Long-term Outcomes of Poly-4-Hydroxybutyrate (P4HB) in Aesthetic Breast Surgery.

BACKGROUND: Over the past decade, the use of poly-4-hydroxybutyrate (P4HB) in aesthetic breast surgery has grown in popularity. Published data on long-term outcomes, however, is scarce. OBJECTIVES: The purpose of this study was to assess long-term outcomes when using P4HB in various aesthetic breast procedures. METHODS: A retrospective review of all patients undergoing breast procedures with P4HB performed by the senior author (WPA) between July 2012 and March 2022. All patients with greater than one year of follow-up were evaluated, including demographics, surgical indications, complications, secondary procedures, and patient satisfaction. A Kruskal-Wallis test was performed to assess the stability of satisfaction over time. RESULTS: A total of 248 patients were evaluated. The mean follow-up length was 2.9 years (range, 1-9.3y). The most common surgical indication was breast ptosis, which comprised 68 percent (n=167) of patients. The overall complication rate was 8.0 percent (n=20), with an unplanned reoperation rate of 2.8 percent (n=7). Across the entire study population, the mean satisfaction score was 3.42 out of 4. When satisfaction scores were compared to follow-up length, Kruskal-Wallis test demonstrated no statistical differences (H = 18.2, p = 0.89, df = 2), suggesting stability of satisfaction over time. CONCLUSIONS: This study presents the senior author's entire experience with P4HB across a wide range of aesthetic breast procedures. With an average follow-up length of almost 3 years, P4HB appears to be both a safe and effective tool to support soft tissue in aesthetic breast surgery. Further, high patient satisfaction appears stable.

Practice Patterns: An American Society of Plastic Surgeons (ASPS) Member Survey, 2000 and 2020-How Much Has Brow Lifting Changed?

BACKGROUND: In 2001, Elkwood and Matarasso published an American Society of Plastic Surgeons (ASPS) member survey detailing brow lift practice patterns. Interval changes in practice patterns have not been studied. OBJECTIVES: The previous survey was revised to elucidate current trends in brow lift surgery. METHODS: A 34-question descriptive survey was distributed to a random group of 2360 ASPS members. Results were compared to the 2001 survey. RESULTS: A total of 257 responses were collected (11% response rate; ± 6% margin of error at 95% CI). The most frequent technique for the correction of brow ptosis in both surveys was the endoscopic approach. The use of hardware fixation has increased in endoscopic brow lifting, whereas the use of cortical tunnels has decreased. Although coronal brow lifting has decreased in frequency, hairline and isolated temporal lift have increased. Neuromodulators have replaced resurfacing techniques as the most common nonsurgical adjunct. Frequent use of neuromodulators has risen from 11.2% to 88.5%. Nearly 30% of current surgeons feel that neuromodulators have replaced formal brow lifting procedures to a significant degree. CONCLUSIONS: In comparing the 2001 and current ASPS member survey there has been a clear transition to less invasive procedures over time. Although the endoscopic approach was the most popular means of forehead correction in both surveys, coronal brow lifting has decreased in frequency and the hairline and temporal approaches have increased. Neurotoxins have replaced laser resurfacing and chemical peeling methods as an adjunct, and in some cases replaced the invasive procedure entirely. Possible explanations for these findings will be discussed.

Can brain signals and anatomy refine contact choice for deep brain stimulation in Parkinson's disease?

INTRODUCTION: Selecting the ideal contact to apply subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease is time-consuming and reliant on clinical expertise. The aim of this cohort study was to assess whether neuronal signals (beta oscillations and evoked resonant neural activity (ERNA)), and the anatomical location of electrodes, can predict the contacts selected by long-term, expert-clinician programming of STN-DBS. METHODS: We evaluated 92 hemispheres of 47 patients with Parkinson's disease receiving chronic monopolar and bipolar STN-DBS. At each contact, beta oscillations and ERNA were recorded intraoperatively, and anatomical locations were assessed. How these factors, alone and in combination, predicted the contacts clinically selected for chronic deep brain stimulation at 6 months postoperatively was evaluated using a simple-ranking method and machine learning algorithms. RESULTS: The probability that each factor individually predicted the clinician-chosen contact was as follows: ERNA 80%, anatomy 67%, beta oscillations 50%. ERNA performed significantly better than anatomy and beta oscillations. Combining neuronal signal and anatomical data did not improve predictive performance. CONCLUSION: This work supports the development of probability-based algorithms using neuronal signals and anatomical data to assist programming of deep brain stimulation.

Concentration Determination of >200 Proteins in Dried Blood Spots for Biomarker Discovery and Validation.

The use of protein biomarkers as surrogates for clinical endpoints requires extensive multilevel validation including development of robust and sensitive assays for precise measurement of protein concentration. Multiple reaction monitoring (MRM) is a well-established mass-spectrometric method that can be used for reproducible protein-concentration measurements in biological specimens collected via microsampling. The dried blood spot (DBS) microsampling technique can be performed non-invasively without the expertise of a phlebotomist, and can enhance analyte stability which facilitate the application of this technique in retrospective studies while providing lower storage and shipping costs, because cold-chain logistics can be eliminated. Thus, precise, sensitive, and multiplexed methods for measuring protein concentrations in DBSs can be used for de novo biomarker discovery and for biomarker quantification or verification experiments. To achieve this goal, MRM assays were developed for multiplexed concentration measurement of proteins in DBSs.The lower limit of quantification (LLOQ) was found to have a median total coefficient of variation (CV) of 18% for 245 proteins, whereas the median LLOQ was 5 fmol of peptide injected on column, and the median inter-day CV over 4 days for measuring endogenous protein concentration was 8%. The majority (88%) of the assays displayed parallelism, whereas the peptide standards remained stable throughout the assay workflow and after exposure to multiple freeze-thaw cycles. For 190 proteins, the measured protein concentrations remained stable in DBS stored at ambient laboratory temperature for up to 2 months. Finally, the developed assays were used to measure the concentration ranges for 200 proteins in twenty same sex, same race and age matched individuals.

Local Infiltration of Tranexamic Acid During Facelift Improves Operating Room Efficiency: A Matched Patient Study.

BACKGROUND: Tranexamic acid (TXA) has rapidly gained popularity in aesthetic surgery. Previous reports have suggested that TXA provides a dry surgical field and significantly reduces operating time during facelift surgery. OBJECTIVES: The aim of this study was to build upon earlier findings by providing a large cohort matched alongside historic controls and more clearly document time saved when performing facelift surgery. METHODS: A retrospective, single-surgeon case-control study was undertaken between July 2016 and October 2021. All patients underwent facelift surgery alone or in combination with fat transfer and perioral chemical peel. All patients received subcutaneous infiltration of 0.5% lidocaine/1:200,000 epinephrine with or without 1 or 2 mg/mL TXA. Patient demographics, TXA dose, surgical time, and minor and major complications were examined. RESULTS: In total 145 consecutive patients were identified: 73 in Group 1 (no-TXA) and 72 in Group 2 (TXA). No differences in terms of gender distribution (P = 0.75), age (P = 0.54), BMI (P = 0.18), frequency of secondary rhytidectomy (P = 0.08), rate of ancillary lipografting (P = 0.44), TXA dose (P = 0.238), and minor complication rate (P = 0.56) were observed. However, mean surgical time in the no-TXA group was 21 minutes longer than in the TXA group (P = 0.016). Six patients (8%) in the no-TXA group experienced minor complications vs 8 patients (11%) in the TXA group. No patients experienced major complications. CONCLUSIONS: Although previous studies have highlighted the potential benefits of TXA in aesthetic surgery, most of the data remain subjective and non-validated. This report adds to the objective body of evidence supporting TXA in facial aesthetic surgery by documenting time saved in the operating room without additional surgical morbidity.

Process and Workflow for Preparation of Disparate Mouse Tissues for Proteomic Analysis.

We investigated the effect of homogenization strategy and protein precipitation on downstream protein quantitation using multiple reaction monitoring mass spectrometry (MRM-MS). Our objective was to develop a workflow capable of processing disparate tissue types with high throughput, minimal variability, and maximum purity. Similar abundances of endogenous proteins were measured in nine different mouse tissues regardless of the homogenization method used; however, protein precipitation had strong positive effects on several targets. The best throughput was achieved by lyophilizing tissues to dryness, followed by homogenization via bead-beating without sample buffer. Finally, the effect of tissue perfusion prior to dissection and collection was explored in 20 mouse tissues. MRM-MS showed decreased abundances of blood-related proteins in perfused tissues; however, complete removal was not achieved. Concentrations of nonblood proteins were largely unchanged, although significantly higher variances were observed for proteins from the perfused lung, indicating that perfusion may not be suitable for this organ. We present a simple yet effective tissue processing workflow consisting of harvest of fresh nonperfused tissue, novel lyophilization and homogenization by bead-beating, and protein precipitation. This workflow can be applied to a range of mouse tissues with the advantages of simplicity, minimal manual manipulation of samples, use of commonly available equipment, and high sample quality.

Beginnings of coinhibition.

Costimulatory and coinhibitory mechanisms appear to be involved throughout immune responses to control their specificity and level. Many mechanisms operate; therefore, various theoretical models should be considered complementary rather than competing. One such coinhibitory model, pictured in 1971, involves the crosslinking of antigen receptors with inhibitory Fc receptors by antigen/antibody complexes. This model was prompted by observations that the Fc portion of antibody was required for potent suppression of immune responses by antibody. The signal via the antigen receptor wakes up T or B cells, providing specificity, while costimulators and coinhibitors stimulate or inhibit these awoken cells. The recent observations that administration of monoclonal anti-SARS-CoV-2 spike antibodies in early COVID-19 patients inhibits the induction of clinically damaging autoimmune antibodies suggest they may provide negative Fc signals that are blocked in COVID-19 patients. Furthermore, the reduced ability of SARS-CoV-2 antigen to localize to germinal centres in COVID-19 patients also suggests a block in binding of the Fc of antibody bound to antigen on FcγRIIb of follicular dendritic cells. The distinction between self and foreign is made not only at the beginning of immune responses but also throughout, and involves multiple mechanisms and models. There are past beginnings (history of models) and current and future beginnings for solving serious clinical problems (such as COVID-19) and different types of models used for understanding the complexities of fundamental immunology.

Vascular Access Complications and Clinical Outcomes of Vascular Surgical Repairs Following Transcatheter Aortic Valve Implantation (TAVI).

BACKGROUND: Transcatheter aortic valve implantation (TAVI) procedures have revolutionized the treatment of aortic stenosis. However, due to large sheaths, improperly deployed closure devices, and the comorbidities and challenges innate to this population, vascular access complications can be devastating. The objective of this study is to evaluate vascular access complications in one of the largest TAVI sites in North America. METHODS: This was a retrospective single center review between January 2014 and December 2018 of vascular access complications necessitating operative intervention by vascular surgery. Patient demographics and preoperative comorbidities were collected. Type of vascular access complication, types of repair, closure device used, and postoperative outcomes were analyzed. RESULTS: A total of 37 cases out of a total of 985 TAVI procedures were identified. TAVI was carried out in the operating suite (70%) or the catheterization lab (30%). Consults to vascular surgery were requested intraoperatively (60%), immediately postoperative (14%), later in the day of the TAVI (20%), and on postoperative day 1 (6%). The location of injury included common femoral artery (49%), superficial femoral artery (11%) and external iliac artery (41%), with some cases injuring multiple vessels. Closure devices were found in the subcutaneous tissue (26%), anterior wall (37%), posterior wall (11%), intra-arterial (11%), closing the anterior to the posterior wall (16%), and in the inguinal ligament (5%). Injuries included tears (11%), dissections (38%), and vessel rupture (19%). The majority of repairs were done primarily (64%), with patch (28%) and bypass (8%) less frequently. Four patients died perioperatively (11%), 2 from hemorrhage, 1 from cardiac arrest, and 1 from progressive respiratory disease. CONCLUSIONS: Access complications during TAVI procedures predispose complex patients to increased risk of morbidity and mortality. Careful patient selection, proper access techniques, and performing high risk patients in the operating suite with vascular surgery are fundamental in minimizing complications.

Prospective Study Assessing the Effect of Local Infiltration of Tranexamic Acid on Facelift Bleeding.

BACKGROUND: Rebound bleeding during facelift surgery is a major cause of facelift hematomas. Subcutaneous infiltration of tranexamic acid (TXA) combined with lidocaine and epinephrine was recently retrospectively shown to decrease rebound bleeding. No study has prospectively examined the effect of subcutaneous TXA on intraoperative and postoperative bleeding during facelift surgery. OBJECTIVES: The aim of this study was to prospectively demonstrate that TXA combined with local anesthesia safely reduces the effects of rebound bleeding, reduces operative time, and decreases postoperative drainage. METHODS: This was a prospective, single-surgeon, case-control study performed between July 2019 and March 2020. Thirty-nine patients (35 female and 4 male; mean age, 64.9 years; age range, 49-80 years) underwent facelift surgery alone or in combination with facial rejuvenation procedures. All patients were injected subcutaneously with 1 or 2 mg/mL TXA + 0.5% lidocaine/1:200,000 epinephrine. Patient demographics, TXA dose, time to hemostasis, drain output, and minor and major complications were recorded. RESULTS: The mean time to hemostasis was 6.4 minutes for the left and right sides each. Average postoperative day (POD) 0 drain outputs were 13.9 mL (left) and 10.1 mL (right). Average POD 1 drain outputs were 15.1 mL (left) and 15.6 mL (right). Drains were removed from all patients on POD 1 or 2. There were 2 minor complications (flap necrosis plus infection, marginal mandibular neuropraxia) and no major complications. CONCLUSIONS: TXA safely and effectively decreased bleeding, operating room time, and drain output compared with traditional local anesthetic techniques. Our future goal is to determine if epinephrine can be completely removed from the local anesthetic and replaced with TXA for facelift surgery.

Trends in Contracting and Common Ownership Between Hospice Agencies and Nursing Homes.

BACKGROUND: In recent years, policymakers have paid particular attention to the emergence of a robust for-profit hospice sector and increased hospice use by nursing home residents. Previous research has explored financial incentives for nursing home-hospice use, but there has been limited research on nursing home-hospice partnerships and none on the extent of nursing home-hospice common ownership. OBJECTIVE: To describe trends in nursing home-hospice contracting and common ownership and to identify potential tradeoffs in care provided by nursing homes and hospice agencies that share common ownership. RESEARCH DESIGN: Retrospective cohort study of nursing home-hospice patients between 2005 and 2015. RESULTS: Between 2005 and 2015, the number of hospice agencies and nursing homes with common ownership grew substantially, now representing almost 1-in-5 providers in each sector. Relative to individuals using hospice in nursing homes without common ownership, adjusted analyses found that individuals receiving hospice from a commonly owned agency had a greater likelihood of having stays of 90 days or more [odds ratio (OR)=1.06; 95% confidence interval (CI), 1.02-1.10], having a stay resulting in a live discharge (OR=1.06; 95% CI, 1.02-1.11), and having at least 1 registered nurse/licensed practical nurse visit during the last 3 days of life (OR=1.17; 95% CI, 1.05-1.29); these individuals also had a lower mean visit hours per day (-0.07; P=0.003). CONCLUSIONS: Common ownership between hospice agencies and nursing homes is an emerging trend that reflects a broader push toward consolidation in the health care sector. Our analyses highlight potential concerns relevant to Medicare payment policy and are a first step toward improving our understanding of these trends and their implications.

Cranial Vault Remodeling in Children With Ventricular Shunts.

INTRODUCTION: Cranial vault surgery in children with ventricular shunts is more complex due to the possible interference of shunt location with surgical planning and increased risk of shunt related complications. The study evaluated the management of ventricular shunts during cranial vault remodeling (CVR) and subsequent outcomes and complications following CVR. METHODS: An IRB-approved retrospective chart review was performed including patients who underwent CVR in presence of a ventricular shunt. Measured outcomes were number of shunt revisions following CVR, 30-day complication rate, 3-month complication rate, and post-CVR Whitaker classification. Finally, a review of the literature was performed, and our results were compared to previous reports. RESULTS: Eleven patients met the inclusion criteria. Ventricular shunt was not exposed in 18%; exposed and not revised in 54%; exposed and left on a bone peninsula in 18% and simultaneously exposed and revised in 18%. Two patients experienced complications within 30-days. Three additional patients experienced complications within 3-months. An average of 2.2 shunt revisions per patient were performed following CVR. Whitaker classification was I in 7 patients, II in 1 patient and III in 2 patients. Shunt revision rate for patients undergoing CVR for hydrocephalic macrocephaly was on average of 1.2 and 1.9 for shunt-induced craniosynostosis in literature. CONCLUSIONS: Cranial vault abnormalities in the presence of a ventricular shunt can be effectively treated with CVR. The presence of a shunt does not seem to interfere with final head shape. While leaving the shunt unexposed may appear less morbid, shunt related complications can still occur with this approach.

Local Infiltration of Tranexamic Acid With Local Anesthetic Reduces Intraoperative Facelift Bleeding: A Preliminary Report.

BACKGROUND: Rebound bleeding as a result of loss of epinephrine effect is a common problem encountered during facelift surgery. Tranexamic acid (TXA) is an anti-fibrinolytic agent whose safety and efficacy in reducing bleeding are well documented. We have found that local infiltration of TXA combined with a lidocaine with epinephrine solution during facelift surgery has been effective in decreasing rebound bleeding and the time required to gain hemostasis. OBJECTIVES: The authors sought to share their local infiltration protocol of TXA combined with epinephrine solution in facelift. METHODS: Patients who underwent facelift received subcutaneous injection of TXA-lidocaine 0.5% solution following the authors' protocol. After completing both sides of the facelift and the submental platysmaplasty, the first and second sides were sequentially closed. The time to gain hemostasis on each side prior to closure was prospectively measured. RESULTS: Twenty-seven consecutive patients who underwent facelift surgery received local infiltration of TXA-lidocaine solution. In 23 of the 27 patients, the time required for hemostasis was prospectively recorded. The mean age was 62.1 years (±9.3) and all were females. The average time spent achieving hemostasis on the right, left, and both sides of the face was 6.5 (±2.7), 6.3 (±2.1), and 12.9 (±4.2) minutes, respectively. The total surgical time saving is approximately 25 to 60 minutes. Although primary facelift [13.6 (± 4.3)] exhibited a longer time of hemostasis compared with the secondary group [10.2 (± 2.8)], this was not statistically significant (P = 0.09). CONCLUSIONS: Local infiltration of TXA with local anesthetic prior to a facelift appears to decrease bleeding, operative time, and postoperative facelift drainage output.Level of Evidence: 4.

The Use of Eye Tracking Technology in Aesthetic Surgery: Analyzing Changes in Facial Attention Following Surgery.

BACKGROUND: The ability to quantitatively analyze how we look at a face and determine if this changes following facial surgery should be of interest to the plastic surgeon. Eye tracking technology (ETT) provides the ability to record where observers fixate when viewing a facial image, enabling quantitative data to be obtained comparing pre- and postoperative changes. OBJECTIVES: The authors sought to investigate ETT as a novel outcome assessment tool, determining if facial rejuvenation surgery shifts attention away from the prominent signs of aging, and if so, where this attention shifts. METHODS: Twenty-five volunteers viewed 32 randomized frontal, oblique, and lateral images of 11 patients pre- and post-facelift. An eye movement monitoring system recorded the observer's eye position, net dwell time, fixation count, fixation time, and revisits into predefined areas of interest. Data were grouped and analyzed by angle and areas of interest. Paired t tests were employed to detect significant differences in pre- and post-images. RESULTS: On frontal images, less dwell time, fixations, and revisits were noted on the bottom third, forehead, perioral region, and neck (P < 0.05). On the lateral view, less visual attention was given to the neck, upper third, and perioral region, with more time in the cheek, nose, and middle third (P < 0.05). On oblique images, less attention was given to the neck and upper lid with more aimed at the middle third of the face (P < 0.05). CONCLUSIONS: ETT provides quantitative data post-facial rejuvenation. Facial aesthetic surgery does alter where observers look when viewing a face, decreasing the time spent inspecting the prominent signs of aging.

Deep brain stimulation for Parkinson's disease modulates high-frequency evoked and spontaneous neural activity.

Deep brain stimulation is an established therapy for Parkinson's disease; however, its effectiveness is hindered by limited understanding of therapeutic mechanisms and the lack of a robust feedback signal for tailoring stimulation. We recently reported that subthalamic nucleus deep brain stimulation evokes a neural response resembling a decaying high-frequency (200-500 Hz) oscillation that typically has a duration of at least 10 ms and is localizable to the dorsal sub-region. As the morphology of this response suggests a propensity for the underlying neural circuitry to oscillate at a particular frequency, we have named it evoked resonant neural activity. Here, we determine whether this evoked activity is modulated by therapeutic stimulation - a critical attribute of a feedback signal. Furthermore, we investigated whether any related changes occurred in spontaneous local field potentials. Evoked and spontaneous neural activity was intraoperatively recorded from 19 subthalamic nuclei in patients with Parkinson's disease. Recordings were obtained before therapeutic stimulation and during 130 Hz stimulation at increasing amplitudes (0.67-3.38 mA), 'washout' of therapeutic effects, and non-therapeutic 20 Hz stimulation. Therapeutic efficacy was assessed using clinical bradykinesia and rigidity scores. The frequency and amplitude of evoked resonant neural activity varied with the level of 130 Hz stimulation (p < .001). This modulation coincided with improvement in bradykinesia and rigidity (p < .001), and correlated with spontaneous beta band suppression (p < .001). Evoked neural activity occupied a similar frequency band to spontaneous high-frequency oscillations (200-400 Hz), both of which decreased to around twice the 130 Hz stimulation rate. Non-therapeutic stimulation at 20 Hz evoked, but did not modulate, resonant activity. These results indicate that therapeutic deep brain stimulation alters the frequency of evoked and spontaneous oscillations recorded in the subthalamic nucleus that are likely generated by loops within the cortico-basal ganglia-thalamo-cortical network. Evoked resonant neural activity therefore has potential as a tool for providing insight into brain network function and has key attributes of a dynamic feedback signal for optimizing therapy.

Subthalamic nucleus deep brain stimulation evokes resonant neural activity.

Deep brain stimulation (DBS) is a rapidly expanding treatment for neurological and psychiatric conditions; however, a target-specific biomarker is required to optimize therapy. Here, we show that DBS evokes a large-amplitude resonant neural response focally in the subthalamic nucleus. This response is greatest in the dorsal region (the clinically optimal stimulation target for Parkinson disease), coincides with improved clinical performance, is chronically recordable, and is present under general anesthesia. These features make it a readily utilizable electrophysiological signal that could potentially be used for guiding electrode implantation surgery and tailoring DBS therapy to improve patient outcomes. Ann Neurol 2018;83:1027-1031.

Structural Transformation and Melting in Gold Shock Compressed to 355 GPa.

Gold is believed to retain its ambient crystal structure at very high pressures under static and shock compression, enabling its wide use as a pressure marker. Our in situ x-ray diffraction measurements on shock-compressed gold show that it transforms to the body-centered-cubic (bcc) phase, with an onset pressure between 150 and 176 GPa. A liquid-bcc coexistence was observed between 220 and 302 GPa and complete melting occurs by 355 GPa. Our observation of the lower coordination bcc structure in shocked gold is in marked contrast to theoretical predictions and the reported observation of the hexagonal-close-packed structure under static compression.

Soft Tissue Reconstruction in Patients With Hemifacial Microsomia: A Systematic Review of the Literature.

INTRODUCTION: Hemifacial microsomia is the most common congenital disorder of the face after cleft lip and palate. While treatment of the bony abnormalities has been well documented, less attention has been paid to correction of the soft tissue deformity. This study aimed to systematically review the literature addressing the techniques utilized to correct the soft tissue deformity in hemifacial microsomia. MATERIALS AND METHODS: A comprehensive review of peer-reviewed literature regarding the management of soft tissue reconstruction in patients with hemifacial microsomia was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Odds ratio was used to assess differences in complication rates between reconstructions performed with free tissue transfer and fat grafting. RESULTS: The literature search yielded 38 articles that were fully reviewed for data extraction. Articles were grouped into one of 5 reconstructive modalities-pedicled flap, microvascular free tissue transfer, structural fat grafting, alloplastic implant, and functional reconstruction. Microvascular free tissue transfer had a complication rate of 27.1%, while structural fat grafting had a complication rate of 4.2% (odds ratio 6.7, P = 0.0003). CONCLUSIONS: Microvascular free tissue transfer likely provides greater volume than fat grafting at the cost of a higher complication rate. Mild to moderate soft tissue deformity can be corrected with serial fat grafting. However, severe soft tissue deformity is better corrected with microvascular free tissue transfer. When performing free tissue transfer, one should be prepared for recipient vessel anomalies. To provide adequate augmentation with isolated fat grafting, multiple sessions are likely required.

Challenges in Microsurgical Reconstruction for Craniofacial Osteomyelitis With Resultant Osteonecrosis.

INTRODUCTION: Chronic osteomyelitis is characterized by compromised blood supply and eventual osteonecrosis. Definitive treatment requires aggressive resection of affected bone. The resultant defect poses a unique challenge to reconstructive surgeons. Much of the literature on craniofacial osteomyelitis focuses on infection eradication, rather than subsequent reconstruction. This article reports representative cases from our experience with free flap reconstruction for defects secondary to chronic osteomyelitis of the craniofacial skeleton. METHODS/RESULTS: The authors selected 5 of the most difficult reconstructive cases of craniofacial osteomyelitis from our experience in a single tertiary referral institution with a follow-up of at least 6 months. Three of the 5 cases arose in the setting of previous head and neck cancer treated with resection and radiation therapy. One case had a previous surgical craniotomy complicated by osteomyelitis and multiple failed alloplastic reconstructions. The final case was due to multiple gunshots to the head, with subsequent cerebral and cranial abscess (>1000cc). In each case, the defect was successfully treated with free tissue transfer. Two cases required creation of recipient vessels with an arteriovenous loop. CONCLUSIONS: Free tissue transfer provides a versatile and effective tool in the reconstruction of extensive craniofacial osteomyelitis defects. Furthermore, the addition of vascularized tissue can protect against further episodes of osteomyelitis. Finally, arteriovenous loops can be employed successfully when prior radiation and infection of the wound bed precludes the use of local recipient target vessels.

Analyte-Driven Disassembly and Turn-On Fluorescent Sensing in Competitive Biological Media.

Many indicator displacement assays can detect biological analytes in water, but these often have reduced performance in the presence of an unavoidable component: NaCl. We report here a new self-assembled sensor, DimerDye, that uses a novel photochemical guest-sensing mechanism and that is intrinsically tolerant of cosolutes. We synthetically integrated a dye into a calixarene macrocycle, forming two new merocyanine calixarenes (MCx-1 and MCx-2). Both compounds self-assemble into nonemissive dimers in water. The addition of good guests like trimethyllysine induces a turn-on fluorescence response of MCx-1 due to simultaneous dimer dissociation and formation of an emissive host-guest complex. DimerDyes remain functional in solutions containing the various salts, metal ions, and cofactors that are needed for enzymatic reactions. MCx-1 provides a real-time, turn-on fluorescence signal in response to the lysine methyltransferase reaction of PRDM9.