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Biomedical subjects

L Q Huang

Publications and source records attributed to L Q Huang.

36 records · Page 2Linked to original sources
PubMed1997

mGluR II agonist inhibition of LTP induction, and mGluR II antagonist inhibition of LTD induction, in the dentate gyrus in vitro.

The effects of the metabotropic glutamate receptor (mGluR) group II agonist (2S,1'R,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV) and the antagonist 2S,1S',2S'-2-methyl-2-(2'-carboxycyclopropyl)glycine (MCCG) on the induction of long-term potentiation (LTP) and long-term depression (LTD) of the field excitatory postsynaptic potential (epsp) in the dentate gyrus of the rat hippocampus were investigated in vitro. In control media, high frequency stimulation (HFS) consisting of a series of trains of stimuli at 200 Hz induced LTP, and low frequency stimulation (LFS) consisting of 900 stimuli at 1 Hz induced LTD. DCG-IV (50 nM) strongly inhibited the induction of LTP. The block of LTP induction was not caused by a frequency-dependent inhibition of the epsp during HFS, as the epsps evoked during HFS were not altered by DCG-IV. MCCG (500 microM) did not inhibit the induction of LTP, but did prevent the block of LTP by DCG-IV. MCCG (500 microM) strongly inhibited the induction of LTD. DCG-IV (50 nM) did not inhibit LTD induction.

Amino Acids, Dicarboxylic↗
PubMed1995

Effects of cyclosporin A and dexamethasone on haemostatic and vasoactive functions of vascular endothelial cells.

Glucocorticoids reduce prostaglandin synthesis in cultured vascular endothelium, but their effects on other haemostatic functions are unclear. We examined the effects of dexamethasone and cyclosporin A (CSA) on cultured human umbilical vein endothelial cells (HUVEC). One, 10 and 50 micrograms/ml CSA and 1 microgram/ml dexamethasone (Dx) were added to the culture medium for 3 h, 3 days and 6 days and compared with HUVEC cultured in medium and serum alone. After assay of accumulated release of tissue type plasminogen activator (t-PA) and endothelin 1 (ET), cells were stimulated with 1 U/ml of human thrombin for 1 h and medium collected for RIA of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha), thrombospondin (TSP), von Willebrand factor (vWf) and ELISA of plasminogen activator inhibitor 1 (PAI-1). CSA at 1 microgram/ml modestly reduced release of prostacyclin (PGI2) but had no reproducible effects on other metabolites. CSA at 10 and 50 micrograms/ml inhibited cell growth and thrombin stimulated release of PGI2 in a time- and dose-dependent manner. Inhibition of other endothelial metabolites was also observed at CSA 10 > micrograms/ml. Dexamethasone 1 microgram/ml reduced both cell number and PGI2 release and increased thrombin stimulated release of vWf, TSP and PAI-1 with increases in t-PA and endothelin 1 in the medium. CSA 1 microgram/ml and dexamethasone 1 microgram/ml together were additive in reducing PGI2 release and increasing PAI-1 secretion. These observations suggest a role for endothelial dysfunction in the hypertensive and thrombotic complications observed in steroid treated patients with CSA potentially contributing to such complications.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Characterization of dibromopolychlorodibenzo-p-dioxins and dibromopolychlorodibenzofurans in municipal waste incinerator fly ash using gas chromatography/mass spectrometry.

Several fly ash samples from different countries were analyzed for dibromopolychlorodibenzo-p-dioxins and -dibenzofurans (DBPCDD/Fs) using capillary column gas chromatography/high-resolution mass spectrometry. Concentrations of these compounds ranged from low to high parts-per-trillion (pptr) depending on the location where the samples were collected. The mass spectrometer, operated at greater than 10,000 mass resolution in combination with the high resolving power of capillary column GC, permitted characterization of DBPCDD/Fs in municipal waste incinerator fly ash for the first time. The isomer patterns of tetra- through octa-congener groups of DBPCDD/Fs are remarkably similar regardless of where the fly ash originated, indicating common mechanisms of formation of these compounds in the incinerators.

Benzofurans↗
PubMed1991

Monobromopolychlorodibenzo-p-dioxins and dibenzofurans in municipal waste incinerator flyash.

Capillary column gas chromatography/high-resolution mass spectrometry was used in two different selected-ion monitoring modes to analyze trace levels of monobromopolychlorodibenzo-p-dioxins and dibenzofurans (BPCDD/Fs) in municipal waste incinerator (MWI) flyash. The mass profile monitoring mode is well-suited for identification of unknown compounds in uncharacterized matrices because it has superior diagnostic capability. Owing to its high sensitivity, conventional peak top monitoring was used to quantify, on the basis of polychlorodibenzo-p-dioxin and dibenzofuran (PCDD/F) standards, the BPCDD/Fs in the sample. The results were compared with those obtained by using two commercial BPCDDs as standards, and the latter results are 4 times greater, indicating the need for appropriate standards. The high certainty and sensitivity obtained from these two mass spectrometric techniques combined with the resolving power of capillary gas chromatography enabled us to compare for the first time the isomer distribution patterns between BPCDD/Fs and their PCDD/F analogues at a high confidence level. The comparison indicates BPCDD/Fs and PCDD/Fs found in MWI flyash are closely related and that many BPCDD/Fs with a 2,3,7,8-substitution configuration may be present in MWI flyash.

Benzofurans↗
PubMed1991

The application of hybrid mass spectrometry/mass spectrometry and high-resolution mass spectrometry to the analysis of fish samples for polychlorinated dibenzo-p-dioxins and dibenzofurans.

A hybrid mass spectrometer operated in low-resolution selected decomposition monitoring (SDM) mode was used for the analysis of whole fish samples for the 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and poly-chlorinated dibenzofurans (PCDD/Fs). These fish samples were previously analyzed for PCDD/Fs using a high-resolution mass spectrometer following EPA protocols. The hybrid tandem mass spectrometric method using loss of COCl gave similar quantification results to those obtained by high-resolution mass spectrometry and eliminated the interferences attributed to polychlorinated biphenyls that were encountered in the high-resolution mass spectrometric analysis. Comparison of the two methods shows that the high-resolution mass spectrometric method surpasses the tandem mass spectrometric method in other analytical figures of merit, such as detection limit, linearity and reproducibility.

Animals↗
PubMed1990

Motion-boundary illusions and their regularization.

Humans use various cues to understand the structure of the world from images. One such cue is the contours of an object formed by occlusion or from surface discontinuities. It is known that contours in the image of an object provide various amounts of information about the shape of the object in view, depending on assumptions that the observer makes. Another powerful cue is motion. The ability of the human visual system to discern structure from a motion stimulus is well known and has a solid theoretical and experimental foundation. However, when humans interpret a visual scene they use various cues to understand what they observe, and the interpretation comes from combining the information acquired from the various modules devoted to specific cues. In such an integration of modules it seems that each cue carries a different weight and importance. We performed several experiments where we made sure that the only cues available to the observer were contour and motion. It turns out that when humans combine information from contour and motion to reconstruct the shape of an object in view, if the results of the two modules--shape from contour and structure from motion--are inconsistent, they experience a perceptual result which is due to the combination of the two modules, with the influence of the contour dominating, thus giving rise to the illusion. We describe here examples of such illusions and identify the conditions under which they happen. Finally, we introduce a computational theory for combining contour and motion using the theory of regularization. The theory explains such illusions and predicts many more.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1990

Peripheral blood and bone marrow lymphocyte subsets in patients with multiple myeloma.

A panel of monoclonal antibodies (McAb) from the Wu series was used to characterize lymphocyte subsets of peripheral blood (PB) from 9 patients with multiple myeloma (MM) by means of indirect immunofluorescence assay. In 7 of these patients bone marrow (BM) cells were also studied. Abnormal distribution of T lymphocyte subsets was observed in these patients, and the alterations were quite similar in both PB and BM. A significant increase in the proportion of WUT8+ cells (P less than 0.001) and a reduced WuT4/WuT8 ratio (P less than 0.001) were found in patient group. In both PB and BM of patients, WuT10+ cell counts were significantly higher than normal (P less than 0.001). There was a good correlation between BM WuT10+ cells and BM myeloma cells (r = 0.76, P less than 0.05), whereas no correlation was found between PB WuT10+ cells and BM myeloma cells. The significance of abnormal T-cell subset distribution and elevated WuT10+ cells in MM is discussed.

Aged↗
PubMed1990

Targeted anti-tumor agents and their cytotoxicity on gastric cancer cells in vitro.

Several chemotherapeutic drugs including methotrexate, daunomycin, mitomycin C and toxin such as ricin, A chain of ricin were chosen to conjugate with murine monoclonal antibodies MGb2 and MG11. The drugs were linked to antibody directly or through human serum albumin as intermediary. The ELISA results showed that the antibody retained well the antigen-binding capacity during conjugation. These conjugates showed highly selective cytotoxic effect on target cells. In chronic cytotoxicity tests, the cytotoxic effect of these conjugates on human gastric cancer cells KATOIII was quite similar to that of free drugs or ricin, but greater than that of irrelevant conjugates, while they had a little effect on non-target cells, suggesting that the selective cytotoxicity on target cells of the conjugates be mediated by antibodies.

Animals↗
PubMed1989

Studies on biological characteristics and modulating factors of long-term cultured bone marrow cells of a myeloma patient in vitro.

In the present study we cultured in vitro bone marrow cells from a patient with multiple myeloma (IgD) and researched into the modulation of supernatant media of various leukemic lines on the growth of culture cells. Cells in the cultures were studied for their morphological, biochemical, immunological and ultrastructural features. Drug sensitivity assay was also performed. The results showed that supernatant media of 6 cell lines promoted cell growth, but most remarkable stimulating activity was displayed by supernatant media from U937 and CEM. Cell cloning effect attained to more than 90%. Cultured cells possessing biological characteristics of malignant cells were probably malignant cells from B cell lineage. This study indicated that long-term cultures of marrow cells might provide a tool useful for clinical and laboratory purpose and a method for studies on pathogenesis, regulation of hematopoiesis, cell differentiation and guide-way drugs.

Antibodies, Monoclonal↗
PubMedDate not supplied

Proteomic analysis of human tears: defensin expression after ocular surface surgery.

Human tear protein profiles were monitored by surface enhanced laser desorption/ionization-time-of-flight mass spectrometry ProteinChip technology (SELDI-TOF ProteinChip) and liquid chromatography-mass spectrometry (LC-MS). Tears were collected from 21 patients scheduled for surgery to remove an ocular surface neoplasm prior to surgery (day 0) and on days 1, 3, and 30 postoperatively. Using this proteomic approach, we verified that three human alpha-defensins (HNP-1, HNP-2, and HNP-3) were significantly up-regulated in their expression after surgery and that their levels decreased to approximately normal by day 30 by which time healing was complete. Further confirmation of the identity of the alpha-defensins in human tears was made by LC purification, trypsin digestion, and ESI-MS/MS analysis of their tryptic digests. The concentrations of HNP-1 and HNP-2 were determined and shown to be markedly increased after ocular surface surgery. The results of the study suggest that human alpha-defensins HNP-1, HNP-2, and HNP-3 are up-regulated after surgery, and may in addition to their antimicrobial properties have an important role in wound healing.

Amino Acid Sequence↗
PubMedDate not supplied

Improved extraction of atrazine and metolachlor in field soil samples.

A method was developed for extraction of weathered residues of atrazine and metolachlor from field soils; soils had last been treated with commercial formulations of the herbicides 8-15 months prior to sample collection. Maximum yields were obtained by batch extraction at 75 degrees C for 2-16 h with methanol-water (80 + 20) in a sealed vial. Hydrolysis or other decomposition reactions were minor or negligible, depending on the extraction time. This method is an improvement over published methods that are validated by spike recoveries; the proposed method gives 1.7-1.8 times higher yields compared to shaking for 2 h at room temperature, and 1.3-1.8 times higher yields compared to Soxhiet extraction. The reproducibility of the method was better than 12%. The results underscore the impact of nonequilibrium sorption of organic compounds on analytical methodology and emphasize the need to validate extraction methods with field samples.

Acetamides↗
PubMedDate not supplied

Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry.

A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of 15N,13C-alachlor and 2H5-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.

Acetamides↗