Biomedical subjects

L Huang

Publications and source records attributed to L Huang.

At least 343 records · Page 19Linked to original sources

PubMed1998

[Molecular cloning of EXT2 and EXT4 gene].

Hereditary multiple exostose(EXT) is an autosomal dominant disorder of skeletal system. Three genetic loci have been identified at 8q24.1(EXT1), 11p11(EXT2) and 19p(EXT3) respectively. In this paper, EXT2 gene was cloned with positional cloning and homologous screening. SSCP and sequencing analysis have been done in 37 EXT patients who came from 20 EXT families, 2 mutations of insertion were tested in 2 patients. This confirmed that the gene cloned in this paper was EXT2 gene which locus at 11p11. Additionally EXT4 gene was cloned with homologous screening and located at 1p36.1 with FISH in this paper.

Amino Acid Sequence↗

PubMed1998

[Effect of tail suspension on mitochondrial Ca2+ and Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle].

Changes of mitochondrial Ca2+, mitochondrial Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle after 15 or 30 d tail suspension were observed. The results showed that mitochondrial Ca2+ [correction of Ma2+] mitochondrial Mg2+ increased and morphometry of mitochondrial in skeletal muscle showed that volume density (Vv), surface density (Sv), numerical density (Nv) increased. Mean volume (V) decreased. Specific surface increased in soleus muscle, while that parameter remain unchanged in gastrocnemus musles. It suggests that these changes may be denoted to the decrease of muscular contractive function in simulated weightlessness.

Animals↗

PubMed1998

[Production, identification and redirected cytotoxicity of CD3/CD19 bispecific monoclonal antibody].

OBJECTIVE: To prepare CD3/CD19 bispecific monoclonal antibody (BsAb) and study its biological effects. METHODS: The CD3/CD19 BsAb was prepared by using hybri-hybridoma technique. The presence of BsAb was demonstrated by double-isotype ELISA and cell conjugate assay. RESULTS: We obtained three strains of CD3/CD19 quadromas, including a stable one. 51Cr release assay showed that CD3/CD19 supernatants, CD3/CD19 purified antibody and CD3/CD19 chemical heterocongjugate greatly enhanced the cytotoxic activity of CD3 AK cells against Nalm-6 cells (P < 0.05-0.001). CONCLUSIONS: The CD3/CD19 BsAb we prepared was efficient in redirecting activated T cells against target tumor cells. This indicates that the CD3/CD19 BsAb has potential value of clinical use.

Animals↗

PubMed1998

[Clinical observation of splenectomy on chronic idiopathic thrombocytopenic purpura in 63 patients].

OBJECTIVES: To investigate the effectiveness of splenectomy in patients with idiopathic thrombocytopenic purpura who failed to respond to conservative management. METHOD: Sixty-three patients were treated with splenectomy and followed up for 2 months to 16 years (average 4.7 years). RESULT: The patients had symptoms of bleeding and their platelet count on average was 24 x 10(9)/L. The first, 3rd, 5th and 7th day after operation, the average platelet count was 110 x 10(9)/L, 202 x 10(9)/L, 251 x 10(9)/L and 246 x 10(9)/L. Their platelet recovered to normal during a week in 51 cases (80.9%). The total effective rate was 86.9% after follow-up for 2 months. The recurrence rate was 17.9% in 39 cases after follow-up for longtime. CONCLUSIONS: The curative effect of splenectomy is better in children than in adults. In patients with increased platelet have a favourable prognosis. Splenectomy is safe and effective in the treatment of idiopathic thrombocytopenic purpura.

Adolescent↗

PubMed1998

[Determination of azathiopurine and 6-mercaptopurine in serum by reversed-phase high performance liquid chromatography].

A method for simultaneous determination of azathiopurine(AZP) and its metabolite 6-mercaptopurine (6-MP) concentration in serum has been developed. Reversed-phase high performance liquid chromatography with gradient elution and dual wavelength detection was employed. After protein precipitation with acetonitrile, the serum sample was evaporated to dryness with a gentle N2 stream at 37 degrees C and 100 microL of the mobile phase were added to dissolve the residue. After centrifugation, 20 microL of the supernatant was injected directly into the HPLC. The detection wavelength was set at 278 nm (AZP) and 325 nm (6-MP). The internal standard was metronidazole. The minimum detectable mass concentration for both AZP and 6-MP in serum was 5 mg/L. The average recoveries were (100.6 +/- 4.2)% for AZP and (102.4 +/- 4.5)% for 6-MP.

Azathioprine↗

PubMed1998

[Synthesis and bioaction of 2-alkyl-4(1H)-quinolone].

Five quinolone alkaloids (IVa, Va, c, d, g) including two new compounds (IVa, Vc) from Evodia rutaecarpa and nine analogs are synthesized in good yield by using acid-catalyzed condensation of a series of 3-oxoalkkanoic acid esters with aniline and further methylized with methyl iodide. The other analogue Vh is prepared through the reaction of lithium enolate methyl ketone with N-methylisatoic anhydride. Eight compounds (IVa, d, f; Vb, c, d, f, h) were synthesized for the first time. Pharmacological studies showed that these compounds have vasoconstriction inhibiting and antiulcer effects. Compound IVb also has cytotoxic effect.

Alkaloids↗

PubMed1998

[Studies on synthesis and bioactivity of 2-alkenyl-4(1H)-quinolone].

Three 2-alkenyl-4(1H)-quinolone compounds(I-III) were synthesized by two methods. III is a new compound from Evodia rutaecarpa and was synthesized through the reaction of the aldehyde intermediate(5) with Wittig reagent. The other two compounds were synthesized for the first time. These compounds showed vasodilating and antibacteria effects in pharmacological tests.

Anti-Infective Agents↗

PubMed1998

[Isolation, purification and physico-chemical properties of immunoactive constituents from the fruit of Lycium barbarum L].

Three glycoconjugates, LbGp3, LbGp4 and LbGp5, were isolated from the fruit of Lycium barbarum L. Molecular weights of LbGp3, LbGp4 and LbGp5 were 9.25 x 10(4), 21.48 x 10(4) and 2.37 x 10(4), respectively. Carbohydrate contents of LbGp3, LbGP4 and LbGp5 were 93.6%, 85.6%, 8.6%, respectively. LbGp3 was composed of Ara and Gal in a molar ratio of 1:1. LbGp4 was composed of Ara, Gal, Rha and Glc in a molar ratio of 1.5:2.5:0.43:0.23. LbGp5 was composed of Rha, Ara, Xyl, Gal, Man and Glc in a molar ratio of 0.33:0.52:0.42:0.94:0.85:1. Elemental analysis of N contents: LbGp3 0.83%, LbGp4 1.72%, LbGp5 9.58%. The linkage between the glycan and protein may be of O-linkage in LbGp4.

Animals↗

PubMed1998

[Problems and solutions in the use of RAPD to the identification of the Chinese drugs "xi-xin" (Herba asari) and its substitutes].

The use of random amplified polymorphic DNAs (RAPD) on the identification of crude drugs has a few special problems, e.g., the influence of the degree of degradation of DNA templates on the amplified products, the reliability of results by one or two primers and the application range of RAPD, etc., so the problems were discussed through researches on Herba Asari. In this experiment, the DNA of twenty-one samples from different locations and collected at different time were extracted. The suitable concentrations of DNA templates and the suitable primers were selected. After this, the DNA of these samples were amplified by RAPD. The results showed that the concentration and the degree of degradation of DNA templates, and the different sources of crude drugs affected the result of RAPD assay. Some suggestions were made to solve these problems, such as the selection of DNA templates concentration, the screening of suitable primers, and the use of contrast groups and cluster analysis. Furthermore, the application range of RAPD to the identification of crude drugs was discussed. All of these will provide the guide to the use of RAPD for the identification of crude drugs.

Asarum↗

PubMed1998

[Effect of Limonium bicolor on bombyxmori life-span].

The effect of limonium bicolor decoction (LBD) (1%, 5%, 10%) on the life-span of bombyxmori was investigated. It was found that LBD could obviously prolong not only average life-span and average of highest life-span of both female bombyxmori and moth, but also the daration of female silkworm stage. Furthermore, LBD clud be antianoxiasis and hunger-resistant, these results showed that BLD could promise longevity.

Aging↗

PubMed1998

Amplification and overexpression of the AKT2 oncogene in a subset of human pancreatic ductal adenocarcinomas.

AKT2, an oncogene encoding a protein serine-threonine kinase implicated in phosphatidylinositol-3-OH kinase signaling, is amplified in some human ovarian and pancreatic carcinomas. We previously demonstrated that the tumorigenicity and invasiveness of pancreatic ductal adenocarcinoma (PDAC) cell lines with amplified AKT2 could be markedly reduced by transfection with antisense AKT2 constructs. To evaluate further the extent of AKT2 alterations in PDAC, DNA and immunohistochemical analyses were performed to assess amplification or overexpression of AKT2, respectively, in 72 PDACs. Thirty-five PDACs were subjected to Southern analyses, and AKT2 amplification was detected in seven tumors (20%). Forty-one formalin-fixed PDAC specimens were examined immunohistochemically with an anti-AKT2 monoclonal antibody, and moderate to intense staining was observed in eight tumors (20%). AKT2 immunostaining paralleled AKT2 genomic status in each of four cases in which both Southern and immunohistochemical analyses were performed. No obvious relationship was observed between AKT2 status and tumor TNM stage or grade. These observations suggest the utility of immunohistochemical analysis in assessing alterations of AKT2 in human cancers. Furthermore, the role played by the AKT2 kinase in the signaling pathways of various mitogenic growth factors implicated in the development of pancreatic cancer suggests that alteration of AKT2 may be an important component in the pathogenesis of a substantial subset of PDACs.

Carcinoma, Ductal, Breast↗

PubMed1998

[Localization of the gene for 4 hereditary multiple exostoses families].

We investigated 11 families with hereditary multiple exostoses (EXT) by linkage analysis using 8 short-tandem-repeat (CA)n polymorphic markers on chromosomes 8, 11 and 19. The Lod score in four families indicated that the gene responsible for EXT is located in the pericentromeric region of chromosome 11.

Chromosome Mapping↗

PubMed1997

In vivo gene delivery to the liver using reconstituted chylomicron remnants as a novel nonviral vector.

Lipoproteins are emulsion particles that consist of lipids and apolipoproteins. Their natural function is to transport lipids and/or cholesterol to different tissues. We have taken advantage of the hydrophobic interior of these natural emulsions to solubilize DNA. Negatively charged DNA was first complexed with cationic lipids containing a quaternary amine head group. The resulting hydrophobic complex was extracted by chloroform and then incorporated into reconstituted chylomicron remnant particles ( approximately 100 nm in diameter) with an efficiency approximately 65%. When injected into the portal vein of mice, there were approximately 5 ng of a transgene product (luciferase) produced per mg of liver protein per 100 microg injected DNA. This level of transgene expression was approximately 100-fold higher than that of mice injected with naked DNA. However, such a high expression was not found after tail vein injection. Histochemical examination revealed that a large number of parenchymal cells and other types of cells in the liver expressed the transgene. Gene expression in the liver increased with increasing injected dose, and was nearly saturated with 50 microg DNA. At this dose, the expression was kept at high level in the liver for 2 days and then gradually reduced and almost disappeared by 7 days. However, by additional injection at day 7, gene expression in the liver was completely restored. By injection of plasmid DNA encoding human alpha1-antitrypsin, significant concentrations of hAAT were detected in the serum of injected animals. This is the first nonviral vector that resembles a natural lipoprotein carrier.

Animals↗

PubMed1997

Growth inhibition of human papillomavirus 16 DNA-positive mouse tumor by antisense RNA transcribed from U6 promoter.

Over 95% of cervical carcinomas are human papillomavirus (HPV) DNA positive, and the expression of the E6 and E7 genes is required for the maintenance of malignant phenotype. Here, antisense sequences targeted against the HPV16 E6 and E7 genes were cloned as U6/antisense chimeric genes under the control of the U6 RNA gene promoter. Cationic liposome-mediated transfection of these plasmids into human 293 cells and HPV16 DNA-positive mouse C3 tumor cells were performed, and the chimeric U6/antisense transcripts were detected. The U6 promoter could express RNA up to 360 nucleotides in length. In a cotransfection study, the E7 antisense plasmid (but not the sense control) caused the down-regulation of E7 gene expression. Similarly, decreased E7 protein levels were observed in the C3 cells that were transfected with E7 antisense plasmid. In vitro growth inhibition was studied by delivering liposome-antisense plasmid complex to C3 tumor cells. Up to 50% growth inhibition was achieved with antisense plasmids, whereas only about 15% growth inhibition was observed with sense plasmids. Transfection into human cervical carcinoma C33A cells and mouse melanoma BL6 cells, which contain no HPV DNA, showed no growth inhibition. These results indicate that growth inhibition resulted from specific E6/E7 down-regulation of the tumors or cells. Furthermore, intratumor injection of DNA-liposome complex containing either E6 or E7 antisense plasmid resulted in significant growth inhibition of C3 tumors but not BL6 tumors, grown in a syngeneic mouse model. This promising result indicates that E6/E7 antisense sequences expressed in the context of the U6 gene might be useful for gene therapy of cervical carcinoma.

Animals↗

PubMed1997

Human immunodeficiency virus type 1 TAT protein activates B lymphocytes.

HIV-1 infection causes B cell hyperactivation. Tat protein, a potent virus-encoded transactivator, has the potential to activate B cells based on its pleiotropic biological properties: (1) Tat regulates cellular gene expression; (2) Tat modulates growth of various cell types; and (3) Tat is released from infected T cells and acts on bystander uninfected cells in a paracrine fashion. To test a possible activating effect of Tat on B cells, we examined the effect of purified Tat on the expression of Fas, an activation marker, in B cells in primary culture. Flow cytometric analysis demonstrated that treatment of peripheral blood mononuclear cells with Tat, at concentrations in the range of extracellular Tat as determined in vivo, up-regulated Fas expression in B cells. Reverse transcriptase-PCR further demonstrated that Tat induced Fas expression in B cells at the mRNA level. These results indicate that exogenous Tat alone can activate B cells, suggesting that Tat may contribute to B cell hyperactivation during the early stage of HIV-1 infection and activation-induced B cell death mediated by Fas during the late stage of HIV-1 infection.

B-Lymphocytes↗

PubMed1997

PCCG-IV inhibits the induction of long-term potentiation in the dentate gyrus in vitro.

The effects of two ligands with previously established high and selective potency for metabotropic glutamate receptors (mGlu receptors) group II have been investigated on the high frequency stimulation (HFS) induced long-term potentiation of the field excitatory postsynaptic potential (EPSP) in the dentate gyrus of the rat hippocampus in vitro. The ligands investigated were (2S,1'S,2'S,3'R)-2-(2"-carboxy-3'-phenylcyclopropyl)glycine (PCCG-IV) and (R,S)-alpha-methyl-4-tetrazolylphenylglycine (MTPG). PCCG-IV (10 microM) strongly inhibited the induction of long-term potentiation of the field EPSP by high frequency stimulation. MTPG (50 microM) did not inhibit the induction of long-term potentiation, but prevented the inhibition of long-term potentiation induction by PCCG-IV. The inhibition of long-term potentiation induction by PCCG-IV is suggested to be due to an agonistic action on mGlu receptor group II, probably mGlu3 receptor, as the inhibition of long-term potentiation can be reversed by the application of MTPG, a well-known selective and potent antagonist of mGlu receptor group II.

Alanine↗

PubMed1997

Desorption Behavior of Surfactant Mixtures at the Alumina-Water Interface

The desorption behavior of cationic-nonionic surfactant mixtures, tetradecyltrimethylammonium chloride (TTAC) and pentadecylethoxylated nonyl phenol (NP-15), at the alumina-water interface was studied. It has been found that while nonionic NP-15 itself does not adsorb at alumina-water interface, it will do so with cationic TTAC preadsorbed at the interface. During the desorption process, however, the presence of NP-15 in the system was discovered to cause desorption of TTAC. This is attributed to changes in equilibrium among surfactant monomers, mixed micelles, hemimicelles, and solloids upon the addition of NP-15: The cationic TTAC species at the interface is solubilized in NP-15 rich micelles in the bulk and perturb the equilibrium. This in turn is proposed to cause the desorption of NP-15 significant. The desorption behavior in the mixed surfactant system depends on the mixing ratio of surfactants in the mixtures. In nonionic NP-15 rich mixtures, negative hysteresis is observed for the desorption of both TTAC and NP-15. In cationic TTAC rich mixtures, the effect of NP-15 on the desorption of TTAC is limited and the desorption of TTAC is similar to that in single TTAC system; in this case some positive hysteresis is observed for both TTAC and NP-15.

Journal Article↗

PubMed1997

Tat protein induces self-perpetuating permissivity for productive HIV-1 infection.

We report that human immunodeficiency virus type 1 (HIV-1) has evolved a self-perpetuating mechanism to actively generate cells permissive for productive and cytopathic infection. Only activated T cells can be productively infected, which leads to their rapid depletion (2 x 10(9)/day in an infected individual). Establishment of productive HIV-1 infection therefore requires continual activations from the large pool of quiescent T cells. Tat protein, which is secreted by infected cells, activated uninfected quiescent T cells in vitro and in vivo. These Tat-activated uninfected cells became highly permissive for productive HIV-1 infection. Activation of primary T cells by Tat protein involved integrin receptors and was associated with activation of mitogen-activated protein kinases, including ERK1 and JNK kinase. Accordingly, these primary T cells progressed from G0 to the late G1 phase of the cell cycle.

Calcium-Calmodulin-Dependent Protein Kinases↗