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Abstract
According to the basic optimization principle of artificial neural networks, a novel kind of neural network model for solving the quadratic programming problem is presented. The methodology is based on the Lagrange multiplier theory in optimization and seeks to provide solutions satisfying the necessary conditions of optimality. The equilibrium point of the network satisfies the Kuhn-Tucker condition for the problem. The stability and convergency of the neural network is investigated and the strategy of the neural optimization is discussed. The feasibility of the neural network method is verified with the computation examples. Results of the simulation of the neural network to solve optimum problems are presented to illustrate the computational power of the neural network method.
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Jabrane-Ferrat N, Bloom D, Wu A, Li L, Lo D, Sreedharan SP, Turck CW, Goetzl AE. Enhancement by vasoactive intestinal peptide of gamma-interferon production by antigen-stimulated type 1 helper T cells. FASEB J 1999; 13:347-53. [PMID: 9973323 DOI: 10.1096/fasebj.13.2.347] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vasoactive intestinal peptide (VIP) is a neuroendocrine mediator in immune tissues that affects many T cell functions through two homologous high-affinity G-protein-coupled receptors, termed VIPR1 and VIPR2. Antigen-stimulated secretion of gamma-interferon (IFN-gamma) by sperm whale myoglobin-specific Th1 cells of DBA/2 mouse I-Ed-restricted clones, which express VIPR1 and VIPR2, was enhanced by 10(-10) M to 10(-7) M VIP. Enhancement of IFN-gamma secretion reached a mean maximum of fourfold for VIP and threefold for a VIPR2-selective agonist, without any effect of a VIPR1-selective agonist. Secretion of IFN-gamma by PMA and ionomycin-stimulated clones of Th1 cells was not altered by VIP. Antigen-stimulated secretion of IFN-gamma by T cell receptor-transgenic, influenza hemagglutinin-specific, and cytokine-differentiated mouse lymph node Th1 cells, which also express VIPR1 and VIPR2, was enhanced by 10(-10) M to 10(-8) M VIP. Enhancement of IFN-gamma secretion increased to a maximum of 14-fold for VIP, 14-fold for the VIPR2-selective agonist, and 20-fold for the VIPR1-selective agonist. In contrast to VIP suppression of interleukin production and lack of effect on IFN-gamma production by T cells stimulated with anti-CD3 antibody or a mitogenic lectin, generation of IFN-gamma by antigen-stimulated T cells is enhanced significantly by physiological concentrations of VIP.
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253
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Wu A, Esnaola NF, Yamada K, Awwad M, Shimizu A, Huang C, Wain J, Zhao Y, Neville DM, Cooper DK, Sykes M, Sachs DH. Xenogeneic thymic transplantation in a pig-to-nonhuman primate model. Transplant Proc 1999; 31:957. [PMID: 10083424 DOI: 10.1016/s0041-1345(98)01854-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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254
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Ebrahimi SA, Wang EH, Wu A, Schreck RR, Passaro E, Sawicki MP. Deletion of chromosome 1 predicts prognosis in pancreatic endocrine tumors. Cancer Res 1999; 59:311-5. [PMID: 9927038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Endocrine tumors, such as parathyroid adenomas and pheochromocytomas, frequently have deletions of chromosome 1, suggesting that inactivation of a tumor suppressor gene from chromosome 1 is important in their tumorigenesis. We hypothesized that deletion of chromosome 1 may contribute to pancreatic endocrine tumor formation. Twenty-nine sporadic and MEN1 pancreatic endocrine tumors were studied for loss of heterozygosity (LOH) with 12 chromosome 1 microsatellite markers. LOH on chromosome 1 was identified in 10 of 29 (34%) tumors studied. Allele loss occurred more frequently in tumors with hepatic metastases (7 of 8) than tumors without metastases (3 of 21) (P = 0.004). Tumors in patients with lymph node involvement and patients with multiple endocrine neoplasia type 1 did not demonstrate LOH for chromosome 1 markers. These data suggest that loss of chromosome 1 is associated specifically with the development of hepatic metastases in patients with sporadic pancreatic endocrine tumors.
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Yu L, Brewer KW, Gates S, Wu A, Wang T, Babu SR, Gottlieb PA, Freed BM, Noble J, Erlich HA, Rewers MJ, Eisenbarth GS. DRB1*04 and DQ alleles: expression of 21-hydroxylase autoantibodies and risk of progression to Addison's disease. J Clin Endocrinol Metab 1999; 84:328-35. [PMID: 9920103 DOI: 10.1210/jcem.84.1.5414] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Of 957 patients with type 1 diabetes without known Addison's disease 1.6% (n = 15) were positive for 21-hydroxylase autoantibodies. Among DQ8/DQ2 heterozygous patients, the percentage expressing 21-hydroxylase autoantibodies was 5% (10 of 208) vs. less than 0.5% of patients with neither DQ8 nor DQ2. Three of the diabetic patients found to have 21-hydroxylase autoantibodies on screening were subsequently diagnosed with Addison's disease. Overall, the genotype DQ8/DQ2, consisting of DRB1*0404/DQ8 with DRB1*0301/DQ2, was present in 14 of 21 patients with Addison's disease (8 of 12 with diabetes and 6 of 9 without diabetes or antiislet autoantibodies) vs. 0.7% of the general population (109 of 15,547; P < 10(-6)) and 11% of patients with DM without Addison's disease (62 of 578; P < 10(-6)). Among patients with diabetes with DQ8, Addison's disease was strongly associated with the specific DRB1 subtype, DRB1*0404 (8 of 9 patients from 8 families, in contrast to only 109 of 408 DQ8 DM patients with diabetes without Addison's disease having DRB1*0404; P < 0.001). Among 21-hydroxylase autoantibody-positive DQ8 patients, 80% with DRB1*0404 (12 of 15) had Addison's disease, in contrast to 1 of 10 autoantibody-positive patients with DRB1*0401 or DRB1*0402 (P < 0.001). We conclude that patients with DRB1*0404 and 21-hydroxylase autoantibodies are at high risk for Addison's disease. Patients with DRB1*0401 and DRB1*0402 have more limited progression to Addison's disease despite the presence of 21-hydroxylase autoantibodies.
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256
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Maitz AH, Wu A. Treatment planning of stereotactic convergent gamma-ray irradiation using Co-60 sources. Med Dosim 1998; 23:169-75. [PMID: 9783270 DOI: 10.1016/s0958-3947(98)00022-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The basic features of the convergent Co-60 gamma-ray unit, known as Gamma Knife and the standard procedures of treatment planning for various cases in general have been described in details. The new generation of the rotating gamma system and the future clinical applications are briefly mentioned.
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257
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Wu A, Nashan B, Messner U, Schmidt HH, Guenther HH, Niesert S, Pichmayr R. Outcome of 22 successful pregnancies after liver transplantation. Clin Transplant 1998; 12:454-64. [PMID: 9787957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
To evaluate course and outcome of pregnancies in liver transplanted patients and to provide a brief summary on the development of these children, 22 pregnancies and 23 children (1 month-99 months old) of 16 patients who had been liver transplanted at our institution (mean interval from transplantation to pregnancy 43.1 months) were reviewed. Standard immunosuppressive regimen during pregnancy consisted of cyclosporine A (CyA), tacrolimus (FK), azathioprine (Aza) and/or a low-dose steroid therapy. CyA and FK whole blood trough levels were monitored on a routinely basis to keep therapeutic range (CyA 80-150 ng/mL; FK 4-8 ng/mL). No patient had a graft loss and there were no lethal complications. Beside de novo hypertension (n = 3) and preeclampsia (n = 3) problems during pregnancy included one steroid-sensitive rejection at 36 wk gestation, one case of tacrolimus toxicity at 24 wk with complete reconstitution, and one case of de novo choledocholithiasis with recurrent cholangitis. Three cases of infections occurred. In total, 23 children, including one set of twins, were born. Terms of gestation (mean = 38.1 wk, +/- 2.2 SD), deliveries (spontaneous n = 13, cesarean section n = 7, forceps n = 1, vacuum extraction (VE) n = 1) and birth weights (2876 g, +/- 589.3 SD) were typical. Three pregnancies were preterm, one being a twin pregnancy. Neither congenital malformations nor unusual infections were seen in the children. Postnatal follow-up revealed appropriate physical growth to date. Psychological development seems to be adequate. Our data indicate that successful pregnancies after liver transplantation (LTX) under careful management by transplant specialists, obstetricians and perinatalogists have a good outcome. So far, neither pre- nor postnatal child development appear to be influenced by maternal immunosuppressive therapy during pregnancy.
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258
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Kovoor A, Celver JP, Wu A, Chavkin C. Agonist induced homologous desensitization of mu-opioid receptors mediated by G protein-coupled receptor kinases is dependent on agonist efficacy. Mol Pharmacol 1998; 54:704-11. [PMID: 9765514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Using Xenopus laevis oocytes coexpressing mammalian mu-opioid receptors (MORs), beta-adrenergic receptor kinase 2 (beta-ARK2) [also called G protein-coupled receptor kinase (GRK3)], and beta-arrestin 2 (beta-arr 2), we compared the rates of beta-ARK2 (GRK3)- and beta-arr 2-mediated homologous receptor desensitization produced by treatment with opioid agonists of different efficacies. The response to MOR activation was measured using two-electrode voltage clamp as an increase in the conductance of the coexpressed G protein-coupled inwardly rectifying potassium (heteromultimer of KIR3.1 and KIR3.4) channels. Treatment with opioids of high efficacy, either [D-Ala2,N-MePhe4,Gly-ol5]-enkephalin, fentanyl, or sufentanyl, produced a GRK3- and beta-arr 2-dependent reduction in response in <20 min, whereas treatment with the partial agonist morphine produced receptor desensitization at a significantly slower rate. Because GRK3 requires activation and membrane targeting by free G protein betagamma subunits released after agonist-mediated activation of G proteins, a low efficacy agonist such as morphine may produce weak receptor desensitization as a consequence of poor GRK3 activation. To address this hypothesis, we substituted GRK5, a GRK that does not require activation by G protein betagamma. In oocytes expressing GRK5 instead of GRK3, both [D-Ala2,N-MePhe4, Gly-ol5]enkephalin and fentanyl, but not morphine, produced desensitization of MOR-activated potassium conductance. Thus, mu-opioid agonists produced significant receptor desensitization, mediated by either GRK3 or GRK5, at a rate dependent on agonist efficacy.
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259
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Neustadt BR, Smith EM, Lindo N, Nechuta T, Bronnenkant A, Wu A, Armstrong L, Kumar C. Construction of a family of biphenyl combinatorial libraries: structure-activity studies utilizing libraries of mixtures. Bioorg Med Chem Lett 1998; 8:2395-8. [PMID: 9873548 DOI: 10.1016/s0960-894x(98)00433-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A set of biphenyl aminoacid building blocks has been synthesized. These were used to construct partially-peptidic combinatorial libraries as equimolar multi-component samples. Activity of members of this library as vitronectin receptor antagonists is described, together with SAR studies of the most active members. These studies illustrate several important features of combinatorial libraries.
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260
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Wu A, Bennett WN, Eigenfeld M, Berry B, Gozdowiak A, Wallace G, Bodemer G, Goldbach C, Holford M, Davids S, Bretl DD, Musich JK. Nitrite contamination in urine collection kit component-absorbent sheet. J Anal Toxicol 1998; 22:401-2. [PMID: 9737337 DOI: 10.1093/jat/22.5.401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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261
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Wu A, Lee YY. Nonisothermal simultaneous saccharification and fermentation for direct conversion of lignocellulosic biomass to ethanol. Appl Biochem Biotechnol 1998; 70-72:479-92. [PMID: 9627393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The enzymatic reaction in the simultaneous saccharification and fermentation (SSF) is operated at a temperature much lower than its optimum level. This forces the enzyme activity to be far below its potential, consequently raising the enzyme requirement. To alleviate this problem, a nonisothermal simultaneous saccharification and fermentation process (NSSF) was investigated. The NSSF is devised so that saccharification and fermentation occur simultaneously, yet in two separate reactors that are maintained at different temperatures. Lignocellulosic biomass is retained inside a column reactor and hydrolyzed at the optimum temperature for the enzymatic reaction (50 degrees C). The effluent from the column reactor is recirculated through a fermenter, which runs at its optimum temperature (20-30 degrees C). The cellulase enzyme activity is increased by a factor of 2-3 when the hydrolysis temperature is raised from 30 to 50 degrees C. The NSSF process has improved the enzymatic reaction in the SSF to the extent that it reduces the overall enzyme requirement by 30-40%. The effect of temperature on beta-glucosidase activity was the most significant among the individual cellulase compounds. Both ethanol yield and productivity in the NSSF are substantially higher than those in the SSF at the enzyme loading of 5 IFPU/g glucan. With 10 IFPU/g glucan, improvement in productivity was more discernible for the NSSF. The terminal yield attainable in 4 d with the SSF was reachable in 40 h with the NSSF.
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262
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Wu A, Esnaola NF, Yamada K, Awwad M, Shimizu A, Huang C, Wain J, Zhao Y, Neville D, Cooper D, Sykes M, Sachs DH. XENOGENEIC THYMIC TRANSPLANTATION IN A PIG-TO-NON-HUMAN-PRIMATE MODEL. Transplantation 1998. [DOI: 10.1097/00007890-199806270-00483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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263
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Wu A, Esnaola NF, Yamada K, Awwad M, Shimizu A, Huang C, Wain J, Zhao Y, Neville D, Cooper DK, Sykes M, Sachs DH. XENOGENEIC THYMIC TRANSPLANTATION IN A PIG-TO-NON-HUMAN-PRIMATE MODEL. Transplantation 1998. [DOI: 10.1097/00007890-199805131-00462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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264
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Wu A, Arshoun Y, Izadbakhsh M, Kalnicki S. Simple look-up table of optimized dwell time intervals using a high-dose-rate remote afterloader for endovascular irradiation. Int J Radiat Oncol Biol Phys 1998; 40:1243-8. [PMID: 9539582 DOI: 10.1016/s0360-3016(97)00946-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE This article's objective is to develop a simple methodology deliver a uniform radiation dose to the wall of a narrow peripheral artery for preventing restenosis using a high-dose-rate (HDR) 192Ir remote afterloader. METHODS AND MATERIALS Based upon published two-dimensional data such as anisotropy factors of an HDR 192Ir source calculated from the Monte-Carlo method, arterial wall doses at a close range from an HDR source may be easily calculated using the special formula suggested in Task Group Report No. 43 published by the American Association of Physicists in Medicine. An optimization procedure was used to calculate the optimized dwell times for delivering a uniform dose along arterial walls for various arterial diameters and lengths of lesions. RESULTS Based on lengths of the stenosis and diameters of arteries or angioplasty balloons, a set of simple look-up tables for optimal dwell time intervals of endovascular radiation treatment have been developed for the MicroSelectron HDR remote afterloader. CONCLUSION Doses for endovascular irradiation have been accurately calculated with anisotropy factors. For delivering uniform doses along the arterial wall, a set of look-up tables listed for optimal dwell times is available for the HDR remote afterloader.
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265
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DiMolfetto L, Neal HA, Wu A, Reilly C, Lo D. The density of the class II MHC T cell receptor ligand influences IFN-gamma/IL-4 ratios in immune responses in vivo. Cell Immunol 1998; 183:70-9. [PMID: 9578721 DOI: 10.1006/cimm.1997.1231] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of CD4+ T cells depends on T cell receptor recognition of MHC class II/peptide and on costimulation provided by CD28/B7. It has been shown that different levels of costimulation can influence T helper cell differentiation into Th1 versus Th2 phenotypes. Similar arguments have been made for different levels of peptide/MHC density on antigen-presenting cells, but to date supportive evidence has only come from in vitro studies. Here, using transgenic mice with reduced MHC class II expression on both B cells and dendritic cells, we demonstrate that T helper cell differentiation in vivo is also influenced by the density of expression of MHC class II. Although priming and expansion of antigen-specific T cells were normal in these mice, T cell responses were dominated by the Th1-associated cytokine IFN-gamma, with reduced levels of the Th2 cytokine IL-4 compared to controls. These results provide direct evidence that the efficiency of antigen presentation in vivo can determine effector cell phenotype.
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266
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Caselitz M, Wagner S, Chavan A, Gebel M, Bleck JS, Wu A, Schlitt HJ, Galanski M, Manns MP. Clinical outcome of transfemoral embolisation in patients with arteriovenous malformations of the liver in hereditary haemorrhagic telangiectasia (Weber-Rendu-Osler disease). Gut 1998; 42:123-6. [PMID: 9505897 PMCID: PMC1726950 DOI: 10.1136/gut.42.1.123] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Arteriovenous malformations of the liver in Osler's disease may present as high output cardiac failure. A few case reports suggested that treatment with arterial embolisation may have beneficial effects in such patients. AIMS To investigate the efficacy and safety of this treatment modality in a prospective pilot study. PATIENTS AND METHODS Four women and one man (aged 39-59 years) with the dominant hepatic manifestation of Osler's disease presented with symptoms of cardiac failure and elevated cardiac output. Arteriovenous malformations were treated in three to five sessions with arterial embolisation using coils. The outcome was analysed by measurement of cardiac output and scoring of clinical symptoms. RESULTS Embolisation was technically feasible in all patients and adequate occlusion of vascular malformations was achieved in four patients. After completion of therapy symptoms improved in four patients, while one patient suffered from abdominal pain due to cholangitis. One patient died seven months after the embolisation treatment from variceal bleeding. Mean cardiac output significantly decreased from 14.2 (range 12-17.3) l/min to 8 (range 5.9-10.6) l/min (p = 0.043). After a median follow up of 23 months (range 7-50 months), three of five patients had a long lasting improvement of clinical symptoms and cardiac function. CONCLUSIONS This first treatment series of patients with dominant hepatic involvement in Osler's disease indicates that arterial embolisation may prevent cardiac failure by significantly lowering cardiac output.
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267
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Azzoli CG, Sagar M, Wu A, Lowry D, Hennings H, Morgan DL, Weinberg WC. Cooperation of p53 loss of function and v-Ha-ras in transformation of mouse keratinocyte cell lines. Mol Carcinog 1998; 21:50-61. [PMID: 9473771 DOI: 10.1002/(sici)1098-2744(199801)21:1<50::aid-mc7>3.0.co;2-t] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We previously demonstrated that after transduction with the v-Ha-ras oncogene and grafting onto nude mouse hosts, primary epidermal keratinocytes with a null mutation in the p53 gene form tumors with increased growth rates and predisposition to malignant conversion relative to p53 wild-type keratinocytes (Weinberg WC, et al., Cancer Res 54:5584-5592, 1994). To further explore the cooperation between p53 loss of function and activation of the ras oncogene, cell lines were established from the normal epidermises of newborn and adult p53-null mice, and parallel subclones were reconstituted with the p53val135 temperature-sensitive mutant. Reconstituted lines C, G, N, and V demonstrated functional p53 transcriptional activator activity at the wild-type-permissive temperature of 32 degrees C, compared with the hygromycin-selected control line X and parental p53-null lines NHK4 and AK1b. Hygromycin-selected subclones, but not the parental lines, made normal skin in vivo; all cell lines made carcinomas after introduction of v-Ha-ras, independent of p53 status. These cell lines were compared in vitro at 32 degrees C to maximize the amount of p53val135 in the wild-type conformation. Expression of v-Ha-ras did not consistently alter p53-mediated transcriptional activity, suggesting tat ras acts downstream or independently of p53. No correlation was observed between p53-mediated transcriptional activity and in vitro growth rates, colony formation after exposure to ultraviolet light, or suppression by normal neighboring keratinocytes. However, keratinocyte cell lines devoid of p53 and expressing v-Ha-ras formed colonies in soft agar; this was blocked at 32 degrees C in all cell lines reconstituted with p53val135. These keratinocyte lines provide a model for exploring the role of p53 and the interaction of p53 and ras in keratinocyte transformation.
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Wu A, Derrico CA, Hatem L, Colvin RA. Alzheimer's amyloid-beta peptide inhibits sodium/calcium exchange measured in rat and human brain plasma membrane vesicles. Neuroscience 1997; 80:675-84. [PMID: 9276485 DOI: 10.1016/s0306-4522(97)00053-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Na+/Ca2+ exchange activity was measured by monitoring vesicular Ca2+ content after incubation in buffers containing 45Ca2+. When Na+-loaded vesicles were placed into Na+-free buffer, vesicular Ca2+ content increased rapidly and reached a plateau after two to three minutes. Only preaggregated amyloid-beta1-40 (Abeta1-40) and Abeta25-35 reduced vesicular Ca2+ content. Both peptides produced a maximal reduction in Ca2+ content of approximately 50%. The peptides reduced Ca2+ content with similar potency and half maximal effects were seen at less than 10 microM for Abeta25-35. Calcium-loaded vesicles mediate a rapid Ca2+/Ca2+ exchange, which also was inhibited by aggregated Abeta25-35. Aggregated Abeta25-35 did not affect the passive Ca2+ permeability of the vesicles. Aggregated Abeta25-35 reduced Ca2+ content in plasma membrane vesicles isolated from normal and Alzheimer's disease frontal cortex with less potency but the same efficacy as seen in rat brain. Aggregated Abeta25-35 did not produce nonspecific effects on vesicle morphology such as clumping or loss of intact vesicles. When placed in the buffer used to measure Ca2+ content, Congo Red at molar ratios of less than one blocked the inhibitory effect of preaggregated Abeta25-35. When added in equimolar concentrations to freshly dissolved and unaggregated Abeta25-35, Congo Red also was effective at blocking the inhibitory effect on Ca2+ content. In contrast, vitamin E (antioxidant) and N-tert-butyl-alpha-phenylnitrone (spin trapping agent) failed to block the inhibitory action of aggregated Abeta25-35. The exact mechanisms of Abeta-induced neurotoxicity in cell culture has yet to be solved. Accumulation of free radicals play a necessary role, but disruptions of Ca2+ homeostasis are also important. The data presented here are consistent with a proposed mechanism where aggregated Abeta peptides directly interact with hydrophobic surfaces of the exchanger protein and/or lipid bilayer and interfere with plasma membrane Ca2+ transport.
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Wu A, Pangalos MN, Efthimiopoulos S, Shioi J, Robakis NK. Appican expression induces morphological changes in C6 glioma cells and promotes adhesion of neural cells to the extracellular matrix. J Neurosci 1997; 17:4987-93. [PMID: 9185536 PMCID: PMC6573314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Appicans are secreted or cell-associated brain chondroitin sulfate proteoglycans produced by glia cells and containing Alzheimer amyloid precursor protein (APP) as a core protein. Here, we report that rat C6 glioma cells transfected with appican displayed a dramatic change in their phenotypic appearance compared with untransfected cells or cells transfected with APP. Appican-transfected cells lost the round appearance of the untransfected control C6 cells, acquired a flat morphology, and elaborated more processes than control cells. Untransfected, or APP-transfected C6, cells were completely dissociated from their substrate after 40 min of treatment with cell dissociation solution. Under the same conditions, however, <20% of the appican-transfected C6 cells were dissociated from their substrate, suggesting that the appican-transfected glia cells attach more avidly to their substrate than do untransfected or APP transfected control cells. In contrast, appican-transfected fibroblast cells showed no morphological changes and dissociated from their substrate similarly to untransfected fibroblast cells. Extracellular matrix (ECM) prepared from appican-transfected C6 cell cultures contained high levels of appican and was a significantly better substrate for the attachment of C6 cells than ECM from either untransfected or APP-transfected cultures. Furthermore, cell adhesion to ECM was independent of the level of appican expression of the plated cells. ECM from appican-transfected C6 cultures stimulated adhesion of other neural cells including primary astrocytes, Neuro2a neuroblastoma, and PC12 pheochromocytoma, but not fibroblast cells. Conditioned media from appican-transfected C6 cultures failed to promote cell adhesion. Together, these data suggest that secreted appican incorporates into ECM and promotes adhesion of neural cells. Furthermore, our data suggest that the chondroitin sulfate chain engenders APP with novel biological functions.
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Pangalos MN, Shioi J, Efthimiopoulos S, Wu A, Robakis NK. Characterization of appican, the chondroitin sulfate proteoglycan form of the Alzheimer amyloid precursor protein. NEURODEGENERATION : A JOURNAL FOR NEURODEGENERATIVE DISORDERS, NEUROPROTECTION, AND NEUROREGENERATION 1996; 5:445-51. [PMID: 9117561 DOI: 10.1006/neur.1996.0061] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this report we focus on the characterization of appican, the chondroitin sulfate proteoglycan form of amyloid precursor protein (APP), and the role that it and other proteoglycans may play in AD. Appican is expressed by certain transformed cell lines of neural origin, namely C6 cells and N2a neuroblastomas. It is detected in both human and rat brain and in primary cultures is expressed by astrocytes, but not neurons. The core protein of appican has been shown to be an alternatively spliced isoform of APP, lacking exon 15 of the APP gene, originally identified in leukocytes (L-APP). Splicing out of exon 15 results in the joining of exons 14 and 16, and formation of an Asp-Xaa-Ser-Gly consensus sequence for chondroitin sulfate chain attachment to serine 619 of L-APP, which lies 16 amino acids upstream of the A beta peptide sequence. Mutation of this serine residue to an alanine prevented chondroitin sulfate chain addition to the core protein. Levels of appican expression could be regulated by growth conditions independently of APP, suggesting that these molecules may serve distinct physiological roles within the cell. Morphological changes were also observed in both astrocytic and transformed cell cultures, that appeared to reflect changes in levels of appican expression. Preliminary data suggest that appican may be a strong cell adhesion molecule. Transfected C6 glioma cells overexpressing appican remained attached to tissue culture dishes markedly better than either C6 cells over-expressing exon-15 containing APP or WT C6 cells. Appican-enriched extracellular matrix (ECM) was also observed to serve as a much better substrate for attachment of N2a neuroblastomas, pheocromocytoma PC12 cells and primary astrocytes compared to APP enriched ECM.
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Wu A, Johnson M, Chen AS, Kalnicki S. Evaluation of dose calculation algorithm of the peacock system for multileaf intensity modulation collimator. Int J Radiat Oncol Biol Phys 1996; 36:1225-31. [PMID: 8985048 DOI: 10.1016/s0360-3016(96)00419-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE To evaluate the dose calculation algorithm used in the inverse treatment planning computer system for the intensity modulation multileaf collimator. METHODS AND MATERIALS The inverse treatment-planning computer system calculates the intensities of multiple pencil beams to achieve an optimal distribution and modulates the beam intensity through the special multileaf collimator. The system's dose calculation algorithm made the two basic assumptions: (a) The tissue-maximum ratios (TMRs) of a single pencil beam have the same values as TMRs for raylines through each pencil beam that are determined from percentage depth dose isodose curves along the long axis of the 2 x 20 cm2 field with all leaves open; and (b) the relative output factors (ROF) of each pencil beam also have the same values as the rayline TMR at d(max) of the 2 x 20 cm2 field. To verify these two assumptions, a special multileaf collimator was installed to our linear accelerator which produces 4 MV x-rays. The TMRs and ROFs for the single leaves 1 through 10 were measured using an ion chamber and TLD dosimeter in either a water or a polystyrene phantom. The values of rayline TMRs were calculated from the measured crossplane isodose curves of the 2 x 20 cm2 field. Comparisons were made between these two sets of data. RESULTS Based on our measurements, we found that the ROFs of a pencil beam obtained from the rayline TMRs at d(max) are as much as 7.6% greater than that of single pencil beams. The ROF of the 1 x 1 cm2 pencil beam is 4 and 6.5% less than that of a cluster of four neighboring pencil beams forming a 2 x 2 cm2, and a 2 x 20 cm2 field respectively. However, the rayline TMRs are generally larger than the TMRs of a single pencil beam. At a depth of 8 cm, the average depth in the middle of intracranial space, the rayline TMRs of the pencil beams of leaves 1 and 10 are 5.4 and 9% higher than a single pencil beam TMR at the same depth, respectively. Also interesting is to note that the TMRs of each of the single pencil beams were found to be equal. CONCLUSIONS In our article, evaluations and comparisons of TMRs and ROFs were made for two extreme conditions. The measured values of TMRs and ROFs of a single beam have been shown to be significantly different from those used in the calculations. Because both the TMR and ROF are influenced by the scattering radiation in the same direction, the deviations for these two factors would be expected to be magnified. Thus, for the two extreme situations we have investigated, dose deviations would be on the order of 15%. In real patient treatment; of course, these deviations may be somewhat less, but still significant. Our results, however, show that further investigations are warranted.
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Zhang W, Wu A, Sun J. [Combined treatment for advanced vulvar cancer]. ZHONGHUA FU CHAN KE ZA ZHI 1996; 31:728-31. [PMID: 9387514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To investigate the combined treatment of surgery and radiotherapy as well as prognosis significance for advanced vulvar cancer. METHODS Fourty-three cases of advanced vulvar cancer treated by surgery and pre- and post-operative radiation were retrospectively analysed. Twenty-nine patients were treated by preoperative radiotherapy with surgery, fourteen by surgery with postoperative irradiation. 43 patients were underwent radical vulvectomy with inguinal lymphadenectomy (20 cases) and with biopsies of inguinal lymph nodes (16 cases). Partial resection of vagina, distant urethra or anus were done concurrently with radical vulvectomy in 41 patients with adjacent organs invaded. The effects with various doses of radiation for local tumor were compared and the recurrences in patients with tumor resected completely and with microresidual disease after surgery were analysed. RESULTS The overall 5-yr survival rate was 45.0% for this group (by Kaplan-Meier). Patients received preoperative irradiation with dose maximum (Dm) > or = 40 Gy had a better tumor regression than with Dm < 40 Gy (75.0% vs 18.2%, P < 0.05). 4 out of 6 patients received postoperative irradiation Dm > 40 Gy were survived over 5-yr, in contrast, 2 out of 8 patients with Dm < or = 40 Gy were survived over 3 and 5 years respectively. The local recurrence rate was 25.0% in patients with no residual disease and 68.4% with microscopic tumor in the surgical margins or nearby (P < 0.05). CONCLUSION The results demonstrate that the dosage of irradiation and the thoroughness of radical surgery are the most important factors influencing the prognosis.
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Cheng S, Chan A, Fong S, Lam M, Leung A, Lee P, Tsang J, Wong J, Wu A. Outcome studies for burn patients in Hong Kong: patients' satisfaction. Burns 1996; 22:623-6. [PMID: 8982541 DOI: 10.1016/s0305-4179(96)00037-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
With the recent advances in burns treatment, many more survive the burn to experience pain, scarring, physical deformity, loss of function and psychological trauma. Pressure therapy prescribed by occupational therapists for more than 20 years in Hong Kong has proved its effectiveness in treating the visible scars. However, the inconvenience and impaired appearance that is brought about by these garments during the long phase of therapy bears some weight in worsening patients' social acceptance and happiness in life, also their families especially in children. The objects of the studies were to measure the subjective rating of the effectiveness of pressure therapy through patients' satisfaction towards treatment effectiveness and its effect on daily life. Seventy cases with burn injuries over 1 year previously were selected randomly among the centres for the survey. The scale used was ordinal from 1 to 6. Eleven items concerning treatment effectiveness, life at home, work and leisure aspects were questioned. Results were analysed into two streams-satisfaction towards pressure therapy and change of life satisfaction pre- and post-injury. Non-parametric tests were used for data analysis. Through the Wilcoxon Sign Rank Test and Cluster analysis, major determinants were identified. These factors also showed significant correlation with this demographic data. The conclusions helped to evaluate and improve the existing service in both the garment properties and our scope of therapy for these patients, especially in work rehabilitation and finally (sexual) counselling which should be addressed by a team with interdepartmental support.
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Wu A, Kalnick S, Schell MC. MRI: an important factor for decreasing the morbidities of treating vestibular schwannoma with radiosurgery. Int J Radiat Oncol Biol Phys 1996; 36:1283-4. [PMID: 8985058 DOI: 10.1016/s0360-3016(96)00519-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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