Improved Posterolateral Lumbar Spinal Fusion Using a Biomimetic, Nanocomposite Scaffold Augmented by Autologous Platelet-Rich Plasma.

Remodeling of the human bony skeleton is constantly occurring with up to 10% annual bone volume turnover from osteoclastic and osteoblastic activity. A shift toward resorption can result in osteoporosis and pathologic fractures, while a shift toward deposition is required after traumatic, or surgical injury. Spinal fusion represents one such state, requiring a substantial regenerative response to immobilize adjacent vertebrae through bony union. Autologous bone grafts were used extensively prior to the advent of advanced therapeutics incorporating exogenous growth factors and biomaterials. Besides cost constraints, these applications have demonstrated patient safety concerns. This study evaluated the regenerative ability of a nanostructured, magnesium-doped, hydroxyapatite/type I collagen scaffold (MHA/Coll) augmented by autologous platelet-rich plasma (PRP) in an orthotopic model of posterolateral lumbar spinal fusion. After bilateral decortication, rabbits received either the scaffold alone (Group 1) or scaffold with PRP (Group 2) to the anatomic right side. Bone regeneration and fusion success compared to internal control were assessed by DynaCT with 3-D reconstruction at 2, 4, and 6 weeks postoperatively followed by comparative osteogenic gene expression and representative histopathology. Both groups formed significantly more new bone volume than control, and Group 2 subjects produced significantly more trabecular and cortical bone than Group 1 subjects. Successful fusion was seen in one Group 1 animal (12.5%) and 6/8 Group 2 animals (75%). This enhanced effect by autologous PRP treatment appears to occur via astounding upregulation of key osteogenic genes. Both groups demonstrated significant gene upregulation compared to vertebral bone controls for all genes. Group 1 averaged 2.21-fold upregulation of RUNX2 gene, 3.20-fold upregulation of SPARC gene, and 3.67-fold upregulation of SPP1 gene. Depending on anatomical subgroup (cranial, mid, caudal scaffold portions), Group 2 had significantly higher average expression of all genes than both control and Group 1-RUNX2 (8.23-19.74 fold), SPARC (18.67-55.44 fold), and SPP1 (46.09-90.65 fold). Our data collectively demonstrate the osteoinductive nature of a nanostructured MHA/Coll scaffold, a beneficial effect of augmentation with autologous PRP, and an ability to achieve clinical fusion when applied together in an orthotopic model. This has implications both for future study and biomedical innovation of bone-forming therapeutics.

3D-Bioprinted Inflammation Modulating Polymer Scaffolds for Soft Tissue Repair.

Development of inflammation modulating polymer scaffolds for soft tissue repair with minimal postsurgical complications is a compelling clinical need. However, the current standard of care soft tissue repair meshes for hernia repair is highly inflammatory and initiates a dysregulated inflammatory process causing visceral adhesions and postsurgical complications. Herein, the development of an inflammation modulating biomaterial scaffold (bioscaffold) for soft tissue repair is presented. The bioscaffold design is based on the idea that, if the excess proinflammatory cytokines are sequestered from the site of injury by the surgical implantation of a bioscaffold, the inflammatory response can be modulated, and the visceral adhesion formations and postsurgical complications can be minimized. The bioscaffold is fabricated by 3D-bioprinting of an in situ phosphate crosslinked poly(vinyl alcohol) polymer. In vivo efficacy of the bioscaffold is evaluated in a rat ventral hernia model. In vivo proinflammatory cytokine expression analysis and histopathological analysis of the tissues have confirmed that the bioscaffold acts as an inflammation trap and captures the proinflammatory cytokines secreted at the implant site and effectively modulates the local inflammation without the need for exogenous anti-inflammatory agents. The bioscaffold is very effective in inhibiting visceral adhesions formation and minimizing postsurgical complications.

Challenges and opportunities for drug delivery to the posterior of the eye.

Drug delivery to the posterior segment of the eye remains challenging even though the eye is readily accessible. Its unique and complex anatomy and physiology contribute to the limited options for drug delivery via non-invasive topical treatment, which is the prevalent ophthalmic treatment. To treat the most common retinal diseases, intravitreal (IVT) injection has been a common and effective therapy. With the advancement of nanotechnologies, novel formulations and drug delivery systems are being developed to treat posterior segment diseases. Here, we discuss the recent advancement in ocular delivery systems, including-sustained release formulations, IVT implants, and preclinical topical formulations, and the challenges faced in their clinical translation.

Ultrasound shear wave elastography effectively predicts integrity of ventral hernia repair using acellular dermal matrix augmented with platelet-rich plasma (PRP).

BACKGROUND: Complications of ventral hernia repair (VHR) may be investigated by computed tomography or ultrasound (US) but neither modality gives a quantifiable metric of repair quality short of identifying hernia recurrence. Platelet-rich plasma (PRP), a growth factor-rich autologous blood product, has been shown to improve incorporation of native tissue with bioprosthetics. In this study, we investigate the effect of PRP on the incorporation and mechanical integrity of a non-crosslinked porcine acellular dermal matrix (pADM) in a rodent model of VHR and the correlative ability of ultrasound shear wave elastography (US-SWE) to assess repair quality. METHODS: PRP was isolated from whole blood of Lewis rats. Twenty-eight Lewis rats underwent chronic VHR using either pADM alone or augmented with autologous PRP prior to non-invasive imaging assessment and specimen harvest at either 3 or 6 months. US-SWE was performed to estimate the Young's modulus prior to histological assessment and data from PRP-treated rodents were compared to controls. RESULTS: Implanted pADM was easily distinguishable by US-SWE imaging in all cases analyzed in this study. The mean Young's modulus measured was 1.78 times and 2.54 times higher in PRP-treated samples versus control at 3-month and 6-month time points respectively (p < 0.05). At 3 months, qualitative and quantitative histology revealed decreased inflammation and improved incorporation in PRP-treated samples along the implant/abdominal wall interface. At 6 months, the PRP cohort had no hernia recurrence and preserved ADM integrity from immunologic degradation, while all control animals suffered hernia recurrence (4/6) or extreme ADM thinning (2/6). CONCLUSION: This study confirms both the efficacy of PRP in augmenting VHR using pADM, as well as the reliability of US-SWE to non-invasively predict the quality of VHR. Although further human studies are necessary, this work supports PRP use to improve VHR outcomes and US-SWE potential for bedside non-invasive hernia characterization.

A Model-Based Approach to Investigate the Effect of a Long Bone Fracture on Ultrasound Strain Elastography.

The mechanical behavior of long bones and fractures has been under investigation for many decades due to its complexity and clinical relevance. In this paper, we report a new subject-specific methodology to predict and analyze the mechanical behavior of the soft tissue at a bone interface with the intent of identifying the presence and location of bone abnormalities with high accuracy, spatial resolution, and contrast. The proposed methodology was tested on both intact and fractured rabbit femur samples with finite element-based 3-D simulations, created from actual femur computed tomography data, and ultrasound elastography experiments. The results included in this study demonstrate that elastographic strains at the bone/soft tissue interface can be used to differentiate fractured femurs from the intact ones on a distribution level. These results also demonstrate that coronal plane axial shear strain creates a unique contrast mechanism that can be used to reliably detect fractures (both complete and incomplete) in long bones. Kruskal-Wallis test further demonstrates that the contrast measure for the fracture group (simulation: 2.1286±0.2206; experiment: 2.7034 ± 1.0672) is significantly different from that for the intact group (simulation: 0 ± 0; experiment: 1.1540±0.6909) when using coronal plane axial shear strain elastography ( < 0.01). We conclude that: 1) elastography techniques can be used to accurately identify the presence and location of fractures in a long bone and 2) the proposed model-based approach can be used to predict and analyze strains at a bone fracture site and to better interpret experimental elastographic data.

Comparison of Radiation Exposure from Fixed Table Fluoroscopy to a Portable C-Arm During Ureteroscopy.

INTRODUCTION: Current treatment practices within the field of endourology require the routine use of radiation exposure to provide adequate imaging during urologic procedures. One such procedure requiring repeated radiation exposure during treatment is ureteroscopy. We set out to compare estimated fluoroscopic radiation exposures employing fixed table and portable C-arm fluoroscopy. MATERIALS AND METHODS: A cross-sectional dosimetry phantom model was placed supine on both fixed fluoroscopy and standard operating room tables. The models were then exposed to three separate 5-minute runs of fluoroscopic exposure. Metal oxide semiconductor field effect transistor dosimeters were utilized in organ-specific locations to determine specific radiation exposure dosages. Absorbed radiation was determined for each organ location for both fluoroscopy units. Organ dose volumetric corrections were performed for skin and red bone marrow, to correct for the nonirradiated portion. Organ dose rate (ODR, mGy/s) and effective dose rate (EDR, mSv/s) were calculated, with values reported as mean ± standard deviation. RESULTS: There were found to be statistically significant elevations for both total EDR and organ-specific dose rates with the use of fixed table fluoroscopy compared with C-arm fluoroscopy. EDR was found to be 0.0240 ± 0.0019 mSv/s for the fixed table unit and 0.0029 ± 0.0005 mSv/s for the C-arm unit (p = 0.0024). Internal organs exposed to the most radiation during fixed table fluoroscopy included the gall bladder and stomach in comparison to C-arm fluoroscopy, which found elevated exposure in the kidneys, pancreas, and spleen. CONCLUSION: The routine use of fixed table fluoroscopy results in significantly elevated estimated organ doses and EDR when directly compared with C-arm fluoroscopy in model trials. This difference should be taken into consideration by practicing urologists when patient treatment requires the use of fluoroscopy to maintain radiation exposure as low as reasonably achievable.

Characterization of ventral incisional hernia and repair using shear wave elastography.

BACKGROUND: To assess the integrity of hernia repair, imaging modalities such as computed tomography or ultrasound (US) are commonly used. Neither modality has currently the capacity to simultaneously image the mesh and quantify a prosthetic and surrounding tissue stiffness. In this pilot study, we hypothesize that US shear wave elastography (SWE) can be used to identify a polyester mesh and a biologic graft and to assess their stiffness noninvasively in a rat model of bridging hernia repair. METHODS: Lewis rats underwent hernia creation and repair with Parietex or Strattice at 30 d. After 3 mo, the animals were euthanized, and the Young's Modulus was measured using SWE. Three-dimensional reconstructions of the hernia pre- and post-repair were performed using in-house image processing algorithms. RESULTS: SWE was capable of accurate and real-time assessment and diagnosis of the hernia defects in vivo. Young's Modulus of Parietex meshes and Strattice grafts as estimated from the shear wave elastograms were found to be statistically different from each other (P < 0.05). Accurate three-dimensional reconstructions of the hernia defects pre- and post-repair were generated. CONCLUSIONS: In this study, we demonstrate the feasibility of using US SWE to detect ventral hernias and evaluate mesh repair in vivo. Our results indicate that the presence of a hernia and repair can be reliably visualized by SWE and three dimensionally reconstructed. Thus, this technique may provide both structural and functional information regarding the hernia and the repair.

Cross-linking of porcine acellular dermal matrices negatively affects induced neovessel formation using platelet-rich plasma in a rat model of hernia repair.

The degree of cross-linking within acellular dermal matrices (ADM) seems to correlate to neovascularization when used in ventral hernia repair (VHR). Platelet-rich plasma (PRP) enhances wound healing through several mechanisms including neovascularization, but research regarding its effect on soft tissue healing in VHR is lacking. We sought to study the effect of cross-linking on PRP-induced neovascularization in a rodent model of bridging VHR. We hypothesized that ADM cross-linking would negatively affect PRP-induced neovessel formation. PRP was extracted and characterized from pooled whole blood. Porcine cross-linked (cADM) and non-cross-linked ADMs (ncADM) were implanted in a rat model of chronic VHR after treatment with saline (control) or PRP. Neovascularization of samples at 2, 4, and 6 weeks was assessed by hematoxylin and eosin and immunohistochemical staining of CD 31. Adhesion severity at necropsy was compared using a previously validated scale. Addition of PRP increased neovascularization in both cADM and ncADM at 2- and 4-week time points but appeared to do so in a dependent fashion, with significantly greater neovascularization in the PRP-treated ncADMs compared to cADMs. Omental adhesions were increased in all PRP-treated groups. Results indicate that, for 2-week measurements when compared with the cADM group without PRP therapy, the mean change in neovascularization due to ncADM was 3.27 (Z = 2.75, p = 0.006), PRP was 17.56 (Z = 14.77, p < 0.001), and the combined effect of ncADM and PRP was 9.41 (Z = 5.6, p < 0.001). The 4-week data indicate that the average neovascularization change due to ncADM was 0.676 (Z = 0.7, p = 0.484), PRP was 7.69 (Z = 7.95, p < 0.001), and combined effect of ncADM and PRP was 5.28 (Z = 3.86, p < 0.001). These findings validate PRP as a clinical adjunct to enhance the native tissue response to implantable biomaterials and suggest that ncADM is more amenable than cADM to induced neovascularization. PRP use could be advantageous in patients undergoing VHR where poor incorporation is anticipated and early-enhanced neovascularization is desired.

Increased use of surgical energy promotes methicillin-resistant Staphylococcus aureus colonization in rabbits following open ventral hernia mesh repair.

BACKGROUND: Surgical energy has been widely implemented because of ease of use, effective hemostasis, and surgical dissection. Studies demonstrate its use to be an independent risk factor for postoperative wound infection. Methicillin-resistant Staphylococcus aureus (MRSA) is the most common bacteria found in postoperative mesh infection. No reports are available on the sequelae of surgical energy use for open ventral hernia repair (oVHR) with mesh. We hypothesized that increasing amounts of surgical energy will result in higher infectious burden after oVHR with composite multifilament polyester mesh (Parietex™ PCO). METHODS: New Zealand rabbits underwent bridging oVHR with Parietex™ PCO and were divided into three surgical treatment groups: (1) scalpel alone, (2) 120 J of energy, and (3) 600 J of energy. The bioprosthesis was then inoculated with 105 colony-forming units of MRSA. Rabbits were survived for 7 days with daily physical examination. Complete blood count, basci metabolic panel, and blood cultures were performed on postoperative days one, four, and seven. Surviving rabbits were killed, and meshes explanted for MRSA colony counts. RESULTS: Rabbits receiving the most surgical energy developed signs and symptoms of severe sepsis and wound necrosis within 24 h. In comparison, rabbits receiving no surgical energy had significantly less MRSA recovered from explanted mesh, significantly less bacteremia, and fewer adhesions. CONCLUSIONS: Increased use of surgical energy promoted greater colonization, exaggerated septic response to bacterial contamination, and more severe adhesions. In the absence of devitalized tissue, rabbits can effectively limit bacterial contamination. These findings support the surgical principles of proper tissue handling and highlight the detrimental effects of indiscriminant surgical energy usage, thus emphasizing the importance of programs such as Fundamental Use of Surgical Energy.

Biomimetic collagen/elastin meshes for ventral hernia repair in a rat model.

Ventral hernia repair remains a major clinical need. Herein, we formulated a type I collagen/elastin crosslinked blend (CollE) for the fabrication of biomimetic meshes for ventral hernia repair. To evaluate the effect of architecture on the performance of the implants, CollE was formulated both as flat sheets (CollE Sheets) and porous scaffolds (CollE Scaffolds). The morphology, hydrophylicity and in vitro degradation were assessed by SEM, water contact angle and differential scanning calorimetry, respectively. The stiffness of the meshes was determined using a constant stretch rate uniaxial tensile test, and compared to that of native tissue. CollE Sheets and Scaffolds were tested in vitro with human bone marrow-derived mesenchymal stem cells (h-BM-MSC), and finally implanted in a rat ventral hernia model. Neovascularization and tissue regeneration within the implants was evaluated at 6weeks, by histology, immunofluorescence, and q-PCR. It was found that CollE Sheets and Scaffolds were not only biomechanically sturdy enough to provide immediate repair of the hernia defect, but also promoted tissue restoration in only 6weeks. In fact, the presence of elastin enhanced the neovascularization in both sheets and scaffolds. Overall, CollE Scaffolds displayed mechanical properties more closely resembling those of native tissue, and induced higher gene expression of the entire marker genes tested, associated with de novo matrix deposition, angiogenesis, adipogenesis and skeletal muscles, compared to CollE Sheets. Altogether, this data suggests that the improved mechanical properties and bioactivity of CollE Sheets and Scaffolds make them valuable candidates for applications of ventral hernia repair. STATEMENT OF SIGNIFICANCE: Due to the elevated annual number of ventral hernia repair in the US, the lack of successful grafts, the design of innovative biomimetic meshes has become a prime focus in tissue engineering, to promote the repair of the abdominal wall, avoid recurrence. Our meshes (CollE Sheets and Scaffolds) not only showed promising mechanical performance, but also allowed for an efficient neovascularization, resulting in new adipose and muscle tissue formation within the implant, in only 6weeks. In addition, our meshes allowed for the use of the same surgical procedure utilized in clinical practice, with the commercially available grafts. This study represents a significant step in the design of bioactive acellular off-the-shelf biomimetic meshes for ventral hernia repair.

Should metabolic evaluation be performed in patients with struvite stones?

Previous studies suggested that patients with pure struvite calculi rarely have underlying metabolic abnormalities. Therefore, most of these patients do not undergo metabolic studies. We report our experience with these patients and their response to directed medical therapy. Between 1/2005 and 9/2012, 75 patients treated with percutaneous nephrolithotomy for struvite stones were identified. Of these, 7 had pure struvite stones (Group 1), 32 had mixed struvite stones (Group 2), both with metabolic evaluation, and 17 had pure struvite stones without metabolic evaluation (Group 3). The frequency of metabolic abnormalities and stone activity (defined as stone growth or stone-related events) was compared between groups. The median age was 55 years and 64 % were female. No significant difference in race, infection history, family history, stone location or volume existed between groups. Metabolic abnormalities were found in 57 % of Group 1 and 81 % of Group 2 patients. A similar proportion of Group 1 and 2 patients received modification to or continuation of metabolic therapy, whereas no Group 3 patients received any directed therapy. In patients with >6 months follow-up, the stone activity rate between Groups 1 and 2 appeared similar whereas Group 3 trended towards higher stone activity rate. Metabolic abnormalities in pure struvite stone formers appear to be more common than previously reported. Directed medical therapy in these patients may reduce stone activity. The role of metabolic evaluation and directed medical therapy needs reconsideration in patients with pure struvite stones.

Platelet-rich plasma: a biomimetic approach to enhancement of surgical wound healing.

Platelets are small anucleate cytoplasmic cell bodies released by megakaryocytes in response to various physiologic triggers. Traditionally thought to be solely involved in the mechanisms of hemostasis, platelets have gained much attention due to their involvement wound healing, immunomodulation, and antiseptic properties. As the field of surgery continues to evolve so does the need for therapies to aid in treating the increasingly complex patients seen. With over 14 million obstetric, musculoskeletal, and urological and gastrointestinal surgeries performed annually, the healing of surgical wounds continues to be of upmost importance to the surgeon and patient. Platelet-rich plasma, or platelet concentrate, has emerged as a possible adjuvant therapy to aid in the healing of surgical wounds and injuries. In this review, we will discuss the wound healing properties of platelet-rich plasma and various surgical applications.

The Emerging Role of Nanotechnology in Cell and Organ Transplantation.

Transplantation is often the only choice many patients have when suffering from end-stage organ failure. Although the quality of life improves after transplantation, challenges, such as organ shortages, necessary immunosuppression with associated complications, and chronic graft rejection, limit its wide clinical application. Nanotechnology has emerged in the past 2 decades as a field with the potential to satisfy clinical needs in the area of targeted and sustained drug delivery, noninvasive imaging, and tissue engineering. In this article, we provide an overview of popular nanotechnologies and a summary of the current and potential uses of nanotechnology in cell and organ transplantation.

Digital Tomosynthesis: A Viable Alternative to Noncontrast Computed Tomography for the Follow-Up of Nephrolithiasis?

OBJECTIVE: Digital tomosynthesis (DT) is a new X-ray-based imaging technique that allows image enhancement with minimal increase in radiation exposure. The purpose of this study was to compare DT with noncontrast computed tomography (NCCT) and to evaluate its potential role for the follow-up of patients with nephrolithiasis in a nonemergent setting. METHODS: A retrospective review of patients with nephrolithiasis at our institution that underwent NCCT and DT from July 2012 to September 2013 was performed. Renal units (RUs) that did not undergo treatment or stone passage were randomly assigned to two blinded readers, who recorded stone count, size area (mm(2)), maximum stone length (mm), and location, for both DT and NCCT. Mean differences per RU were compared. Potential variables affecting stone detection rate, including stone size and body mass index (BMI), were evaluated. Interobserver agreement was determined using the intraclass correlation coefficient to measure the consistency of measurements made by the readers. RESULTS: DT and NCCT demonstrated similar stone detection rates in terms of stone counts and stone area mm(2). Of the 79 RUs assessed, 41 RUs showed exact stone counts on DT and NCCT. The mean difference in stone area was 16.5 mm(2) (-4.6 to 38.5), p = 0.121. The mean size of the largest stone on NCCT and DT was 9.27 and 8.87 mm, respectively. Stone size and BMI did not cause a significant difference in stone detection rates. Interobserver agreement showed a strong correlation between readers and adequate reproducibility. CONCLUSION: We found DT to be a comparable imaging modality to NCCT for the detection of intrarenal stones, without a significant effect from stone size and BMI and adequate reproducibility between multiple readers. DT appears to be an ideal alternative for following patients with nephrolithiasis due to its acceptable stone detection rates, low radiation exposure, and decreased cost compared to NCCT.

Porcine acellular lung matrix for wound healing and abdominal wall reconstruction: A pilot study.

Surgical wound healing applications require bioprosthetics that promote cellular infiltration and vessel formation, metrics associated with increased mechanical strength and resistance to infection. Porcine acellular lung matrix is a novel tissue scaffold known to promote cell adherence while minimizing inflammatory reactions. In this study, we evaluate the capacity of porcine acellular lung matrix to sustain cellularization and neovascularization in a rat model of subcutaneous implantation and chronic hernia repair. We hypothesize that, compared to human acellular dermal matrix, porcine acellular lung matrix would promote greater cell infiltration and vessel formation. Following pneumonectomy, porcine lungs were processed and characterized histologically and by scanning electron microscopy to demonstrate efficacy of the decellularization. Using a rat model of subcutaneou implantation, porcine acellular lung matrices (n = 8) and human acellular dermal matrices (n = 8) were incubated in vivo for 6 weeks. To evaluate performance under mechanically stressed conditions, porcine acellular lung matrices (n = 7) and human acellular dermal matrices (n = 7) were implanted in a rat model of chronic ventral incisional hernia repair for 6 weeks. After 6 weeks, tissues were evaluated using hematoxylin and eosin and Masson's trichrome staining to quantify cell infiltration and vessel formation. Porcine acellular lung matrices were shown to be successfully decellularized. Following subcutaneous implantation, macroscopic vessel formation was evident. Porcine acellular lung matrices demonstrated sufficient incorporation and showed no evidence of mechanical failure after ventral hernia repair. Porcine acellular lung matrices demonstrated significantly greater cellular density and vessel formation when compared to human acellular dermal matrix. Vessel sizes were similar across all groups. Cell infiltration and vessel formation are well-characterized metrics of incorporation associated with improved surgical outcomes. Porcine acellular lung matrices are a novel class of acellular tissue scaffold. The increased cell and vessel density may promote long-term improved incorporation and mechanical properties. These findings may be due to the native lung scaffold architecture guiding cell migration and vessel formation. Porcine acellular lung matrices represent a new alternative for surgical wound healing applications where increased cell density and vessel formation are sought.

Radiation Dosimetry for Ureteroscopy Patients: A Phantom Study Comparing the Standard and Obese Patient Models.

PURPOSE: To determine the effect of obesity on radiation exposure during simulated ureteroscopy. METHODS: A validated anthropomorphic adult male phantom with a body mass index (BMI) of approximately 24 kg/m(2), was positioned to simulate ureteroscopy. Padding with radiographic characteristics of human fat was placed around the phantom to create an obese model with BMI of 30 kg/m(2). Metal oxide semiconductor field effect transistor (MOSFET) dosimeters were placed at 20 organ locations in both models to measure organ dosages. A portable C-arm was used to provide fluoroscopic x-ray radiation to simulate ureteroscopy. Organ dose rates were calculated by dividing organ dose by fluoroscopy time. Effective dose rate (EDR, mSv/sec) was calculated as the sum of organ dose rates multiplied by corresponding ICRP 103 tissue weighting factors. RESULTS: The mean EDR was significantly increased during left ureteroscopy in the obese model at 0.0092 ± 0.0004 mSv/sec compared with 0.0041 ± 0.0003 mSv/sec in the nonobese model (P < 0.01), as well as during right ureteroscopy at 0.0061 ± 0.0002 and 0.0036 ± 0.0007 mSv/sec in the obese and nonobese model, respectively (P < 0.01). EDR during left ureteroscopy was significantly greater than right ureteroscopy in the obese model (P = 0.02). CONCLUSIONS: Fluoroscopy during ureteroscopy contributes to the overall radiation dose for patients being treated for nephrolithiasis. Obese patients are at even higher risk because of increased exposure rates during fluoroscopy. Every effort should be made to minimize the amount of fluoroscopy used during ureteroscopy, especially with obese patients.

Evaluation of Novel Ball-Tip Holmium Laser Fiber: Impact on Ureteroscope Performance and Fragmentation Efficiency.

PURPOSE: A novel ball tip (BT) holmium laser fiber has recently been developed, which features a modified rounded tip. The modification is purported to aid in insertion and minimize damage to the ureteroscope working channel. We evaluated this laser fiber with regard to stone comminution, tip degradation, insertional force into the ureteroscope, and impact on ureteroscope deflection. MATERIALS AND METHODS: A 242 µm BT fiber and a standard flat tip (SF) fiber were compared. Four kilojoules was delivered to a BegoStone over a constant surface area using settings of 0.2/50, 0.6/6, 0.8/8, and 1 J/10 Hz. Fiber tip degradation was measured at 1 and 4 kJ. Ureteroscope deflection was measured with the Olympus URF-P5, URF-P6, and URF-V. Insertion force into a 270° angled ureteroscope sheath model was measured. RESULTS: A sample size of five fibers was used for each comminution energy setting. Comminution increased with pulse energy without significant difference between fibers. No significant differences in tip degradation were observed. Both fibers reduced deflection (10°-30°) in all ureteroscopes without significant differences between fibers. Four new fibers paired with new sheath models were used to test insertion force. The BT insertion forces were approximately one-third of the SF. One SF fiber caused significant damage to the sheath and could not be advanced completely. CONCLUSIONS: The BT fiber has comparable comminution, tip degradation, and ureteroscope deflection performance compared with the SF fiber while exhibiting reduced insertion force within an aggressively deflected working sheath. The new tip design is likely protective of the working channel without loss of performance.

Platelet rich plasma enhances tissue incorporation of biologic mesh.

BACKGROUND: High recurrence rates because of poor tissue incorporation limit the use of acellular dermal matrices (ADMs) in ventral hernia repair (VHR). Platelet rich plasma (PRP) is a growth factor-rich autologous blood product known to enhance tissue repair through cellular proliferation and neovascularization. We sought to study the effect of PRP on a porcine noncross-linked ADM in an in vivo model of VHR. We hypothesized that PRP would enhance ADM-tissue incorporation in a rat model of VHR. METHODS: Whole blood was extracted from Lewis rats followed by PRP isolation and characterization. Using a rat model of VHR, a noncross-linked ADM (Strattice) was implanted and activated PRP applied before closure. Rats were sacrificed at 2, 4, and 6 wk. Immunohistochemical staining of CD 31 on endothelial cells was used to quantify neovascularization. Hematoxylin eosin stained tissues were measured to quantify tissue deposition. RESULTS: Platelet concentration of PRP was standardized to 1 × 10(6) platelets/µL. Grossly, vessels were more evident in PRP-treated rats. Immunohistochemical analysis demonstrated neovascularization was significantly greater in the PRP-treated ADMs at all time points. This increase in neovascularization correlated with an increased thickness of tissue deposition at 4 and 6 wk. CONCLUSIONS: PRP enhanced neovascularization and incorporation in a rat model of VHR. Enhanced neovascularization was associated with earlier and greater tissue deposition on the ADM. This suggests that PRP could be used as an adjunct to VHR in clinical scenarios where poor wound healing is anticipated and enhanced neovascularization and early tissue deposition are desired.

Evaluation of the osteoinductive potential of a bio-inspired scaffold mimicking the osteogenic niche for bone augmentation.

Augmentation of regenerative osteogenesis represents a premier clinical need, as hundreds of thousands of patients are left with insufficient healing of bony defects related to a host of insults ranging from congenital abnormalities to traumatic injury to surgically-induced deficits. A synthetic material that closely mimics the composition and structure of the human osteogenic niche represents great potential to successfully address this high demand. In this study, a magnesium-doped hydroxyapatite/type I collagen scaffold was fabricated through a biologically-inspired mineralization process and designed to mimic human trabecular bone. The composition of the scaffold was fully characterized by XRD, FTIR, ICP and TGA, and compared to human bone. Also, the scaffold microstructure was evaluated by SEM, while its nano-structure and nano-mechanical properties were evaluated by AFM. Human bone marrow-derived mesenchymal stem cells were used to test the in vitro capability of the scaffold to promote osteogenic differentiation. The cell/scaffold constructs were cultured up to 7 days and the adhesion, organization and proliferation of the cells were evaluated. The ability of the scaffold to induce osteogenic differentiation of the cells was assessed over 3 weeks and the correlate gene expression for classic genes of osteogenesis was assessed. Finally, when tested in an ectopic model in rabbit, the scaffold produced a large volume of trabecular bone in only two weeks, that subsequently underwent maturation over time as expected, with increased mature cortical bone formation, supporting its ability to promote bone regeneration in clinically-relevant scenarios. Altogether, these results confirm a high level of structural mimicry by the scaffold to the composition and structure of human osteogenic niche that translated to faster and more efficient osteoinduction in vivo--features that suggest such a biomaterial may have great utility in future clinical applications where bone regeneration is required.

Antiretropulsion devices.

PURPOSE OF REVIEW: Stone migration during the treatment of ureteral stones can prove frustrating and increases both healthcare cost and patient morbidity. Antiretropulsion devices have been engineered to prevent stone migration. RECENT FINDINGS: Improvements in antiretropulsion devices allow for efficient prevention of stone migration during ureteroscopic lithotripsy with minimal adverse effects or complications. Multiple devices are now available each with advantages and disadvantages. New devices are currently engineered to prevent stone migration and maintain ureteral access. Antiretropulsion devices appear to be cost-effective to prevent stone migration during intracorporeal lithotripsy. SUMMARY: Antiretropulsion devices have been safely and effectively used during ureteroscopic procedures. These tools increase stone-free rates, decrease morbidity and new studies have demonstrated their cost-effectiveness.