Eugenia H. Cho

In vivo detection of SERS-encoded plasmonic nanostars in human skin grafts and live animal models

Surface-enhanced Raman scattering (SERS)-active plasmonic nanomaterials have become a promising agent for molecular imaging and multiplex detection. Among the wide variety of plasmonics-active nanoparticles, gold nanostars offer unique plasmon properties that efficiently induce strong SERS signals. Furthermore, nanostars, with their small core size and multiple long thin branches, exhibit high absorption cross sections that are tunable in the near-infrared region of the tissue optical window, rendering them efficient for in vivo spectroscopic detection. This study investigated the use of SERS-encoded gold nanostars for in vivo detection. Ex vivo measurements were performed using human skin grafts to investigate the detection of SERS-encoded nanostars through tissue. We also integrated gold nanostars into a biocompatible scaffold to aid in performing in vivo spectroscopic analyses. In this study, for the first time, we demonstrate in vivo SERS detection of gold nanostars using small animal (rat) as well as large animal (pig) models. The results of this study establish the usefulness and potential of SERS-encoded gold nanostars for future use in long-term in vivo analyte sensing.

Vascular considerations in foot and ankle free tissue transfer: Analysis of 231 free flaps

Successful foot and ankle soft tissue reconstruction is dependent on a clear understanding of the vascular supply to the foot. The aim of this study was to identify risk factors for reconstructive failure following foot and ankle free tissue transfer.

Role of Platelet Inhibition in Microvascular Surgery

Thrombosis remains a significant complication of microvascular free tissue transfer. Recent discoveries in the field of vascular biology have led to a greater understanding of thrombogenesis and the pivotal role that platelets play in the formation of a clot. However, current antithrombotic strategies in the clinical practice of free tissue transfer have not typically focused on platelet inhibition. Decades of cardiovascular clinical trials have delineated the essential role of platelet inhibitor therapy in patients with acute coronary syndromes and those undergoing percutaneous coronary interventions. Understanding the current treatment guidelines for antiplatelet therapy across the spectrum of patients with coronary heart disease may provide insights into their use in the prevention and treatment of thrombosis in microvascular surgery. In this review, we examine the current antiplatelet agents in clinical use and discuss the potential role of platelet inhibition in free flap surgery, particularly in the setting of repeated microvascular thrombosis.

Surface-enhanced Raman scattering nanosensors for in vivo detection of nucleic acid targets in a large animal model

Although nanotechnology has led to important advances in in vitro diagnostics, the development of nanosensors for in vivo detection remains very challenging. Here, we demonstrated the proof-of-principle of in vivo detection of nucleic acid targets using a promising type of surface-enhanced Raman scattering (SERS) nanosensor implanted in the skin of a large animal model (pig). The in vivo nanosensor used in this study involves the “inverse molecular sentinel” detection scheme using plasmonics-active nanostars, which have tunable absorption bands in the near infrared region of the “tissue optical window”, rendering them efficient as an optical sensing platform for in vivo optical detection. Ex vivo measurements were also performed using human skin grafts to demonstrate the detection of SERS nanosensors through tissue. In this study, a new core–shell nanorattle probe with Raman reporters trapped between the core and shell was utilized as an internal standard system for self-calibration. These results illustrate the usefulness and translational potential of the SERS nanosensor for in vivo biosensing.

Preoperative Platelet Count Predicts Lower Extremity Free Flap Thrombosis: A Multi-Institutional Experience.

Background: Thrombocytosis in patients undergoing lower extremity free tissue transfer may be associated with increased risk of microvascular complications. This study assessed whether preoperative platelet counts predict lower extremity free flap thrombosis. Methods: All patients undergoing lower extremity free tissue transfer at Duke University from 1997 to 2013 and at the University of Pennsylvania from 2002 to 2013 were retrospectively identified. Logistic regression was used to assess whether preoperative platelet counts independently predict flap thrombosis, controlling for baseline and operative factors. Results: A total of 565 patients underwent lower extremity free tissue transfer, with an overall flap thrombosis rate of 16 percent (n = 91). Elevated preoperative platelet counts were independently associated with both intraoperative thrombosis (500 ± 120 versus 316 ± 144 × 109/liter; p < 0.001) and postoperative thrombosis (410 ± 183 versus 320 ± 143 × 109/liter; p = 0.040) in 215 patients who sustained acute lower extremity trauma within 30 days before reconstruction. In acute trauma patients, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 403 × 109/liter; OR, 4.08; p < 0.001) and a two-fold increased risk of postoperative thrombosis (cutoff value, 361 × 109/liter; OR, 2.16; p = 0.005). In patients who did not sustain acute trauma, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 352 × 109/liter; OR, 3.82; p = 0.002). Conclusions: Acute trauma patients with elevated preoperative platelet counts are at increased risk for lower extremity free flap complications. Prospective evaluation is warranted for guiding risk stratification and targeted treatment strategies. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Bioburden after Staphylococcus aureus inoculation in type 1 diabetic rats undergoing internal fixation.

Summary: Fracture stabilization in the diabetic patient is associated with higher complication rates, particularly infection and impaired wound healing, which can lead to major tissue damage, osteomyelitis, and higher amputation rates. With an increasing prevalence of diabetes and an aging population, the risks of infection of internal fixation devices are expected to grow. Although numerous retrospective clinical studies have identified a relationship between diabetes and infection, currently there are few animal models that have been used to investigate postoperative surgical-site infections associated with internal fixator implantation and diabetes. The authors therefore refined the protocol for inducing hyperglycemia and compared the bacterial burden in controls to pharmacologically induced type 1 diabetic rats after undergoing internal fracture plate fixation and Staphylococcus aureus surgical-site inoculation. Using an initial series of streptozotocin doses, followed by optional additional doses to reach a target blood glucose range of 300 to 600 mg/dl, the authors reliably induced diabetes in 100 percent of the rats (n = 16), in which a narrow hyperglycemic range was maintained 14 days after onset of diabetes (mean ± SEM, 466 ± 16 mg/dl; coefficient of variation, 0.15). With respect to their primary endpoint, the authors quantified a significantly higher infectious burden in inoculated diabetic animals (median, 3.2 × 1010 colony-forming units/mg dry tissue) compared with inoculated nondiabetic animals (7.2 × 104 colony-forming units/mg dry tissue). These data support the authors’ hypothesis that uncontrolled diabetes adversely affects the immune system’s ability to clear Staphylococcus aureus associated with internal hardware.

Antibiotic-induced changes in the microbiota disrupt redox dynamics in the gut

How host and microbial factors combine to structure gut microbial communities remains incompletely understood. Redox potential is an important environmental feature affected by both host and microbial actions. We assessed how antibiotics, which can impact host and microbial function, change redox state and how this contributes to post-antibiotic succession. We showed gut redox potential increased within hours of an antibiotic dose in mice. Host and microbial functioning changed under treatment, but shifts in redox potentials could be attributed specifically to bacterial suppression in a host-free ex vivo human gut microbiota model. Redox dynamics were linked to blooms of the bacterial family Enterobacteriaceae. Ecological succession to pre-treatment composition was associated with recovery of gut redox, but also required dispersal from unaffected gut communities. As bacterial competition for electron acceptors can be a key ecological factor structuring gut communities, these results support the potential for manipulating gut microbiota through managing bacterial respiration.

Breast Cancer after Augmentation: Oncologic and Reconstructive Considerations among Women Undergoing Mastectomy

Background: Breast augmentation with subglandular versus subpectoral implants may differentially impact the early detection of breast cancer and treatment recommendations. The authors assessed the impact of prior augmentation on the diagnosis and management of breast cancer in women undergoing mastectomy. Methods: Breast cancer diagnosis and management were retrospectively analyzed in all women with prior augmentation undergoing therapeutic mastectomy at the authors’ institution from 1993 to 2014. Comparison was made to all women with no prior augmentation undergoing mastectomy in 2010. Subanalyses were performed according to prior implant placement. Results: A total of 260 women with (n = 89) and without (n = 171) prior augmentation underwent mastectomy for 95 and 179 breast cancers, respectively. Prior implant placement was subglandular (n = 27) or subpectoral (n = 63) (For five breasts, the placement was unknown). Breast cancer stage at diagnosis (p = 0.19) and detection method (p = 0.48) did not differ for women with and without prior augmentation. Compared to subpectoral augmentation, subglandular augmentation was associated with the diagnosis of invasive breast cancer rather than ductal carcinoma in situ (p = 0.01) and detection by self-palpation rather than screening mammography (p = 0.03). Immediate two-stage implant reconstruction was the preferred reconstructive method in women with augmentation (p < 0.01). Conclusions: Breast cancer stage at diagnosis was similar for women with and without prior augmentation. Among women with augmentation, however, subglandular implants were associated with more advanced breast tumors commonly detected on palpation rather than mammography. Increased vigilance in breast cancer screening is recommended among women with subglandular augmentation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Micovascular integration into porous polyHEMA scaffold

Surface-enhanced Raman scattering (SERS) spectroscopy can be a useful tool in regard to disease diagnosis and prevention. Advantage of SERS over conventional Raman spectroscopy is its significantly increased signal (up to factor of 106-108) which allows detection of trace amounts of substances in the sample. So far, this technique is successfully used for analysis of food, pieces of art and various biochemical/biomedical samples. In this work, we survey the possibility of applying SERS spectroscopy for detection of trace components in urinary deposits. Early discovery together with the identification of the exact chemical composition of urinary sediments could be crucial for taking appropriate preventive measures that inhibit kidney stone formation or growth processes. In this initial study, SERS spectra (excitation wavelength - 1064 nm) of main components of urinary deposits (calcium oxalate, uric acid, cystine, etc.) were recorded by using silver (Ag) colloid. Spectra of 10-3-10-5 M solutions were obtained. While no/small Raman signal was detected without the Ag colloid, characteristic peaks of the substances could be clearly separated in the SERS spectra. This suggests that even small amounts of the components could be detected and taken into account while determining the type of kidney stone forming in the urinary system. We found for the first time that trace amounts of components constituting urinary deposits could be detected by SERS spectroscopy. In the future study, the analysis of centrifuged urine samples will be carried out.

Abstract 88: microvascular integration into versatile tissue engineering platforms.

Methods: We implanted 1cm-diameter poly-hydroxyethylmethacrylate (polyHEMA) disks with 40 and 80μm nominal interconnected pores into rat subcutis. Solid polyHEMA, silicone, and cotton disks were also implanted. We also investigated a minimally-invasive trocar-assisted delivery of ribbon-shaped porous polyHEMA implants and a suspension of polyHEMA microparticles. Microvessel density was quantified in 50μm-wide zones both into the implants and into the adjacent tissues.