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Wang MH, Tseng CD, Bair SY. Q-T interval prolongation and pleomorphic ventricular tachyarrhythmia ('Torsade de pointes') in organophosphate poisoning: report of a case. Hum Exp Toxicol 1998; 17:587-90. [PMID: 9821023 DOI: 10.1177/096032719801701010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
1. A 63-year-old woman presented with drowsy consciousness and dyspnea, followed by respiratory failure, after taking a bottle of parathion for suicide. 2. Sinus tachycardia was noted initially by ECG and Q-T interval prolongation with pleomorphic ventricular tachyarrhythmia ('Torsade de pointes') occurred on the third day of admission. 3. Torsade de pointes was relieved by magnesium sulfate and atropine sulfate intravenously. Q-T interval returned to normal on the fifth day of admission. 4. Practicing physicians should be aware of this uncommon type of cardiac toxicity caused by organophosphate poisoning, Q-T interval prolongation and pleomorphic ventricular tachyarrhythmia.
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77
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Nanney LB, Skeel A, Luan J, Polis S, Richmond A, Wang MH, Leonard EJ. Proteolytic cleavage and activation of pro-macrophage-stimulating protein and upregulation of its receptor in tissue injury. J Invest Dermatol 1998; 111:573-81. [PMID: 9764835 DOI: 10.1046/j.1523-1747.1998.00332.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Macrophage stimulating protein (MSP) exists in blood as inactive pro-MSP. Cleavage yields active MSP, the ligand for a membrane receptor (RON) that is expressed on keratinocytes as well as macrophages. Because both cells have roles in tissue injury, we looked for active MSP and expressed RON in wounds. Concentration of pro-MSP + MSP in wound exudates was in the range for optimal activity. Western blot showed that MSP comprised about half the total, in contrast to less than 10% of the total in blood plasma. The presence of MSP was attributed to an exudate pro-MSP convertase that had an inhibitor profile consistent with a trypsin-like serine protease. Exudate evoked morphologic changes in macrophages in vitro like that of MSP. Removal of this activity by an anti-MSP column shows that exudate stimulation of macrophages is due to MSP. RON was infrequently detected in normal skin. RON protein was markedly upregulated in burn wound epidermis and accessory structures, in proliferating cells or differentiated cells, or both. RON was also detected on macrophages and capillaries. Tissue injury leads to cleavage of pro-MSP to MSP, which has potential to act on keratinocytes, macrophages, and capillaries, all components of the wound healing response.
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78
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Yao Y, Wang MH, Zhao KY, Wang CC. Assay for enzyme activity by following the absorbance change of pH-indicators. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1998; 36:119-30. [PMID: 9711498 DOI: 10.1016/s0165-022x(98)00005-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Based on the absorbance change of indicators with the concentration of hydrogen ion released from an enzyme-catalyzed reaction, a convenient colorimetric method was established for the assay of acidic phospholipase A2 and glycogen phosphorylase b. Brilliant yellow and bromothymol blue were chosen as indicators for assays of acidic phospholipase A2 and glycogen phosphorylase b by following the absorbance changes at 495 and 615 nm, respectively. The method is simple, sample-saving, sensitive and valid for a wide range of enzyme concentrations. It can be extended for assaying other enzymes catalyzing reactions with hydrogen ion concentration changes.
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79
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Willett CG, Wang MH, Emanuel RL, Graham SA, Smith DI, Shridhar V, Sugarbaker DJ, Sunday ME. Macrophage-stimulating protein and its receptor in non-small-cell lung tumors: induction of receptor tyrosine phosphorylation and cell migration. Am J Respir Cell Mol Biol 1998; 18:489-96. [PMID: 9533936 DOI: 10.1165/ajrcmb.18.4.2978] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Previously, we identified macrophage-stimulating protein (MSP) as being expressed during hamster lung injury induced by nitrosamine carcinogens. Transient, generalized epithelial-cell hyperplasia during the preneoplastic period, and eventually nonneuroendocrine (non-NE) lung tumors, are known to develop in these nitrosamine-treated hamsters. We wished to test the hypothesis that MSP and its tyrosine kinase receptor, RON, might represent an autocrine/paracrine system involved in the pathogenesis of human nonneuroendocrine lung tumors, the non-small-cell carcinomas (NSCLCs). We found that this occurred in a paracrine fashion in three of eight primary human NSCLCs that expressed messenger RNA (mRNA) for MSP at high levels in histologically normal lung adjacent to the tumor, but not in the primary tumor, together with mRNA for RON in both normal and tumor tissue. MSP and RON could also constitute an autocrine/paracrine system in human NSCLC cell lines: five of 16 cell lines (squamous and adenosquamous) expressed both MSP and RON; and an additional five of 16 cell lines expressed RON without detectable MSP. Although three cases of primary squamous-cell carcinomas expressed MSP (two of three in the tumor and one of three in nonneoplastic lung), mRNA for RON was not detectable in these cases. RON was functional in all tested RON mRNA-positive cell lines, with exogenous MSP inducing RON-mediated tyrosine phosphorylation. Treatment of a RON-positive adenosquamous carcinoma cell line with MSP additionally resulted in increased motility in a cell-migration assay, suggesting that MSP might promote cell migration of some NSCLCs. In conclusion, MSP and RON might represent an autocrine/paracrine system involved in the pathogenesis of lung cancer, although the nature of the biologic responses in different cell types might vary considerably.
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80
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Wang MH, Brand-Schieber E, Zand BA, Nguyen X, Falck JR, Balu N, Schwartzman ML. Cytochrome P450-derived arachidonic acid metabolism in the rat kidney: characterization of selective inhibitors. J Pharmacol Exp Ther 1998; 284:966-73. [PMID: 9495856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We characterized the inhibitory activity of several acetylenic and olefinic compounds on cytochrome P450 (CYP)-derived arachidonic acid omega-hydroxylation and epoxidation using rat renal cortical microsomes and recombinant CYP proteins. Among the acetylenic compounds, 6-(2-propargyloxyphenyl)hexanoic acid (PPOH) and N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide were found to be potent and selective inhibitors of microsomal epoxidation with IC50 values of 9 and 13 microM, respectively. On the other hand, 17-octadecynoic acid inhibited both omega-hydroxylation and epoxidation of arachidonic acid with IC50 values of 7 and 5 microM, respectively. The olefinic compounds N-methylsulfonyl-12, 12-dibromododec-11-enamide (DDMS) and 12, 12-dibromododec-11-enoic acid (DBDD) exhibited a high degree of selectivity inhibiting microsomal omega-hydroxylation with an IC50 value of 2 microM, whereas the IC50 values for epoxidation were 60 and 51 microM for DDMS and DBDD, respectively. Studies using recombinant rat CYP4A isoforms showed that PPOH caused a concentration-dependent inhibition of omega-hydroxylation and 11, 12-epoxidation by CYP4A3 or CYP4A2 but had no effect on CYP4A1-catalyzed omega-hydroxylase activity. On the other hand, DDMS inhibited both CYP4A1- and CYP4A3- or CYP4A2-catalyzed arachidonic acid oxidations. Inhibition of microsomal activity by PPOH, but not DDMS, was time- and NADPH-dependent, a result characteristic of a mechanism-based irreversible inhibitor. These studies provide information useful for evaluating the role of the CYP-derived arachidonic acid metabolites in the regulation of renal function and blood pressure.
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81
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Chen LJ, Lin JH, Lee TL, Luo CH, Hsieh WY, Liang JM, Wang MH. High resolution electron microscopy of amorphous interlayers between metal thin films and silicon. Microsc Res Tech 1998; 40:136-51. [PMID: 9504125 DOI: 10.1002/(sici)1097-0029(19980115)40:2<136::aid-jemt5>3.0.co;2-t] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
High-resolution electron microscopy of amorphous interlayers (a-interlayer) formed by solid-state diffusion between metal thin films and silicon is reviewed. In this paper, an overview of the development is presented. Pertinent data obtained on the growth kinetics and structure of a-interlayers in polycrystalline metal thin films on single-crystal silicon are reported. For the Ti/Si, Zr/Si, Hf/Si, V/Si, Nb/Si and Ta/Si systems, the growth of a-interlayer was found to follow a linear law in the initial stage. Si atoms were found to be the dominant diffusing species in the solid phase amorphization in the Ti/Si, Zr/Si, and Hf/Si systems. For the Y/Si system, the stability of amorphous interlayer depends critically on the composition of the amorphous films. Auto-correlation function analysis was utilized to determine the structure of the amorphous interlayers. HRTEM in conjunction with the fast Fourier transform were applied to determine the first nucleated crystalline phase. Simultaneous presence of multiphases was observed to occur in a number of refractory metal/Si systems.
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82
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Waltz SE, McDowell SA, Muraoka RS, Air EL, Flick LM, Chen YQ, Wang MH, Degen SJ. Functional characterization of domains contained in hepatocyte growth factor-like protein. J Biol Chem 1997; 272:30526-37. [PMID: 9374547 DOI: 10.1074/jbc.272.48.30526] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To delineate the functional protein domains necessary for the biological activity of hepatocyte growth factor-like protein (HGFL), we created various site-directed and deletion mutated cDNAs coding for this protein. Wild-type and mutated versions of HGFL were produced after transfection of the corresponding cDNAs into tissue culture cells. The biological importance of the domains within HGFL was then examined by addition of recombinant wild-type or mutant forms of HGFL to assays aimed at elucidating regions involved in the stimulation of DNA synthesis, the induction of shape changes in macrophages, and the ability to stimulate cell scattering. Mutant proteins lacking the serine protease-like domain (light chain) were not biologically active in any of the assays tested and could not compete with wild-type HGFL in cell scattering experiments. These data, in addition to direct enzyme-linked immunosorbent assay analyses, suggest that the light chain may play an important role in the interaction of HGFL with its receptor, Ron. Elimination of the proposed protease cleavage site between the heavy and light chains (by mutation of Arg-483 to Glu) produced a protein with activity comparable to wild-type HGFL. Further studies with this mutated protein uncovered an additional proteolytic cleavage site that produces biologically active protein. Deletion of the various kringle domains or the amino-terminal hairpin loop had various effects in the multiple assays. These data suggest that the heavy chain may play a pivotal role in determining the functional aspects of HGFL.
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83
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Schwartz GG, Wang MH, Zang M, Singh RK, Siegal GP. 1 alpha,25-Dihydroxyvitamin D (calcitriol) inhibits the invasiveness of human prostate cancer cells. Cancer Epidemiol Biomarkers Prev 1997; 6:727-32. [PMID: 9298581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1 alpha,25-Dihydroxyvitamin D (1,25 D; also know as calcitriol), the hormonal form of vitamin D, can inhibit the proliferation and promote the differentiation of human prostate adenocarcinoma cells. However, little is known about the effects of 1,25 D on the invasive ability of prostate cancer cells. We used an in vitro bioassay of cell invasion (Amgel assay) to examine the effects of 1,25 D and a "noncalcemic" vitamin D analogue, 1,25-dihydroxy-16-ene-23-yne-cholecalciferol (16-23-D3), on the invasiveness of three well-characterized human prostate carcinoma cell lines: DU 145, PC-3, and LNCaP. PC-3 and LNCaP cells were poorly invasive in Amgel and were hardly affected by treatment with 1,25 D or 16-23-D3 (< 3%). Conversely, DU 145 cells were highly invasive in Amgel, and their invasion was markedly inhibited by 1,25 D and 16-23-D3 (maximally 66 and 59.4% respectively). This effect was both dose-dependent, with maximal inhibition at 1 x 10(-7) M and 72 h. Significant inhibition of invasion was observed at physiological levels of 1,25 D. Neither proliferative indices nor cell cycle kinetics were altered during the experimental exposure. Treatment with 1,25 D and 16-23-D3 caused a selective decrease in the secreted levels of type IV collagenases (MMP-2 and MMP-9). These findings support the hypothesis that 1,25 D reduces the risk of invasive prostate cancer and suggest a role for vitamin D compounds in the chemoprevention of invasive prostate cancer.
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84
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Wang MH, Zhao KY. A simple method for determining kinetic constants of complexing inactivation at identical enzyme and inhibitor concentrations. FEBS Lett 1997; 412:425-8. [PMID: 9276440 DOI: 10.1016/s0014-5793(97)00771-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The kinetics of complexing inactivation at identical enzyme and inhibitor concentrations were analyzed and the equations of product generation were derived when the free enzyme concentration is great, larger or smaller than the dissociation constant of inhibitor, K(I). The kinetic constants can be obtained by fitting the derived equations to the progress curve. Numerical examples show that this method is valid and gives satisfactory results.
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85
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Wang MH, Julian FM, Breathnach R, Godowski PJ, Takehara T, Yoshikawa W, Hagiya M, Leonard EJ. Macrophage stimulating protein (MSP) binds to its receptor via the MSP beta chain. J Biol Chem 1997; 272:16999-7004. [PMID: 9202013 DOI: 10.1074/jbc.272.27.16999] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Macrophage stimulating protein (MSP) is a 78-kDa disulfide-linked heterodimer belonging to the plasminogen-related kringle protein family. MSP activates the RON receptor protein-tyrosine kinase, which results in cell migration, shape change, or proliferation. A structure-activity study of MSP was performed using pro-MSP, MSP, MSP alpha and beta chains, and a complex including the first two kringles and IgG Fc (MSP-NK2). Radioiodinated MSP and MSP beta chain both bound specifically to RON. The Kd of 1.4 nM for MSP beta chain is higher than the reported Kd range of 0.6-0.8 nM for MSP. Pro-MSP, MSP alpha chain, and MSP-NK2 did not bind. Only MSP stimulated RON autophosphorylation. Although the beta chain bound to RON and partially inhibited MSP-induced RON phosphorylation in kidney 293 cells, it did not induce RON phosphorylation. Pro-MSP, MSP alpha chain, or MSP-NK2 failed to activate RON, consistent with their inability to bind to the RON receptor. Functional studies showed that only MSP induced cell migration, and shape change in resident macrophages, and growth of murine keratinocytes. Our data indicate that the primary receptor binding domain is located in a region of the MSP beta chain, in contrast to structurally similar hepatocyte growth factor, in which the receptor binding site is in the alpha chain. However, full activation of RON requires binding of the complete MSP disulfide-linked alphabeta chain heterodimer.
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86
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Willett CG, Smith DI, Shridhar V, Wang MH, Emanuel RL, Patidar K, Graham SA, Zhang F, Hatch V, Sugarbaker DJ, Sunday ME. Differential screening of a human chromosome 3 library identifies hepatocyte growth factor-like/macrophage-stimulating protein and its receptor in injured lung. Possible implications for neuroendocrine cell survival. J Clin Invest 1997; 99:2979-91. [PMID: 9185522 PMCID: PMC508150 DOI: 10.1172/jci119493] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Transient pulmonary neuroendocrine cell hyperplasia and non-neuroendocrine lung tumors develop in nitrosaminetreated hamsters, which we hypothesized might modulate epithelial cell phenotype by expressing gene(s) homologous to human chromosome 3p gene(s) deleted in small cell carcinoma of the lung (SCLC). We differentially screened a chromosome 3 library using nitrosamine-treated versus normal hamster lung cDNAs and identified hepatocyte growth factor-like/macrophage-stimulating protein (HGFL/MSP) in injured lung. HGFL/MSP mRNA is low to undetectable in human SCLC and carcinoid tumors, but the HGFL/MSP tyrosine kinase receptor, RON, is present and functional on many of these neuroendocrine tumors. In H835, a pulmonary carcinoid cell line, and H187, a SCLC cell line, HGFL/ MSP induced adhesion/flattening and apoptosis. Using viable cell counts to assess proliferation after 14 d of treatment with HGFL/MSP, there is growth inhibition of H835 but not H187. Nitrosamine-treated hamsters also demonstrate pulmonary neuroendocrine cell apoptosis in situ during the same time period as expression of the endogenous HGFL/ MSP gene, immediately preceding the spontaneous regression of neuroendocrine cell hyperplasia. These observations suggest that HGFL/MSP might regulate neuroendocrine cell survival during preneoplastic lung injury, which could influence the ultimate tumor cell phenotype.
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87
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Yan YL, Kameie T, Zheng LF, Wang MH, Iino A. [Study on the organization of chromatin and chromosome in mouse spermatogenic cells by scanning electron microscopy]. SHI YAN SHENG WU XUE BAO 1997; 30:213-9. [PMID: 11039030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
It remains unclear about the intermediate construction of chromosome due to its highly compact nature and the limitation in methods. The present study was designed to investigate the construction of chromatin and mitotic chromosome in situ with scanning electron microscopy. Mouse testes were selected as the material, because of in which the spermatogenic cells divide actively and successively to form the sperm. Such a feature would be able to study the structure of mammalian chromatin and chromosomes along with the change of nuclear cycle. The animal were perfused with 200 ml of 0.075 mol/L KCl hypotonic solution to remove blood and placed for 15-20 min on ice followed by 0.5% glutaraldehyde and 0.5% formaldehyde for fixing. Through treated by the routine process of fractured and freeze dried with t-butyl alcohol, the specimens were then coated with a 3 nm thick platinum and observed with Hitachi S-430 scanning electron microscopy. It was found that the hypotonic treatment with 0.075 mol/L KCl solution was suit for demonstrating the nuclear structure, when the organelles were well preserved. The chromatin fibers of 10-30 nm and 80-125 nm in diameter could be recognized in the interphase nuclei, which were arranged losely at the region of euchromatin, and folded with each other into chromatin masses at the region of heterochromatin, while the chromatin fibers with the diameter of 80-125 nm often could be viewed on the mitotic chromosomes. Since its presence in interphase nuclei and mitotic chromosomes, it was considered that the chromatin fibers with 80-125 nm in diameter might play a role in the condensation of chromosome, serve as a type of the intermediate structure.
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88
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Merchant TE, Haida T, Wang MH, Finlay JL, Leibel SA. Anaplastic ependymoma: treatment of pediatric patients with or without craniospinal radiation therapy. J Neurosurg 1997; 86:943-9. [PMID: 9171172 DOI: 10.3171/jns.1997.86.6.0943] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The authors conducted a retrospective review of the clinical and treatment characteristics and outcomes in 28 pediatric patients with anaplastic ependymoma treated with radiation therapy since the advent of computerized tomography (CT) (1978-1994). Twelve patients received craniospinal irradiation followed by a boost to the primary site, two received whole-brain radiation therapy followed by a boost to the primary site, and the remaining 14 were treated with focal radiation therapy. The mean dose to the primary site was 5486 cGy. With a median follow-up period of 86 months for the 14 surviving patients (range 31-201 months), the median disease-free survival, measured from the date of diagnosis to the time of recurrence after radiation therapy, was 40 months. The median disease-free survival measured from the start of radiation therapy was 32 months. The median overall survival rate has not been reached and the actuarial estimates of overall survival rates at 5 and 10 years were 56% and 38%, respectively. According to univariate analysis, the disease-free survival rate was significantly improved (p < 0.01) in patients who underwent a gross-total resection at diagnosis. Overall survival rates were negatively influenced by treatment with craniospinal and whole-brain irradiation. As calculated by multivariate analysis, increasing dosage to the primary site (p < 0.05), infratentorial location (p < 0.01), and gross-total resections (p < 0.02) resulted in the longest disease-free survival times. All 19 patients in whom treatment failed after radiation therapy suffered a recurrence at the primary site. In addition, one of these patients experienced subarachnoid dissemination. Radiation treatment recommendations for patients with ependymoma have been based on the tumor's location, perceived risk for dissemination, and malignant propensity. The significance of anaplastic histological classification is controversial. Differences in the disease-free and overall survival rates have been demonstrated between ependymomas and anaplastic ependymomas treated in the pre-CT era. The results of this study show that there is no benefit from craniospinal irradiation in this group of patients.
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89
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Zhang M, Wang MH, Singh RK, Wells A, Siegal GP. Epidermal growth factor induces CD44 gene expression through a novel regulatory element in mouse fibroblasts. J Biol Chem 1997; 272:14139-46. [PMID: 9162042 DOI: 10.1074/jbc.272.22.14139] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Growth factors coordinately regulate a variety of genes associated with pathological states including tumor invasion and metastasis. Overexpressed epidermal growth factor receptor (EGFR) on tumor cell surfaces is associated with enhanced cell attachment and migration into extracellular matrices, which promotes tumor aggressiveness. We have demonstrated that epidermal growth factor (EGF) up-regulates the cell surface adhesion molecule CD44 at both the mRNA and protein levels on mouse fibroblasts expressing full-length wild-type EGFR (NR6-WT) but not on EGFR-deficient cells (NR6-P). This increases cell attachment to hyaluronic acid. In this investigation, transcriptional regulation of CD44 by EGF was confirmed by defining an EGF-regulatory element. By employing human CD44 gene promoter-chloramphenicol acetyltransferase (CAT) constructs transfected into NR6-WT cells, EGF inducibility was observed within a 120-base pair (bp) DNA fragment located 450 bp upstream of the RNA initiation site. Differential EGF inducibility was found among different cell lines chosen, indicating a 3.2- and 1.8-fold enhancement in DU145 cells carrying exogenous wild-type EGFR and in MCF-7 cells, respectively, while minimal EGF induction was found in cervical cancer HeLa cells. Utilizing gel shift assays, a time-dependent increase of DNA-protein complex formation was found upon EGF stimulation in NR6-WT cells but not in NR6-P cells. Based upon these observations, a novel 22-bp EGF regulatory element (ERE) (5'--604CCCTCTCTCCAGCTCCTCTCCC-583-3') was isolated from the CD44 gene promoter. This ERE conferred DNA-protein binding ability in vitro, as well as the full functional recovery of EGF inducibility of CAT activity when linked to a homologous CD44 promoter or a SV40 promoter driving a CAT reporter gene. A two-base mutation of the ERE completely eliminated its binding activity as well as its EGF inducibility of CAT expression. Our studies indicate that EGF induces CD44 gene expression through an interaction between a specific ERE and putative novel transcriptional factor so as to regulate cell attachment to extracellular matrix.
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90
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Fang CT, Ferng WF, Hwang JJ, Yu CJ, Chen YC, Wang MH, Chang SC, Hsieh WC. Life-threatening scrub typhus with meningoencephalitis and acute respiratory distress syndrome. J Formos Med Assoc 1997; 96:213-6. [PMID: 9080762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A 21-year-old man presented with fever, rash, seizure, stiff neck and rapidly progressive bilateral pulmonary infiltrates. Cerebrospinal fluid (CSF) study revealed pleocytosis with predominant polymorphonuclear cells, and hypo-glycorrhachia. Status epilepticus occurred, followed by acute respiratory distress syndrome with respiratory failure. Blood and CSF cultures for bacteria were negative, but an indirect immunofluorescence assay revealed a fourfold rise in antibody to Rickettsia tsutsugamushi in paired serum and a 1:2560 (+) IgM antibody titer. Severe scrub typhus with meningoencephalitis and extensive pneumonitis was diagnosed. The patient survived after intravenous minocycline therapy and intensive care, including aggressive seizure control, supportive mechanical ventilation and avoidance of fluid overloading. He had a nearly complete recovery. Practicing physicians in Taiwan should be aware of this reportable disease and its potentially serious complications if not promptly diagnosed and treated.
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91
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Wang MH, Stec DE, Balazy M, Mastyugin V, Yang CS, Roman RJ, Schwartzman ML. Cloning, sequencing, and cDNA-directed expression of the rat renal CYP4A2: arachidonic acid omega-hydroxylation and 11,12-epoxidation by CYP4A2 protein. Arch Biochem Biophys 1996; 336:240-50. [PMID: 8954571 DOI: 10.1006/abbi.1996.0554] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), the omega-hydroxylation product of arachidonic acid, is the major metabolite produced in the kidney. It has potent biological effects on renal tubular and vascular functions and on the long-term control of arterial pressure. The synthesis of 20-HETE is catalyzed by enzymes of the CYP4A family, among which CYP4A2 is the most abundant isozyme expressed in the kidneys of rats. We have cloned and sequenced the CYP4A2 cDNA from the kidney of Lewis-Wistar rats and directed its expression using baculovirus and Sf9 insect cells. A high level of expression of CYP4A2 was evident by Northern, Western, and spectral analyses revealing a P450 content of 0.3 nmol/mg microsomal protein. To study CYP4A2-catalyzed arachidonic acid omega-hydroxylation, Sf9 cells were coinfected with CYP4A2 and NADPH cytochrome P450 oxidoreductase (OR) recombinant viruses. CYP4A2/OR membranes metabolized lauric acid at a high rate (7 and 5.5 nmol/min/nmol P450 in the presence and absence of b5, respectively). However, arachidonic acid omega-hydroxylase activity was barely detectable. When purified OR was added to the membranes expressing CYP4A2 protein, a concentration-dependent production of 20-HETE was observed. Maximal synthesis of 20-HETE of 0.89 nmol/min/nmol P450 was achieved at OR:CYP4A2 ratio of 14:1. The omega-hydroxylation of arachidonic acid was dependent on the presence of b5. Furthermore, increasing OR concentrations yielded additional arachidonic acid metabolite identified by GC/MS as 11,12-EET. Microsomes prepared from isolated renal microvessels selectively expressed CYP4A2 protein and readily metabolized arachidonic acid to two major metabolites, 20-HETE and 11,12-DHET, the hydrolytic metabolite of 11, 12-EET. It is suggested that CYP4A2 functions as the renal microvessel arachidonate omega-hydroxylase and that it can also catalyze the 11,12-epoxidation of arachidonic acid.
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MESH Headings
- 8,11,14-Eicosatrienoic Acid/analogs & derivatives
- 8,11,14-Eicosatrienoic Acid/metabolism
- Animals
- Arachidonic Acid/metabolism
- Baculoviridae
- Capillaries/metabolism
- Catalysis
- Cell Line
- Cloning, Molecular
- Cytochrome P-450 CYP4A
- Cytochrome P-450 Enzyme System/metabolism
- DNA, Complementary
- Gas Chromatography-Mass Spectrometry
- Hydroxyeicosatetraenoic Acids/metabolism
- Hydroxylation
- Kidney/metabolism
- Lauric Acids/metabolism
- Microsomes/metabolism
- Mixed Function Oxygenases/metabolism
- NADH, NADPH Oxidoreductases/genetics
- NADH, NADPH Oxidoreductases/metabolism
- NADPH-Ferrihemoprotein Reductase
- Rats
- Rats, Inbred Lew
- Rats, Sprague-Dawley
- Spodoptera
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92
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Wang MH, Montero-Julian FA, Dauny I, Leonard EJ. Requirement of phosphatidylinositol-3 kinase for epithelial cell migration activated by human macrophage stimulating protein. Oncogene 1996; 13:2167-75. [PMID: 8950984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Macrophage stimulating protein (MSP) is a ligand for the RON receptor protein tyrosine kinase. Activation of RON in murine resident macrophages results in cell shape change and migration. We studied cell movement induced by MSP in different types of human epithelial cells and the possible role of phosphatidylinositol-3 (PI-3) kinase in RON-mediated signal transduction. We observed specific and saturable binding of 125I-MSP to RON on several epithelial cell lines. In addition to activation and phosphorylation of RON, MSP also induced tyrosine phosphorylation of the PI-3 kinase p85 subunit in a time-dependent manner, with a peak at 15 min. Moreover, phosphorylated RON formed a complex with PI-3 kinase in both HK-NOC keratinocyte and RON cDNA-transfected MDCK cells. An in vitro protein interaction assay confirmed that PI-3 kinase from a lysate of MSP-activated cells bound to pure RON protein. MSP, at a concentration range of 1 to 5 nM, induced migration of three epithelial cell lines. This effect was inhibited by wortmannin, a specific inhibitor for PI-3 kinase, with an IC50 of 10 nM. MSP-induced shape change in murine resident peritoneal macrophages was also abolished by wortmannin. These data suggest that activation of PI-3 kinase is required for MSP-induced epithelial cell migration. The stimulation by MSP of epithelial cell movement may have implications for tissue repair, wound healing, and tumor metastasis.
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93
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Wang MH, Wang ZX, Zhao KY. Kinetics of inactivation of bovine pancreatic ribonuclease A by bromopyruvic acid. Biochem J 1996; 320 ( Pt 1):187-92. [PMID: 8947485 PMCID: PMC1217915 DOI: 10.1042/bj3200187] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The kinetic theory of substrate reaction during the modification of enzyme activity [Duggleby (1986) J. Theor. Biol. 123, 67-80; Wang and Tsou (1990) J. Theor. Biol. 142, 531-549] has been applied to a study of the inactivation kinetics of ribonuclease A by bromopyruvic acid. The results show that irreversible inhibition belongs to a non-competitive complexing type inhibition. On the basis of the kinetic equation of substrate reaction in the presence of the inhibitor, all microscopic kinetic constants for the free enzyme, the enzyme-substrate complex and the enzyme-product complex have been determined. The non-competitive inhibition type indicates that neither the substrate nor the product affects the binding of bromopyruvic acid to the enzyme and that the ionization state of His-119 may be the same in both the enzyme-substrate and the enzyme-product complexes.
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94
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Wang MH, Peng ZH, Wang FL. [The holistic-medicinal approach of diagnosis and treatment of sexual transmitted diseases by integrated traditional and Western medicine]. ZHONGGUO ZHONG XI YI JIE HE ZA ZHI ZHONGGUO ZHONGXIYI JIEHE ZAZHI = CHINESE JOURNAL OF INTEGRATED TRADITIONAL AND WESTERN MEDICINE 1996; 16:690-2. [PMID: 9772622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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95
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Wang MH, Patten CJ, Yang GY, Paranawithana SR, Tan Y, Yang CS. Expression and coupling of human cytochrome P450 2E1 and NADPH-cytochrome P450 oxidoreductase in dual expression and co-infection systems with baculovirus in insect cells. Arch Biochem Biophys 1996; 334:380-8. [PMID: 8900414 DOI: 10.1006/abbi.1996.0468] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In order to study the interaction between human cytochrome P450 2E1 (h2E1) and NADPH-P450 oxidoreductase (hOR) in a native membrane environment, we used two approaches to express both h2E1 and hOR in a baculovirus expression system. For a dual-expression system, h2E1 and hOR were coexpressed in Spodoptera frugiperda (Sf9) insect cells using a recombinant baculovirus carrying both h2E1 and hOR cDNAs (v-h2E1-hOR). The h2E1 cDNA was expressed under the control of the polyhedrin promoter P(Polh), whereas hOR cDNA was expressed under the control of the P10 promoter. The expressed enzymes were catalytically active in the cell membrane preparations. The estimated molar expression ratio of h2E1 to hOR in the membranes was 1:5. The apparent Km and kcat for N-nitrosodimethylamine (NDMA) demethylase activity were 145 microM and 2.4 min-1, respectively. When Sf9 cells were co-infected with the dual-expression virus (v-h2E1-hOR) and human cytochrome b5 recombinant virus (v-hb5), a 9-fold decrease in the Km of NDMA demethylase activity (16 microM) was observed in the membrane preparations, whereas the kcat was increased to 4 min-1. In the second approach, recombinant viruses of h2E1 and hOR (v-h2E1 and v-hOR) were used to co-infect the Sf9 cells. In this double-expression system, with a fixed amount of v-h2E1, the expression of h2E1 in the Sf9 cells decreased as the amount of v-hOR increased. Western blot analysis of the membrane preparations showed that the level of hOR increased, but the level of h2E1 decreased with increasing amounts of v-hOR. A corresponding decrease in h2E1 mRNA, however, was not observed. In the presence of human cytochrome b5 (hb5), the optimal h2E1:hOR molar ratio for h2E1 catalytic activity was 1:1. In order to further investigate the hb5 effect on h2E1-catalyzed reactions in the native membranes, we co-infected Sf9 cells with v-h2E1, v-hOR, and v-hb5 and obtained a membrane preparation containing h2E1, hOR, and hb5. Stoichiometric analysis with membrane preparations from double-infection and triple-infection systems revealed that the presence of hb5 decreased NADPH oxidation and H202 formation by 72 and 80%, respectively, but increased product formation from NDMA 13-fold. These results suggest that hb5 enhances the coupling between h2E1 and hOR for product formation. These studies also demonstrate that the baculovirus-insect cell system can produce high levels of expression of functional h2E1, hOR, and hb5 for mechanistic studies.
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96
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Jiao D, Conaway CC, Wang MH, Yang CS, Koehl W, Chung FL. Inhibition of N-nitrosodimethylamine demethylase in rat and human liver microsomes by isothiocyanates and their glutathione, L-cysteine, and N-acetyl-L-cysteine conjugates. Chem Res Toxicol 1996; 9:932-8. [PMID: 8870979 DOI: 10.1021/tx9502094] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Natural and synthetic isothiocyanates and their conjugates were examined for their inhibitory effects toward rat and human liver microsomal N-dimethylnitrosoamine demethylase (NDMAd) activity using a radiometric NDMAd assay. Substrate concentrations of 30 and 60 microM were used to probe the activity of cytochrome P4502E1 isozyme through the alpha-hydroxylation of NDMA. It was found that alkyl isothiocyanates such as sulforaphane and allyl isothiocyanate displayed very weak inhibition, whereas the arylalkyl isothiocyanates such as benzyl and phenethyl isothiocyanate showed significant inhibition toward rat liver NDMAd activity with IC50 values of 9.0 and 8.3 microM, respectively. More interestingly, glutathione conjugates of benzyl, phenethyl, and 6-phenylhexyl isothiocyanates all inhibited NDMAd at the comparable concentrations. In the phenethyl isothiocyanate conjugates series, there exist marked differences in their inhibitory activity; i.e., its conjugates with L-cysteine (IC50 = 4.3 microM) and with glutathione (IC50 = 4.0 microM) are more potent than its conjugate of N-acetylcysteine (IC50 = 24.0 microM). The same trend was also observed for the human liver microsomal NDMAd activity. The half-lives of these conjugates were determined in the presence of other free thiols from L-cysteine or glutathione using an HPLC system. It was shown that isothiocyanates are released from their conjugates and react with the free thiols present in the solution. The longer half-life of N-acetylcysteine conjugate of phenethyl isothiocyanate as compared to the other conjugates is consistent with its lower inhibitory activity. The inhibition of NDMAd, and therefore cytochrome P4502E1, by isothiocyanate conjugates is most likely due to the action of the free isothiocyanates released from the conjugates. Since cytochrome P4502E1 and other isozymes play important roles in the activation of the tobacco-specific nitrosoamines, these results provide a basis for investigating the potential of isothiocyanate conjugates as chemopreventive agents.
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Patten CJ, Smith TJ, Murphy SE, Wang MH, Lee J, Tynes RE, Koch P, Yang CS. Kinetic analysis of the activation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by heterologously expressed human P450 enzymes and the effect of P450-specific chemical inhibitors on this activation in human liver microsomes. Arch Biochem Biophys 1996; 333:127-38. [PMID: 8806763 DOI: 10.1006/abbi.1996.0373] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is enzymatically activated by the hydroxylation of the alpha-methyl and alpha-methylene groups, leading to the formation of reactive species which can pyridyloxobutylate and methylate DNA, respectively. The present study examined the kinetic parameters of NNK-derived keto alcohol (alpha-methyl hydroxylation), and keto aldehyde (alpha-methylene hydroxylation) formation catalyzed by human P450s heterologously expressed by either the baculovirus-insect cell expression system (P450s 2A6, 2D6, 2E1, and 3A4) or by stable expression in CHO cells (P450s 3A4 and 2D6) and human B-lymphoblastoid cells (P450 2D6). Membrane preparations of the expressed P450s catalyzed the alpha-hydroxylation of NNK, leading to the formation of keto aldehyde and keto alcohol. Human P450 2A6 showed the lowest KM (118 microM) for the formation of keto aldehyde. A similar KM was observed for keto alcohol formation by expressed P450 2A6, but the kcat was lower than the value obtained for keto aldehyde formation. The addition of exogenous b5 increased the expressed 2A6-dependent NNK hydroxylation activity 2.5-fold for both alpha-hydroxylation products. Human P450s 2E1 and 2D6 exhibited a high capacity for keto alcohol formation; however, their KM values for this reaction were in the millimolar range. Expressed human P450 3A4 oxidized NNK to keto aldehyde also with a high KM. Ten human liver microsomal samples were each shown to activate NNK to keto aldehyde and keto alcohol. A positive correlation coefficient of 0.74 was found between keto aldehyde formation and both coumarin 7-hydroxylation (P450 2A6) and 6 beta-testosterone hydroxylation (3A4) activity in characterized human liver microsomes. Keto alcohol formation showed a significant correlation with ethoxyresorufin O-dealkylation (P450 1A2) in human liver microsomes. Both coumarin and troleandomycin, specific inhibitors of P450 2A6 and 3A4, respectively, inhibited the formation of keto aldehyde, but inhibited the formation of keto alcohol only slightly in human liver microsomes. Both furafylline, a P450 1A2 inhibitor, and N-nitrosodimethylamine, a P450 2E1 substrate, inhibited the formation of keto alcohol but not keto aldehyde in human liver microsomes. Quinidine, a specific inhibitor of P450 2D6, was not an effective inhibitor of NNK metabolism. These results demonstrate that P450s 2A6 and 3A4 may be important P450s for the activation of NNK to a DNA-methylating agent and keto aldehyde via the alpha-methylene hydroxylation pathway. P450s 1A2, 2E1, and 2D6 are shown to be selective for alpha-methyl hydroxylation of NNK leading to keto alcohol and a DNA-pyridyloxobutylating agent.
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Merchant TE, Wang MH, Haida T, Lindsley KL, Finlay J, Dunkel IJ, Rosenblum MK, Leibel SA. Medulloblastoma: long-term results for patients treated with definitive radiation therapy during the computed tomography era. Int J Radiat Oncol Biol Phys 1996; 36:29-35. [PMID: 8823256 DOI: 10.1016/s0360-3016(96)00274-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE We performed a retrospective evaluation of the patterns of failure and outcome for medulloblastoma patients treated with craniospinal irradiation therapy during the computed tomography (CT) era. MATERIALS AND METHODS The records of 100 patients treated at Memorial Sloan-Kettering Cancer Center between 1979 and 1994 were reviewed. CT scans or magnetic resonance imaging were used to guide surgical intervention and evaluate the extent of resection postoperatively. All patients were treated with conventional fractionation (1.8 Gy/day) and the majority received full-dose neuraxis radiation therapy and > 50 Gy to the primary site. RESULTS With a median follow-up of 100 months, the median, 5-year, and 10-year actuarial overall survival for the entire group were 58 months, 50%, and 25%, respectively. The median, 5- and 10-year actuarial disease-free survivals were 37 months, 41%, and 27%, respectively. Patients with localized disease (no evidence of disease beyond the primary site) had significantly improved overall (p < 0.02) and disease-free (p < 0.02) survivals compared to those with nonlocalized disease. For patients with localized disease, the 5- and 10-year overall survival rates were 59% and 31%, whereas the disease-free survivals were 49% and 31%, respectively. Disease-free and overall survivals at similar intervals for patients with nonlocalized disease were 29% and 30% (5 years), and 29% and 20% (10 years), respectively. Sixty-four of 100 patients failed treatment. Local failure as any component of first failure occurred in 35% of patients or 55% (35 of 64) of all failures and as the only site of first failure in 14% or 22% (14 of 64) of all failures. For patients presenting with localized disease (n = 68), local failure as any component of first failure occurred in 32% (22 of 68) and in 18% (12 of 68) as the only site. A multivariate analysis showed that M stage was the only prognostic factor to influence overall survival. For disease-free survival, M stage and the extent of resection were prognostic factors. Ventriculoperitoneal shunting and the use of chemotherapy were associated with a poor outcome; however, these results were confounded by the positive impact of chemotherapy in decreasing the risk of extraneural metastases and the use of these therapies in the more advanced patients. CONCLUSION These long-term follow-up data represent one of the largest series of patients with complete follow-up who were treated with a consistent radiation therapy treatment policy during the CT era. Local failure in patients with localized disease, the persistent risk of late failures, treatment-related toxicity, and the ever-present risk of secondary malignancies demonstrate the limitations of standard therapies. Strategies used to increase the total dose to the primary site should be pursued along with other adjuvant therapies such as intensive chemotherapy.
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Wang MH, Dlugosz AA, Sun Y, Suda T, Skeel A, Leonard EJ. Macrophage-stimulating protein induces proliferation and migration of murine keratinocytes. Exp Cell Res 1996; 226:39-46. [PMID: 8660937 DOI: 10.1006/excr.1996.0200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Macrophage stimulating protein (MSP) is a chemotactic factor for murine peritoneal macrophages. The receptor for human MSP was recently identified as the ron gene product, a transmembrane protein tyrosine kinase cloned from a human keratinocyte cDNA library. Here we report that MSP induced proliferation of murine primary keratinocytes and established keratinocyte cell lines in a concentration-dependent manner. The growth efficacy of MSP was comparable to that of epidermal growth factor and keratinocyte growth factor. In three of four cell lines tested in a chemotaxis chamber, MSP also stimulated migration of keratinocytes on a collagen type IV substratum. The action of MSP was mediated by specific binding of MSP to the STK gene product, a murine homologue of the RON MSP receptor. Binding of MSP to keratinocyte STK induced phosphorylation of the 150 kDa STK beta chain. Herbimycin A, a protein tyrosine kinase inhibitor, blocked MSP-mediated phosphorylation of the STK receptor as well as proliferation of keratinocytes, suggesting the importance of tyrosine kinase activity for transduction of the message delivered by MSP. Previously, the only known target cell for MSP was the resident peritoneal macrophage. These studies establish the keratinocyte as a new target cell for MSP. The action of MSP on keratinocytes may have implications for tissue repair, wound healing, and tumor growth.
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Broxmeyer HE, Cooper S, Li ZH, Lu L, Sarris A, Wang MH, Chang MS, Donner DB, Leonard EJ. Macrophage-stimulating protein, a ligand for the RON receptor protein tyrosine kinase, suppresses myeloid progenitor cell proliferation and synergizes with vascular endothelial cell growth factor and members of the chemokine family. Ann Hematol 1996; 73:1-9. [PMID: 8695717 DOI: 10.1007/s002770050192] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Macrophage-stimulating protein (MSP), originally identified as an inducer of murine resident macrophage responsiveness to chemoattractants, is a ligand for human RON/murine STK receptor protein tyrosine kinases. Since STK was cloned from populations enriched for hematopoietic stem cells, we initiated studies on the effects of MSP on colony formation by granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) myeloid progenitor cells. MSP alone had no colony stimulating activity. However, MSP caused about a 50% suppression of CFU-GM colony formation induced by synergistic combinations of SLF or Flt-L plus GM-CSF, G-CSF, or IL-3 and of BFU-E and CFU-GEMM colonies induced by SLF or Flt3-L plus Epo or Epo and IL-3. In contrast, MSP had no effect on progenitors stimulated by one growth factor. MSP also suppressed colony formation by stimulated cord blood progenitors, but only after preinduction to a rapidly cycling state. It was previously reported that several members of the chemokine family synergistically suppress myeloid progenitor proliferation. Likewise, synergistic suppression was observed when MSP was paired with VEGF, MIP-1 alpha, IL-8, PF4, MCP-1, IP-10, or ENA-78, or when VEGF was paired with the chemokines; and the required MSP concentration was more than 100-fold less than for MSP alone. Additionally, MSP or VEGF inhibited proliferation of the human myeloid growth factor-dependent cell line, M07e, but a sustained effect required multiple additions over time. At the least, some of the MSP suppressive effects on myeloid progenitors, as assessed on single isolated CD34 marrow cells, appeared to be directly on the progenitors; sustained additions of MSP were required to see this effect. The suppressive action of MSP and its synergism with proteins of the chemokine family may be of relevance to regulation of blood cell production.
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