Browsing by Subject "Vascular Endothelial Growth Factor A"

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    Characterization of topographical effects on macrophage behavior in a foreign body response model.
    (Biomaterials, 2010-05) Chen, Sulin; Jones, Jacqueline A; Xu, Yongan; Low, Hong-Yee; Anderson, James M; Leong, Kam W
    Current strategies to limit macrophage adhesion, fusion and fibrous capsule formation in the foreign body response have focused on modulating material surface properties. We hypothesize that topography close to biological scale, in the micron and nanometric range, provides a passive approach without bioactive agents to modulate macrophage behavior. In our study, topography-induced changes in macrophage behavior was examined using parallel gratings (250 nm-2 mum line width) imprinted on poly(epsilon-caprolactone) (PCL), poly(lactic acid) (PLA) and poly(dimethyl siloxane) (PDMS). RAW 264.7 cell adhesion and elongation occurred maximally on 500 nm gratings compared to planar controls over 48 h. TNF-alpha and VEGF secretion levels by RAW 264.7 cells showed greatest sensitivity to topographical effects, with reduced levels observed on larger grating sizes at 48 h. In vivo studies at 21 days showed reduced macrophage adhesion density and degree of high cell fusion on 2 mum gratings compared to planar controls. It was concluded that topography affects macrophage behavior in the foreign body response on all polymer surfaces examined. Topography-induced changes, independent of surface chemistry, did not reveal distinctive patterns but do affect cell morphology and cytokine secretion in vitro, and cell adhesion in vivo particularly on larger size topography compared to planar controls.
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    Effect of Prior Anti-VEGF Injections on the Risk of Retained Lens Fragments and Endophthalmitis after Cataract Surgery in the Elderly.
    (Ophthalmology, 2016-02) Hahn, Paul; Yashkin, Arseniy P; Sloan, Frank A
    PURPOSE: To investigate the effect of prior intravitreal anti-vascular endothelial growth factor (VEGF) injections on surgical and postoperative complication rates associated with cataract surgery in a nationally representative longitudinal sample of elderly persons. DESIGN: Retrospective, longitudinal cohort analysis. PARTICIPANTS: A total of 203 643 Medicare beneficiaries who underwent cataract surgery from January 1, 2009, to December 31, 2013. METHODS: By using the 5% sample of Medicare claims data, the study assessed risks of 3 adverse outcomes after receipt of cataract surgery for beneficiaries with a history of intravitreal injections. Risks of these outcomes in beneficiaries with a history of intravitreal injections relative to those without were calculated using the Cox proportional hazard model. MAIN OUTCOME MEASURES: The primary outcome was the risk of subsequent removal of retained lens fragments (RLFs) within 28 days after cataract surgery. Secondary outcomes were a new diagnosis of acute (<40 days) or delayed-onset (40+ days) endophthalmitis and risk of a new primary open-angle glaucoma (POAG) diagnosis within 365 days after cataract surgery. RESULTS: Prior intravitreal anti-VEGF injections were associated with a significantly increased risk of subsequent RLF removal within 28 days after cataract surgery (hazard ratio [HR], 2.26; 95% confidence interval [CI], 1.19-4.30). Prior injections were also associated with increased risk of both acute (HR, 2.29; 95% CI, 1.001-5.22) and delayed-onset endophthalmitis (HR, 3.65; 95% CI, 1.65-8.05). Prior injections were not a significant indicator of increased risk of a new POAG diagnosis. CONCLUSIONS: A history of intravitreal injections may be a risk factor for cataract surgery-related intraoperative complications and endophthalmitis. Given the frequency of intravitreal injections and cataract surgery, increased preoperative assessment, additional intraoperative caution, and postoperative vigilance are recommended in patients with a history of intravitreal injections undergoing cataract extraction.
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    Genotypes and haplotypes of the VEGF gene and survival in locally advanced non-small cell lung cancer patients treated with chemoradiotherapy.
    (BMC cancer, 2010-08-16) Guan, Xiaoxiang; Yin, Ming; Wei, Qingyi; Zhao, Hui; Liu, Zhensheng; Wang, Li-E; Yuan, Xianglin; O'Reilly, Michael S; Komaki, Ritsuko; Liao, Zhongxing
    Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis involving in carcinogenesis, including lung cancer. We hypothesized that VEGF polymorphisms may affect survival outcomes among locally advanced non-small cell lung cancer (LA-NSCLC) patients.We genotyped three potentially functional VEGF variants [-460 T > C (rs833061), -634 G > C (rs2010963), and +936 C > T (rs3025039)] and estimated haplotypes in 124 Caucasian patients with LA-NSCLC treated with definitive radiotherapy. We used Kaplan-Meier log-rank tests, and Cox proportional hazard models to evaluate the association between VEGF variants and overall survival (OS).Gender, Karnofsky's performance scores (KPS) and clinical stage seemed to influence the OS. The variant C genotypes were independently associated with significantly improved OS (CT+CC vs. TT: adjusted hazard ratio [HR] = 0.58; 95% confidence interval [CI] = 0.37-0.92, P = 0.022), compared with the VEGF -460 TT genotype.Our study suggests that VEGF -460 C genotypes may be associated with a better survival of LA-NSCLC patients after chemoradiotherapy. Large studies are needed to confirm our findings.
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    Interception of host angiogenic signalling limits mycobacterial growth.
    (Nature, 2015-01-29) Oehlers, Stefan H; Cronan, Mark R; Scott, Ninecia R; Thomas, Monica I; Okuda, Kazuhide S; Walton, Eric M; Beerman, Rebecca W; Crosier, Philip S; Tobin, David M
    Pathogenic mycobacteria induce the formation of complex cellular aggregates called granulomas that are the hallmark of tuberculosis. Here we examine the development and consequences of vascularization of the tuberculous granuloma in the zebrafish-Mycobacterium marinum infection model, which is characterized by organized granulomas with necrotic cores that bear striking resemblance to those of human tuberculosis. Using intravital microscopy in the transparent larval zebrafish, we show that granuloma formation is intimately associated with angiogenesis. The initiation of angiogenesis in turn coincides with the generation of local hypoxia and transcriptional induction of the canonical pro-angiogenic molecule Vegfaa. Pharmacological inhibition of the Vegf pathway suppresses granuloma-associated angiogenesis, reduces infection burden and limits dissemination. Moreover, anti-angiogenic therapies synergize with the first-line anti-tubercular antibiotic rifampicin, as well as with the antibiotic metronidazole, which targets hypoxic bacterial populations. Our data indicate that mycobacteria induce granuloma-associated angiogenesis, which promotes mycobacterial growth and increases spread of infection to new tissue sites. We propose the use of anti-angiogenic agents, now being used in cancer regimens, as a host-targeting tuberculosis therapy, particularly in extensively drug-resistant disease for which current antibiotic regimens are largely ineffective.
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    Metronomic chemotherapy with daily, oral etoposide plus bevacizumab for recurrent malignant glioma: a phase II study.
    (Br J Cancer, 2009-12-15) Reardon, DA; Desjardins, A; Vredenburgh, JJ; Gururangan, S; Sampson, JH; Sathornsumetee, S; McLendon, RE; Herndon, JE; Marcello, JE; Norfleet, J; Friedman, AH; Bigner, DD; Friedman, HS
    BACKGROUND: We evaluated bevacizumab with metronomic etoposide among recurrent malignant glioma patients in a phase 2, open-label trial. METHODS: A total of 59 patients, including 27 with glioblastoma (GBM) and 32 with grade 3 malignant glioma, received 10 mg kg(-1) bevacizumab biweekly and 50 mg m(-2) etoposide daily for 21 consecutive days each month. The primary end point was a 6-month progression-free survival, and secondary end points included safety and overall survival. Vascular endothelial growth factor (VEGF), VEGFR-2, carbonic anhydrase 9 (CA9) and hypoxia-inducible factor-2alpha (HIF-2alpha) were assessed semiquantitatively in archival tumours using immunohistochemistry and were correlated with outcome. RESULTS: Among grade 3 and GBM patients, the 6-month progression-free survivals were 40.6% and 44.4%, the radiographic response rates were 22% and 37% and the median survivals were 63.1 and 44.4 weeks, respectively. Hypertension predicted better outcome among both grade 3 and GBM patients, whereas high CA9 and low VEGF were associated with poorer progression-free survival (PFS) among those with GBM. The most common grade > or = 3 adverse events included neutropaenia (24%), thrombosis (12%), infection (8%) and hypertension (3%). Two patients had asymptomatic, grade 1 intracranial haemorrhage and one on-study death occurred because of pulmonary embolism. CONCLUSION: Bevacizumab with metronomic etoposide has increased toxicity compared with previous reports of bevacizumab monotherapy. Its anti-tumour activity is similar to that of bevacizumab monotherapy or bevacizumab plus irinotecan. (ClinicalTrials.gov: NCT00612430).
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    Palmitoyl acyltransferase, Zdhhc13, facilitates bone mass acquisition by regulating postnatal epiphyseal development and endochondral ossification: a mouse model.
    (PLoS One, 2014) Song, I-Wen; Li, Wei-Ru; Chen, Li-Ying; Shen, Li-Fen; Liu, Kai-Ming; Yen, Jeffrey JY; Chen, Yi-Ju; Chen, Yu-Ju; Kraus, Virginia Byers; Wu, Jer-Yuarn; Lee, MT Michael; Chen, Yuan-Tsong
    ZDHHC13 is a member of DHHC-containing palmitoyl acyltransferases (PATs) family of enzymes. It functions by post-translationally adding 16-carbon palmitate to proteins through a thioester linkage. We have previously shown that mice carrying a recessive Zdhhc13 nonsense mutation causing a Zdhcc13 deficiency develop alopecia, amyloidosis and osteoporosis. Our goal was to investigate the pathogenic mechanism of osteoporosis in the context of this mutation in mice. Body size, skeletal structure and trabecular bone were similar in Zdhhc13 WT and mutant mice at birth. Growth retardation and delayed secondary ossification center formation were first observed at day 10 and at 4 weeks of age, disorganization in growth plate structure and osteoporosis became evident in mutant mice. Serial microCT from 4-20 week-olds revealed that Zdhhc13 mutant mice had reduced bone mineral density. Through co-immunoprecipitation and acyl-biotin exchange, MT1-MMP was identified as a direct substrate of ZDHHC13. In cells, reduction of MT1-MMP palmitoylation affected its subcellular distribution and was associated with decreased VEGF and osteocalcin expression in chondrocytes and osteoblasts. In Zdhhc13 mutant mice epiphysis where MT1-MMP was under palmitoylated, VEGF in hypertrophic chondrocytes and osteocalcin at the cartilage-bone interface were reduced based on immunohistochemical analyses. Our results suggest that Zdhhc13 is a novel regulator of postnatal skeletal development and bone mass acquisition. To our knowledge, these are the first data to suggest that ZDHHC13-mediated MT1-MMP palmitoylation is a key modulator of bone homeostasis. These data may provide novel insights into the role of palmitoylation in the pathogenesis of human osteoporosis.
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    Polymorphisms of TGFB1 and VEGF genes and survival of patients with gastric cancer.
    (Journal of experimental & clinical cancer research : CR, 2009-06-30) Guan, Xiaoxiang; Zhao, Hui; Niu, Jiangong; Tan, Dongfeng; Ajani, Jaffer A; Wei, Qingyi
    Some TGFB1 and VEGF polymorphisms are believed to be functional. Given that these genes are involved in tumor growth and progression including angiogenesis, dissemination, and invasiveness, we hypothesized that these polymorphisms would be associated with survival in patients with gastric cancer.We genotyped TGFB1 -509 C>T, +1869 T>C, and +915 G>C and VEGF -1498T>C, -634G>C, and +936C>T in 167 patients with gastric cancer. Using the Kaplan and Meier method, log-rank tests, and Cox proportional hazard models, we evaluated associations among TGFB1 and VEGF variants with overall, 1-year, and 2-year survival rates.Although there were no significant differences in overall survival rates among all polymorphisms tested, patients with TGFB1+915CG and CC genotypes had a poorer 2-year survival (adjusted hazard ratio (HR), 3.06; 95% confidence interval (CI), 1.09-8.62; P = 0.034) than patients with the GG genotype had. In addition, patients heterozygous for VEGF -634CG also had a poorer 1-year survival (adjusted HR, 2.08; 95% CI, 1.03-4.22; P = 0.042) than patients with the -634GG genotype.Our study suggested that TGFB1+915CG/CC and VEGF -634CG genotypes may be associated with short-term survival in gastric cancer patients. However, larger studies are needed to verify these findings.
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    The VEGF -634G>C promoter polymorphism is associated with risk of gastric cancer.
    (BMC gastroenterology, 2009-10-16) Guan, Xiaoxiang; Zhao, Hui; Niu, Jiangong; Tang, Dongfeng; Ajani, Jaffer A; Wei, Qingyi
    Both TGF-beta1 and VEGF play a critic role in the multiple-step process of tumorgenesis of gastric cancer. Single nucleotide polymorphisms (SNPs) of the TGFB1 and VEGF genes have been associated with risk and progression of many cancers. In this study, we investigated the association between potentially functional SNPs of these two genes and risk of gastric cancer in a US population.The risk associated with genotypes and haplotypes of four TGFB1 SNPs and four VEGF SNPs were determined by multivariate logistic regression analysis in 171 patients with gastric cancer and 353 cancer-free controls frequency-matched by age, sex and ethnicity.Compared with the VEGF-634GG genotype, the -634CG genotype and the combined -634CG+CC genotypes were associated with a significantly elevated risk of gastric cancer (adjusted OR = 1.88, 95% CI = 1.24-2.86 and adjusted OR = 1.56, 95% CI = 1.07-2.27, respectively). However, none of other TGFB1 and VEGF SNPs was associated with risk of gastric cancer.Our data suggested that the VEGF-634G>C SNP may be a marker for susceptibility to gastric cancer, and this finding needs to be validated in larger studies.
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    Tissue engraftment of hypoxic-preconditioned adipose-derived stem cells improves flap viability.
    (Wound Repair Regen, 2012-11) Hollenbeck, Scott T; Senghaas, Annika; Komatsu, Issei; Zhang, Ying; Erdmann, Detlev; Klitzman, Bruce
    Adipose-derived stem cells (ASCs) have the ability to release multiple growth factors in response to hypoxia. In this study, we investigated the potential of ASCs to prevent tissue ischemia. We found conditioned media from hypoxic ASCs had increased levels of vascular endothelial growth factor (VEGF) and enhanced endothelial cell tubule formation. To investigate the effect of injecting rat ASCs into ischemic flaps, 21 Lewis rats were divided into three groups: control, normal oxygen ASCs (10(6) cells), and hypoxic preconditioned ASCs (10(6) cells). At the time of flap elevation, the distal third of the flap was injected with the treatment group. At 7 days post flap elevation, flap viability was significantly improved with injection of hypoxic preconditioned ASCs. Cluster of differentiation-31-positive cells were more abundant along the margins of flaps injected with ASCs. Fluorescent labeled ASCs localized aside blood vessels or throughout the tissue, dependent on oxygen preconditioning status. Next, we evaluated the effect of hypoxic preconditioning on ASC migration and chemotaxis. Hypoxia did not affect ASC migration on scratch assay or chemotaxis to collagen and laminin. Thus, hypoxic preconditioning of injected ASCs improves flap viability likely through the effects of VEGF release. These effects are modest and represent the limitations of cellular and growth factor-induced angiogenesis in the acute setting of ischemia.
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    Treatment with Imatinib in NSCLC is associated with decrease of phosphorylated PDGFR-beta and VEGF expression, decrease in interstitial fluid pressure and improvement of oxygenation.
    (Br J Cancer, 2006-10-23) Vlahovic, G; Rabbani, ZN; Herndon, JE; Dewhirst, MW; Vujaskovic, Z
    Elevated intratumoral interstitial fluid pressure (IFP) and tumour hypoxia are independent predictive factors for poor survival and poor treatment response in cancer patients. However, the relationship between IFP and tumour hypoxia has not yet been clearly established. Preclinical studies have shown that lowering IFP improves treatment response to cytotoxic therapy. Interstitial fluid pressure can be reduced by inhibition of phosphorylated platelet-derived growth factor receptor-beta (p-PDGFR-beta), a tyrosine kinase receptor frequently overexpressed in cancer stroma, and/or by inhibition of VEGF, a growth factor commonly overexpressed in tumours overexpressing p-PDGFR-beta. We hypothesised that Imatinib, a specific PDGFR-beta inhibitor will, in addition to p-PDGFR-beta inhibition, downregulate VEGF, decrease IFP and improve tumour oxygenation. A549 human lung adenocarcinoma xenografts overexpressing PDGFR-beta were grown in nude mice. Tumour-bearing animals were randomised to control and treatment groups (Imatinib 50 mg kg(-1) via gavage for 4 days). Interstitial fluid pressure was measured in both groups before and after treatment. EF5, a hypoxia marker, was administered 3 h before being killed. Tumours were sectioned and stained for p-PDGFR-beta, VEGF and EF5 binding. Stained sections were viewed with a fluorescence microscope and image analysis was performed. Imatinib treatment resulted in significant reduction of p-PDGFR-beta, VEGF and IFP. Tumour oxygenation was also significantly improved. This study shows that p-PDGFR-beta-overexpressing tumours can be effectively treated with Imatinib to decrease tumour IFP. Importantly, this is the first study demonstrating that Imatinib treatment improves tumour oxygenation and downregulates tumour VEGF expression.