bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of the ubiquitination-triggered active form of SETDB1 in Escherichia coli for biochemical and structural analyses
Authors: Funyu Tomoko , Kanemaru Yuka , Onoda Hiroki , Arita Kyohei
Published: July 2021

Trimethylation of histone H3 at K9 by the lysine methyltransferase, SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) plays a pivotal role in silencing tissue-specific genes and retrotransposable elements. In mammalian cells, SETDB1 undergoes monoubiquitination in the insertion region of the SET domain in an E3 ubiquitin ligase-independent manner. This ubiquitination has been shown to enhance the histone H3-K9 methyltransferase activity of SETDB1; however, the molecular mechanism underlying SETDB1 activation by ubiquitination is unknown. In this study, we developed an Escherichia coli ubiquitination plasmid for the preparation of ubiquitinated SETDB1. Western blotting and mutational analyses showed that co-expression of the SET domain of SETDB1 with the proteins encoded by the ubiquitination plasmid led to site-specific monoubiquitination of the SET domain at K867. An in vitro histone H3 methylation assay demonstrated that the ubiquitinated SET domain of SETDB1 acquired enzymatic activity. Taken together, these findings demonstrate successful preparation of the active form of SETDB1 with the E.coli ubiquitination system, which will aid biochemical and structural studies of ubiquitinated SETDB1.
Management of a Pediatric Burn Center During the Covid-19 Pandemic
Authors: Erturk Ahmet , Demir Sabri , Oztorun Can İhsan , Erten Elif Emel , Guney Dogus , Bostanci Suleyman Arif , Sahin Vildan Selin , Kiris Atike Gulsah , Bay Hatice Kübra , Bedir Demirdag Tugba , Keskin Gulsen , Azili Mujdem Nur , Senel Emrah
Published: July 2021

The aim of this study was to evaluate the results of an algorithm that was created to prevent coronavirus disease-2019 (COVID-19) transmission during the management of children with burns in a tertiary pediatric burn center. Children admitted to the burn center between May 2020 and November 2020 were prospectively evaluated for cause, burn depth, TBSA, length of stay, symptoms suggesting COVID-19, suspicious contact history, history of travel abroad, and COVID-19 polymerase chain reaction (PCR) test results. Patients were divided into two groups: unsuspected (group 1) and suspected (group 2), depending on any history of suspicious contact, travel abroad, and/or presence of symptoms. A total of 101 patients were enrolled in the study, which included 59 boys (58.4%) and 42 girls (41.6%). Group 1 included 79 (78.2%) patients, and group 2 consisted of 22 (21.8%) patients. The most common cause of the burns was scald injuries (74.2%). The mean age, TBSA, and length of stay were 4.5 years, 12.0%, and 13.2 days, respectively. Four patients (3.9%) had a positive PCR test (two patients in each group). Comparing groups, males were more commonly found in group 2 (P = .042), but no differences were found for the other variables. No patients or burn center staff members developed COVID-19 during the course of hospitalization. In conclusion, every child should be tested for COVID-19 upon admission to a burn unit, and a modified algorithm should be constructed for the handling and management of pediatric burn patients.
Novel mannosylerythritol lipid biosurfactant structures from castor oil revealed by advanced structure analysis
Authors: Beck Alexander , Haitz Fabian , Thier Isabel , Siems Karsten , Jakupovic Sven , Rupp Steffen , Zibek Susanne
Published: July 2021

Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by fungi of the Ustilaginaceae family in the presence of hydrophobic carbon sources like plant oils. In the present study, we investigated the structural composition of MELs produced from castor oil using seven different microorganisms and compared them to MEL structures resulting from other plant oils. Castor oil is an industrially relevant plant oil that presents as an alternative to currently employed edible plant oils like rapeseed or soybean oil. The main fatty acid in castor oil is the mono-hydroxylated ricinoleic acid, providing the possibility to produce novel MEL structures with interesting features. Analysis of the produced MELs from castor oil by different chromatographic and mass spectrometry techniques revealed that all seven microorganisms were generally able to integrate hydroxylated fatty acids into the MEL molecule, although at varying degrees. These novel MELs containing a hydroxy fatty acid (4-O-[2′-O-alka(e)noyl-3′-O-hydroxyalka(e)noyl-4′/6′-O-acetyl-β-D-mannopyranosyl]-erythritol) were more hydrophilic than conventional MEL and therefore showed a different elution behavior in chromatography. Large shares of novel hydroxy MELs (around 50% of total MELs) were found for the two MEL-B/C producing species Ustilago siamensis and Ustilago shanxiensis, but also for the MEL-A/B/C producer Moesziomyces aphidis (around 25%). In addition, tri-acylated hydroxylated MELs with a third long-chain fatty acid esterified to the free hydroxyl group of the hydroxy fatty acid were identified for some species. Overall, production of MEL from castor oil with the investigated organisms provided a complex mixture of various novel MEL structures that can be exploited for further research.
A free market in extreme speech: Scientific racism and bloodsports on YouTube
Authors: de Keulenaar Emillie , Tuters Marc , Osborne-Carey Cassian , Jurg Daniel , Kisjes Ivan
Published: July 2021

Around 2018, YouTube became heavily criticized for its radicalizing function by allowing far-right actors to produce hateful videos that were in turn amplified through algorithmic recommendations. Against this ‘algorithmic radicalization’ hypothesis, Munger and Phillips (2019, A supply and demand framework for YouTube politics. Preprint. https://osf.io/73jys/download; Munger and Phillips, 2020, Right-wing YouTube: a supply and demand perspective. The International Journal of Press/Politics, 21(2). doi: 10.1177/1940161220964767.)) argued that far-right radical content on YouTube fed into audience demand, suggesting researchers adopt a ‘supply and demand’ framework. Navigating this debate, our article deploys novel methods for examining radicalization in the language of far-right pundits and their audiences within YouTube’s so-called ‘Alternative Influence Network’ (Lewis, 2018, Alternative Influence. Data & Society Research Institute. https://datasociety.net/library/alternative-influence/ (accessed 9 December 2020).). To that end, we operationalize the concept ‘extreme speech’—developed to account for ‘the inherent ambiguity of speech contexts’ online (Pohjonen and Udupa, 2017, Extreme speech online: an anthropological critique of hate speech debates. International Journal of Communication, 11: 1173–91)—to an analysis of a right-wing ‘Bloodsports’ debate subculture that thrived on the platform at the time. Highlighting the topic of ‘race realism’, we develop a novel mixed-methods approach: repurposing the far-right website Metapedia as a corpus to detect unique terms related to the issue. We use this corpus to analyze the transcripts and comments from an archive of 950 right-wing channels, collected from 2008 until 2018. In line with Munger and Phillips’ framework, our empirical study identifies a market for extreme speech on the platform, which came into public view in 2017.
Sequence-specific dynamics of DNA response elements and their flanking sites regulate the recognition by AP-1 transcription factors
Authors: Hörberg Johanna , Moreau Kevin , Tamás Markus J , Reymer Anna
Published: July 2021

Activator proteins 1 (AP-1) comprise one of the largest families of eukaryotic basic leucine zipper transcription factors. Despite advances in the characterization of AP-1 DNA-binding sites, our ability to predict new binding sites and explain how the proteins achieve different gene expression levels remains limited. Here we address the role of sequence-specific DNA flexibility for stability and specific binding of AP-1 factors, using microsecond-long molecular dynamics simulations. As a model system, we employ yeast AP-1 factor Yap1 binding to three different response elements from two genetic environments. Our data show that Yap1 actively exploits the sequence-specific flexibility of DNA within the response element to form stable protein–DNA complexes. The stability also depends on the four to six flanking nucleotides, adjacent to the response elements. The flanking sequences modulate the conformational adaptability of the response element, making it more shape-efficient to form specific contacts with the protein. Bioinformatics analysis of differential expression of the studied genes supports our conclusions: the stability of Yap1–DNA complexes, modulated by the flanking environment, influences the gene expression levels. Our results provide new insights into mechanisms of protein–DNA recognition and the biological regulation of gene expression levels in eukaryotes.
Careful feature selection is key in classification of Alzheimer’s disease patients based on whole-genome sequencing data
Authors: Osipowicz Marlena , Wilczynski Bartek , Machnicka Magdalena A ,   for the Alzheimer’s Disease Neuroimaging Initiative
Published: July 2021

Despite great increase of the amount of data from genome-wide association studies (GWAS) and whole-genome sequencing (WGS), the genetic background of a partially heritable Alzheimer’s disease (AD) is not fully understood yet. Machine learning methods are expected to help researchers in the analysis of the large number of SNPs possibly associated with the disease onset. To date, a number of such approaches were applied to genotype-based classification of AD patients and healthy controls using GWAS data and reported accuracy of 0.65–0.975. However, since the estimated influence of genotype on sporadic AD occurrence is lower than that, these very high classification accuracies may potentially be a result of overfitting. We have explored the possibilities of applying feature selection and classification using random forests to WGS and GWAS data from two datasets. Our results suggest that this approach is prone to overfitting if feature selection is performed before division of data into the training and testing set. Therefore, we recommend avoiding selection of features used to build the model based on data included in the testing set. We suggest that for currently available dataset sizes the expected classifier performance is between 0.55 and 0.7 (AUC) and higher accuracies reported in literature are likely a result of overfitting.
Impact of total sleep deprivation and related mood changes on approach-avoidance decisions to threat-related facial displays
Authors: Grèzes Julie , Erblang Mégane , Vilarem Emma , Quiquempoix Michael , Van Beers Pascal , Guillard Mathias , Sauvet Fabien , Mennella Rocco , Rabat Arnaud
Published: July 2021

Study Objectives

Total sleep deprivation is known to have significant detrimental effects on cognitive and socio-emotional functioning. Nonetheless, the mechanisms by which total sleep loss disturbs decision-making in social contexts are poorly understood. Here, we investigated the impact of total sleep deprivation on approach/avoidance decisions when faced with threatening individuals, as well as the potential moderating role of sleep-related mood changes.

Methods

Participants (n = 34) made spontaneous approach/avoidance decisions in the presence of task-irrelevant angry or fearful individuals, while rested or totally sleep deprived (27 h of continuous wakefulness). Sleep-related changes in mood and sustained attention were assessed using the Positive and Negative Affective Scale and the psychomotor vigilance task, respectively.

Results

Rested participants avoided both fearful and angry individuals, with stronger avoidance for angry individuals, in line with previous results. On the contrary, totally sleep deprived participants favored neither approach nor avoidance of fearful individuals, while they still comparably avoided angry individuals. Drift-diffusion models showed that this effect was accounted for by the fact that total sleep deprivation reduced value-based evidence accumulation toward avoidance during decision making. Finally, the reduction of positive mood after total sleep deprivation positively correlated with the reduction of fearful display avoidance. Importantly, this correlation was not mediated by a sleep-related reduction in sustained attention.

Conclusions

All together, these findings support the underestimated role of positive mood-state alterations caused by total sleep loss on approach/avoidance decisions when facing ambiguous socio-emotional displays, such as fear.
Shared philanthropy: how to boost effectiveness in the Swiss foundation sector
Authors: Studen Goran
Published: July 2021

While everyone seems to be talking about the “shared economy,” the non-profit sector continues to struggle with the very concept of cooperation. Yet it is clear that Switzerland does not have too few foundations, but too few efficiently interconnected stakeholders. What can be done to make best use of the resources available and to better connect the philanthropic community?
Sex differences in cardiopulmonary effects of acute bromine exposure
Authors: Masjoan Juncos Juan Xavier , Shakil Shazia , Ahmad Aamir , Mariappan Nithya , Zafar Iram , Bradley Wayne E , Dell’Italia Louis J , Ahmad Aftab , Ahmad Shama
Published: July 2021

Accidental occupational bromine (Br>2>) exposures are common, leading to significant morbidity and mortality; however, the specific effects of Br>2> inhalation in female victims are unclear. Our studies demonstrated that acute high-concentration Br>2> inhalation is fatal, and cardiac injury and dysfunction play an important role in Br>2> toxicity in males. In this study, we exposed female Sprague Dawley rats, age-matched to those males from previously studied, to 600 ppm Br>2> for 45 min and assessed their survival, cardiopulmonary injury and cardiac function after exposure. Br>2> exposure caused serious mortality in female rats (59%) 48 h after exposure. Rats had severe clinical distress, reduced heart rates and oxygen saturation after Br>2> inhalation as was previously reported with male animals. There was significant lung injury and edema when measured 24 h after exposure. Cardiac injury biomarkers were also significantly elevated 24 h after Br>2> inhalation. Echocardiography and hemodynamic studies were also performed and revealed that the mean arterial pressure was not significantly elevated in females. Other functional cardiac parameters were also altered. Aside from the lack of elevation of blood pressure, all other changes observed in female animals were also present in male animals as reported in our previous study. These studies are important to understand the toxicity mechanisms to generate therapies and better-equip first responders to deal with these specific scenarios after bromine spill disasters.>
Novel Small Molecule Growth Inhibitors ofXanthomonasspp. Causing Bacterial Spot of Tomato
Authors: Srivastava Vishal , Deblais Loic , Kathayat Dipak , Rotondo Francesca , Helmy Yosra A. , Miller Sally A. , Rajashekara Gireesh
Published: July 2021

Bacterial spot (BS) of tomato, caused by Xanthomonas gardneri, X. perforans, X. vesicatoria, and X. euvesicatoria, is difficult to control because of the high prevalence of copper- and streptomycin-resistant strains and the lack of resistance cultivars and effective bactericides. The objective of this study was to identify novel growth inhibitors of BS-causing Xanthomonas (BS-X) species by using small molecules (SM; n = 4,182). Several SMs (X1, X2, X5, X9, X12, and X16) completely inhibited the growth of BS-X isolates (n = 68 X. gardneri, 55 X. perforans, 4 X. vesicatoria, and 32 X. euvesicatoria) at ≥12.5 µM by disrupting Xanthomonas cell integrity through weakening of the cell membrane and formation of pores. These SMs were also effective against biofilm-embedded, copper- and streptomycin-resistant Xanthomonas strains while having minimal impact on other plant pathogenic (n = 20) and beneficial bacteria (n = 12). Furthermore, these SMs displayed equivalent antimicrobial activity against BS-X in seeds and X. gardneri in seedlings compared with conventional control methods (copper sulfate and streptomycin) at similar concentrations while having no detectable toxicity to tomato tissues. SMs X2, X5, and X12 reduced X. gardneri, X. perforans, X. vesicatoria, and X. euvesicatoria populations in artificially infested seeds ≤3.4-log CFU/seed 1 day postinfection (dpi) compared with the infested untreated control (P ≤ 0.05). SMs X1, X2, X5, and X12 reduced disease severity ≤72% and engineered bioluminescent X. gardneri populations ≤3.0-log CFU/plant in infected seedlings at 7 dpi compared with the infected untreated control (P ≤ 0.05). Additional studies are needed to increase the applicability of these SMs for BS management in tomato production.
6: Biomimetic Microtissue Keloid Scar System Using Keloid-derived Fibroblasts and Macrophages
Authors: Tan Yu , Oles Norah , Cooney Damon , Andres Garza Luis , Coon Devin
Published: July 2021

Purpose: Keloid is a disease that affects millions of patients and has relatively few effective treatment options. Unfortunately, traditional 2D monolayer culture of keloid derived fibroblasts show little resemblance to the pathological process in vivo. Additionally, keloid is notably a pathology largely specific to humans, without good in vivo models available. To fill this gap, we have developed a 3D in vitro microtissue keloid scar model with human keloid derived fibroblasts and peripheral blood derived macrophages.

Methods: Under IRB approval, keloid tissue was from patients and used to develop a human keloid derived fibroblast line. Keloid spheroids were fabricated from these keloid derived fibroblasts and human peripheral blood derived macrophages. Commercial human skin-derived fibroblast and 2D monolayers were used as controls. Quantitative PCR with fibrosis genes (collagen-1, aSMA, TNF, IL1β, IL6 and TGFβ) and immunofluorescent staining with (collagen-1, aSMA, CD68 and pSTAT3 were performed to validate the keloid spheroids as an effective keloid model in vitro. In addition, we performed qPCR fibrosis microarray for fibrosis-specific gene expression. Lastly, the Affymetrix PrimeView array was used to evaluate genome-wide comprehensive gene expression to assess whether the keloid spheroid mimicking behavior of keloid tissue regarding gene expression level.

Results: Spheroids had significantly higher expression levels of all fibrosis related genes compared to the 2D monolayer control. Among the spheroid groups, keloid spheroids had much higher gene expression levels of collagen-1 and aSMA, which was confirmed by the immunofluorescent staining with the same correspondence proteins. Interestingly, keloid spheroids showed lower gene expression levels of common fibrosis related cytokines (TNF, IL1β, IL6 and TGFβ). However, IF of pSTAT3 was upregulated in keloid spheroid, which is consistent with previous literature of keloid research. Lastly, qPCR fibrosis array and human comprehensive gene expression assay validated the result of qPCR and indicated that macrophages in the keloid spheroids showed signs of polarization in both M1 and M2 directions.

Conclusions: We have developed a keloid mimicking spheroid microtissue as a more physiologically relevant in vitro keloid model for drug development and research exploring gene and protein expression pathways. This platform recapitulates important features of keloid behavior not seen in 2D culture. Future work will include screening of keloid spheroid responses to potential therapeutic treatments.
QS3: CRISPR/Cas9 Editing of Autologous Dendritic Cells to Enhance Angiogenesis and Wound Healing
Authors: Henn Dominic , Zhao Dehua , Bonham Clark A. , Chen Kellen , Greco Autumn H. , Padmanabhan Jagannath , Trotsyuk Artem A. , Barrera Janos A. , Januszyk Michael , Stanley Qi Lei , Gurtner Geoffrey C.
Published: July 2021

Purpose: Dendritic cells (DCs) are a heterogeneous cell population which critically regulates the adaptive immune response. Depending on their activation status, DCs can also promote peripheral immune tolerance, thus limiting the activation of the immune system and tissue damage. The N-myc downregulated gene 2 (Ndrg2) is highly expressed in DCs and limits the secretion of vascular endothelial growth factor (VEGF), which is critical for wound healing. Cell based therapy approaches using DCs have been approved by the FDA and clinical trials using DC immunotherapy are being performed against a variety of cancer types. However, the role of DC therapy for wound healing has not yet been investigated.

Methods: Hematopoietic progenitor cells were isolated from the bone marrow of mice and differentiated into DCs over a 7-day in vitro culture period. Pharmacologic down-regulation of Ndrg2 was performed by treatment of cultures with 1,25-dihydroxyvitamin D3 (VD3) and the angiogenic potential of the treated cells was evaluated by endothelial cell (EC) tube formation assays. Cytokine secretion of DCs was measured in the conditioned media using Luminex multiplex assays. To permanently knock out Ndrg2 in DCs, a CRISPR/Cas9 gene editing approach was developed, using Cas9/sgRNA-ribonucleoproteins and electroporation. The determine the impact of genetically edited DCs on wound healing, splinted excisional wounds in C57BL6/J (wild-type) mice were treated weekly with pullulan-collagen hydrogels seeded with Ndrg2-knockout (KO) DCs, control DCs which had undergone electroporation only, or blank hydrogels. The transcriptomic impact of Ndrg2 downregulation on DC fate was evaluated by microfluidic single-cell RNA sequencing (scRNA seq) of Ndrg2-KO DCs, VD3-treated DCs and control DCs.

Results: Ndrg2 down-regulation lead to a significantly stronger EC tube formation in co-cultures with VD3-treated DCs, and strongly enhanced VEGF secretion compared to untreated DCs in vitro. A CRISPR/Cas9 editing pipeline was developed for KO of Ndrg2 in DCs with a transfection rate and editing efficiency of > 90% shown by Sanger Sequencing. Excisional wounds treated with Ndrg2-KO DCs demonstrated significantly accelerated healing compared to control DCs and blank hydrogels. scRNA seq revealed that Ndrg2 downregulation strongly induced Vegfa expression and anti-oxidant transcriptomic signatures.

Conclusion: Our data indicate that KO of Ndrg2 in DCs strongly enhances their secretion of VEGF, thus promoting angiogenesis and accelerating wound healing. Given the ready availability of DCs from the human blood through established leukapheresis protocols and easy multiplication in vitro, CRISPR/Cas9 editing of DCs is a promising new approach to induce wound healing and soft-tissue regeneration.
1: Eye Tracking Analysis as a Means of Evaluating Aesthetic Result Following Toe to Thumb Transfers: A Pilot Study
Authors: Boonipat Thanapoom , Elgendy Tarek , Hebel Nathan SD , Moran Steven
Published: July 2021

Purpose: Exceptional functional results can be obtained with toe to thumb transfers; however objective measures to evaluate the aesthetic outcome of a toe to thumb transfers remains elusive. Aesthetic evaluation of a reconstruction when performed by external raters or the patient, may be influenced by expert knowledge, emotional antecedent, or ethnic or regional bias. In this study, we were interested in determining the observers’ instantaneous, reflexive responses to the toe to thumb transfer as determined by eye-tracking analysis.

Methods: 13 patients with unilateral great toe to thumb transfers were photographed using a standardized technique. None had undergone secondary procedures that changed the appearance of the transferred toe. Both hands were photographed side by side in each image. A dorsal and palmar image was taken, producing 26 photos in total. 40 observers (Average age 41.39, 14-65 yo, 18 males, 22 females), blinded to the procedure, were asked to evaluate each image for symmetry between the hands. An infrared eye-tracking camera continuously recorded their eye movements. Participants were allowed to evaluate each image for 6 seconds. Data was evaluated to determine the percent of time that was devoted to evaluating each portion of the photograph. The percent time spent in each of the lookzones was recorded.

Results: i) Observers spent an average of 17.7% of their time evaluating the reconstructed thumb compared to the entire bilateral hand. This was on average 63% more time looking at the reconstructed thumb compared to the normal control thumb. (p value<0.01) ii) Observers spent 43.9% of the time looking at the reconstructed thumb compared to the entire hand of the same side. They spent 31.6% of the time looking at the normal control thumb compared to the entire hand of the same side (p value<0.01, mean 0.36 seconds on the abnormal thumb (SD 0.439)), vs. mean 0.22 seconds on normal control thumb (SD 0.305); mean 0.82 seconds on abnormal hand (SD 0.45), mean 0.69 seconds on normal contralateral hand (SD 0.423); mean 0.74 on entirely normal bilateral hand (SD 0.41)). iii) Areas of significant attention as visualized by heatmaps representing where observers focus their attention include abnormal nailbed and scar tissue at the junction between the toe and native hand skin.

Conclusion: The technique described above may represent a novel and objective technique for quantifying observers’ gaze with respect to toe to thumb reconstructions and the un-altered contralateral thumb. It could be applied to other areas of hand reconstruction to help determine aesthetic outcomes. The present pilot suggests that symmetric nail size may be an area of importance for creating the sense of aesthetic success. Incorporation of this data into surgical counseling may assist the patient and medical team focus on surgical-decision making priorities.
QS3: Practice Trends in Plastic Hand Surgery: An Evaluation of Cases in the ASPS TOPs Database
Authors: King Thomas , Williams Eric , Samant Sonja , Chopan Mustafa , Chim Harvey , Mast Bruce , Satteson Ellen
Published: July 2021

Purpose: Despite making up 20-25% of hand surgeons with subspecialty certification in the field, little data exists characterizing the clinical practice of hand surgery among plastic surgeons. This study sought to evaluate hand surgery cases in the national Tracking Operations and Outcomes for Plastic Surgeons (TOPS) database.

Methods: All hand procedures logged in the TOPS database between 2002 and 2016 were identified by CPT code and/or “upper extremity” anatomic classification. Trends in the total number and types of procedures, facility type, admission type, modes and providers of anesthesia, and patient demographics were reviewed.

Results: A total of 182,137 hand procedures performed on 82,811 patients were logged during the 15-year period reviewed. Sixty-eight percent of procedures were classified as involving soft tissue only, and 22.7% involved only bone and/or joint. The most common procedure categories included: wound closure/coverage (15.8%), debridement/drainage (15.3%), nerve (13.2%), tendon (12.9%), and fracture/dislocation (12.9%). This category breakdown remained relatively stable over time. Evaluation of longitudinal trends identified an increase over time in procedures performed in the ambulatory and office-based settings and the use of local anesthetic, as well as a transition from the procedural surgeon providing anesthesia to the use of anesthesiologists and nurse anesthetists. The average patient ASA increased from 1.27 to 1.83.

Conculsions: Plastic surgeons play an important role in the field of hand surgery, performing a large breadth of procedure types, which has remained stable over time. The trends in facility type and anesthesia characteristics have, however, varied.
QS5: The Effect of Stem Cells and Local Tacrolimus on Neurite Extension
Authors: Saffari Sara , Saffari Tiam M. , Chan Katelyn , Borschel Gregory H. , Shin Alexander Y.
Published: July 2021

Purpose: Application of mesenchymal stem cells (MSCs) or tacrolimus (FK506), an FDA approved immunosuppressant, to nerve grafts has been a topic of interest to enhance peripheral nerve regeneration. The aim of this study was to investigate the combined effect of MSCs and local delivery of FK506 on nerve regeneration when applied to nerve autografts and decellularized nerve allografts.

Methods: A three-dimensional (3D) in vitro compartmented cell culture system, validated by Tajdaran et al (2019), consisted of rat neonatal dorsal root ganglion (DRG) adjacent to rat nerve autograft or decellularized allograft. This model was used to evaluate regenerating neurites from the DRG into the peripheral nerve scaffold. Nerve autografts and decellularized allografts were augmented with (i) dynamic undifferentiated MSC seeding, (ii) local application of FK506 (100 ng/mL) or (iii) both (N=9/group). Local application was ensured by isolating the central system (i.e. DRG side) from the peripheral system (i.e. nerve graft side), where treatment was applied. After 48-hours of incubation, DRG-nerve graft constructs were collected, fixed, sectioned and stained against neurofilament-160 to measure neurite extension. CD90 staining was used to confirm stem cell characterization.

Results: All grafts treated with MSCs confirmed CD90 expression. Compared to untreated autografts, neurite extension in autografts treated with FK506 and autografts treated with MSCs and FK506 combined were found superior (P<0.001 and P=0.0001, respectively), and comparable to autografts treated with MSCs (P=0.12). Compared to untreated allografts, allografts treated with FK506, and allografts treated with MSCs and FK506 were found superior (P<0.001 and P=0.0001, respectively), and allografts treated with MSCs were found comparable (P=0.09). All autograft groups were found superior compared to their respective allograft treatment group (P<0.05). Solely allografts receiving combined treatment were found superior to untreated autografts (P<0.05).

Conclusion: MSCs or FK506 treatment improved neurite outgrowth and when combined, this resulted in significant synergistic neurite extension in both autografts and allografts in comparable patterns. Schematic overview of 3D compartmented cell culture system for isolated evaluation of treatment with MSCs and local FK506 in vitro.
A 3.5 mm autograft or allograft with or without undifferentiated MSC seeding is attached to a DRG. DRG-nerve graft constructs are placed through a silicone isolator in the middle of a 24-wells plate to isolate the DRG from the nerve graft. FK506 containing media was added to the nerve graft side.
QS7: Physiologic Signaling of the Muscle Cuff Regenerative Peripheral Nerve Interface (MC-RPNI) During Volitional Behavior
Authors: Svientek Shelby R. , Bratley Jarred , Dehdashtian Amir , Kubiak Carrie , Cederna Paul , Kemp Stephen
Published: July 2021

Purpose: Exoskeletons have become a promising device to restore extremity function to those with limb weakness. However, these devices have not become widely adopted due to the inadequacy of current nerve interfacing methods. The Muscle Cuff Regenerative Peripheral Nerve Interface (MC-RPNI) was developed as a potential solution to this problem. Consisting of a segment of autologous free muscle secured around an intact nerve, the MC-RPNI is able to regenerate and reinnervate, amplifying its contained nerve’s signals through generation of EMG signals. These amplified, high-fidelity signals can then be used to intuitively and accurately control exoskeletons. The purpose of this study was to characterize MC-RPNI physiologic signaling during volitional behavior and determine long-term effects on the associated nerve.

Methods: Eighteen rats were randomly assigned to one of three groups: (1) sham surgery/control; (2) nerve transection; and (3) MC-RPNI. MC-RPNIs were surgically fabricated by wrapping isogenic donor muscle graft circumferentially around the common peroneal (CP) nerve. At six months, CP nerve cuff electrodes were implanted in Groups 1 and 2,and patch electrodes were placed on all MC-RPNIs. Gait analysis and electrophysiological evaluations were performed the following day. Rats were trained to walk on a treadmill, and electrode recordings were obtained and correlated with gait videocapture. All rats had their proximal CP nerve stimulated, with efferent signals obtained at (1) downstream nerve (CSNAP), (2) MC-RPNI (CMAP), and (3) downstream-innervated extensor digitorum longus (EDL) muscle (CMAP). EDL muscle force testing was also performed following stimulation of the CP nerve.

Results: All MC-RPNIs remained viable and demonstrated appropriate regeneration, revascularization, and reinnervation on histology. The MC-RPNI was found to generate large-amplitude CMAPs (2.77+/-0.926mV), amplifying its associated nerve’s signal (50.5+/-8.18µV) over 50-fold on average. The MC-RPNI was not found to affect muscle function when evaluating downstream-innervated EDL CMAPs (control: 13.4+/-2.33mV vs MC-RPNI: 14.1+/-1.44mV) or maximal twitch force (control: 562+/-70.8mN vs MC-RPNI: 653+/-34.6mN). On gait analysis, recordings from the MC-RPNI correlated with the toe-off phase of gait; for the control groups, nerve signaling could not be differentiated from background noise. When comparing MC-RPNI to control animal gait, no significant differences were noted on qualitative or joint-angle analysis.

Conclusion: The MC-RPNI has the ability to chronically amplify physiologic nerve signals from intact peripheral nerves by several magnitudes while avoiding functional impairment of downstream-innervated muscle. This amplification has the capability to facilitate high accuracy detection of motor intent in order to intuitively and reliably control advanced exoskeleton devices.
QS10: Clinical Practice Patterns and Evidence-based Medicine in Dupuytren’s Contracture: A Twelve-year Review of Continuous Certification Tracer Data From The American Board of Plastic Surgery
Authors: Yuksel Selcen S. , Shah Nikhil B. , Sasson Daniel C. , Kearney Aaron M. , Gosain Arun K.
Published: July 2021

Purpose: Since 2008, The American Board of Plastic Surgery (ABPS) has collected clinical practice data on Dupuytren’s contracture repair as part of their Continuous Certification (CC) process. Submitted twice every ten years by each plastic surgeon, this collection can help describe clinical trends in Dupuyren’s contracture repair as they relate to Evidence-Based Medicine (EBM) articles published in this timeframe.

Methods: Cumulative tracer data for Dupuytren’s contracture repair from February, 2008 through December, 2014 were reviewed and compared to data from January, 2015 through March, 2020 with the goal of identifying national practice trends. These trends were then evaluated alongside EBM reviews published in 2010, 2014 and 2017.

Results: As of March 2020, 230 cases of Dupuytren’s contracture were included in the tracer. The median age at time of surgery was 65 years (range, 38-91 years), and the average age of disease onset was 47 years. The most common surgical technique was limited fasciectomy, comprising 62% of cases. There were no postoperative adverse events reported in 77% of cases. The most common complications were loss of finger flexion (3%) and skin loss (2%). Topics addressed in EBM articles but not tracer data included adjuvant treatments and non-operative techniques such as tamoxifen administration. The use of minimally invasive procedures such as percutaneous cordotomy (0% vs. 13%) and collagenase injections (0% vs. 9%, p = .001) showed significant increases between the two time periods. More invasive procedures such as radical fasciectomy decreased in popularity (34% vs. 16%, p = .002). Use of Z-plasty also decreased between 2015 and 2020 (67% vs. 45%, p < .001). General anesthesia was the most commonly used form of anesthesia, being employed in 54% of tracer cases. There was an increase in the use of Bier block regional anesthesia (1% vs. 9%, p = 0.029) as well as in the use of epinephrine for hemostasis (0 vs. 8%, p = 0.006). Significant changes were also noted in post-operative management, including a decrease in the employment of formal postoperative hand therapy. This is consistent with evidence showing that it has no significant clinical benefit.

Conclusion: The tracer data collected on Dupuytren’s contracture repair over a twelve-year period allow us to describe national trends in presentation and surgical techniques, and can help plastic surgeons evaluate their surgical practice in the context of these trends and EBM.
QS4: A Quantitative Analysis Of The Upper Airway Volume In Patients With Attention Deficit Hyperactivity Disorder: A Cone-Beam Computed Tomography Study
Authors: ElNaghy Rahma , Hasanin Majd , Olson Douglas , Kumar Anand , Al-Jewair Thikriat , Alqawasmi Riyad
Published: July 2021

Purpose: Attention deficit hyperactivity disorder (ADHD) is a developmental disorder affecting the quality of life. The etiology of ADHD is unclear, yet it has been believed to be multifactorial. he aim of this Cone-beam computed tomography (CBCT) study was to assess the upper airway morphology in adolescents with ADHD compared to controls.

Methods: A total of 454 patients who had CBCT taken as part of their initial orthodontic records were reviewed for eligibility. 87 subjects were included in the study. CBCTs volumes were utilized for three-dimensional evaluation of volumetric, minimum cross-section area and linear measurements of the upper airway in different planes. Two sample T-test and Man-Whitney U test were used to calculate and compare the mean values of the airway measurements between ADHD and control groups.

Results: There were significant differences in airway widths at planes A (p =0.002), C (p =0.042) and D (p <0.001), and in airway area at plane D (lower hypopharynx) (p <0.001), with the ADHD group showing narrower widths and area compared to controls. The mean overall airway volume in the ADHA group was smaller than in the control group but the difference was not significant.

Conclusion: ADHD-affected adolescents have narrower upper airway dimensions compared to controls. Further investigations with larger samples are warranted to further elucidate the relationship between sleep-disordered breathing and ADHD.
QS9: Decellularization Of Vascularized Composite Allografts In The Rat
Authors: LUPON ELISE , Acun Aylin , Goutard Marion , Lellouch Alexandre G. , Oganesyan Ruben , Andrews Alec R. , Lantieri Laurent , Randolph Mark A. , Cetrulo Curtis L. , Uygun Basak
Published: July 2021

Purpose: The decellularization of Vascularized Composite Allotransplantation (VCA) represents a first step in circumventing the need for immunosuppression by depleting donor cells from VCAs. Here we present a model of decellularization of VCAs in rats.

Methods: Rat hind limbs based upon the common femoral artery were harvested and perfused through the vascular pedicle at 1ml/min through with 1% sodium dodecyl sulfate (SDS) (group 1) or 0.2% SDS (group 2) or were immersed in SDS 1% (group 3), followed by perfusion (group 1 and 2) or immersion (group 3) in 1% Triton X-100. The degree of decellularization was assessed quantitatively by determining DNA content and qualitatively by histology in all groups at the same locations. The group yielding best decellularization outcome was selected for further assessment for the preservation of ECM content and vasculature and was transplanted orthotopically to assess the ability to reperfuse these decellularized limbs in vivo. RESULTS - Gross examination and DNA quantification of less than 50 ng/mg tissue demonstrated successful decellularization only in group 2 while preserving tissue matrix architecture, including vessels. The arterial network was found to be perfusable and intact during in vivo orthotopic transplantation of the decellularized limb. No outflow was observed, however, after 115 minutes of arterial reperfusion.

Conclusions: We describe a successful decellularization protocol for rat hindlimb VCAs by perfusion ex-vivo of 1% SDS. During its in vivo transplantation, decellularization alone allows for a perfusable arterial network and with further optimization, we aim to achieve venous perfusion as well.
6: ICG-Fluorescence Lymphography After Immediate Lymphatic Reconstruction
Authors: Buchan Graham , Cakmakoglu Cagri , Schwarz Graham S.
Published: July 2021

Purpose: Immediate lymphatic reconstruction (ILR), performed at the time of axillary lymph node dissection (ALND), has demonstrated promising reductions in the development of breast-cancer associated lymphedema. However, questions remain regarding the effects of adjuvant therapies on the continued patency of the lymphaticovenous anastomosis. The aim of our study is to assess lymphographic outcomes, including ICG pattern and LVB patency, following axillary ILR in patients at high risk for breast cancer associated lymphedema..

Methods: Baseline ICG studies of 15 patients who underwent ILR were compared to studies obtained during secondary stage breast reconstructive procedures to assess for any changes in lymphatic morphology and transit in the at-risk arm.

Results: All 15 patients in this study demonstrated linear lymphatic flow in intra-operative lymphography studies performed during the initial lymphatic reconstruction. An average of 2.4 (range 1-4) LVBs were performed per patient. Only 1 patient in this study group had preservation of in-continuity lymphatics at time of ALND. Followup lymphographic studies showed clear, linear lymphatic transit in 12/15 patients. Of these 12 patients, an average of 2.5 LVBs were performed, 10 received chemotherapy (7 neoadjuvant, 3 adjuvant), and all 12 received post mastectomy radiation (PMRT). Dermal backflow patterns of varying severity were recorded in 3/15 patients, two of whom showed signs of lymphedema prior to their followup study and the last went on to develop clinically detectable lymphedema. Of these 3 patients, an average of 2 LVBs were performed, all received chemotherapy (2 neoadjuvant, 1 adjuvant) and 2/3 underwent PMRT. Of the 12 patients that remain lymphedema-free, 7 post-operative studies demonstrated clear visualization of linear ICG flow from the lymphatics of the arm into the axilla without evidence of lymphatic collateralization. An average of 3 LVBs were performed in this group and 100% of these patients received adjuvant radiation.

Conclusion: We have demonstrated that ICG lymphography can be implemented as a post-operative tool to assess lymphatic function in patients who have undergone ILR in the axilla. Post-operative imaging studies in the majority of patients demonstrated linear ICG flow with evidence of lymphatic contractility and velocity similar to baseline studies obtained at the time of lymphadenectomy and ILR. Additionally, ICG flow patterns through the axilla in post-operative imaging studies provided visual evidence supporting sustained LVB patency despite inflammation and tissue fibrosis associated with axillary irradiation.
QS6: Venous Thromboembolism After Deep Inferior Epigastric Perforator Flap Breast Reconstruction: Review Of Outcomes After A Postoperative Prophylaxis Protocol
Authors: Tuaño Krystle R. , Yang Jerry H. , Le Elliot , Colakoglu Salih , Cohen Justin B. , Kaoutzanis Christodoulos , Chong Tae W. , Mathes David W.
Published: July 2021

Purpose: Although breast cancer patients undergoing microsurgical breast reconstruction represent a relatively high risk group for venous thromboembolism events, there has been no standardized postoperative prophylactic regimen described to address this problem. An ideal dose of effective antithrombotic therapy that reduces the risk of VTE, while minimizing the cumulative risk of bleeding with on board antiplatelet therapy, is yet to be established. This study is a single-institution review on the rates of VTE following implementation of a postoperative VTE prophylaxis regimen.

Methods: A new chemoprophylaxis protocol was introduced starting March 2019 that involved two-weeks of treatment with enoxaparin, regardless of patient risk factors. A retrospective chart review was conducted on all patients who underwent DIEP flap breast reconstruction at our institution between January 2014 and March 2020. Patients were grouped based on whether they enrolled in new VTE protocol in the postoperative period or not. Patient demographics, prophylaxis type and outcomes data were recorded, retrospectively. The primary outcome measure was postoperative VTE incidence. Categorical variables were analyzed with a Chi-Square Test and continuous variables by Student’s t-test.

Results: A total of 265 patients underwent DIEP flap breast reconstruction between January 2014 and March 2020, of which, 63 (23.8%) patients were discharged with VTE prophylaxis and 202 (76%) patients were discharged without. Patient characteristics were found to be similar between patients before and after the protocol. A total of 9 (3.4%) VTE events were identified, all of which were in the group prior to the protocol.

Conclusion: This retrospective study demonstrates successful implementation of a two-week chemoprophylaxis regimen for patients undergoing DIEP flap breast reconstruction. Additional analysis of patient characteristics with VTE at our institution can lead to establishment of a local protocol, with individually tailored prophylaxis regimens. This can further be improved by prospective risk assessment and inclusion of Caprini Score and patient anti-Xa levels in our institution’s DIEP flap database.
QS10: Morphological Changes Of Skin Related To Acellular Dermal Matrix Incorporation In Tissue Expansion
Authors: Applebaum Sarah A. , Ledwon Joanna K. , Chang Alec B. , Han Tianhong , Buganza Tepole Adrian , Gosain Arun K.
Published: July 2021

Purpose: Acellular dermal matrix (ADM) is used to create an inferolateral sling nearly three-quarters of the time in breast reconstruction and has proven a valuable alternative to total submuscular coverage of the implant. Previous work has demonstrated decreased inflammation and fibrosis of the pocket lining the ADM sling; however there has been minimal investigation into the role of ADM in skin growth and regeneration. The present study evaluates morphologic and molecular changes mediated by use of ADM in tissue expansion.

Methods: Two tissue expanders, one wrapped in ADM, were placed subcutaneously on the back of Yucatan minipigs. All expanders were inflated with two weekly fills of 60cc of normal saline and skin biopsies were harvested after two weeks of expansion from each condition: control, tissue expansion (TE), and tissue expansion with ADM (TE+ADM). Three biopsies per condition were embedded in paraffin or OCT medium and stained with Russell Movat Pentachrome and Immunofluorescence of CD31, respectively. Collagen in the papillary dermis of pentachrome-stained images were analyzed using an ImageJ plug-in, Fibril Tool, that applies circular statistics to estimate average fibril orientation as the direction angle from -90 to 90 with respect to the x-axis. One-way ANOVA evaluated seventy-two measurements per condition and post-hoc analysis with Tukey’s HSD test identified significant comparisons between the groups. Number of fluorescent cells expressing CD31 (a marker of endothelial cells) were counted on 12 photographs per condition. P-values ≤ .05 were considered significant. Total deformation was calculated using a computational model and isogeometric analysis.

Results: The mean fibril orientation of TE and TE+ADM underwent -85% change (P < .001) and -15% change (P = .65), respectively, compared to control. Three times more CD31+ cells were observed in TE+ADM compared to control (P < .001), but no significant changes were detected in TE alone. Histogram of total deformation revealed more even distribution of forces in TE+ADM compared to TE and control.

Conclusions: The use of ADM in a porcine tissue expansion model appears to mitigate disarray of the collagen network in adjacent tissue, thereby creating a more extensive, yet even, distribution of stretched skin. This observation, combined with the finding of increased angiogenesis, suggests it is the incorporation of ADM that confers these protective benefits. Future studies will evaluate whether the protective effects of ADM can serve to improve TE in compromised tissue beds, as seen in patients undergoing TE concurrent with perioperative radiation therapy.