Publications by authors named "Keyianoosh Z Paydar"

Background: Poly-trauma patients often sustain complex head/neck injuries requiring prolonged hospitalizations and multiple operations. Few studies have evaluated the associated injury patterns and risk factors for poor clinical outcomes.

Methods: Consecutive poly-trauma patients with operative maxillofacial fractures treated at a level 1 trauma medical center between 1995 and 2013 were evaluated.

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Diabetes mellitus (DM) is a chronic disease that results in a variety of systemic complications. Recently, stem cell-based therapies have been proposed as potential modalities to manage DM related complications. Mesenchymal stem cell (MSC) based therapies are often considered as an ideal stem cell-based treatment for DM management due to their immunosuppressive characteristics, anti-inflammatory properties and differentiation potential.

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Fenestrated acellular dermal matrix (ADM) has improved patient outcomes in both direct-to-implant and 2-stage tissue expander/implant breast reconstruction. This technical alteration utilizes optimal fenestration overlap to enhance the breast reconstruction experience. We present a novel, surgeon-designed shaped fenestrated ADM, placed in the recently repopularized prepectoral pocket for anterior coverage of implants in direct-to-implant and 2-stage breast reconstruction.

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Background: Rhinoplasty is a popular aesthetic and reconstructive surgical procedure. It is one of the top five surgical cosmetic procedures performed worldwide.

Objectives: To evaluate global trends in rhinoplasty research spanning 20 years between 1994 and 2013.

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Background: Rhinoplasty is a popular aesthetic and reconstructive surgical procedure. However, little is known about the content and readability of online materials for patient education. The recommended grade level for educational materials is 7th to 8th grade according to the National Institutes of Health (NIH).

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Treatment of hypertrophic scars and other fibrotic skin conditions with autologous fat injections shows promising clinical results; however, the underlying mechanisms of its antifibrotic action have not been comprehensively studied. Adipose-derived stem cells, or stromal cell-derived factors, inherent components of the transplanted fat tissue, seem to be responsible for its therapeutic effects on difficult scars. The mechanisms by which this therapeutic effect takes place are diverse and are mostly mediated by paracrine signaling, which switches on various antifibrotic molecular pathways, modulates the activity of the central profibrotic transforming growth factor β/Smad pathway, and normalizes functioning of fibroblasts and keratinocytes in the recipient site.

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Background: Current teaching suggests increased perfusion in free transverse rectus abdominis myocutaneous (TRAM) flaps over pedicled TRAM flaps, broadening indications for its use in high risk patients. This study compared perfusion analysis of free muscle-sparing versus pedicle TRAM flaps in the peri-operative and late post-operative periods.

Methods: The SPY-Elite system using indocyanine green dye was used to analyze flap perfusion intra-operatively and at 1 week and 3 months post-operatively.

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Background: Venous thromboembolic events result in significant morbidity, mortality, and costly therapeutic interventions. As medical resource allocation strategies are becoming more pervasive, appropriate risk stratification and prophylactic regimens are essential. Previous studies have shown a decreased incidence of perioperative venous thromboembolism in the chronic spinal cord injury population.

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Since its introduction 20 years ago for the treatment of chronic wounds, negative pressure wound therapy use has expanded to a variety of other wound types. Various mechanisms of action for its efficacy in wound healing have been postulated, but no unifying theory exists. Proposed mechanisms include induction of perfusion changes, microdeformation, macrodeformation, exudate control and decreasing the bacterial load in the wound.

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The last decade has ushered in a rapidly expanding global discussion regarding acellular dermal matrix (ADM) applications, economic analyses, technical considerations, benefits, and risks, with recent emphasis on ADM use in breast surgery. This study aims to evaluate global trends in ADM research using bibliometric analysis. The top nine Plastic Surgery journals were determined by impact factor (IF).

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Background: Optimization of fat grafting continues to gain increasing attention in the field of regenerative medicine. "Nanofat grafting" implements mechanical emulsification and injection of standard lipoaspirate for the correction of superficial rhytides and skin discoloration; however, little is known about the cellular constituents of the graft. Based on recent evidence that various stressors can induce progenitor activity, the authors hypothesized that the shear forces used in common fat grafting techniques may impact their regenerative capacities.

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Scarring following burn injury and its accompanying aesthetic and functional sequelae still pose major challenges. Hypertrophic scarring (HTS) can greatly impact patients' quality of life related to appearance, pain, pruritus and even loss of function of the injured body region. The identification of molecular events occurring in the evolution of the burn scar has increased our knowledge; however, this information has not yet translated into effective treatment modalities.

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Background: Tamoxifen is an important adjunct therapy in breast cancer treatment; however, it has been implicated in increasing microvascular flap complications. Current recommendations on stopping tamoxifen are conflicting and do not address tamoxifen therapy that is continued perioperatively. The purpose of this study is to determine whether tamoxifen taken at the time of free transverse rectus abdominis myocutaneous (TRAM) and deep inferior epigastric perforator (DIEP) flap breast reconstruction affects thrombotic complication rates.

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Stromal Vascular Fraction (SVF) is a heterogeneous collection of cells contained within adipose tissue that is traditionally isolated using enzymes such as collagenase. With the removal of adipose cells, connective tissue and blood from lipoaspirate, comes the SVF, a mix including mesenchymal stem cells, endothelial precursor cells, T regulatory cells, macrophages, smooth muscle cells, pericytes and preadipocytes. In part 1 of our 2-part series, we review the literature with regards to the intensifying interest that has shifted toward this mixture of cells, particularly due to its component synergy and translational potential.

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Adipose tissue is a rich source of cells with emerging promise for tissue engineering and regenerative medicine. The stromal vascular fraction (SVF), in particular, is an eclectic composite of cells with progenitor activity that includes preadipocytes, mesenchymal stem cells, pericytes, endothelial cells, and macrophages. SVF has enormous potential for therapeutic application and is being investigated for multiple clinical indications including lipotransfer, diabetes-related complications, nerve regeneration, burn wounds and numerous others.

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Background: Acellular dermal matrices have been proposed to decrease the incidence of capsular contracture in implant-based breast reconstructions. The authors have modified acellular dermal matrices with fenestrations to facilitate greater lower pole expansion and improve contour. The effect of fenestrations on the ability of matrices to suppress capsule formation, however, has not been examined.

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Background: There are limited data regarding blood transfusion following abdominoplasty, especially in post-bariatric surgery patients. The purpose of this study was to evaluate (1) the frequency and outcomes of blood transfusion in post-bariatric surgery patients undergoing abdominoplasty and (2) the predictive risk factors of blood transfusion in this patient population.

Methods: Using the Nationwide Inpatient Sample database, the authors examined the clinical data of patients with a history of bariatric surgery who underwent abdominoplasty from 2007 to 2011 in the United States.

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Background: The use of nerve conduits to facilitate nerve regrowth after peripheral nerve injury is limited to defects less than 3 cm. The purpose of this study is to determine the capability of novel single and multi-lumen poly(ethylene glycol) (PEG) conduits manufactured by stereolithography to promote peripheral nerve regeneration.

Materials And Methods: Eight Sprague Dawley rats with sharp transection injuries of the sciatic nerve were randomly assigned to receive single-lumen or multi-lumen PEG conduits to bridge a 10-mm gap.

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The objectives of this study were to evaluate 1) the rate of immediate breast reconstruction; 2) the frequency of immediate tissue expander placement; and 3) to compare perioperative outcomes in patients who underwent breast reconstruction after mastectomy for breast cancer with immediate tissue expander placement (TE) with those with no reconstruction (NR). Using the Nationwide Inpatient Sample database, we examined the clinical data of patients with breast cancer who underwent mastectomy with or without immediate TE from 2006 to 2010 in the United States. A total of 344,253 patients with breast cancer underwent mastectomy in this period in the United States.

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Background: The aims of this study were (1) to evaluate the frequency of various reconstructive techniques for autologous breast reconstruction and (2) to compare perioperative outcomes of autologous breast reconstruction in teaching versus nonteaching hospitals.

Materials: The authors analyzed clinical data of patients who underwent autologous breast reconstructive surgery from 2009 to 2010 using the Nationwide Inpatient Sample database. Autologous breast reconstruction operations included latissimus dorsi myocutaneous, pedicled transverse rectus abdominis myocutaneous (TRAM), free TRAM, free deep inferior epigastric artery perforator (DIEP), free superficial inferior epigastric artery, and free gluteal artery perforator flaps.

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Unlabelled: The authors present a new technique of alteration of the acellular dermal matrix through strategically placed fenestrations, improving the reconstructive experience and overall cosmetic outcome. The authors present a retrospective chart review following two surgeons' experience at the University of California, Irvine, Department of Plastic Surgery using surgeon-designed fenestrated acellular dermal matrices in two-stage tissue expander breast reconstruction. The authors found that this leads to improved intraoperative fill volume, decreased number of postoperative expansions, increased expansion rate with subjectively less pain, decreased time to full expansion, and subjectively improved cosmetic outcome.

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Vascular thrombosis is one of the major postoperative complications of free flap microvascular breast reconstruction operations. It is associated with higher morbidity, higher cost, increased length of hospital stay, and potentially flap loss. Our purpose is to evaluate the rate of this complication and whether patient characteristics play a role.

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