Influence of the substitution position on spin communication in photoexcited perylene-nitroxide dyads.

By virtue of the modularity of their structures, their tunable optical and magnetic properties, and versatile applications, photogenerated triplet-radical systems provide an ideal platform for the study of the factors controlling spin communication in molecular frameworks. Typically, these compounds consist of an organic chromophore covalently attached to a stable radical. After formation of the chromophore triplet state by photoexcitation, two spin centres are present in the molecule that will interact. The nature of their interaction is governed by the magnitude of the exchange interaction between them and can be studied by making use of transient electron paramagnetic resonance (EPR) techniques. Here, we investigate three perylene-nitroxide dyads that only differ with respect to the position where the nitroxide radical is attached to the perylene core. The comparison of the results from transient UV-vis and EPR experiments reveals major differences in the excited state properties of the three dyads, notably their triplet state formation yield, excited state deactivation kinetics, and spin coherence times. Spectral simulations and quantum chemical calculations are used to rationalise these findings and demonstrate the importance of considering the structural flexibility and the contribution of rotational conformers for an accurate interpretation of the data.

References for Small Fluorescence Quantum Yields.

Three compounds with fluorescence quantum yields in the range of 10- 5 to 10- 4 and emission spectra covering the UV/Vis spectral range are suggested as new references for the determination of small fluorescence quantum yields. The compounds are thymidine (dT) in water, dibenzoylmethane (DBM) in ethanol, and malachite green chloride (MG) in water, representing the blue, green, and red regions of the spectrum, respectively. All compounds are easily handled, photostable, and commercially available. Furthermore, these compounds exhibit a mirror-image symmetry between their absorption and fluorescence spectra. This symmetry, along with closely aligned fluorescence excitation and absorption spectra, confirms that the observed emissions originate from the compounds themselves. The fluorescence quantum yields were determined via a relative approach as well as Strickler-Berg analysis in conjunction with time resolved fluorescence spectroscopy. Within the respective error margins, the two approaches yielded identical results.

The Combined Auricular Graft: A New Technique for Mestizo Nasal Tip Surgery.

BACKGROUND: Current literature lacks a single cartilage graft to address problems in projection, rotation, and/or definition in mestizo patients that considers the alar cartilage structure, length, and shape characteristics of this population. OBJECTIVES: The authors sought to describe a novel technique and evaluate the aesthetic outcomes of the combined auricular graft in mestizo patients undergoing primary rhinoplasty. METHODS: A retrospective cohort study of consecutive patients who underwent primary rhinoplasty using the combined auricular graft between January 2015 and June 2017 was performed. The minimum duration of follow-up was 6 months. Main outcomes were nasal tip projection and tip rotation angle. RESULTS: Among the 61 patients (38 women [62.2%] and 23 men [37.8%]; mean age, 29.3 ± 10.8 years), the mean differences in projection were statistically significant between T0 and T1, T0 and T2, and T0 and T3 (1.63, 1.39, and 1.32 mm, respectively). Thus, 80.9% of the increase in projection that had been achieved at T1 was maintained at T3 (P < 0.001). The relapse ratio measured 19.1% (mean difference T1-T3, 0.31 ± 0.10 mm). The mean tip rotation angle at T0 (111.69 ± 3.59°) significantly increased by 2.37 ± 3.13° (T3, 114.06 ± 2.50°, P < 0.001). CONCLUSIONS: One single auricular cartilage graft can significantly improve projection and/or rotation by simultaneously addressing structure, length, and shape of lower lateral cartilages. Misbalance between the medial and lateral crura is avoided and retraction risks are prevented. Consequently, a more natural, precise, and accurate tip position is obtained.

The new LassoLoop360° technique for biomechanically superior tissue grip.

PURPOSE: Suprapectoral tenodesis is a frequently used technique for treating pathologies of the long head of the biceps brachii (LHBB) tendon. However, so far, no Gold Standard treatment exist. Hence, the arthroscopic LassoLoop360 (LL360) technique is introduced aiming to provide secure fixation and improved biomechanical properties. It was hypothesized, that the LL360 technique would show superior biomechanical response to cyclic loading and ultimate load-to-failure testing compared to the commonly used simple Lasso Loop (SLL). METHODS: Twenty-two porcine superficial flexor digitorum tendons were prepared using a No. 2 suture according to either the SLL or the LL360 technique. Displacement after cyclic loading (1.000 cycles) between 5 and 30 N, ultimate load-to-failure (ULTF), mode of failure as well as the construct stiffness were tested. RESULTS: Significantly less displacement was found in the LL360 group (SLL 2.25 ± 0.51 mm; LL360 1.67 ± 0.37 mm; p = 0.01). Ultimate Load to Failure was significantly higher in the LL360 (168.6 ± 29.6 N) as compared to the SLL (124.1 ± 25.8 N, p = 0.02). The LL360 also revealed a significant higher stiffness compared to the SLL (SLL 13.1 ± 0.9 N/mm vs. LL360 19.1 ± 1.0 N/mm, p < 0.001). The most common mode of failure was the suture cutting through the tendon, with a significantly less suture cutting through for the LL360 compared with the SLL (p < 0.05). CONCLUSION: The LassoLoop360-technique offers superior biomechanical characteristics regarding the tendon-suture-interface compared to the SLL. In the initial healing phase, the suture-tendon-interface is the most vulnerable part of the tendon-suture-anchor construct, the aim of this new technique is to reduce this weakest part of the chain (Ponce et al., Am J Sports Med 39:188-194, 2011). This technique may therefore be beneficial for arthroscopic suprapectoral biceps tenodesis at the entrance of the bicipital groove.

Ultrasound melted polymer sleeve for improved primary pedicle screw anchorage: A novel augmentation technique.

BACKGROUND: Cement augmentation of pedicle screws to prevent screw loosening is associated with significant complications, such as cement leakage or bone necrosis. Therefore, an alternative strategy to improve pedicle screw anchorage has been recently developed: Polymer reinforcement of pedicle screws uses an in situ melted polymer sleeve in order to enhance screw anchorage. This biomechanical study evaluated the effect of polymer-reinforcement by comparing polymer-reinforced pedicle screws to non-augmented as well as cement-augmented screws under cyclic loading. METHODS: For each of the two comparisons (polymer-reinforced vs. non-augmented screws and polymer-reinforced vs. cement-augmented screws), polymer-reinforced screws and control screws were placed into the left and right pedicle of seven vertebrae (mean age: 74.0 (SD 9.3) years) to allow for pairwise left-right comparisons. Each screw was subjected to cyclic cranio-caudal loading with an initial load ranging from -50 N to +50 N and with stepwise increasing compressive loads (5 N every 100 cycles) until screw loosening. FINDINGS: Polymer-reinforced pedicle screws resisted a higher number of load cycles until loosening than the contralateral non-augmented control screws (4300 SD 2018 vs. 2457 SD 1116 load cycles, p = 0.015). Screw anchorage of polymer-reinforced pedicle screws was comparable to that of cement augmented control screws (3857 (SD2085) vs. 4300 (SD1257) load cycles until failure, p = 0.64). INTERPRETATION: Our findings indicate that polymer-reinforcement significantly enhances pedicle screw anchorage in low quality bone and that its effect is similar in size than that of cement augmentation.

Long-Term Outcomes in Breast Augmentation in Trans-Women: A 20-Year Experience.

BACKGROUND: Breast augmentation in trans-women requires special consideration and thorough preoperative planning. OBJECTIVES: This study aimed to present our long-term outcome and experience gained over the past 21 years. METHODS: Trans-women who have undergone breast augmentation since 1995 were reviewed for primary surgery, type of incision, implant site, implant size and shape, and revisions. RESULTS: A total of 138 patients with a follow-up of 4.6 years (range, 2.0-13.3) were included. In 112 patients (82.4%), the inframammary incision was chosen. Subpectoral implantation was performed in 70 patients (51.5%). Round breast implants (91 patients, 66.9%, P = 0.010) with low projection (103 patients, 75.7%, P < 0.001) were favored. The implant size used during 2011-2016 of 363.3 ± 97.3 cc was significantly increased as compared to the implant size reported during 1995-1999 (mean difference, +142.1 cc, P < 0.001) and 2000-2004 (mean difference, +113.5 cc, P < 0.001). Simultaneously, revision rates dropped significantly over time (52.9% during 1995-1999 as compared to 6.9% during 2011-2016, P < 0.001). Overall, request for larger implants was the most common indication for revision (13 patients, 9.4%) after 6 months (range, 4.0-18.7). At revision, implant volume was 355.4 ± 132.8 cc, showing significant increase of 107.0 ± 48.1 cc as compared to primary implants (+30.0%, P = 0.048). CONCLUSIONS: Request for larger breast implants was the most common reason for revision. Depending on the various degrees of breast tissue growth due to hormonal therapy, whenever applicable, we recommend round, low projection implants with a mean size of 360 cc in the prepectoral pocket.

Outcome of Stromal Vascular Fraction-Enriched Fat Grafting Compared to Intramuscular Transposition in Painful End-Neuromas of Superficial Radial Nerve: Preliminary Results.

INTRODUCTION: The management of painful end-neuromas of the superficial branch of the radial nerve (SBRN) remains challenging due to high levels of pain relapse. The novel technique of stromal vascular fraction (SVF)-enriched fat grafting showed continuous pain relief, although failed to prove statistically significant. Besides acting as a mechanical barrier, SVF-enriched fat grafting might also affect the cellular level. The aim of this study was to compare clinical outcomes of SVF to the widely popular intramuscular transposition technique. PATIENTS AND METHODS: In this cohort study, 10 consecutive patients treated for painful end-neuromas of the SBRN between 2010 and 2013 were analyzed retrospectively. Microsurgical resection of end-neuromas was performed in all patients. Five patients were treated with subsequent intramuscular transposition into the brachioradialis muscle and five patients received SVF-enriched fat grafting. Five different pain modalities and various predictors were compared pre- and up to 36 months post-operatively. RESULTS: In the transposition group, sustained pain reduction was not observed after an initial significant reduction 2 months' post-surgery, resulting in pain relapse at 36 months and comparable to the preoperative assessment. In the graft group, some degree of pain reduction was observed at 2 months after the surgery and proved to be constant in the long-term outcome, although not statistically significant compared to preoperative levels. CONCLUSION: Both SVF-enriched fat grafting and intramuscular transposition failed to prove statistical significant pain reduction in treating symptomatic neuromas of peripheral nerves.

The novel treatment of SVF-enriched fat grafting for painful end-neuromas of superficial radial nerve.

INTRODUCTION: None of the existing treatments in the management of painful end-neuromas of the superficial branch of the radial nerve (SBRN) has been proven superior due to high levels of pain relapse. Fat grafts enriched with the stromal vascular fraction (SVF) could act as a mechanic barrier with biological effects decreasing the resorption rate and boosting the graft's regenerative potential. This study describes the novel surgical treatment technique of SVF-enriched fat grafting. PATIENTS AND METHODS: In this clinical study, five consecutive patients treated for painful end-neuromas of the SBRN between 2012 and 2013 were analyzed retrospectively. Microsurgical resection of end-neuromas followed by SVF-enriched fat grafting around the nerve stump was performed in all patients. Five different pain modalities and various predictors were compared pre- and up to 36 months postoperatively. RESULTS: Pain reduction observed at 2 months after surgery was constant over time, though not statistically significant compared to preoperative levels. Spontaneous pain could be reduced from 1.6 ± 0.55 to 1.2 ± 1.1 (p = 0.414), spikes from 2.2 ± 1.3 to 1.4 ± 1.34 (p = 0.180), hyperaesthesia from 1.6 ± 1.14 to 1.2 ± 1.64 (p = 0.713), tap pain from 2.8 ± 0.45 to 1.8 ± 1.3 (p = 0.197) and motion pain from 2.8 ± 0.45 to 1.4 ± 1.34 (p = 0.066). An improvement in overall pain reduction could be observed from 2.2 ± 0.97 to 1.4 ± 1.26 3 years after the surgery (p = 0.104). CONCLUSION: SVF-enriched fat grafting represents another alternative to numerous available treatments of painful end-neuromas of the SBRN. Our preliminary results could not show any significant difference in pain reduction following SVF-enriched fat grafting. Further larger trials are required in order to evaluate the therapeutic potential of SVF-enriched fat grafting.

Stromal Vascular Fraction-enriched Fat Grafting for the Treatment of Symptomatic End-neuromata.

The purpose of this study was to methodically illustrate and highlight the crucial steps of stromal vascular fraction (SVF)-enriched fat grafting as a novel treatment of symptomatic end-neuromata of peripheral sensory nerves, and in this study, specifically of the superficial branch of the radial nerve (SBRN). Despite a multitude of existing treatments, persistent postoperative pain and common pain relapse are still very common, independent of the procedure assessed. The neuroma is microsurgically excised accordingly to standardized protocol. Instead of the relocation of the regenerating nerve stump in neighboring anatomical structures, such as muscle or bone, a fat graft is applied perifocally and acts as a mechanical barrier. In order to reduce the fat resorption rate and boost the regenerative potential of the graft, the highly concentrated SVF is integrated in the grafting. The SVF is isolated from subcutaneous fat by enzymatic and mechanic separation of the lipoaspirate by a specific commercial isolation system. The SVF-enriched fat graft provides both a mechanical barrier and various biological effects at the cellular level, including improving angiogenesis, inflammation, and fibrosis. Both mechanical and biologic effects help to reduce the disorganized axonal outgrowth of the nerve stump during nerve regeneration and hence prevent the recurrence of painful end-neuromata.

Reconstruction of Penile Shaft Defects Following Silicone Injection by Bipedicled Anterior Scrotal Flap.

PURPOSE: Numerous causalities, including attempts at penile augmentation with silicone or paraffin, can lead to extensive circular penile shaft defects. Reconstruction is challenging and skin grafting is a suboptimal option despite its widespread use. We present a surgical technique for penile shaft reconstruction with a bipedicled anterior scrotal flap. MATERIALS AND METHODS: A retrospective data analysis was performed of patients treated for symptomatic penile siliconomas who underwent subsequent penile reconstruction with a bipedicled anterior scrotal flap between 2010 and 2015. The surgical technique is described and depicted in detail. RESULTS: A total of 43 men were treated with radical circular excision of penile siliconomas and extensive shaft defects were reconstructed with a bipedicled anterior scrotal flap. Mean ± SD age was 36.95 ± 11.27 years, mean followup duration was 10.69 ± 9.54 months and mean operative time was 2.53 ± 0.46 hours. The operation proved uneventful in all cases. Only minor complications were observed, such as partial necrosis in 9% of patients, hematoma of the donor site in 12% and partial wound disruption in 19%. The mean patient satisfaction score was 4.37 on a scale of 1 to 5. All patients reported postoperative erection ability and the ability to achieve sexual intercourse. CONCLUSIONS: We present a surgical technique to reconstruct extensive penile shaft defects with an axial scrotal flap, which provides well vascularized coverage with comparable donor skin quality and thickness. The results are associated with minor donor site morbidity, good functional and aesthetic outcomes, and high patient satisfaction.

All-inside meniscal repair devices compared with their matched inside-out vertical mattress suture repair: introducing 10,000 and 100,000 loading cycles.

BACKGROUND: All-inside arthroscopic meniscal repairs are favored by most clinicians because of their lower complication rate and decreased morbidity compared with inside-out techniques. Until now, only 1000 cycles have been used for biomechanical testing. HYPOTHESIS: All-inside meniscal repairs will show inferior biomechanical response to cyclic loading (up to 100,000 cycles) and load-to-failure testing compared with inside-out suture controls. STUDY DESIGN: Controlled laboratory study. METHODS: Bucket-handle tears in 72 porcine menisci were repaired using the Omnispan and Fast-Fix 360 (all-inside devices) and Orthocord 2-0 and Ultrabraid 2-0 sutures (matched controls). Initial displacement, displacement after cyclic loading (100, 500, 1000, 2000, 5000, 10,000, and 100,000 cycles) between 5 and 20 N, ultimate load to failure, and mode of failure were recorded, as well as stiffness. RESULTS: Initial displacement and displacement after cyclic loading were not different between the groups. The Omnispan repair demonstrated the highest load-to-failure force (mean ± SD, 151.3 ± 21.5 N) and was significantly stronger than all the other constructs (Orthocord 2-0, 105.5 ± 20.4 N; Ultrabraid 2-0, 93.4 ± 22.5 N; Fast-Fix 360, 76.6 ± 14.2 N) (P < .0001 for all). The Orthocord vertical inside-out mattress repair was significantly stronger than the Fast-Fix 360 repair (P = .003). The Omnispan (30.8 ± 3.5 N/mm) showed significantly higher stiffness compared with the Ultrabraid 2-0 (22.9 ± 6.9 N/mm, P < .0001) and Fast-Fix 360 (23.7 ± 3.9 N/mm, P = .001). The predominant mode of failure was suture failure. CONCLUSION: All-inside meniscal devices show comparable biomechanical properties compared with inside-out suture repair in cyclic loading, even after 100,000 cycles. CLINICAL RELEVANCE: Eight to 10 weeks of rehabilitation might not pose a problem for all repairs in this worst-case scenario.