Search PubMed⌕ Search

Biomedical subjects

F Huang

Publications and source records attributed to F Huang.

177 records · Page 10Linked to original sources
PubMed1991

[Granulocyte differentiation of human promyelocytic leukemic cells induced by coordinate action of granulocyte colony stimulating factor and retinoic acid].

We analysed the effects of recombinant human G-CSF (rhG-CSF) and retinoic acid (RA) on proliferation and differentiation of HL-60 cells and human acute myeloid leukemic (AML) cells. A synergistic effect on granulocyte differentiation was observed when HL-60 cells and primary cultured acute promyelocyte leukemic cells were cocultured with 10(-8)mol/L RA plus 1:2000 or 1:1000 rhG-CSF. The rhG-CSF plus RA treated cells demonstrated significant increase in the percentage of mature cells. Morphological changes and nitroblue tetrazolium (NBT) reduction activity evidenced more increase than RA treatment alone (P less than 0.001). The results suggest that RA not only inhibits the proliferative action of G-CSF, but also retains and enhances the action of G-CSF to induce differentiation. Therefore, we believe that the combined use of G-CSF with RA may improve the treatment of leukemia.

Cell Differentiation↗
PubMed1991

Antioxidant action of certain simple phenolic compounds derived from Chinese herbs.

H2O2 and hydroxyl free radical active oxygen generation systems were utilized to define the antioxidant activities of simple phenolic compounds derived from Chinese herbs. Although the antioxidant activities of compounds differed when assessed in the two systems, all compounds tested were found to be effective at preventing red blood cell membrane lipid peroxidation, with the propyl and butyl esters of gallic acid being especially potent. No compound was able to prevent hemoglobin oxidation. All compounds but salicylic acid were found to interact dose-dependently with H2O2 and hydroxyl free radical as determined by a chemiluminescence method.

Antioxidants↗
PubMed1987

B-lymphocyte activation mediated by anti-immunoglobulin antibody in the absence of protein kinase C.

B-cell activation induced by crosslinking of surface immunoglobulin is known to stimulate hydrolysis of phosphatidylinositol to diacylglycerol and inositol trisphosphate. We now provide evidence that alternative pathways of activation may also be recruited during such activation. We utilized depletion of protein kinase C activity to determine whether this enzyme is required under all conditions for anti-immunoglobulin-stimulated B-cell activation. Although anti-immunoglobulin does not induce B-cell proliferation in protein kinase C-depleted cells, it stimulates an earlier event in B-cell activation as reflected by its ability to enhance the expression of major histocompatibility complex-encoded class II molecules. Furthermore, the ribonucleoside 8-mercaptoguanosine restores the ability of anti-immunoglobulin to induce B-cell proliferation in protein kinase C-depleted cells. This restoration is also demonstrated by an enhancement of synthesis of a nuclear protein that we find is increased during B-cell mitogenesis. These results indicate that B-cell activation stimulated by anti-immunoglobulin may recruit pathways in addition to the one dependent on protein kinase C.

Animals↗
PubMed1986

A pilot study on universal immunization of newborn infants in an area of hepatitis B virus and primary hepatocellular carcinoma prevalence with a low dose of hepatitis B vaccine.

Hepatitis B virus (HBV) had been considered as the main causative factor of primary hepatocellular carcinoma and universal immunization of newborns was recommended as the major approach to control hepatitis and hepatoma in areas of prevalence. As the initial phase of the first vaccination program for such a purpose, a pilot study was done from September 1983 to May 1984 in a high incidence rural area of China. In an area of 214,343 inhabitants, 1,703 newborns (99% of all births) were vaccinated. Ninety-seven percent of all vaccinees were followed up at 1 year. The vaccine used was Hep-B Vax, given intramuscularly at 0, 1, and 6 months after birth. Four immunization regimes were used: 5-micrograms or 2.5-micrograms doses with or without hepatitis B immune globulin (HBIG) added in the case of carriers children. These groups were defined by drawing lots at community level. A matched control was selected on a voluntary basis. Each group consisted of 400 infants. Vaccination was proven to be very safe and well accepted by the public. The prevalence of HBV infection in the area was further demonstrated by the high HBsAg-positive rate measured: 14.2% of the 1,180 mothers (3.9% were also e-antigen positive), 7.6% and 10.1% of the unvaccinated children at 6.5 months and 1 year of age, respectively. It was shown that vaccination with a 5-micrograms or 2.5-micrograms dose significantly lowered the HBsAg positives to a level close to 1.5% versus 10% in the control group at 1 year. An 85% protection was thus achieved. A 5-micrograms dose plus HBIG did not show additional benefit. A 2.5-micrograms dose plus HBIG gave less protection, and anti-HB levels were also significantly lower than in other groups. Among the 12 failures found in the 5-micrograms and 2.5-micrograms groups, 11 were born to HBsAg-positive mothers, nine of whom also had e-antigen. Available data showed that 29% of children born by e-antigen-positive and 2.7% of children born by e-antigen-negative carriers had the risk of becoming carriers during the first year of life following vaccination. The present study demonstrated the feasibility and rationale of conducting universal immunization of newborns in endemic rural area for controlling hepatitis and hepatoma. The significance of the possible use of the vaccination at lower dose had also been stressed.

Adult↗
PubMed1984

Antiallergic activity profiles in vitro of RHC 3164 and related compounds. I. A lack of correlation between inhibition of cyclic nucleotide phosphodiesterases and antigen-induced release of histamine from rat mast cells.

A series of 26 compounds belonging to the chemical class of (1,2,4)triazolo(4,3-a)-quinoxaline-1,4-diones have been investigated for their antiallergic activities in 3 in vitro models of anaphylaxis. Effects of these and other known antiallergic agents on cyclic nucleotide phosphodiesterases (cNUC-PDE) from purified rat mast cells have also been investigated. 18 compounds were potent (I50 less than or equal to 45 microM) inhibitors of antigen-induced release of histamine (AIR) from rat mast cells (RMC), 3 compounds inhibited anti-IgE-induced release of histamine from human basophils (I50 less than or equal to 25 microM) and none of the compounds significantly affected AIR from guinea pig lung slices. 13 of the compounds were more potent than theophylline as inhibitors of cyclic AMP-PDE and/or cyclic GMP-PDE from RMC. Parallel concentration-response curves for the inhibition of cyclic AMP-PDE and cyclic GMP-PDE indicated that these compounds probably interact with enzyme in the same manner. Paired regression analysis of the I50 values for inhibition of AIR and cNUC-PDE from RMC by these compounds revealed no statistically significant correlation between the inhibition of AIR and inhibition of cyclic AMP-PDE or cyclic GMP-PDE. We conclude: (1) some of these compounds are potent inhibitors of immunologic release of histamine from RMC with an in vitro activity profile similar to that of DSCG, and (2) inhibition of cyclic AMP or cyclic GMP hydrolysis by cNUD-PDE by these compounds, DSCG, and 6 known antiallergic agents is not the biochemical mechanism by which they inhibit AIR from RMC.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1984

Antiallergic activity profiles in vitro of RHC 3164 and related compounds. II. Comparison of RHC 3164 with disodium cromoglycate.

RHC 3164 has been investigated for its antiallergic activities in 3 in vitro models of anaphylaxis. RHC 3164 was 6 times more potent than DSCG as an inhibitor of antigen-induced release of histamine (AIR) from rat mast cells (RMC) and had an activity profile identical to that of DSCG in the following respects: loss of inhibitory activity with increasing preincubation time, tachyphylactic properties, cross-tachyphylaxis to DSCG, and inability to inhibit nonimmunologic release of histamine. Neither RHC 3164 nor DSCG had any effect on immunologic release of histamine from human basophils or guinea pig lung slices. We conclude that RHC 3164 is a potent inhibitor of immunologic release of histamine from RMC with a mechanism of action similar to that of DSCG.

Animals↗
PubMed1983

Physiological and mutational protein variations in the ciliary membrane of Paramecium.

The proteins in the ciliary membrane of wild-type and mutant Paramecium tetraurelia are examined with SDS and IEF gels. Over 80% of the proteins in the ciliary membrane belong to two groups: the immobilization antigen (I-Ag), which is a 220-280 kD surface protein, and a set of at least four integral proteins slightly over 40 kD (the 40 k), most of which focus near pH 4.0 (the acidic 40 k). Variations of the I-Ag in its apparent molecular weight appear spontaneously in different clones of the same strain and can be triggered by changing the culture temperatures. We discovered that the members of the acidic 40 k family also vary in their relative proportion. Furthermore, the variations in I-Ag and those in acidic 40 k are tightly coupled. The concerted changes suggest a co-regulation in the synthesis of these proteins. The ciliary membranes of 20 mutants of 11 complementation groups known for their behavioral and electrophysiological defects are examined. Coupled variations of I-Ag and acidic 40 k among clones, similar to those of the wild type, are seen. Besides the I-Ag and the acidic 40 k, this membrane has over 60 other species of proteins, most of which are invariant. Shifts in the isoelectric points of two of these minor proteins have been correlated with two different mutations, 'fast-2' and 'paranoiac A'. No electrophoretic shifts can be correlated with the 'pawn B' mutation as found by Merkel et al. [35].

Animals↗
PubMedDate not supplied

Time of symptom onset of eight common medical emergencies.

Specific time periods of the day may be associated with different frequencies of symptom onset in different diseases. The purpose of the current study was to examine times of symptom onset in eight commonly encountered emergent conditions--cerebral infarction, cerebral hemorrhage, transient ischemic attacks, cardiac dysrhythmias, angina pectoris, acute myocardial infarction, gastrointestinal bleeding, and acute asthma. Data from 4554 cases were retrospectively reviewed. Symptom onset frequency curve diagrams were derived, illustrating peak hours of symptom presentation for each of the eight emergent conditions. Hormonal and metabolic factors that may be related to diurnal variations in symptom onset of the eight diseases are briefly discussed.

Acute Disease↗
PubMedDate not supplied

Boranophosphate nucleic acids--a versatile DNA backbone.

Important chemical and biochemical properties of boranophosphate DNA and RNA oligonucleotides are reviewed. Stereoregular boranophosphate oligomers can be synthesized enzymatically and form stable duplexes with DNA. Fully boronated, non-stereoregular oligothymidylates, synthesized chemically, form hybrids with poly(A) that have lower melting points than oligothymidylate:poly(A), yet they nevertheless can support the RNase H mediated cleavage of RNA.

Boron Compounds↗
PubMedDate not supplied

The genetically-engineered secretory B27/Q10 chimeric molecule inhibits HLA-B27 restricted alloreactive T-lymphocytes.

OBJECTIVES: Intracellularly persisting bacterial infections and high association with HLA-B27 are the hallmarks of reactive arthritis. Soluble HLA-B27 molecules are induced by bacterial infection; however their biological role in arthritis is unknown. It was the aim of this study to generate soluble HLA-B27 molecule and to analyze its effect on cytotoxic HLA-B27 alloreactive CD8+ T-lymphocytes in order to better understand potential functional links between persistent infection and HLA-B27 association. METHODS: Using PCR Exons 1 through 4 of HLA-B*2705 were fused to Exon 5 of the soluble murine MHC class I variant Q10 and stably transfected into Hela-cells. Transfectants were analyzed using specific PCR, RT-PCR and intracellular and extracellular staining with anti-HLA-B27 monoclonal antibody ME1. Secretion of B27Q10 in the supernatant was examined by isoelectric focusing (IEF). The effect of B27Q10 on T-cells was analyzed using either HLA-B27- or HLA-A2-restricted alloreactive T-cells in a standard 51Cr-release assay. RESULTS: PCR and RT-PCR demonstrated the DNA and mRNA of B27Q10 in the transfectants. By intracellular and extracellular staining with ME1 B27Q10-molecule was detected intracellularly but was not expressed in the cell membrane. Using IEF soluble B27Q10-molecules were found in supernatants of transfectants in a concentration of up to 1.342 microg/ml. Soluble B27QJO-molecule inhibited specifically the cytotoxicity of HLA-B27-restricted alloreactive T-cells by about 30%. CONCLUSION: The secretory non-membrane-expressed molecule B27Q10 inhibits HLA-B27 specific T-cells. The inhibition of cytotoxic T-cells by bacteria induced soluble HLA-B27 may thus enable bacterial persistence.

Animals↗
PubMedDate not supplied

Thalidomide in ankylosing spondylitis.

Despite potential side effects dominated by teratogenicity and peripheral neuropathy, thalidomide has recently been used to treat severe ankylosing spondylitis (AS). Over 50 patients have been treated across several 6-12 month open studies. Altogether 68% of the patients improved and the drop-out rate was 19%. Inhibition of NF-kappaB and/or TNFalpha is a putative mechanism for thalidomide efficacy in AS.

Clinical Trials as Topic↗