a new scientific connotation and enter a new developing stage which may be called "The Period of Natural Pharmacognosy".

China↗
PubMed1999

Role of protein kinases A and C in the induction of mGluR-dependent long-term depression in the medial perforant path of the rat dentate gyrus in vitro.

The involvement of protein kinases A and C in the induction of low frequency stimulation-induced long-term depression (LTD) in the medial perforant path of the dentate gyrus in vitro has been studied using the selective PKA inhibitors H-89 and KT 5720 and PKC inhibitors Bisindolylmaleimide and Ro-31-8220. The PKC inhibitors Bisindolylmaleimide I and Ro-31-8220 and the PKA inhibitors H-89 and KT5720 all partially inhibited LTD induction. However, the presence of both a PKC and a PKA inhibitor was necessary to completely block LTD induction. The induction of long-term potentiation was not blocked by the inhibitors. It is suggested that the induction of LTD by LFS involves activation of PKC and PKA following activation of group I and group II metabotropic glutamate receptors (mGluR).

Animals↗
PubMed1999

Cytolytic T lymphocytes recognize an antigen encoded by MAGE-A10 on a human melanoma.

From melanoma patient LB1751, cytolytic T lymphocytes (CTL) were generated that lysed specifically autologous tumor cells. To establish whether these CTL recognized one of the Ags that had previously been defined, a CTL clone was stimulated with cells expressing various MAGE genes. It produced TNF upon stimulation with target cells expressing MAGE-A10. The Ag was found to be nonapeptide GLYDGMEHL (codons 254-262), which is presented by HLA-A2.1. This is the first report on the generation of anti-MAGE CTL by autologous mixed lymphocyte-tumor cell culture (MLTC) from a melanoma patient other than patient MZ2, from whom the first MAGE gene was identified. MAGE genes are expressed in many tumors but not by normal tissues except male germline cells and placenta, which do not express HLA molecules. Therefore, the identification of an antigenic peptide derived from MAGE-A10 adds to the repertoire of tumor-specific shared Ags available for anti-tumoral vaccination trials.

Aged↗
PubMed1998

Presynaptic inhibitory action of the group II metabotropic glutamate receptor agonists, LY354740 and DCG-IV.

Electrophysiological studies were carried out on the presynaptic inhibitory action of the group II metabotropic glutamate (mGlu) receptor agonists (+)-2-aminobicyclo[3.1.0]hexane-2-6-dicarboxylic acid (LY354740) and (2S,1'R,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV) in three paths of the rat hippocampus, the medial and lateral perforant path to the dentate gyrus, and the Schaffer collateral/commissural path to CA1. LY354740 caused a dose-dependent reversible inhibition of the field excitatory postsynaptic potential (EPSP) in the medial and lateral perforant paths, with an EC50 of 115 +/- 16 nM and 230 +/- 58 nM, respectively. Maximal inhibition by LY354740 was much greater in the medial path (about 80%) than in the lateral path (about 50%). No inhibition was observed in CA1. A presynaptic inhibition was confirmed by LY354740 inducing dose-dependent changes in paired-pulse depression/facilitation. DCG-IV had a similar action to LY354740, but with a lower potency.

Animals↗
PubMed1998

Application of capillary electrophoresis, liquid chromatography, electrospray-mass spectrometry and matrix-assisted laser desorption/ionization - time of flight - mass spectrometry to the characterization of recombinant human erythropoietin.

High performance capillary electrophoresis (HPCE), high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization - time of flight - mass spectrometry (MALDI-TOF-MS), on-line CE-electrospray ionization-mass spectrometry (CE-ESI-MS) and on-line LC-ESI-MS have been employed to characterize a heterogeneous glycoprotein, recombinant human erythropoietin (rHuEPO) expressed from Chinese hamster ovary (CHO) cells. The analysis was demonstrated through two specific levels of detail: the intact protein and tryptic digests of the protein. Six glycoforms of rHuEPO were separated by HPCE; seventeen tryptic fragments in a total of 21 nonglycosylated and glycosylated peptides were characterized; the O-linked glycopeptides were analyzed directly by CE-ESI-MS and LC-ESI-MS. In particular, four glycans of O-acetylation of sialic acid were identified in the O-linked glycosylated fragments. The molecular weight of rHuEPO was accurately determined by MALDI-TOF-MS.

Amino Acid Sequence↗
PubMed1997

Detection and identification of transient enzyme intermediates using rapid mixing, pulsed-flow electrospray mass spectrometry.

Rapid chemical quench methods coupled with off-line detection have proven to be very useful in identifying enzyme reaction intermediates. However, a limitation to this approach involves enzyme intermediates which are too labile under the chemical quenching conditions to allow detection and characterization. In this report, we describe the development of a novel approach for the detection and characterization of enzyme intermediates on the subsecond time scale using a "pulsed flow" method which employs a direct interface between a rapid-mixing device and electrospray ionization mass spectrometry. The application of this technique with the enzyme 5-enolpyruvoyl-shikimate-3-phosphate (EPSP) synthase is demonstrated. This enzyme converts shikimate-3-phosphate (S3P) and phosphoenol pyruvate (PEP) to EPSP and inorganic phosphate. Previous rapid chemical quench studies have shown that this reaction proceeds through a tetrahedral intermediate [Anderson, K. S., et al. (1988) J. Am.Chem. Soc. 110, 6577-6579] formed transiently at the enzyme active site. We have shown that this tetrahedral intermediate can be directly detected on a subsecond time scale without chemical quenching by interfacing a rapid mixing apparatus directly with an on-line electrospray ionization ion trap mass spectrometer. Negative ion mass spectra collected by electrospray ionization indicate peaks for S3P (m/z 253), PEP (m/z 167), EPSP (m/z323), and the tetrahedral intermediate (m/z 421). Further confirmation was provided by performing the same experiment with [13C-1]-labeled PEP. These spectra confirmed the anticipated shift of 1 atomic mass unit for PEP (m/z 168), EPSP (m/z 324), and the tetrahedral intermediate (m/z 422) with no change in S3P (m/z 253). The collision-induced dissociation of the unlabeled tetrahedral intermediate peak (m/z421) produced a daughter ion at m/z 323, which is most likely EPSP resulting from the loss of phosphate and is consistent with previous studies which have examined the chemical breakdown of the tetrahedral intermediate in solution [Anderson, K. S., et al. (1990) J. Biol. Chem. 265, 5567-6672]. This technique is under development and should be a useful method to study the transient formation of enzyme intermediates.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗