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Biomedical subjects

J M Wang

Publications and source records attributed to J M Wang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Isolation and initial characterization of 13(2)-hydroxychlorophyll a induced by cyclohexanedione derivatives in tobacco cell suspension cultures.

This paper reports that a new photobleaching compound, 2-(2-chloro-5-propoxycarbonylphenyl)aminomethylidene-5-5-dim ethyl- cyclohexane-1,3-dione (RWH-21), stimulates accumulation of 13(2)-hydroxychlorophyll a in cultured tobacco cells. This was shown based on isolation of 13(2)-hydroxychlorophyll a from pigment extracts of cultured tobacco cells by diode-array HPLC and subsequent fast atom bombardment mass spectrometry analysis. 13(2)-Hydroxychlorophyll a rapidly accumulates in tobacco cells both in the light and dark in the presence of RWH-21 (50 microM). Analysis of 13(2)-hydroxychlorophyll a formation in tobacco cells indicates that 13(2)-hydroxychlorophyll a is rapidly accumulated within 20 h incubation time both in the dark and light. Although the amount of 13(2)-hydroxychlorophyll a is continuously increased in the dark, the amount of 13(2)-hydroxychlorophyll a decreased remarkably in the light after 20 h incubation. Analysis of 13(2)-hydroxychlorophyll a formation and lipid peroxidation by determination malondialdehyde in tobacco cells suggests that RWH-21-induced 13(2)-hydroxychlorophyll a has the potential to cause a photodynamic action in cultured tobacco cells.

Cells, Cultured↗
PubMed2000

A burgeoning family of biological mediators: chemokines and chemokine receptors.

Chemokines are a superfamily of pro-inflammatory polypeptide cytokines that selectively attract and activate different cell types. Most of its members are small proteins that exhibit conserved cysteines in specific positions. Chemokines activate cells through their binding to shared or unique cell surface receptors which belong to the seven-transmembrane (STM), G-protein-coupled receptors (GPCRs). The large number of chemokines and chemokine receptors are indicative of the importance of these molecules in a variety of pathophysiological conditions.

Animals↗
PubMed1999

Insulin-like growth factor-1 affects expressions of cyclin-dependent kinase 5 and its activator p35 in reperfused rat brain.

Insulin-like growth factor-1 (IGF-1) was applied topically on the brain surface of reperfused rat brain after 60 min of transient middle cerebral artery (MCA) occlusion. In contrast to the cases treated with vehicle, the infarct volume was greatly reduced at 24 h of reperfusion by the treatment with IGF-1. Immunohistochemical analysis in the MCA territory showed that the increase of cyclin-dependent kinase 5 (cdk5) was greatly reduced, and that the decrease of the critical regulatory subunit of cdk5, p35, was preserved with treatment of IGF-1. The present results suggest that IGF-1 has a significant effect on ameliorating brain injury after transient focal brain ischemia with affecting the expressions of cdk5 and its activator p35.

Animals↗
PubMed1999

Utilization of two seven-transmembrane, G protein-coupled receptors, formyl peptide receptor-like 1 and formyl peptide receptor, by the synthetic hexapeptide WKYMVm for human phagocyte activation.

Trp-Lys-Tyr-Val-D-Met (WKYMVm) is a synthetic leukocyte-activating peptide postulated to use seven-transmembrane, G protein-coupled receptor(s). In the study to characterize the receptor(s) for WKYMVm, we found that this peptide induced marked chemotaxis and calcium flux in human phagocytes. The signaling induced by WKYMVm in phagocytes was attenuated by high concentrations of the bacterial chemotactic peptide fMLP, suggesting that WKYMVm might use receptor(s) for fMLP. This hypothesis was tested by using cells over expressing genes encoding two seven-transmembrane receptors, formyl peptide receptor (FPR) and formyl peptide receptor-like 1 (FPRL1), which are with high and low affinity for fMLP, respectively. Both FPR- and FPRL1-expressing cells mobilized calcium in response to picomolar concentrations of WKYMVm. While FPRL1-expressing cells migrated to picomolar concentrations of WKYMVm, nanomolar concentrations of the peptide were required to induce migration of FPR-expressing cells. In contrast, fMLP elicited both calcium flux and chemotaxis only in FPR-expressing cells with an efficacy comparable with WKYMVm. Thus, WKYMVm uses both FPR and FPRL1 to stimulate phagocytes with a markedly higher efficacy for FPRL1. Our study suggests that FPR and FPRL1 in phagocytes react to a broad spectrum of agonists and WKYMVm as a remarkably potent agonist provides a valuable tool for studying leukocyte signaling via these receptors.

Cell Migration Inhibition↗
PubMed1999

Reduction of tyrosine kinase B and tyrosine kinase C inductions by treatment with neurotrophin-3 after transient middle cerebral artery occlusion in rat.

Infarct volume and immunoreactivities for trkB and trkC in rat brain were compared at 24 h after 90 min of transient middle cerebral artery occlusion (MCAO) between animal groups with or without neurotrophin-3 (NT-3, 10 microg/250 g animal). Treatment of rat brain with topical application of NT-3 significantly reduced infarct volume (P = 0.02) and trkB and trkC inductions. These data suggest that NT-3 reduced the ischemic injury along with the reduction of trkB and trkC inductions.

Administration, Topical↗
PubMed1999

Regulation of the amiloride-sensitive epithelial sodium channel by syntaxin 1A.

The first step in transepithelial sodium absorption lies at the apical membrane where the amiloride-sensitive, epithelial sodium channel, ENaC, facilitates sodium entry into the cell. Here we report that the vesicle traffic regulatory (SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)) protein, syntaxin 1A (S1A), inhibits ENaC mediated sodium entry. This inhibitory effect is selective for S1A and is not reproduced by syntaxin 3. The inhibition does not require the membrane anchoring domain of syntaxin 1A. It was reversed by the S1A-binding protein, Munc-18, but not by a Munc-18 mutant, which lacks syntaxin affinity. Immunostaining of epitope-tagged ENaC subunits showed that syntaxin 1A decreases ENaC current by reducing the number of ENaC channels in the plasma membrane; S1A does not interfere with ENaC protein expression. Immunoprecipitation of syntaxin 1A from the sodium-transporting epithelial cell line, A6, co-precipitates ENaC. These findings indicate that syntaxin 1A and other members of the SNARE machinery are involved in the control of plasma membrane ENaC content, and they suggest that SNARE proteins participate in the regulation of sodium absorption in relation to agonist mediated vesicle insertion-retrieval processes.

Animals↗
PubMed1999

Beta-defensins: linking innate and adaptive immunity through dendritic and T cell CCR6.

Defensins contribute to host defense by disrupting the cytoplasmic membrane of microorganisms. This report shows that human beta-defensins are also chemotactic for immature dendritic cells and memory T cells. Human beta-defensin was selectively chemotactic for cells stably transfected to express human CCR6, a chemokine receptor preferentially expressed by immature dendritic cells and memory T cells. The beta-defensin-induced chemotaxis was sensitive to pertussis toxin and inhibited by antibodies to CCR6. The binding of iodinated LARC, the chemokine ligand for CCR6, to CCR6-transfected cells was competitively displaced by beta-defensin. Thus, beta-defensins may promote adaptive immune responses by recruiting dendritic and T cells to the site of microbial invasion through interaction with CCR6.

Antibodies↗
PubMed1999

Changes in the expression of alpha(2)-adrenergic receptor subtypes during maturation of neuronal cells from fetal pig superior cervical ganglia.

The expression of presynaptic alpha(2)-adrenergic receptor (alpha(2)-AR) subtypes was investigated in cultured neurons from fetal pig superior cervical ganglion (SCG). Cells were incubated with chicken antibodies against alpha(2)A-, alpha(2)B- or alpha(2)C-AR subtypes either alone or together with antibodies against dopamine-beta-hydroxylase (DbetaH, a marker for adrenergic neurons) or against choline acetyl transferase (ChAT, a marker for cholinergic neurons). We found immunoreactivity for all three alpha(2)-AR subtypes in SCG-cells when cultured for 8-11 days. The relative expression of the alpha(2)A-subtype was approximately 1/3 of that of alpha(2)B- and alpha(2)C-AR. Co-localisation of all three alpha(2)-AR subtypes was observed in cells expressing DbetaH or ChAT. Increasing the potassium concentration in the culture medium increased the expression of DbetaH and decreased the expression of the alpha(2)A- and alpha(2)C-subtype without altering the expression of the alpha(2)B-subtype. Co-culture of neurons with pig splenocytes enhanced the expression of ChAT and decreased the expression of the alpha(2)B-subtype without altering the expression of alpha(2)A- and alpha(2)C-subtypes. Our results indicate that the three alpha(2)-receptor subtypes are expressed on both noradrenergic and cholinergic nerves. Induction of the noradrenergic phenotype favours the expression of the alpha(2)B-subtype over that of the alpha(2)A- and alpha(2)C-subtype. Conversely, enhancement of the cholinergic phenotype favours the expression of the alpha(2)A- and alpha(2)C-subtypes over that of the alpha(2)B-subtype. Our results suggest that the alpha(2)B-receptor is preferentially associated with noradrenergic nerve endings.

Animals↗
PubMed1999

A synthetic peptide derived from human immunodeficiency virus type 1 gp120 downregulates the expression and function of chemokine receptors CCR5 and CXCR4 in monocytes by activating the 7-transmembrane G-protein-coupled receptor FPRL1/LXA4R.

Because envelope gp120 of various strains of human immunodeficiency virus type 1 (HIV-1) downregulates the expression and function of a variety of chemoattractant receptors through a process of heterologous desensitization, we investigated whether epitopes derived from gp120 could mimic the effect. A synthetic peptide domain, designated F peptide, corresponding to amino acid residues 414-434 in the V4-C4 region of gp120 of the HIV-1 Bru strain, potently reduced monocyte binding and chemotaxis response to macrophage inflammatory protein 1beta (MIP-1beta) and stromal cell-derived factor 1alpha (SDF-1alpha), chemokines that use the receptors CCR5 and CXCR4, respectively. Further study showed that F peptide by itself is an inducer of chemotaxis and calcium mobilization in human monocytes and neutrophils. In cross-desensitization experiments, among the numerous chemoattractants tested, only the bacterial chemotactic peptide fMLF, when used at high concentrations, partially attenuated calcium mobilization induced by F peptide in phagocytes, suggesting that this peptide domain might share a 7-transmembrane, G-protein-coupled receptor with fMLF. By using cells transfected with cDNAs encoding receptors that interact with fMLF, we found that F peptide uses an fMLF receptor variant, FPRL1, as a functional receptor. The activation of monocytes by F peptide resulted in downregulation of the cell surface expression of CCR5 and CXCR4 in a protein kinase C-dependent manner. These results demonstrate that activation of FPRL1 on human moncytes by a peptide domain derived from HIV-1 gp120 could lead to desensitization of cell response to other chemoattractants. This may explain, at least in part, the initial activation of innate immune responses in HIV-1-infected patients followed by immune suppression.

Acquired Immunodeficiency Syndrome↗
PubMed1999

T20/DP178, an ectodomain peptide of human immunodeficiency virus type 1 gp41, is an activator of human phagocyte N-formyl peptide receptor.

Human immunodeficiency virus type 1 (HIV-1) envelope protein gp41 mediates viral fusion with human host cells. The peptide segment T20/DP178, located in the C-terminus of the ectodomain of gp41, interacts with the N-terminal leucine zipper-like domain on gp41 to establish the fusogenic conformation of the virus. Synthetic T20/DP178 peptide is highly efficacious in inhibiting HIV-1 infection in vitro by disrupting the transformation of fusogenic status of viral gp41; thus, it has been proposed for clinical trial. We report that synthetic T20/DP178 is a chemoattractant and activator of human peripheral blood phagocytes but not of T lymphocytes. We further demonstrate that T20/DP178 specifically activates a seven-transmembrane, G-protein-coupled phagocyte receptor for N-formylated chemotactic peptides, formyl peptide receptor (FPR). Moreover, synthetic T20/DP178 analogs lacking N-terminal amino acids acted as FPR antagonists. Our results suggest that gp41 peptides regulate phagocyte function via FPR and identify a novel mechanism by which HIV-1 may modulate innate immunity.

Cells, Cultured↗
PubMed1999

T21/DP107, A synthetic leucine zipper-like domain of the HIV-1 envelope gp41, attracts and activates human phagocytes by using G-protein-coupled formyl peptide receptors.

A leucine zipper-like domain, T21/DP107, located in the amino terminus of the ectodomain of gp41, is crucial to the formation of fusogenic configuration of the HIV-1 envelope protein gp41. We report that the synthetic T21/DP107 segment is a potent stimulant of migration and calcium mobilization in human monocytes and neutrophils. The activity of T21/DP107 on phagocytes was pertussis toxin-sensitive, suggesting this peptide uses Gi-coupled seven-transmembrane receptor(s). Since the bacterial chemotactic peptide fMLP partially desensitized the calcium-mobilizing activity of T21/DP107 in phagocytes, we postulated that T21/DP107 might preferentially use a lower affinity fMLP receptor. By using cells transfected to express cloned prototype chemotactic N-formyl peptide receptor (FPR) or its variant, FPR-like 1 (FPRL1), we demonstrate that T21/DP107 activates both receptors but has a much higher efficacy for FPRL1. In addition, T21/DP107 at nM concentrations induced migration of FPRL1-transfected human embryonic kidney 293 cells. In contrast, fMLP did not induce significant chemotaxis of the same cells at a concentration as high as 50 microM. Although a lipid metabolite, lipoxin A4, was a high-affinity ligand for FPRL1, it was not reported to induce Ca2+ mobilization or chemotaxis in FPRL1-transfected cells. Therefore, T21/DP107 is a first chemotactic peptide agonist identified thus far for FPRL1. Our results suggest that this peptide domain of the HIV-1 gp41 may have the potential to activate host innate immune response by interacting with FPR and FPRL1 on phagocytes.

Amino Acid Sequence↗
PubMed1999

Breast carcinoma: vascular density determined using CD105 antibody correlates with tumor prognosis.

Angiogenesis is essential for tumor growth and metastasis. There are conflicting reports as to whether microvessel density (IMD) in breast cancers is associated with prognosis. This could be due to the use of different antibodies to endothelial cell markers, variation in tissue pretreatment protocols, and nonstandardized counting methods. We have assessed the IMD in 106 breast carcinomas using a pan-endothelial marker, CD34, and a recently described mAb to CD105, which preferentially reacts with endothelial cell in angiogenic tissues. IMD values (separated as above or below median) for CD105 expression showed a statistically significant correlation with overall (P = 0.0029) and disease-free survival (P = 0.0362). In contrast, blood vessel counts using a panendothelial marker CD34 did not correlate with overall or disease-free survival (P = 0.2912 and P = 03153, respectively). When IMD values were subdivided into quartiles and assessed for their prognostic values, there was a statistically significant difference in the overall survival across CD105, but not CD34, values (P = 0.0017 and P = 0.7997, respectively) and also disease-free survival (P = 0.0431 and P = 0.5066, respectively). Further analysis of IMD values demonstrated that there were no deaths in the lowest quartile for CD105 and it differed from the other three quartiles. However, examination of clinical details of patients in the lowest quartile failed to reveal clustering of patients known to be associated with low-risk factors. Multivariate analysis confirmed that IMD values using CD105 were an independent prognostic factor. These results suggest that the ability to quantitatively distinguish between tumor neovascularization and preexisting vessels may be important in the assessment of tumor angiogenesis, but requires confirmation in a greater number of patients with a longer follow-up.

Adult↗
PubMed1999

A seven-transmembrane, G protein-coupled receptor, FPRL1, mediates the chemotactic activity of serum amyloid A for human phagocytic cells.

We have previously reported (Badolato, R., J.M. Wang, W.J. Murphy, A. R. Lloyd, D.F. Michiel, L.L. Bausserman, D.J. Kelvin, and J.J. Oppenheim. 1994. J. Exp. Med. 180:203; Xu, L., R. Badolato, W.J. Murphy, D.L. Longo, M. Anver, S. Hale, J.J. Oppenheim, and J.M. Wang. 1995. J. Immunol. 155:1184.) that the acute phase protein serum amyloid A (SAA) is a potent chemoattractant for human leukocytes in vitro and mouse phagocytes in vivo. To identify the signaling mechanisms, we evaluated patterns of cross-desensitization between SAA and other leukocyte chemoattractants. We found that the chemotactic bacterial peptide, N-formyl- methionyl-leucyl-phenylalanine (fMLP), was able to specifically attenuate Ca2+ mobilization in human phagocytes induced by SAA, but only at very high concentrations, suggesting that SAA uses a low affinity fMLP receptor. Here we demonstrate that SAA selectively induced Ca2+ mobilization and migration of HEK cells expressing FPRL1, a human seven-transmembrane domain phagocyte receptor with low affinity for fMLP, and high affinity for lipoxin A4. Furthermore, radiolabeled SAA specifically bound to human phagocytes and FPRL1-transfected 293 cells. In contrast, SAA was not a ligand or agonist for FPR, the high affinity fMLP receptor. Thus, SAA is the first chemotactic ligand identified for FPRL1. Our results suggest that FPRL1 mediates phagocyte migration in response to SAA.

Amino Acid Sequence↗
PubMed1999

Multicentre trial on the efficacy and toxicity of single-dose samarium-153-ethylene diamine tetramethylene phosphonate as a palliative treatment for painful skeletal metastases in China.

A multicentre trial was organized in China as part of an international coordinated research project to study the efficacy and toxicity of single-dose samarium-153 ethylene diamine tetramethylene phosphonate (EDTMP) as a palliative treatment for painful skeletal metastases. One hundred and five patients with painful bone metastases from various primaries were treated with 153Sm-EDTMP at a dose of 37 MBq/kg(group I) or 18.5 MBq/kg (group II). The effects were evaluated according to change in daily analgesic consumption, pain score, sum of effect product (SEP), Physician's Global Assessment (PGA), blood counts, and organ function tests conducted regularly for 16 weeks. Fifty-eight of 70 patients in group I and 30 of 35 in group II had a positive response, with SEPs of 22.29+/-14. 47 and 20.13+/-13.90 respectively. Of 72 patients who had been receiving analgesics, 63 reduced their consumption. PGA showed that the Karnofsky score (KS) increased from 58.54+/-25.90 to 71.67+/-26. 53, indicating improved general condition, but the difference was not significant. Among subgroups of patients, only those with breast cancer showed a significant change in the Karnofsky score after treatment. Inter-group differences were found for net change in KS between patients with lung and patients with breast cancer, and between patients with lung and patients with oesophageal cancer. Seventeen patients showed no response. No serious side-effects were noted, except for falls in the white blood cell (nadir 1.5x10(9)/l) and platelet (nadir 6.0x10(10)/l) counts in 44/105 and 34/105 cases, respectively. Ten patients had an abnormal liver function test. Response and side-effects were both independent of dose. In conclusion, 153Sm-EDTMP provided effective palliation in 83.8% of patients with painful bone metastases; the major toxicity was temporary myelosuppression. Further studies are needed to identify better ways of determining the appropriate dose in the individual case and the efficacy of treatment.

Analgesics, Non-Narcotic↗
PubMed1999

Chemokines as molecular targets for therapeutic intervention.

Despite the youth of the chemokine field, many antagonists of chemokine function have already been identified and tested at the preclinical level. These include neutralizing antibodies, peptidyl and non-peptidyl antagonists and non-specific immunosuppressive agents. These early studies suggest that chemokine agonists have the potential to regulate many diseases, ranging from HIV-1 infection and tumor growth to acute and chronic inflammation. Clinical application will depend on pharmaceutical development. Great strides have been made in defining structural domains of the chemokines involved in receptor binding and activation. The identification of receptors is rapidly progressing, but with 50 potential ligands and 15 characterized receptors, it is obvious that additional molecular studies are needed. The intriguing observation that several pathogens either use chemokine receptors as entry portals or produce chemokine decoys to subvert the immune system suggests that there is much to be learned about the immune system from studies of "virokines." Future studies should lead to the discovery and design of more effective inhibitors and antagonists with therapeutic benefit.

Animals↗
PubMed1999

Developmental effects of ectopic expression of the glucocorticoid receptor DNA binding domain are alleviated by an amino acid substitution that interferes with homeodomain binding.

Steroid hormone receptors are distinguished from other members of the nuclear hormone receptor family through their association with heat shock proteins and immunophilins in the absence of ligands. Heat shock protein association represses steroid receptor DNA binding and protein-protein interactions with other transcription factors and facilitates hormone binding. In this study, we investigated the hormone-dependent interaction between the DNA binding domain (DBD) of the glucocorticoid receptor (GR) and the POU domains of octamer transcription factors 1 and 2 (Oct-1 and Oct-2, respectively). Our results indicate that the GR DBD binds directly, not only to the homeodomains of Oct-1 and Oct-2 but also to the homeodomains of several other homeodomain proteins. As these results suggest that the determinants for binding to the GR DBD are conserved within the homeodomain, we examined whether the ectopic expression of GR DBD peptides affected early embryonic development. The expression of GR DBD peptides in one-cell-stage zebra fish embryos severely affected their development, beginning with a delay in the epibolic movement during the blastula stage and followed by defects in convergence-extension movements during gastrulation, as revealed by the abnormal patterns of expression of several dorsal gene markers. In contrast, embryos injected with mRNA encoding a GR peptide with a point mutation that disrupted homeodomain binding or with mRNA encoding the DBD of the closely related mineralocorticoid receptor, which does not bind octamer factors, developed normally. Moreover, coinjection of mRNA encoding the homeodomain of Oct-2 completely rescued embryos from the effects of the GR DBD. These results highlight the potential of DNA-independent effects of GR in a whole-animal model and suggest that at least some of these effects may result from direct interactions with homeodomain proteins.

Animals↗
PubMed1999

The antiapoptotic gene mcl-1 is up-regulated by the phosphatidylinositol 3-kinase/Akt signaling pathway through a transcription factor complex containing CREB.

mcl-1 is an immediate-early gene activated by the granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 3 (IL-3) signaling pathways and plays an important role in the viability response of these cytokines. In this study, we demonstrated that cytokine stimulation of mcl-1 mRNA and protein expression were attenuated by pretreatment of cells with phosphatidylinositol 3-kinase (PI3-K) inhibitors. Reporter gene assays further showed that the PI3-K/Akt signaling pathway was involved in IL-3 activation of mcl-1 gene transcription. Analysis of the mcl-1 promoter revealed that both promoter elements, SIE at position -87 and CRE-2 at -70, contribute to IL-3 stimulation of mcl-1 gene expression. Although either the SIE site or the CRE-2 site alone was sufficient to confer IL-3 inducibility on a heterologous promoter, only IL-3 activation of the CRE-2 reporter was mediated via the PI3-K/Akt pathway. The SIE binding activity was constitutively high in cells deprived of or stimulated by IL-3. In contrast, the CRE-2 binding activity was low in cytokine-starved cells and was strongly induced within 1 h following cytokine treatment of cells. In addition, cytokine induction of the CRE-2 but not of the SIE binding activity was dependent on activation of the PI3-K/Akt signaling pathway. Lastly, we showed that CREB was one component of the CRE-2 binding complex and played a role in IL-3 activation of the mcl-1 reporter gene. Taken together, our results suggest that both PI3-K/Akt-dependent and -independent pathways contribute to the IL-3 activation of mcl-1 gene expression. Activation of mcl-1 by the PI3-K/Akt-dependent pathway is through a transcription factor complex containing CREB.

Apoptosis↗