Biomedical subjects

L Dong

Publications and source records attributed to L Dong.

At least 73 records · Page 4Linked to original sources

PubMed1999

Effect of ligustrazine on expression of adherent molecule CD49d and cyclin D2 in hematopoietic cells in acute radiation injured mice.

After irradiation by 8.0 Gy gamma-ray, each mouse was stomach-fed by 4 mg ligustrazine injection twice a day. On the 7th day after irradiation, CD49d expression in ligustrazine-treated group was significantly higher than that in control group (P < 0.01), and showed no difference from that in normal group (P > 0.05). On the 14th day after irradiation. CD49d expression was increased in control group, but decreased significantly in ligustrazine-treated group (P < 0.01). The expression of Cyclin D2 in spleen mononuclear cells (MNC) in ligustrazine-treated group was significantly higher than that in control group, but the ratio of G0 + G1 phase cells was significantly lower in ligustrazine-treated group (P < 0.01). This finding indicated that ligustrazine could increase the expression of adherent molecule on bone marrow hematopoietic cells and Cyclin D2 in spleen MNC, thereby promoting the growth of hematopoietic cells.

Animals↗

PubMed1999

Expression of adherent molecule and cyclin by ligustrazine in bone marrow of mice with immune-induced aplastic anemia.

Mice with immune-induced aplastic anemia (AA) were given 5 mg ligustrazine intraperitoneally twice a day. On the 14th day, the expression of CD49d, CD49c, cyclinD2 in bone marrow mononuclear cells (MNC) was examined by flow cytometry, and VCAM-1 on stromal cells was immunohistochemically measured by Strept Avidin-Biotin Complex (SABC). The expression of CD49d, CD49c, VCAM-1 and cyclinD2 in ligustrazine-treated group was significantly higher than that in AA group (P < 0.01), but the ratio of G0 + G1 phase cells was significantly lower than that in AA group (P < 0.01). The results showed that ligustrazine could improve the expression of adherent molecule and cyclin D2 in the bone marrow of mice with immune-induced aplastic anemia, thereby promoting the growth of hematopoietic cells.

Anemia, Aplastic↗

PubMed1999

Characterization of neutralizing anti-pre-S1 and anti-pre-S2 (HBV) monoclonal antibodies and their fragments.

Single-chain Fv fragments (scFv) were generated from two murine monoclonal antibodies directed to the neutralizing epitopes of the pre-S1 and pre-S2 region of hepatitis B virus, respectively, using different assembly cloning strategies. The scFv fragments were solubly expressed in E. coli. Dissociation constants were in the nanomolar range for all forms (whole IgG antibodies, Fab fragment and scFv fragments). The epitopes of both antibodies were mapped using solid phase peptide synthesis on continuous cellulose membranes and turned out to be linear determinants. The minimal epitope for the anti-pre-S2 antibody 1F6 was identified to be DPRVRGLYF (amino acid 133-141 of the pre-S region). For the anti-pre-S1 antibody MA 18/7 the minimal epitope proved to be the hexamer LDPAFR (amino acid 30-35 of the pre-S region). Complete substitutional analyses as well as truncation experiments revealed key residues for these antibody-antigen interactions. On the basis of those results we used computer-assisted modeling techniques to suggest models for both antibody-peptide interactions providing insight into the structural basis of these molecular recognitions.

Amino Acid Sequence↗

PubMed1999

Spot synthesis: observations and optimizations.

Positionally addressable syntheses of peptides on continuous cellulose membranes (spot synthesis) have often been reported in detail, but important questions dealing with synthesis quality, reproducibility and subsequent binding assays have largely been under-emphasized. In this report we have investigated some of these problems. The most important results were: (i) the signal intensity of ligate binding to cellulose-bound peptides and the affinity of the corresponding soluble peptides show good correlation, illustrated by three different ligate binding assays; (ii) reducing peptide density on the cellulose avoids the 'ring spot' effect, i.e. where less binding is observed in the spot-center compared to the rim. We recommend a peptide density of 10 nmol/cm2 as a reasonable starting point for further optimization; (iii) statistical analysis of binding assay reproducibility with more than 15000 peptides resulted in a mean standard signal deviation of 0.18; and (iv) optimization of side-chain deprotection revealed that a 30-min pretreatment of the cellulose with 90% trifluoroacetic acid followed by the standard deprotection protocol resulted in higher purity of the synthesized products.

Amino Acid Sequence↗

PubMed1999

Partial purification and characterization of the active entity responsible for inducing interleukin-6 production by human gingival fibroblasts from Mycoplasma salivarium cells.

The active entity responsible for inducing interleukin-6 production by human gingival fibroblasts was partially purified by ion-exchange chromatography from the water-soluble fraction of Mycoplasma salivarium cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the final preparation revealed one densely stained band with a molecular weight of 20.6 kilodaltons and two faint bands with molecular weights of 40.5 and 82.5 kilodaltons. The specific activity of the final preparation was 34-fold higher than that of the starting water-soluble fraction. The interleukin-6-inducing activity was destroyed by proteinase K and reduced 70% by lipoprotein lipase and heat treatment, but was not affected by deoxyribonuclease I or endoglucosidase D. The final preparation induced small amounts of tumor necrosis factor-alpha and interleukin-lbeta in a myelomonocytic cell line, THP-1 cells, but did not induce interleukin-6. The ability of Escherichia coli lipopolysaccharide to stimulate human gingival fibroblasts to release interleukin-6 was dependent upon the presence of serum in the assay medium, but that of the final preparation from M. salivarium was not. Thus, we partially purified the protein(s) from M. salivarium which were capable of stimulating human gingival fibroblasts to release interleukin-6 by a mechanism different from that of E. coli lipopolysaccharide.

Bacterial Proteins↗

PubMed1999

Detection of Mycoplasma fermentans in saliva sampled from infants, preschool and school children, adolescents and adults by a polymerase chain reaction-based assay.

Attempts were made to detect Mycoplasma fermentans in saliva sampled from 201 subjects (108 males and 93 females) aged from 4 months to 59 years by a polymerase chain reaction-based assay. M. fermentans was detected in saliva from 110 (54.7%) of 201 subjects, and 10 (28.6%) of 35 subjects aged from 4 months to 3 years. Of ten positive subjects, three were aged from 16 to 23 months and five were from 26 to 31 months. The incidence tended to increase with age up to the teens. The incidence was significantly greater in teenagers than in subjects aged from 7 to 12 years, but there was no significant difference in the incidence between the group of teenagers and each of the groups of subjects older than the teenagers. Thus, it was suggested that M. fermentans colonized the mouth at the age of about 16 months up to the age of 19 years.

Adolescent↗

PubMed1999

Transcriptional activation of mRNA of intercellular adhesion molecule 1 and induction of its cell surface expression in normal human gingival fibroblasts by Mycoplasma salivarium and Mycoplasma fermentans.

Lipoproteins in the cell membranes of both Mycoplasma salivarium and Mycoplasma fermentans were demonstrated to trigger the transcription of intercellular adhesion molecule-1 mRNA in normal fibroblasts isolated from human gingival tissue and to induce its cell surface expression by a mechanism distinct from that of Escherichia coli lipopolysaccharide. The lipid moiety of the lipoproteins was suggested to play a key role in the expression of the activity.

Bacterial Proteins↗

PubMed1999

Transcripts of immunoglobulin germline mu: an amplified myeloid and B-lymphoid common gene program in various leukemias.

To investigate the clinical implications of germline C mu transcription, the splice region between the 3' end of the enhancer and the first exon of immunoglobulin germline mu; was analyzed by RT-PCR in 63 samples from 59 patients with leukemia. Immunophenotypes of 33 samples from patients with acute leukemia were analyzed using a panel of these monoclonal antibodies: anti-immature/stem cell (HLA-DR, CD34); anti-mature myeloid (CD33, CD15); anti-T lymphoid (CD2, CD3, CD5, CD7, CD8), and anti-B lymphoid (CD10, CD19, CD20). Of the 63 samples, 33 (52%) contained germline C mu transcripts: 2/2 patients with chronic lymphocytic leukemia; 17/26 (65.4%) patients with acute myeloblastic leukemia; all 4 patients with chronic myelogenous leukemia in blast crisis and 1 in accelerated phase; 9/12 patients with acute lymphocytic leukemia. A clear correlation between germline transcripts and HLA-DR expression was observed among germline-positive cases (p < 0. 01). C mu expression and response to therapy clearly indicated that germline-mu-positive leukemia patients responded poorly to chemotherapy and had a worse clinical prognosis compared with C mu-negative patients (p < 0.01). After two courses of chemotherapy, 7/9 C mu-negative patients achieved complete remission compared to only 7/29 C mu-positive patients (p < 0.01). We conclude that the gene-regulating immunoglobulin germline C mu may be amplified in myeloid and B-lymphoid cells during leukemogenesis. Such genetic changes may be correlated with cellular terminal differentiation injury, resistance to chemotherapy and uncontrolled malignant cell proliferation.

Adolescent↗

PubMed1999

Transcriptional activation of E2F1 gene expression by 17beta-estradiol in MCF-7 cells is regulated by NF-Y-Sp1/estrogen receptor interactions.

17beta-Estradiol (E2) stimulated proliferation and DNA synthesis in MCF-7 human breast cancer cells, and this was accompanied by induction of E2F1 mRNA and protein levels. Analysis of the E2F1 gene promoter showed that the -146 to -54 region was required for E2-responsiveness in transient transfection assays, and subsequent deletion/mutation analysis showed that a single upstream GC-rich and two downstream CCAAT-binding sites were required for transactivation by E2. Gel mobility shift assays with multiple oligonucleotides and protein antibodies (for supershifts) showed that the -146 to -54 region of the E2F1 gene promoter bound Sp1 and NF-Y proteins in MCF-7 cells. The estrogen receptor (ER) protein enhanced Sp1 interactions with upstream GC-rich sites, and interactions of ER, Sp1, and ER/Sp1 with downstream DNA bound-NF-Y was investigated by kinetic analysis for protein-DNA binding (on- and off-rates), coimmunoprecipitation, and pulldown assays using wild-type and truncated glutathione S-transferase (GST)-Sp1 chimeric proteins. The results showed that Sp1 protein enhanced the Bmax of NF-Y-DNA binding by more than 5-fold (on-rate); in addition, the Sp1-enhanced NF-Y-DNA complex was further stabilized by coincubation with ER and the rate of dissociation (t1/2) was decreased by approximately 50%. Sp1 antibodies immunoprecipitated [35S]NF-YA after coincubation with unlabeled Sp1 protein. Thus, transcriptional activation of E2F1 gene expression in MCF-7 cells by E2 is regulated by multiprotein ER/Sp1-NF-Y interactions at GC-rich and two CCAAT elements in the proximal region of the E2F1 gene promoter. This represents a unique trans-acting protein complex in which ligand-dependent transactivation by the ER is independent of direct ER interactions with promoter elements.

Breast Neoplasms↗

PubMed1999

[Expression and its clinical significance of tissue factor pathway inhibitor and antithrombin-III in patients with hepatic inflammatory diseases].

OBJECTIVE: To investigate the change and clinical significance of tissue factor pathway inhibitor (TFPI) and antithrombin-III (AT-III) in the plasma of patients with hepatic inflammatory disease (HID). METHODS: The plasma levels and activation of TFPI and AT-III in patients with HID (Group I, n = 82) were compared to that in healthy people (Group II as control, n = 30). RESULTS: The plasma level of TFPI:Ag in Group I was higher (P < 0.05) and its activation was also increased dramatically (P < 0.01), the level of AT-III: A was lower in patients with chronic hepatitis B (P < 0.05) and no difference was found in other indices between the two groups. CONCLUSIONS: The elevation of TFPI:Ag and TFPI:A in hepatic inflammatory diseases is an indication of inflammation, and hepatic tissue injury in broad, the lower level of AT-III liver secretions.

Adult↗

PubMed1999

Reconstructing the duplication history of a tandem repeat.

One of the less well understood mutational transformations that act upon DNA is tandem duplication. In this process, a stretch of DNA is duplicated to produce two or more adjacent copies, resulting in a tandem repeat. Over time, the copies undergo additional mutations so that typically, multiple approximate tandem copies are present. An interesting feature of tandem repeats is that the duplicated copies are preserved together, making it possible to do "phylogenetic analysis" on a single sequence. This involves using the pattern of mutations among the copies to determine a minimal or a most likely history for the repeat. A history tries to describe the interwoven pattern of substitutions, indels, and duplication events in such a way as to minimize the number of identical mutations that arise independently. Because the copies are adjacent and ordered, the history problem can not be solved by standard phylogeny algorithms. In this paper, we introduce several versions of the tandem repeat history problem, develop algorithmic solutions and evaluate their performance. We also develop ways to visualize important features of a history with the goal of discovering properties of the duplication mechanism.

Algorithms↗

PubMed1999

[Hypoxia-induced increase in nerve activity of rabbit carotid body mediated by noradrenaline].

The responses of 39 hypoxia-sensitive units of chemoreceptive afferent in sinus nerve to noradrenaline (NA) and its antagonist were recorded in carotid body-sinus nerve preparations from 30 rabbits. The results are as follows. (1) Discharges of the units increased from 0.13 +/- 0.06 to 0.25 +/- 0.12 imp/s (P < 0.001, n = 19) upon lowering PO2 of modified Tyrode solution. (2) Adding NA (10(-6) mol/L) to the perfusate led to an increase in the unit discharge from 0.14 +/- 0.08 to 0.23 +/- 0.13 imp/s (P < 0.01, n = 19). (3) Prazosin (10(-6) mol/L) did not alter the basal frequency of chemosensory unit discharges under normoxic conditions (P > 0.05, n = 4). (4) Yohimbine (10(-6) mol/L) did not alter the basal frequency of chemosensory unit discharges under normoxic conditions (P > 0.05, n = 6). (5) Chemosensory responses to hypoxia were not altered after pretreatment with prazosin. (6) Chemosensory responses to hypoxia were inhibited by pretreatment with yohimbine. The present results suggest that (1) NA is not mainly concerned with spontaneous discharges of chemoreceptor sensitive to hypoxia, but does elicit an increase in spontaneous discharges, and (2) the increase of chemosensory unit discharges produced by hypoxia can be inhibited by yohimbine. It is likely that the excitatory action of hypoxia on chemoreceptive process is mediated by NA.

Animals↗

PubMed1999

[Study on the effect of ligustrazine on adherent molecule expression of bone marrow cells in immune-mediated aplastic anemia mice].

OBJECTIVE: To explore the effect of ligustrazine on the expression of adherent molecule of bone marrow cells in immune-mediated aplastic anemia(AA) mice. METHODS: Each immune-mediated AA mouse was intraperitoneally injected with 5 mg ligustrazine twice a day. On the 14th day, expressions of CD49d and CD49c in bone marrow mononuclear cells(MNC) were detected by flow cytometry, and VCAM-1 on stromal cells by immunohistochemistry SABC. RESULTS: Expressions of CD49d, CD49e and VCAM-1 were significantly lower in AA group than in normal group(t = 11.96, 17.18 and 7.09 respectively, P < 0.001), and were much higher in ligustrazine treated group than in non-treated group(t = 9.05, 14.61 and 6.91 respctively, P < 0.001). Expressions of CD49d and VCAM-1 were in the normal range in ligustrazine group. CONCLUSIONS: Ligustrazine can increase the expression of adherent molecule of bone marrow cells in immune-mediated AA mice, thus promote the growth of hematopoietic cells.

Anemia, Aplastic↗

PubMed1999

[Effect of composite blood-activating decoction on expression of adherent molecule and cyclin in bone marrow hematopoietic cells in mice of immune-induced aplastic anemia].

OBJECTIVE: To study the effect of composite blood-activating decoction (CBAD) on expression of adherent molecule CD49 d and cyclin D2 in bone marrow hematopoietic cells in experimental immune-mediated aplastic anemia (AA) mice. METHODS: After the model of AA was established, the animals were fed with 0.2 ml of 100% CBAD, twice a day for 12 days. Te CD49 d and cyclin D2 expression level of bone marrow hematopoietic cells in model mice were measured by flow cytometor analysis system at the 13th day of experiment. RESULTS: CD49 d expression level in CBAD group was significantly higher than that in the AA group (P < 0.05), and was similar to that in the normal group (P > 0.05). The expression of cyclin D2 in CBAD group was significantly higher than that in the AA group (P < 0.01), but the cell count of G0 + G1 phase was significantly lower in the CBAD group, as compared with the AA group, P < 0.01. CONCLUSION: CBAD can increase the expression of adherent molecule CD49 d and cyclin D2 in bone marrow hematopoietic cells, and promote the growth of hematopoietic cells.

Anemia, Aplastic↗

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↗

PubMed1998

Glutamate potentiates the toxicity of mutant Cu/Zn-superoxide dismutase in motor neurons by postsynaptic calcium-dependent mechanisms.

Mutations in the Cu/Zn-superoxide dismutase (SOD-1) gene are responsible for a subset of familial cases of amyotrophic lateral sclerosis. Using a primary culture model, we have demonstrated that normally nontoxic glutamatergic input, particularly via calcium-permeable AMPA/kainate receptors, is a major factor in the vulnerability of motor neurons to the toxicity of SOD-1 mutants. Wild-type and mutant (G41R, G93A, or N139K) human SOD-1 were expressed in motor neurons of dissociated cultures of murine spinal cord by intranuclear microinjection of plasmid expression vector. Both a general antagonist of AMPA/kainate receptors (CNQX) and a specific antagonist of calcium-permeable AMPA receptors (joro spider toxin) reduced formation of SOD-1 proteinaceous aggregates and prevented death of motor neurons expressing SOD-1 mutants. Partial protection was obtained by treatment with nifedipine, implicating Ca2+ entry through voltage-gated calcium channels as well as glutamate receptors in potentiating the toxicity of mutant SOD-1 in motor neurons. Dramatic neuroprotection was obtained by coexpressing the calcium-binding protein calbindin-D28k but not by increasing intracellular glutathione levels or treatment with the free radical spin trap agent, N-tert-butyl-alpha-phenylnitrone. Thus, generalized oxidative stress could have contributed in only a minor way to death of motor neurons expressing the mutant SOD-1. These studies demonstrated that the toxicity of these mutants is calcium-dependent and provide direct evidence that calcium entry during neurotransmission, coupled with deficiency of cytosolic calcium-binding proteins, is a major factor in the preferential vulnerability of motor neurons to disease.

2-Amino-5-phosphonovalerate↗

PubMed1998

A novel response to dioxin. Induction of ecto-ATPase gene expression.

We used differential display to discover a new gene that the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) regulates in mouse hepatoma cells. Its predicted amino acid sequence suggests that the gene encodes an ecto-ATPase that contains multiple glycosylation sites, conserved cysteine residues, and apyrase conserved regions. cDNA expression experiments in mouse hepatoma cells confirm that the new gene encodes an ecto-ATPase. Wild-type mouse hepatoma cells contain both constitutive and TCDD-inducible ecto-ATPase activity. Induction of ecto-ATPase gene expression by TCDD is direct and occurs at the transcriptional level. Studies in mutant hepatoma cells indicate that induction requires both the aromatic hydrocarbon receptor (AhR) and the AhR nuclear translocator (Arnt). Furthermore, induction requires AhR's transactivation domain, but not that of Arnt. Our findings reveal new aspects of dioxin's biological effects and TCDD-dependent gene regulation.

Adenosine Triphosphatases↗

PubMed1998

Detection of Mycoplasma salivarium and Mycoplasma fermentans in synovial fluids of temporomandibular joints of patients with disorders in the joints.

Thirty-six synovial fluid samples of temporomandibular joints were obtained from 33 patients with pain and anterior disk displacement (closed lock) in the joints. DNAs were prepared from the samples and amplified by a PCR-based assay specific for Mycoplasma salivarium or Mycoplasma fermentans. Of the 36 samples, five (14%), three (8%), and 19 (53%) were positive for M. salivarium, M. fermentans and both, respectively.

Adolescent↗