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Articles by R Virmani
Total Records ( 3 ) for R Virmani
  Z Fu , M Wang , M Gucek , J Zhang , J Wu , L Jiang , R. E Monticone , B Khazan , R Telljohann , J Mattison , S Sheng , R. N Cole , G Spinetti , G Pintus , L Liu , F. D Kolodgie , R Virmani , H Spurgeon , D. K Ingram , A. D Everett , E. G Lakatta and J. E. Van Eyk
 

Advancing age induces aortic wall thickening that results from the concerted effects of numerous signaling proteins, many of which have yet to be identified. To search for novel proteins associated with aortic wall thickening, we have performed a comprehensive quantitative proteomic study to analyze aortic proteins from young (8 months) and old (30 months) rats and identified 50 proteins that significantly change in abundance with aging. One novel protein, the milk fat globule protein epidermal growth factor 8 (MFG-E8), increases 2.3-fold in abundance in old aorta. Transcription and translation analysis demonstrated that aortic MFG-E8 mRNA and protein levels increase with aging in several mammalian species including humans. Dual immunolabeling shows that MFG-E8 colocalizes with both angiotensin II and monocyte chemoattractant protein (MCP)-1 within vascular smooth muscle cells (VSMCs) of the thickened aged aortic wall. Exposure of early passage VSMCs from young aorta to angiotensin II markedly increases MFG-E8 and enhances invasive capacity to levels observed in VSMCs from old rats. Treatment of VSMCs with MFG-E8 increases MCP-1 expression and VSMCs invasion that are inhibited by the MCP-1 receptor blocker vCCI. Silencing MFG-E8 RNA substantially reduces MFG-E8 expression and VSMCs invasion capacity. The data indicate that arterial MFG-E8 significantly increases with aging and is a pivotal relay element within the angiotensin II/MCP-1/VSMC invasion signaling cascade. Thus, targeting of MFG-E8 within this signaling axis pathway is a potential novel therapy for the prevention and treatment of the age-associated vascular diseases such as atherosclerosis.

  A. V Finn , M John , G Nakazawa , R Polavarapu , V Karmali , X Xu , Q Cheng , T Davis , C Raghunathan , E Acampado , T Ezell , S Lajoie , M Eppihimer , F. D Kolodgie , R Virmani and H. K. Gold
 

Rationale: Sirolimus-eluting coronary stents (SESs) and paclitaxel-eluting coronary stents (PESs) are used to reduce restenosis but have different sites of action. The molecular targets of sirolimus overlap with those of the peroxisome proliferator-activated receptor (PPAR) agonist rosiglitazone (RSG) but the consequence of this interaction on endothelialization is unknown.

Objective: Using the New Zealand white rabbit iliac model of stenting, we examined the effects of RSG on SESs, PESs, and bare metal stents endothelialization.

Methods and Results: Animals receiving SESs, PESs, or bare metal stents and either RSG (3 mg/kg per day) or placebo were euthanized at 28 days, and arteries were evaluated by scanning electron microscopy. Fourteen-day organ culture and Western blotting of iliac arteries and tissue culture experiments were conducted. Endothelialization was significantly reduced by RSG in SESs but not in PESs or bare metal stents. Organ culture revealed reduced vascular endothelial growth factor in SESs receiving RSG compared to RSG animals receiving bare metal stent or PESs. Quantitative polymerase chain reaction in human aortic endothelial cells (HAECs) revealed that sirolimus (but not paclitaxel) inhibited RSG-induced vascular endothelial growth factor transcription. Western blotting demonstrated that inhibition of molecular signaling in SES+RSG–treated arteries was similar to findings in HAECs treated with RSG and small interfering RNA to PPAR, suggesting that sirolimus inhibits PPAR. Transfection of HAECs with mTOR (mammalian target of rapamycin) short hairpin RNA and with Akt2 small interfering RNA significantly inhibited RSG-mediated transcriptional upregulation of heme oxygenase-1, a PPAR target gene. Chromatin immunoprecipitation assay demonstrated sirolimus interferes with binding of PPAR to its response elements in heme oxygenase-1 promoter.

Conclusions: mTOR/Akt2 is required for optimal PPAR activation. Patients who receive SESs during concomitant RSG treatment may be at risk for delayed stent healing.

  N Tada , R Virmani , G Grant , L Bartlett , A Black , C Clavijo , U Christians , R Betts , D Savage , S. H Su , J Shulze and S. Kar
 

Background— Drug-eluting stents effectively reduce restenosis but may increase late thrombosis and delayed restenosis. Persistent polymer, the drug, or a combination of both could be responsible. Local delivery of Biolimus A9, a rapamycin derivative, from a polymer-free BioFreedom stent (Biosensors International) may prevent these complications.

Methods and Results— We compared high-dose (HD) (225 µg/14 mm Biolimus A9) and low-dose (LD) (112 µg/14 mm Biolimus A9) BioFreedom stents with a polymer-coated sirolimus-eluting Cypher stent (SES) and a bare-metal stent (BMS) at 28 days and 180 days in an overstretch coronary mini-swine model with histomorphometric and histological analysis. At 28 days, there was a reduction in neointimal proliferation by HD, LD, and SES compared with BMS (neointimal thickness: HD, 0.080±0.032; LD, 0.085±0.038; SES, 0.064±0.037; BMS, 0.19±0.111 mm; P<0.001; BMS > HD/LD/SES). At 180 days, both BioFreedom stents were associated with reduced neointimal proliferation, whereas SES exhibited increased neointima (neointimal thickness: HD, 0.12±0.034; LD, 0.10±0.040; SES, 0.20±0.111; BMS, 0.17±0.099 mm; P<0.001; SES > HD/LD; BMS > LD). At 180 days, BioFreedom stents showed decreased fibrin and inflammation, including granuloma and giant cells, compared with SES.

Conclusions— The polymer-free Biolimus A9-coated stent demonstrates equivalent early and superior late reduction of intimal proliferation compared with SES in a porcine model. After implantation of BioFreedom stent, delayed arterial healing was minimal, and there was no increased inflammation at 180 days compared with SES implantation. The use of polymer-free stents may have a potential long-term benefit over traditional polymeric-coated drug-eluting stents.

 
 
 
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