Biomedical subjects

Z Dong

Publications and source records attributed to Z Dong.

At least 91 records · Page 5Linked to original sources

PubMed2001

[Influence of anisodamine on guinea pig experimental nasal hypersensitivity].

OBJECTIVE: To observe the influence of anisodamine on guinea pig experimental nasal hypersensitivity. METHOD: Experimental animals were divided into normal control group, TDI group, reserpine group and anisodamine group. The scores of symptom of nose and the cytologic changes of nasal mucosa were parameters of observing. RESULT: The nasal symptom of reserpine group was significantly stronger than the TDI group, and the eosinophilia evidently increased (both P < 0.01). The nasal symptom of the anisodamine group reduced and the eosinophilia decreased. It is significantly difference between the TDI group and the reserpine group (both P < 0.01). CONCLUSION: Anisodamine may play a role in therapy of the experimental nasal hypersensitivity with hyperfunction of parasympathetic nerve.

Animals↗

PubMed2001

[Expression and the role of vascular endothelial growth factor mRNA in nasal polyps].

OBJECTIVE: To explore the pathogenesis of nasal polyps, the aim of this study is to detect the expression of vascular endothelial growth factor (VEGF) in nasal polyp(NP) tissue, and compare these findings with normal nasal turbinate. METHOD: We examined the expression of VEGF in human nasal polyps from patients underwent nasal polypectomy (n = 7) and nasal turbinate from patients with snoring (n = 6). VEGF mRNA expression was determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULT: VEGF mRNA expression was significantly stronger in the eight NP than in the turbinate tissue group (P < 0.05). CONCLUSION: We conclude that VEGF expression is upregulated in NP, which suggests a potential role of VEGF in the formation and growth and recrudescence of NP.

Adult↗

PubMed2001

[Cloning of trehalose-6-phosphate synthase gene from S. cerevisiae and its plant expression vector construction].

Total RNA, mRNA were isolated from baker's yeast S. cerevisiae, the cDNA was prepared with AMV Reverse Transcriptase from the total mRNA. The gene of trehalose-6-phosphate synthase was cloned from the cDNA with PCR amplification. The gene was sequenced and the results showed that the tpsl gene contains 1507 nucleotides and 99.6% identity with S. cerevisiae. The tps1 gene was constructed on the plant expression vector pBin438.

Base Sequence↗

PubMed2001

[Empty nose syndrome].

OBJECTIVE: The aim of this article is to present the concept of empty nose syndrome(ENS) and help ENT doctors take care of regular nasal turbinate surgery. METHODS: Fourteen patients who was diagnosed as ENS in our department were reviewed retrospectively. All patients had undergone various forms of nasal surgery (all had had turbinectomy). Their age ranged from 13 to 52 years. All patients were treated conservatively, among these patients 5 subjects who had more serious symptoms received submucous and subperiostal nasal implantation with ilium. RESULTS: All patients had nasal obstruction and dryness of nasal cavity, nasopharynx and oto-pharynx in 6 months--5 years after their first nasal surgery, some presented symptoms of depression. Nasoscope examination showed all patients had a cylindrically enlarged nasal cavity. Conservative treatment was effective in most cases. The effectiveness of operative treatment was encouraging during short-term follow-up. CONCLUSION: Extensive turbinectomy may cause secondary nasal mucosal atrophy and a series of subsequent symptoms. The presentation of this concept is to remind the ENT doctors prudently performing turbinectomy to avoid the occurrence of irreversible injury to the nasal cavity.

Adolescent↗

PubMed2001

[Expression and distribution of Aquaporin 1 in the nasal polyps].

OBJECTIVE: To confirm the expression and distribution of Aquaporin 1 (AQP1) in the nasal polyps and to investigate the relation between AQP1 and the nasal polyp edema. METHODS: fourteen cases of normal inferior turbinates and 26 cases of nasal polyps were used. The expression and distribution of AQP1 in nasal polyps were examined by immunohistochemical technique. RESULTS: The level of AQP1 in the epithelial cells and serous cells from nasal polyps was higher than that in inferior turbinates, and the level of AQP1 in the epithelial cells and cilium cells from inferior turbinate was higher than that in nasal polyps. CONCLUSION: There is close relationship between AQP1 and nasal polyp edema.

Adult↗

PubMed2001

[Expression of the inducible isoform of nitric oxide synthase mRNA and the role in nasal polyps].

OBJECTIVE: To explore the pathogenesis of nasal polyps. The aim of this study is to detect the expression of inducible isoform of nitric oxide synthase (iNOS) in nasal polyp tissue, and to compare these findings with that in normal nasal turbinate. METHODS: We examined the expression of iNOS in human nasal polyps from patients undergoing nasal polypectomy (n = 8) and nasal turbinectomy(n = 6). The iNOS mRNA expression was determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The iNOS mRNA expression was significantly stronger in the nasal polyps (NP) than that in turbinate tissues (P < 0.01). CONCLUSIONS: iNOS expression is upregulated in NP, which indicate that iNOS and NO may play a potential role in the formation and growth of NP.

Adult↗

PubMed2000

Phorbol ester-induced expression of airway squamous cell differentiation marker, SPRR1B, is regulated by protein kinase Cdelta /Ras/MEKK1/MKK1-dependent/AP-1 signal transduction pathway.

The transcriptional induction of SPRR1B by phorbol 12-myristate 13-acetate (PMA) is mainly mediated by the first -152-base pair 5'-flanking region containing two functional AP-1 sites. In this study, we have analyzed the signaling pathways that mediate the induction in tracheobronchial epithelial cells. PKC inhibitor ablated PMA-stimulated expression of endogenous SPRR1B and reporter gene expression driven by SPRR1B promoter. PKC activator promoted the transcription. The dominant negative protein kinase Cdelta (dn-PKCdelta) and rottlerin (PKCdelta inhibitor) completely suppressed PMA-stimulated promoter activity. dn-Ras or dn-MEKK1 inhibited PMA-stimulated promoter activity, while their corresponding constitutively active mutants augmented it. dn-c-Raf-1 did not have any effect on reporter gene expression. Since MEKK1 activates multiple parallel pathways, we examined involvement of JNK/SAPK, p38, and MKK1 in promoter regulation. Co-expression of the dominant negative forms of MKK4, MKK7, JNK/SAPK, MKK3, MKK6, or p38alpha did not suppress PMA-stimulated reporter gene expression. However, MKK1 inhibitors UO126 and PD98095 suppressed gene expression. Consistent with this, expression of dn-MKK1 strongly suppressed PMA-stimulated promoter activity, while the constitutively active MKK1 augmented it. However, MKK1-mediated induction of SPRR1B probably does not depend on extracellular signal-regulated kinases 1 and 2, suggesting the requirement of another kinase(s). dn-c-Jun mutants abolished PMA-stimulated expression supporting an important role for AP-1 proteins in SPRR1B expression. Together, these results suggest that a PKCdelta/Ras/MEKK1/MKK1-dependent/AP-1 pathway regulates the PMA-inducible expression of the SPRR1B in tracheobronchial epithelial cells.

Cell Differentiation↗

PubMed2000

Humanization of a mouse monoclonal antibody neutralizing TNF-alpha by guided selection.

With the advent of phage display antibody libraries, humanization of murine antibodies can be achieved by epitope guided selection. In present study, guided selection was applied to the humanization of the mouse mAb Z8 that is directed to human TNF-alpha and can neutralize the cytotoxicity of TNF-alpha. First, the Z8 Fd gene was paired as a template with a repertoire of human kappa chains, and displayed on the filamentous phage, forming a hybrid phage antibody library. Selected by four rounds of panning against TNF-alpha, hybrid antibody fragments that bound to TNF-alpha and contained human kappa chains were obtained. Meanwhile human Fd genes were selected by pairing the human Fd repertoire with the Z8 kappa chain and performing the same procedure of panning. One of the isolated human Fd genes (huFd2), which showed the strongest reactivity, was chosen to pair with 12 of selected human kappa chains. Two of the resulting human Fabs (huFd2-hukappa1 and huFd2-hukappa2), with same Fd and different kappa chains, bound to TNF-alpha specifically. Their human origin was proved by ELISA and sequencing analysis. The human Fabs competitive ELISA and in vitro TNF-alpha neutralization assay demonstrated that the human Fabs resembled its parental mouse mAb Z8 in that they both recognized the same epitope and neutralized the cytotoxicity of TNF-alpha. These results suggest that guided selection is a promising strategy in murine mAb humanization.

Amino Acid Sequence↗

PubMed2000

ERKs and p38 kinases mediate ultraviolet B-induced phosphorylation of histone H3 at serine 10.

Histone H3 is the core protein of the nucleosome. Phosphorylation of H3 involves immediate early gene expression, chromatin remodeling, and chromosome condensation during mitosis. Very recently, Rsk2 or MSK1 kinase-mediated phosphorylation of H3 at serine 10 was reported. In the present study, we show that both ERKs and p38 kinase may mediate ultraviolet B-induced phosphorylation of H3 at serine 10. PD 98059, a MEK1 inhibitor, and SB 202190, a p38 kinase inhibitor, efficiently inhibited ultraviolet B-induced phosphorylation of H3. Phosphorylation of H3 was also inhibited in cells expressing dominant negative mutant (DNM) ERK2 and DNM p38 kinase. In contrast, no inhibition of H3 phosphorylation in Jnk1 or Jnk2 knockout cells (Jnk1(-/-) or Jnk2(-/-)) and cells expressing DNM JNK1 was observed. More importantly, incubation of active ERK2 or p38 kinase with H3 protein resulted in phosphorylation of H3 at serine 10 in vitro. These results suggest that ERK and p38 kinase are at least two important mediators of phosphorylation of H3 at serine 10.

Animals↗

PubMed2000

ERKs and p38 kinase phosphorylate p53 protein at serine 15 in response to UV radiation.

Phosphorylation of the p53 tumor suppressor protein is likely to play an important role in regulating its activity. Serine 15 phosphorylation of p53 leads to a stabilization of p53 by reducing its interaction with murine double minute 2, a negative regulatory partner. Recently, p53 was reported to be activated and phosphorylated at serine 15 following UV radiation. However, the signaling pathway that mediates UV-induced phosphorylation is less well characterized. Here, we provide evidence that UVB-induced phosphorylation of p53 at serine 15 is mediated directly by ERKs and p38 kinase. We find that in a mouse JB6 epidermal cell line, ERKs and p38 kinase form a complex with p53 following UVB radiation. Inhibition of ERKs or p38 kinase activity by the use of a dominant negative mutant of ERK2 or p38 kinase or their respective specific inhibitor, PD98059 or SB202190, results in abrogation of UVB-induced phosphorylation of p53 at serine 15. Strikingly, incubation of UVB-activated ERKs or p38 kinase immunoprecipitated complex with exogenous p53 shows serine 15 phosphorylation of both exogenous and co-precipitated endogenous p53 protein. Additionally, active recombinant ERK1/2 and p38 kinase but not JNKs are also able to phosphorylate p53 at serine 15 in vitro. Furthermore, pretreatment of cells with PD98059 or SB202190 blocks p53-dependent transcription activity but increases the level of p53 co-precipitated murine double minute. These results strongly suggest that both ERKs and p38 kinase have a direct role in UVB-induced phosphorylation of p53 at serine 15 in vivo.

Animals↗

PubMed2000

Major DNA replication initiation sites in the c-myc locus in human cells.

DNA replication initiation sites and initiation frequencies over 12. 5 kb of the human c-myc locus, including 4.6 kb of new 5' sequence, were determined based on short nascent DNA abundance measured by competitive polymerase chain reaction using 21 primer sets. In previous measurements, no comparative quantitation of nascent strand abundance was performed, and distinction of major from minor initiation sites was not feasible. Two major initiation sites were identified in this study. One predominant site has been located at approximately 0.5 kb upstream of exon 1 of the c-myc gene, and a second new major site is located in exon 2. The site in exon 2 has not been previously identified. In addition, there are other sites that may act as less frequently used initiation sites, some of which may correspond to sites in previous reports. Furthermore, a comparison of the abundance of DNA replication intermediates over this same region of the c-myc locus between HeLa and normal skin fibroblast (NSF) cells indicated that the relative distribution was very similar, but that nascent strand abundance in HeLa cells was approximately twice that in NSF relative to the abundance at the lamin B2 origin. This increased activity at initiation sites in the c-myc locus may mainly be influenced by regulators at higher levels in transformed cells like HeLa.

Cells, Cultured↗

PubMed2000

Serine protease inhibitors suppress cytochrome c-mediatedcaspase-9 activation and apoptosis during hypoxia-reoxygenation.

We have shown that reoxygenation of hypoxic rat kidney proximaltubule cells leads to apoptosis. This is mediated by translocation ofBax from the cytosol to mitochondria, accompanied by release ofmitochondrial cytochrome c (cyt.c). The present studyhas examined the proteolytic mechanisms responsible for apoptosisduring hypoxia-reoxygenation. Caspases were activated duringhypoxia, as shown by cleavage of fluorogenic peptide substrates. By5 h caspase-3-like activity to cleave carbobenzoxy-Asp-Glu-Val-Asp-7-amino-4-trifluoromethyl coumarin was increased approx. 30-fold. Thiswas accompanied by specific processing of pro-caspase-3, -8 and -9 intoactive forms. Caspase activation during hypoxia was blocked bycarbobenzoxy-Val-Ala-Asp-fluoromethyl ketone and overexpression of Bcl-2. Of particular interest, caspase activation was also suppressed bythe chymotryptic inhibitors N-tosyl-L-phenylalaninechloromethyl ketone (TPCK) and Ala-Pro-Phe chloromethyl ketone (APF),and the general serine protease inhibitor 4-(2-aminoethyl)benzenesulphonyl fluoride. Inhibition of caspase activationby these compounds resulted in arrest of apoptosis. On the other hand,the serine protease inhibitors did not prevent release of mitochondrialcyt.c during hypoxia, suggesting that these compounds blockeda critical step in post-mitochondrial caspase activation. Furtherstudies using an in vitro reconstitution model showedthat cyt. c/dATP stimulated caspase-9 processing and downstreamcaspase activation were significantly suppressed in the presence ofTPCK and APF. Based on these results, we speculate that serineproteases may be involved in post-mitochondrial apoptotic events thatlead to activation of the initiator, caspase-9.

Adenosine Triphosphate↗

PubMed2000

Developmental switches in chemokine response profiles during B cell differentiation and maturation.

Developing B cells undergo dramatic changes in their responses to chemoattractant cytokines (chemokines) and in expression of chemokine receptors. Bone marrow pre-pro-B cells (AA4.1(+)/natural killer 1.1(-) Fraction A cells) and cells capable of generating pro-B colonies in the presence of interleukin 7 and flt3 ligand migrate to thymus-expressed chemokine (TECK), a response lost in later stages of B cell development. B cell-attracting chemokine 1 (BCA-1) responses correlate with CXC chemokine receptor (CXCR)5 expression, are first displayed by a pro-B cell subset, are lost in pre-B cells, and then are regained just before and after egress from the marrow. All peripheral B cell subsets, including follicular and germinal center as well as marginal zone and peritoneal B1 B cells, respond to BCA-1, implying that responsiveness to this follicular chemokine is not sufficient to predict follicle localization. Responses to the CC chemokine receptor (CCR)7 ligands secondary lymphoid tissue chemoattractant (SLC) and macrophage inflammatory protein (MIP)-3beta, implicated in homing to lymphoid tissues, are upregulated before B cell exit from the marrow, but increase further in the periphery and are shared by all peripheral B cells. In contrast, responsiveness to MIP-3alpha and expression of CCR6 are acquired only after emigration to the periphery and during maturation into the recirculating B cell pool. Chemotaxis to stromal cell-derived factor 1alpha is observed at all stages of B cell differentiation. Thus, unique patterns of chemokine responses may help define developing B cell populations and direct their maturation in the marrow and migration to the periphery.

Animals↗

PubMed2000

Involvement of nuclear factor of activated T cells activation in UV response. Evidence from cell culture and transgenic mice.

Mammalian cells respond to UV radiation by signaling cascades leading to activation of transcription factors, such as activated protein 1, NFkappaB, and p53, a process known as the "UV response." Nuclear factor of activated T cells (NFAT) was first identified as an inducible nuclear factor in immune response and subsequently found to be expressed in other tissues and cells. To date, however, the regulation and function of NFAT in tissues and cells, other than the immune system, are not well understood. In this study, we demonstrate that UV radiation activates NFAT-dependent transcription through a calcium-dependent mechanism in mouse epidermal JB6 cell lines, as well as in the skin of NFAT-luciferase reporter transgenic mice. Exposure of JB6 cells to UV radiation leads to the transactivation of NFAT in a dose-dependent manner. A23187 had a synergistic effect with UV for NFAT induction, whereas pretreatment of cells with nifedipine, a calcium channel blocker, dramatically impaired the NFAT activity induced by either UV or UV plus A23187. Calcium-dependent activation of NFAT by UV was further confirmed by an in vivo study using NFAT-luciferase reporter transgenic mice. These results demonstrated that UV radiation is a strong activator for skin NFAT transactivation through calcium-dependent pathways, suggesting that NFAT activation may be a part of the UV response.

Animals↗

PubMed2000

Influences of amino acid sequences in FR1 region on binding activity of the scFv and Fab of an antibody to human gastric cancer cells.

Murine anti-gastric cancer mAb 3H11 has promising clinical applications. In this work, engineering of 3H11 scFv and Fab was conducted to increase its usefulness. 3H11 scFv and Fab were constructed by PCR amplification of the V-domains with degenerate primers for FR1. The bacterially expressed 3H11 Ab fragments showed no antigen binding activity. Then the N-terminal sequences of V regions were mutated to the 3H11 original sequence. The expressed scFv and Fab in bacterial culture supernatant showed binding activity to gastric cancer cells. Comparing the expression of unmutated and mutated 3H11 Fab, we found that the sequence changes of the V region N terminus introduced by PCR may seriously affect antigen binding but not the expression of antibody. Correction of either VL or VH N-terminal sequences can partially restore the antigen binding activity (61% for VL and 73% for VH).

Amino Acid Sequence↗

PubMed2000

Stress-induced generation of N-acylethanolamines in mouse epidermal JB6 P+ cells.

It has long been known that N-acylethanolamine phospholipids [N-acylphosphatidylethanolamine (N-acyl PE)] and N-acylethanolamines (NAEs) accumulate in mammalian tissues undergoing degenerative membrane changes associated with necrosis. Here we studied the effects of stress factors (UVB irradiation and serum deprivation) on the endogenous levels of N-acyl PE and NAE in mouse epidermal JB6 P(+) cells. We found that 16:0, 18:0, 18:1,n-9 and 18:1,n-7 are the predominant amide-linked fatty acids in both N-acyl PE and NAE in these cells. UVB irradiation and serum deprivation resulted in significantly increased levels of N-acyl PE and NAE, especially 18:1, n-9 N-acyl PE and NAE. UVB challenge increased the cellular content of anandamide (20:4,n-6 NAE), but this increase was the lowest of all NAEs measured. Serum deprivation resulted in a decreased cellular anandamide level, as well as a decrease in 20:4,n-6 N-acyl PE. Interestingly, the replacement of serum-free medium with medium containing 5% (v/v) fetal calf serum after 36 h of serum deprivation restored N-acyl PE and NAE levels almost completely within 4-8 h. These data suggest the involvement of N-acyl PE and NAE in cellular responses to stress.

Animals↗

PubMed2000

Therapy of human pancreatic carcinoma implants by irinotecan and the oral immunomodulator JBT 3002 is associated with enhanced expression of inducible nitric oxide synthase in tumor-infiltrating macrophages.

We determined the therapeutic effect of irinotecan (CPT-11) combined with the immunomodulator JBT 3002, a synthetic bacterial lipopeptide (N-acylated derivative of psi-amino-C1-C3-alkane-sulfonic acid), against highly metastatic human pancreatic carcinoma cells injected into the pancreas of athymic nude mice. Mice received four courses consisting of three daily oral doses of JBT 3002, followed by once weekly i.p. injection of CPT-11. Control mice were treated with CPT-11 alone, JBT 3002 alone, or saline. Tumor growth and metastasis were assessed by gross pathology and confirmed by histological examination. Treatment with CPT-11 alone significantly decreased the median volume of pancreatic tumors and the incidence of metastasis, whereas treatment with only JBT 3002 did not. The combination therapy of CPT-11 plus JBT 3002 decreased tumor volume and incidence of metastasis significantly more than CPT-11 alone. The number of apoptotic cells (terminal deoxynucleotidyl transferase-mediated nick end labeling assay), the number of scavenger-receptor-positive macrophages, and expression level of inducible nitric oxide synthase (iNOS) within lesions directly correlated with therapeutic effects. Indeed, the in vitro incubation of tumor cells with macrophages activated by JBT 3002 plus IFN-gamma produced a significant lysis of tumor cells that could be blocked by a specific inhibitor of iNOS. Collectively, these data demonstrate that the oral administration of the immunomodulator JBT 3002 combined with i.p. injection of CPT-11 can decrease the growth of human pancreatic carcinoma and the incidence of metastasis in nude mice by both a direct antitumor effect and the activation of iNOS in infiltrating macrophages.

Adjuvants, Immunologic↗

PubMed2000

Effects of food factors on signal transduction pathways.

Consumption of plant-derived foods, especially fruits and vegetables, has been linked to decreased risk of cancer. Laboratory studies with animals and cells in culture have shown cancer preventive activity of chemicals isolated from soy, tea, rice and many green, yellow and orange fruits and vegetables. Using cell culture, transgenic mice and knockout mice models to examine the anti-cancer effects of these dietary factors at the molecular level, we found that (11) (-)-epigallocatechin gallate (EGCG), the major active polyphenol in green tea, and theaflavins, the major active components in black tea, inhibit epidermal growth factor (EGF)- or 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced JB6 cell transformation. At the same dose range that inhibited cell transformation, EGCG and theaflavins inhibited activator protein-1 (AP-1) activation. These compounds also inhibited ultraviolet B (UVB)-induced AP-1 and nuclear factor kappa B (NFkappaB)-dependent transcriptional activation; (2) resveratrol, found at high levels in grapes, inhibited cell transformation through the induction of apoptosis, mediated through JNK and p53-dependent pathways; (3) inositol hexaphosphate (InsP6), an active compound from rice and other grains, inhibited TPA- or EGF-induced transformation and signal transduction through its effects on phosphatidylinositol-3 kinase (PI-3) kinase; (4) phenethyl isothiocyanate (PEITC), which occurs as a conjugate in certain cruciferous vegetables, inhibited cell transformation corresponding with the induction of apoptosis. An elevation of p53 is required for PEITC-induced apoptosis. Our studies indicated that the chemopreventive effect of these food factors may be mediated by their effects on different signal transduction pathways; (5) retinoids (vitamin A and its metabolites) inhibited tumor promoter-induced cell transformation and tumor promotion in transgenic mice through the inhibition of AP-1 action but not through the activation of retinoic acid response element (RARE).

Anticarcinogenic Agents↗