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Biomedical subjects

F Yang

Publications and source records attributed to F Yang.

At least 217 records · Page 12Linked to original sources
PubMed1999

Complete homology maps of the rabbit (Oryctolagus cuniculus) and human by reciprocal chromosome painting.

Fluorescence in situ hybridization (FISH) was used to construct a homology map to analyse the extent of evolutionary conservation of chromosome segments between human and rabbit (Oryctolagus cuniculus, 2n = 44). Chromosome-specific probes were established by bivariate fluorescence activated flow sorting followed by degenerate oligonucleotide-primed PCR (DOP-PCR). Painting of rabbit probes to human chromosomes and vice versa allowed a detailed analysis of the homology between these species. All rabbit chromosome paints, except for the Y paint, hybridized to human chromosomes. All human chromosome paints, except for the Y paint, hybridized to rabbit chromosomes. The results obtained revealed extensive genome conservation between the two species. Rabbit chromosomes 12, 19 and X were found to be completely homologous to human chromosomes 6, 17 and X, respectively. All other human chromosomes were homologous to two or sometimes three rabbit chromosomes. Many conserved chromosome segments found previously in other mammals (e.g. cat, pig, cattle, Indian muntjac) were also found to be conserved in rabbit chromosomes.

Animals↗
PubMed1999

Surfactant proteins A and D in premature baboons with chronic lung injury (Bronchopulmonary dysplasia). Evidence for an inhibition of secretion.

Surfactant proteins A and D (SP-A and SP-D) are believed to participate in the pulmonary host defense and the response to lung injury. In order to understand the effects of prematurity and lung injury on these proteins, we measured the amounts of SP-A and SP-D and their mRNAs in three groups of animals: (1) nonventilated premature baboon fetuses; (2) neonatal baboons delivered prematurely at 140 d gestation age (ga) and ventilated with PRN O(2); (3) animals of the same age ventilated with 100% O(2) to induce chronic lung injury. In nonventilated fetuses, tissue and lavage SP-A were barely detectable in baboons of 125 and 140 d ga, but they equaled or exceeded adult SP-A concentrations (g/g lung dry wt) at 175 d (term gestation, 185 d). In contrast, SP-D was readily detectable in tissue and lavage at 125 and 140 d ga. When the baboons of 140 d ga were ventilated for 10 d with 100% oxygen to produce chronic lung injury, the tissue concentration of SP-A was five times greater than that of normal adults; SP-D 16-times greater. Despite the sizable tissue pools of SP-A and SP-D, however, lavage SP-A was only 7% of that of normal adults and lavage SP-D just equaled the amount in normal adults. Nevertheless, because SP-D is normally in much lower concentration than is SP-A, their total comprised less than 12% of the SP-A and SP-D found in the lavage of a healthy adult. The results indicate that in chronic lung injury, SP-A is significantly reduced in the alveolar space. SP-D concentration in lavage is about equal to that in normal adults, possibly because of the 16-fold excess in tissue, but the total collectin pool in lavage is still significantly reduced. Because these collectins may bind and opsonize bacteria and viruses, decrements in their amounts may present additional risk to those premature infants who require prolonged periods of ventilatory support.

Analysis of Variance↗
PubMed1999

[Determination of trisomy 9p by molecular cytogenetic technology].

OBJECTIVE: To use molecular cytogenetic techniques for the determination of complex chromosomal aberrations that could not be distinguished by conventional cytogenetic method. METHODS: Chromosome painting, comparative genomic hybridization (CGH) and color banding chromosome analysis (RxFISH) were used to identify a case with chromosome 9 aberration by G-banding. RESULTS: The patient has a karyotype of 46,XX,9p+ by G-banding. Both chromosomes 9 were uniformly painted, including the extra segment on one of the 9p alleles. CGH revealed a duplication of the entire 9p short arm. After analysis with RxFISH the patient's karyotype could be accurately described as 46,XX,dup9p (p11-->p24::p24-->qter). CONCLUSION: The present report shows that some late technological developments in the field of cytogenetics can facilitate the study of the diseases linked to complex chromosomal aberrations and may find significant application in basic and clinical medical studies.

Child, Preschool↗
PubMed1999

[The construction and expression of 6B11scFv anti-idiotypic antibody and human granulocyte-macrophage-colony stimulating factor in Escherichia coli].

OBJECTIVE: To enhance the antigenicity of an anti-idiotypic single chain antibody 6B11 mimicking ovarian cancer antigen. METHODS: Using DNA recombinant technique, a recombinant fusion protein expression vector was constructed. This vector linked 6B11scFv cDNA and human GM-CSF with a linker. Protein productions were induced with the temperature change in E. Coli and analyzed with western blot. RESULTS: The expressed fusion protein can be reacted with both anti-human antibody and COC166-9(AB1 of 6B11). CONCLUSION: The recombinant fusion protein keeps the activities of both components and may be used as tumor vaccine for ovarian cancer.

Antibodies, Anti-Idiotypic↗
PubMed1999

[In vitro study of 6B11GM to induce cellular immunity in patients with ovarian carcinoma].

OBJECTIVE: In order to explore the possibility of ovarian carcinoma anti-idiotypic single chain antibody (6B11scFV) and human granueocyte-macrophage colony stimulating factor (hGM-CSF) fusion protein 6B11GM as tumor vaccine. METHODS: Mononuclear cells, T cells and monocyte used as antigen presenting cell (APC) were separated from peripheral blood, and tumor cells were obtained from ascitic fluid in the same patients. In vitro T cell proliferation and autologous tumor cell cytotoxicity assay were applied. RESULTS: 6B11GM could induce T cell proliferation in vitro which was antigen specific. Cytotoxicity of mononuclear cells to autologous tumor cells increased after primed with 6B11GM. CONCLUSION: 6B11GM could induce efficient cellular immunity in patients with ovarian carcinoma, hopefully may be used for ovarian carcinoma vaccine.

Adenocarcinoma↗
PubMed1999

[Effects of overexpression of p21WAF1/CIP1 on the malignant phenotype and apoptosis of human hepatocellular carcinoma cells].

OBJECTIVE: To study the effects of overexpression of p21WAF1/CIP1 on the malignant phenotype and apoptosis of human hepatocellular carcinoma cells. METHODS: p21WAF1/CIP1 gene was transfected into a human hepatocellular carcinoma cell line, HCC-9204 with p53 mutation. Flow cytometry (FLC), transmission electron microscopy (EM) and DNA electrophoresis were used to identity apoptosis. RESULTS: The transfected HCC-9204 showed increase in cell number in G1 phase of cell cycle. Apoptosis was confirmed by the appearance of apoptotic peak on FLC, characteristic ultrastructural changes on EM and DNA laddering on electrophoresis. Apoptotic cells accounted for 22.5% of the total p21 transfected cells. An alteration of the malignant phenotype of cells was evidenced by the loss of anchorage-independent growth in soft agar and reduction BrdU incorporation. CONCLUSION: The results indicate that the p21WAF1/CIP1 can inhibit proliferation and induce apoptosis of hepatocellular carcinoma cells with p53 mutation.

Apoptosis↗
PubMed1999

[Evaluation of atrial natriuretic peptide in differentiating benign and malignant pleural effusion].

OBJECTIVE: To discuss the value of atrial natriuretic peptide (ANP) in differentiating benign and malignant pleural effusion. METHODS: Direct radioimmunoassay was used to detect ANP of pleural effusion and serum in 30 tuberculous and 26 cancerous pleural effusion patients. RESULTS: The ANP in tuberculous and cancerous pleural effusion were (75 +/- 9) ng/L, (157 +/- 45) ng/L respectively, and significant difference was found (P < 0.001). The ANP of tuberculous pleural effusion was apparently lower [(75 +/- 9) ng/L] than serum [(170 +/- 37) ng/L], and significant difference was also found (P < 0.001). The ratio of ANP of pleural effusion to that of serum were 0.47 +/- 0.17, 0.99 +/- 0.46 respectively in tuberculous and cancerous pleural effusion patients. The sensitivity of ANP was 81% and specificity 100% in diagnosing malignant pleural effusion. CONCLUSIONS: Detecting ANP of pleural effusion is one of important methods for differentiating benign and malignant pleural effusion.

Adolescent↗
PubMed1999

[Advances of research on speech signal processing strategy in cochlear implant].

Cochlear implant is a new technology to restore hearing ability to totally deaf people. First of all, this paper presents its principle and system design. Then, the advances of research on its speech signal processing strategy is reviewed in detail. Finally, on the basis of preliminary results, further promising development in cochlear implant is proposed.

Algorithms↗
PubMed1999

[The modulation of collagen synthesis and expressions of type I and III collagen mRNAs in aorta smooth muscle cell by PDGF and heparin].

OBJECTIVE: The effect of platelet derived growth factor (PDGF) and heparin on the modulation of human aorta smooth muscle cell(hASMC) proliferation, collagen synthesis, expressions of type I and III collagen mRNAs as well as transforming growth factor-beta (TGF-beta) mRNA were investigated. METHODS: 3H-TdR and 3H-proline incorporation and Northern blot analysis were done. 3H-TdR and 3H-proline incorporation was statistically analyzed with t test among different experimental groups. RESULTS: In comparison to the control group, PDGF possessed the ability in promoting markedly the DNA synthesis (3H-TdR incorporation: PDGF group vs control, P < 0.01), synthesis and secretion of collagen protein (3H-proline incorporation of SMC and medium: PDGF group vs control, P < 0.01), expressions of type I and type III collagen mRNAs, and transforming growth factor mRNA in hASMC. Whereas heparin significantly decreased the DNA synthesis (heparin group vs control, P < 0.01), synthesis and secretion of collagen protein (heparin group vs control, P < 0.01) of hASMC in vitro. Heparin also inhibited the promoting effect of PDGF on DNA synthesis, the synthesis and secretion of collagen protein, and reduced the up-regulation of expressions of type I and type III collagen mRNAs as well as TGF-beta mRNA that stimulated by PDGF. CONCLUSIONS: PDGF could promote the collagen synthesis through upregulating type I and type III collagen mRNA expressions while heparin just inhibiting SMC DNA and collagen synthesis effected in the way of anti-atherosclerosis.

Anticoagulants↗
PubMed1998

Application of analytical and preparative high-speed counter-current chromatography for separation of alkaloids from Coptis chinensis Franch.

Analytical high-speed counter-current chromatography (HSCCC) was used for the systematic selection and optimization of the two-phase solvent system to separate alkaloids from Coptis chinensis Franch. The optimum solvent system thus obtained led to the successful separation of alkaloids from C. chinensis Franch by preparative HSCCC. One batch separation yielded four pure alkaloids, including palmatine, berberine, epiberberine and coptisine from the crude alkaloid extract.

Alkaloids↗
PubMed1998

Fighting nerve agent chemical weapons with enzyme technology.

The extreme toxicity of organophosphorous-based compounds has been known since the late 1930s. Starting in the mid-1940s, many nations throughout the world have been producing large quantities of organophosphorous (OP) nerve agents. Huge stockpiles of nerve agents have since developed. There are reportedly more than 200,000 tons of nerve agents in existence worldwide. There is an obvious need for protective clothing capable of guarding an individual from exposure to OP chemical weapons. Also, chemical processes that can effectively demilitarize and detoxify stored nerve agents are in great demand. The new and widely publicized Chemical Weapons Treaty requires such processes to soon be in place throughout the world. Biotechnology may provide the tools necessary to make such processes not only possible, but quite efficient in reducing the nerve agent dilemma. The following paper discusses some of the history in developing enzyme technology against nerve agents. Our laboratory has interest in enhancing the productivity and potential utility of these systems in both demilitarization and decontamination applications. Freeze-dried nerve agent-hydrolyzing enzyme preparations have been shown to be effective in decontaminating gaseous nerve agents. The direct incorporation of nerve agent-hydrolyzing enzymes within cross-linked polyurethane foam matrices during polymer synthesis has been shown to dramatically enhance the productivity of two different enzyme systems. The future goal of such work lies in building a bridge between the clinical application of nerve agent-hydrolyzing enzymes and practical processing techniques that may take advantage of the initial results already achieved in the laboratory.

Acetylcholinesterase↗
PubMed1998

[A rapid method for subtractive screening of hepatoma apoptotic cells cDNA library].

OBJECTIVE: To expedite the subtractive screening of human hepatoma apoptotic cells cDNA library. METHODS: The method of subtractive hybridization combined with dot blot hybridization was adopted. First, minus cDNA probe was used to screen the cDNA library, the minus clones that did not hybridize with the minus cDNA probe were picked up as the source of the second grade dot blot hybridization. Secondly, two probes of the plus and minus cDNA were used to screen the clones;the clones that only hybridize with the plus cDNA probe were picked up as the source of the third grade dot blot hybridization. RESULTS: Four clones were obtained and the lengths of the inserted cDNA fragments were about 1.5kb long. CONCLUSION: The results demonstrate this is a feasible, simple and quick method for subtractive screening of the cDNA library.

Apoptosis↗
PubMed1998

Structural basis for inactivating mutations and pH-dependent activity of avian sarcoma virus integrase.

Crystallographic studies of the catalytic core domain of avian sarcoma virus integrase (ASV IN) have provided the most detailed picture so far of the active site of this enzyme, which belongs to an important class of targets for designing drugs against AIDS. Recently, crystals of an inactive D64N mutant were obtained under conditions identical to those used for the native enzyme. Data were collected at different pH values and in the presence of divalent cations. Data were also collected at low pH for the crystals of the native ASV IN core domain. In the structures of native ASV IN at pH 6.0 and below, as well as in all structures of the D64N mutants, the side chain of the active site residue Asx-64 (Asx denotes Asn or Asp) is rotated by approximately 150 degrees around the Calpha---Cbeta bond, compared with the structures at higher pH. In the new structures, this residue makes hydrogen bonds with the amide group of Asn-160, and thus, the usual metal-binding site, consisting of Asp-64, Asp-121, and Glu-157, is disrupted. Surprisingly, however, a single Zn2+ can still bind to Asp-121 in the mutant, without restoration of the activity of the enzyme. These structures have elucidated an unexpected mechanism of inactivation of the enzyme by lowering the pH or by mutation, in which a protonated side chain of Asx-64 changes its orientation and interaction partner.

Amino Acid Sequence↗
PubMed1998

Protease inhibitor coinfusion with amyloid beta-protein results in enhanced deposition and toxicity in rat brain.

Amyloid beta-protein, Abeta, is normally produced in brain and is cleared by unknown mechanisms. In Alzheimer's disease (AD), Abeta accumulates in plaque-like deposits and is implicated genetically in neurodegeneration. Here we investigate mechanisms for Abeta degradation and Abeta toxicity in vivo, focusing on the effects of Abeta40, which is the peptide that accumulates in apolipoprotein E4-associated AD. Chronic intraventricular infusion of Abeta40 into rat brain resulted in limited deposition and toxicity. Coinfusion of Abeta40 with the cysteine protease inhibitor leupeptin resulted in increased extracellular and intracellular Abeta immunoreactivity. Analysis of gliosis and TUNEL in neuron layers of the frontal and entorhinal cortex suggested that leupeptin exacerbated Abeta40 toxicity. This was supported further by the neuronal staining of cathepsin B in endosomes or lysosomes, colocalizing with intracellular Abeta immunoreactivity in pyknotic cells. Leupeptin plus Abeta40 caused limited but significant neuronal phospho-tau immunostaining in the entorhinal cortex. Intriguingly, Abeta40 plus leupeptin induced intracellular accumulation of the more toxic Abeta, Abeta42, in a small group of septal neurons. Leupeptin infusion previously has been reported to interfere with lysosomal proteolysis and to result in the accumulation of lipofuscin, dystrophic neurites, tau- and ubiquitin-positive inclusions, and structures resembling paired helical filaments. Coinfusion of Abeta40 with the serine protease inhibitor aprotinin also increased diffuse extracellular deposition but reduced astrocytosis and TUNEL and was not associated with intracellular Abeta staining. Collectively, these data suggest that an age or Alzheimer's-related defect in lysosomal/endosomal function could promote Abeta deposition and DNA fragmentation in neurons and glia similar to that found in Alzheimer's disease.

Alzheimer Disease↗
PubMed1998

Effect of chloroquine and leupeptin on intracellular accumulation of amyloid-beta (A beta) 1-42 peptide in a murine N9 microglial cell line.

Murine N9 microglia accumulated A beta from media containing 0.67 microM A beta within 6 h. In N9 and in primary rat microglia, chloroquine, which disrupts lysosomal pH, increased A beta-induced accumulation of A beta, particularly A beta1-42. Leupeptin similarly enhanced A beta accumulation. The scavenger receptor antagonist fucoidan did not affect acute chloroquine-dependent A beta1-42 accumulation, demonstrating uptake of non-aggregated A beta. After prolonged incubations, chloroquine enhanced A beta multimer (8-12 kDa) accumulation, an effect inhibited by fucoidan. Disruptions of the lysosomal system enhance A beta and its multimer formation. Despite negligible effects of fucoidan on initial A beta uptake, chronic exposure inhibits multimer accumulation, demonstrating a role for scavenger receptor in multimer accumulation.

Amyloid beta-Peptides↗