Parameters and determinants of responses to selection in antibody libraries.

The sequences of antibodies from a given repertoire are highly diverse at few sites located on the surface of a genome-encoded larger scaffold. The scaffold is often considered to play a lesser role than highly diverse, non-genome-encoded sites in controlling binding affinity and specificity. To gauge the impact of the scaffold, we carried out quantitative phage display experiments where we compare the response to selection for binding to four different targets of three different antibody libraries based on distinct scaffolds but harboring the same diversity at randomized sites. We first show that the response to selection of an antibody library may be captured by two measurable parameters. Second, we provide evidence that one of these parameters is determined by the degree of affinity maturation of the scaffold, affinity maturation being the process by which antibodies accumulate somatic mutations to evolve towards higher affinities during the natural immune response. In all cases, we find that libraries of antibodies built around maturated scaffolds have a lower response to selection to other arbitrary targets than libraries built around germline-based scaffolds. We thus propose that germline-encoded scaffolds have a higher selective potential than maturated ones as a consequence of a selection for this potential over the long-term evolution of germline antibody genes. Our results are a first step towards quantifying the evolutionary potential of biomolecules.

Receptor-independent modulation of cAMP-dependent protein kinase and protein phosphatase signaling in cardiac myocytes by oxidizing agents.

The contraction and relaxation of the heart is controlled by stimulation of the ß1-adrenoreceptor (AR) signaling cascade, which leads to activation of cAMP-dependent protein kinase (PKA) and subsequent cardiac protein phosphorylation. Phosphorylation is counteracted by the main cardiac protein phosphatases, PP2A and PP1. Both kinase and phosphatases are sensitive to intramolecular disulfide formation in their catalytic subunits that inhibits their activity. Additionally, intermolecular disulfide formation between PKA type I regulatory subunits (PKA-RI) has been described to enhance PKA's affinity for protein kinase A anchoring proteins, which alters its subcellular distribution. Nitroxyl donors have been shown to affect contractility and relaxation, but the mechanistic basis for this effect is unclear. The present study investigates the impact of several nitroxyl donors and the thiol-oxidizing agent diamide on cardiac myocyte protein phosphorylation and oxidation. Although all tested compounds equally induced intermolecular disulfide formation in PKA-RI, only 1-nitrosocyclohexalycetate (NCA) and diamide induced reproducible protein phosphorylation. Phosphorylation occurred independently of ß1-AR activation, but was abolished after pharmacological PKA inhibition and thus potentially attributable to increased PKA activity. NCA treatment of cardiac myocytes induced translocation of PKA and phosphatases to the myofilament compartment as shown by fractionation, immunofluorescence, and proximity ligation assays. Assessment of kinase and phosphatase activity within the myofilament fraction of cardiac myocytes after exposure to NCA revealed activation of PKA and inhibition of phosphatase activity thus explaining the increase in phosphorylation. The data suggest that the NCA-mediated effect on cardiac myocyte protein phosphorylation orchestrates alterations in the kinase/phosphatase balance.

Instillation negative pressure wound therapy: An effective approach for hardware salvage.

Wound infection involving hardware can be notoriously difficult to treat, often requiring the removal of the infected implant. The goal of this study was to determine the utility of instillation negative pressure wound therapy to help eradicate infection and allow for definitive wound closure in patients without removing the infected hardware. A retrospective review was performed on the outcomes of 28 patients who presented with open wounds with exposed or infected hardware and who were treated with a combination of surgical debridement and negative pressure wound therapy with instillation (NPWTi). Eleven patients were treated for infected spinal hardware, 12 for extremity, and 5 for sternal hardware. Twenty-five of 28 (89%) patients had successful retention or replacement of hardware, with clearance of infection and healed wounds. Original hardware was maintained in 17 of 28 (61%) patients. In 11 patients, original hardware was removed, with subsequent replacement in eight of those patients after a clean wound was achieved. Average time to definitive closure was 12.6 days. Average follow-up was 135 days. This series supports NPWTi as an effective adjunct therapy to help expeditiously eradicate hardware infection, allowing for hardware retention.

Comparison of Polypropylene and Bioabsorbable Mesh for Abdominal Wall Reinforcement following Microsurgical Breast Reconstruction.

BACKGROUND: Abdominal wall morbidity following microvascular breast reconstruction continues to be an area of interest due to both functional and aesthetic concerns. Donor-site closure technique has been shown to affect bulge and hernia rates and ranges from primary closure to various uses of mesh. Few studies to date have compared types of mesh. The present study compares BARD polypropylene to bioabsorbable GORE Bio-A (polyglycolic acid/trimethylene carbonate) mesh used as a fascial underlay with primary fascial closure. METHODS: A retrospective review of all consecutive deep inferior epigastric artery-based microvascular breast reconstructions, including perforator and muscle-sparing flaps, performed between September 2014 and February 2017 was performed. All patients underwent primary fascial closure with mesh underlay. Risk factors for the formation of an abdominal bulge or hernia were identified by multivariate logistic regression. RESULTS: Eighty-seven patients, with 123 abdominal donor sites, were included. Heavy-weight polypropylene mesh was used for 58 donor sites, while polyglycolic acid/trimethylene carbonate mesh was used in 65 donor sites. The overall incidence of bulge or hernia was 11.4%. The bioabsorbable cohort experienced significantly more bulges/hernias than the polypropylene mesh cohort (20% vs. 1.7% by donor site). Time to diagnosis of bulge was longer for the bioabsorbable group (219 ± 107 vs. 69 days). Flap type and perforator row were not associated with bulge/hernia. The polyglycolic acid/trimethylene carbonate mesh was associated with a 13.3-fold risk of bulge/hernia (p = 0.016). CONCLUSION: Polyglycolic acid/trimethylene carbonate mesh is not appropriate for anterior rectus fascia reinforcement following abdominal tissue transfer.

Combined Autologous and Prosthetic Breast Reconstruction: Defining the Upper Limits of Safe Expansion in Obesity.

BACKGROUND: Combined latissimus dorsi and prosthetic reconstruction is a useful reconstructive option in patients with a history of breast radiation who are not good candidates for abdominally based autologous reconstruction. One difficulty, particularly in obese patients, is that the thickness of the flap can impair port localization, increasing the risk of inadvertent puncture during expansion. The authors sought to investigate the upper limits of tissue thickness at which tissue expansion can be reliably performed. METHODS: A cadaveric study was designed in which 2 blinded observers attempted to localize the port of a Mentor CPX-4 expander under tissue 1, 2, 3, 4, 5, and 6 cm thick. Thirty attempts were made per tissue thickness. RESULTS: For tissue thicknesses of 1 to 4 cm, the success rate was 100% (k = 1). At 5 cm, the success rate decreased to 86.6% (k = 1); at 6 cm, 43.3% (k = 0.85). Point biserial correlation revealed a negative correlation between tissue thickness and accuracy at a thicknesses of greater than 4 cm (r = -0.55, P < 0.00001). Converting tissue thickness to a dichotomous variable based on the results (thickness, <4 and >4 cm), Fisher exact test revealed a statistically significant difference between these 2 populations (P < 0.00001). CONCLUSIONS: In obese patients with a skin pinch of greater than 8 cm or a flap thickness of greater than 4 cm, steps should be taken to minimize the risk of inadvertent puncture of the expander during postoperative expansion. This can include foregoing tissue expander placement in favor of an implant, port localization with ultrasound guidance, or the use of remote port expanders. These findings are relevant not only in breast reconstruction with latissimus flaps and implants but also in any setting where autologous and prosthetic reconstructions are combined.

Attitudes and beliefs regarding direct-to-consumer advertising of pharmaceutical drugs: an exploratory comparison of physicians and pharmaceutical sales representatives.

Even with many changes in regulation in recent years, direct-to-consumer advertising (DTCA) of pharmaceutical drugs remains a complicated and contentious issue. Many in our society argue for increased legislation of DTCA while others believe that DTCA serves a useful purpose and should not be overregulated. This study was designed to compare attitudes and beliefs regarding DTCA held by two key stakeholder groups, physicians and pharmaceutical sales representatives. A questionnaire was created, pretested, and administered to 30 physicians and 30 pharmaceutical sales representatives to investigate these issues. Significant differences between these two groups were found and implications for DTCA are discussed.

Anticipated Effects of Higher-valency Pneumococcal Conjugate Vaccines on Colonization and Acute Otitis Media.

BACKGROUND: Bacterial etiologies of acute otitis media (AOM) have shifted from the introduction of pneumococcal conjugate vaccines (PCVs), antibiotic selection and competition among species. We characterized Streptococcus pneumoniae ( Spn ), Haemophilus influenzae ( Hflu ) and Moraxella catarrhalis ( Mcat ) in the nasopharynx during well-child healthy visits and at the onset of AOM, and in middle ear fluid (MEF) of children with AOM to assess anticipated effects of higher-valency PCVs (PCV15 and PCV20). METHODS: From September 2021 to September 2023, we conducted a prospective longitudinal cohort study of PCV13 immunized children 6-36 months old. MEF was collected via tympanocentesis. Serotyping and antibiotic susceptibility testing were performed on Spn , Hflu and Mcat isolates. RESULTS: We obtained 825 nasopharyngeal and 216 MEF samples from 301 children. The order of frequency of nasopharyngeal colonization was Mcat , Spn and Hflu ; Hflu was the predominant otopathogen in MEF. Among Spn isolates, non-PCV15, non-PCV20 serotypes predominated in the nasopharynx and in MEF; the most frequent serotype was 35B. Among MEF samples, 30% of Spn isolates were amoxicillin nonsusceptible; 23% of Hflu isolates and 100% of Mcat isolates were ß-lactamase-producing. CONCLUSION: The majority of Spn isolates among young children were non-PCV15, non-PCV20 serotypes, especially serotype 35B; therefore, the impact of higher-valency PCVs in reducing pneumococcal colonization or AOM is expected to be limited. Hflu continues to be the most frequent AOM pathogen. Antibiotic susceptibility data suggest a high dose of amoxicillin/clavulanate or alternative drugs that are effective against contemporary mix of otopathogens could be considered for optimal empiric selection to provide the best efficacy.

Targeted Muscle Reinnervation at the Time of Amputation Decreases Recurrent Symptomatic Neuroma Formation.

BACKGROUND: Targeted muscle reinnervation (TMR) is an effective technique for the prevention and management of phantom limb pain (PLP) and residual limb pain (RLP) among amputees. The purpose of this study was to evaluate symptomatic neuroma recurrence and neuropathic pain outcomes between cohorts undergoing TMR at the time of amputation (ie, acute) versus TMR following symptomatic neuroma formation (ie, delayed). METHODS: A cross-sectional, retrospective chart review was conducted using patients undergoing TMR between 2015 and 2020. Symptomatic neuroma recurrence and surgical complications were collected. A subanalysis was conducted for patients who completed Patient-Reported Outcome Measurement Information System (PROMIS) pain intensity, interference, and behavior scales and an 11-point numeric rating scale (NRS) form. RESULTS: A total of 105 limbs from 103 patients were identified, with 73 acute TMR limbs and 32 delayed TMR limbs. Nineteen percent of the delayed TMR group had symptomatic neuromas recur in the distribution of original TMR compared with 1% of the acute TMR group ( P < 0.05). Pain surveys were completed at final follow-up by 85% of patients in the acute TMR group and 69% of patients in the delayed TMR group. Of this subanalysis, acute TMR patients reported significantly lower PLP PROMIS pain interference ( P < 0.05), RLP PROMIS pain intensity ( P < 0.05), and RLP PROMIS pain interference ( P < 0.05) scores in comparison to the delayed group. CONCLUSIONS: Patients who underwent acute TMR reported improved pain scores and a decreased rate of neuroma formation compared with TMR performed in a delayed fashion. These results highlight the promising role of TMR in the prevention of neuropathic pain and neuroma formation at the time of amputation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Very early life microbiome and metabolome correlates with primary vaccination variability in children.

IMPORTANCE: We show that simultaneous study of stool and nasopharyngeal microbiome reveals divergent timing and patterns of maturation, suggesting that local mucosal factors may influence microbiome composition in the gut and respiratory system. Antibiotic exposure in early life as occurs commonly, may have an adverse effect on vaccine responsiveness. Abundance of gut and/or nasopharyngeal bacteria with the machinery to produce lipopolysaccharide-a toll-like receptor 4 agonist-may positively affect future vaccine protection, potentially by acting as a natural adjuvant. The increased levels of serum phenylpyruvic acid in infants with lower vaccine-induced antibody levels suggest an increased abundance of hydrogen peroxide, leading to more oxidative stress in low vaccine-responding infants.

Longitudinal Durability of Patient-Reported Pain Outcomes after Targeted Muscle Reinnervation at the Time of Major Limb Amputation.

BACKGROUND: Phantom limb pain (PLP) and residual limb pain (RLP) are debilitating sequelae of major limb amputation. Targeted muscle reinnervation (TMR), when performed at the time of amputation, has been shown to be effective for management of this pain; however, its long-term effects and the longitudinal trend of patient-reported outcomes is unknown. The purpose of this study was to characterize the longitudinal patient-reported outcomes of pain and quality of life following TMR at the time of initial amputation. STUDY DESIGN: A prospective case series of patients undergoing major limb amputation with TMR performed at the time of amputation were followed from October 2015 to December 2020 with outcomes measured 3, 6, 12, and 18 months or longer after amputation and TMR. Outcomes included patient-reported severity of PLP and RLP as measured by the numeric rating scale (NRS). Secondary outcomes included the Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference and Pain Behavior Questionnaires. RESULTS: Eighty-one patients with 83 treated limbs were included in the study, and 23 patients completed surveys at 18 months or later, with an average follow-up time of 2.4 years. By 3 months after operation, all patient-reported outcomes for PLP and RLP were consistent with previously reported data that demonstrated superiority to non-TMR amputees. Mixed-model linear regression analysis showed that PLP NRS severity scores continued to improve over the study period (p = 0.022). The remaining outcomes for RLP severity and PROMIS quality-of-life measures demonstrated that these scores remained stable over the study period (p > 0.05). CONCLUSION: TMR is an effective surgical procedure that improves the chances of having reduced RLP and PLP when performed at the time of amputation, and our study demonstrates the long-term durability of its efficacy.

Evaluating hip disarticulation outcomes in a 51-patient series.

Background: Hip disarticulations are proximal lower extremity amputations with high postoperative complication and mortality rates. The purpose of the study was to evaluate hip disarticulation outcomes at our institution. Targeted Muscle Reinnervation (TMR) is an effective surgical technique shown to reduce pain in amputees. A secondary goal of the study was to evaluate the impact of implementing TMR on this patient population. Methods: A retrospective review was performed for patients who underwent hip disarticulation with and without TMR between 2009 and 2020. Information on one-year mortality, thirty-day complication rates, operation times, surgical charges, and pain scores was collected. Results: Fifty-one patients underwent hip disarticulation, eight of which had TMR performed at the time of their hip disarticulation. The one-year mortality rate was 37% with 30-day infection, readmission, reoperation, and rates of 37%, 39%, and 27% respectively. The thirty-day major complication rate was 47% overall but not statistically significantly different between groups. There were no differences between groups with regard to 30-day readmission, reoperation, and infection rates. Conclusions: Our results represent one of the largest series of hip disarticulation outcomes. Performing TMR at the time of hip disarticulation did not negatively affect outcomes and may be a beneficial adjunct to improve pain. Further research is warranted.

COVID-19 Pandemic Impact on Respiratory Infectious Diseases in Primary Care Practice in Children.

Background: The coronavirus disease 2019 (COVID-19) pandemic led to day care and school closures and children staying home for several months. When they gradually returned, aggressive regulations were implemented in New York State to reduce viral transmission. Method: An ongoing prospective study occurring in the Rochester, NY region, focused on early childhood respiratory infectious diseases, afforded an opportunity to assess the impact of the pandemic on the incidence of these illnesses in a primary care outpatient setting. Physician-diagnosed, medically attended infection visits were assessed in two child cohorts, age 6-36 months old: from March 15 to December 31, 2020 (the pandemic period) compared to the same months in 2019 (prepandemic). Nasopharyngeal colonization by potential otopathogens during healthy/well-child and acute otitis media (AOM) visits was evaluated. Results: One hundred and forty-four children were included in the pandemic cohort and 215 in the prepandemic cohort. The pandemic cohort of children experienced 1.8-fold less frequent infectious disease visits during the pandemic (p < 0.0001). Specifically, visits for AOM were 3.7-fold lower (p < 0.0001), viral upper respiratory infections (URI) 3.8-fold lower (p < 0.0001), croup 27.5-fold lower (p < 0.0001), and bronchiolitis 7.4-fold lower (p = 0.04) than the prepandemic cohort. Streptococcus pneumoniae (p = 0.03), Haemophilus influenzae (p < 0.0001), and Moraxella catarrhalis (p < 0.0001) nasopharyngeal colonization occurred less frequently among children during the pandemic. Conclusion: In primary care pediatric practice, during the first 9 months of the COVID-19 pandemic, significant decreases in the frequency of multiple respiratory infections and nasopharyngeal colonization by potential bacterial respiratory pathogens occurred in children age 6-36 months old.

The application of indocyanine green (ICG) and near-infrared (NIR) fluorescence imaging for assessment of the lymphatic system in reconstructive lymphaticovenular anastomosis surgery.

INTRODUCTION: Lymphedema has traditionally been managed through noninvasive means with complete decongestive therapy. However, complete decongestive therapy is an intensive program that requires lifelong adherence by patients with lymphedema. More recently, reconstructive surgical procedures have shown promise in improving lymphedema by physiologically restoring lymphatic function. One of these types of procedures, lymphaticovenular anastomosis, relies on technological advances in imaging, particularly indocyanine green lymphangiography. AREAS COVERED: This article reviews indocyanine green and near-infrared fluorescence imaging. In addition, this article discusses the application of this imaging to the preoperative, intraoperative, and postoperative assessment of the lymphatic system in the setting of lymphaticovenular anastomosis surgery. EXPERT OPINION: Indocyanine green lymphangiography offers significant advantages over other types of imaging of the lymphatic system. In the future, it is hopeful that additional options for these imaging devices will become available which may increase their accessibility by centers interested in performing reconstructive lymphatic surgery, including in relation to cost. Finally, more studies with higher levels of evidence are needed to better define the long-term outcomes associated with lymphatic surgery including LVA. In this regard, practitioners should fully harness the information conferred by ICG lymphangiography as both a clinical and research tool.

Negative pressure wound therapy: device design, indications, and the evidence supporting its use.

Introduction: Negative pressure wound therapy (NPWT) has become a mainstay in the armamentarium for wound care. Since the initial commercial vacuum-assisted closure device became available in 1995, subsequent research has confirmed the positive physiological effects of negative pressure on wound healing. Traditionally, NPWT has been used to improve healing of open nonsurgical wounds by secondary intention. However, the clinical applications of NPWT have significantly broadened, and now also include use in open surgical wounds, closed surgical incisions, and skin graft surgery. In addition, devices have evolved and now include functionality and features such as instillation, antimicrobial sponges, and portability.Areas covered: This article reviews the history, background, and physiology underlying NPWT, as well as the most commonly used devices. In addition, an evidence-based discussion of the current clinical applications of NPWT is presented, with a focus on those with high levels of evidence.Expert opinion: Future directions for device development include modifications to increase ease of use by patients and to allow its use in a broader array of anatomic areas. Lastly, more research with high levels of evidence is needed to better define the outcomes associated with NPWT, including in relation to specific clinical applications and cost.

Prospective pilot study protocol evaluating the safety and feasibility of robot-assisted nipple-sparing mastectomy (RNSM).

INTRODUCTION: Nipple-sparing mastectomy (NSM) can be performed for the treatment of breast cancer and risk reduction, but total mammary glandular excision in NSM can be technically challenging. Minimally invasive robot-assisted NSM (RNSM) has the potential to improve the ergonomic challenges of open NSM. Recent studies in RNSM demonstrate the feasibility and safety of the procedure, but this technique is still novel in the USA. METHODS AND ANALYSIS: This is a single-arm prospective pilot study to determine the safety, efficacy and potential risks of RNSM. Up to 12 RNSM will be performed to assess the safety and feasibility of the procedure. Routine follow-up visits and study assessments will occur at 14 days, 30 days, 6 weeks, 6 months and 12 months. The primary outcome is to assess the feasibility of removing the breast gland en bloc using the RNSM technique. To assess safety, postoperative complication information will be collected. Secondary outcomes include defining benefits and challenges of RNSM for both surgeons and patients using surveys, as well as defining the breast and nipple-areolar complex sensation recovery following RNSM. Mainly, descriptive analysis will be used to report the findings. ETHICS AND DISSEMINATION: The RNSM protocol was reviewed and approved by the US Food and Drug Administration using the Investigational Device Exemption mechanism (reference number G200096). In addition, the protocol was registered with ClinicalTrials.gov (NCT04537312) and approved by The Ohio State University Institutional Review Board, reference number 2020C0094 (18 August 2020). The results of this study will be distributed through peer-reviewed journals and presented at surgical conferences. TRIAL REGISTRATION NUMBER: NCT04537312.

Targeted Muscle Reinnervation in Partial Hand Amputations.

Targeted muscle reinnervation (TMR) surgery has been shown to aid in prevention and treatment of neuropathic pain. Technical and anatomical descriptions of TMR surgery for upper extremity amputees (including transradial, transhumeral, and forequarter amputations) have been reported, yet such descriptions of TMR surgery for partial hand amputations are currently lacking. Herein we outline the technique of different types of partial hand amputation TMR surgeries to serve as a reference and guide. A retrospective review was performed by our multi-institutional team to identify clinical cases where partial hand TMR surgeries were performed. Patient demographics, characteristics, amputation subtype, nerve transfer, pain score, pain outcome, and functional outcome data were collected and analyzed. From January 2018 to September 2019, 13 patients underwent partial hand TMR procedures. Eight cases resulted from trauma, and 6 were secondary to oncologic procedures. The amputations consisted of 8 ray, 2 trans-metacarpal, 2 radial-sided hand, and 1 index finger amputation with recurrent painful neuromas. Twelve patients were weaned off narcotics completely and only 3 remained on a neuromodulator for ongoing pain control. Technical considerations for partial hand TMR surgery have been outlined, with early pilot data showing beneficial pain control outcomes.

Factors influencing the detection of treatable epileptogenic lesions on MRI. A randomized prospective study.

BACKGROUND: To prospectively analyze factors associated with detecting epileptogenic lesions on MRI within the work-sharing process of neurologists, epileptologists, radiologists and neuroradiologists. METHODS: We assembled four sets of six MRI scans, each set representing five typical epileptogenic lesions (hippocampal sclerosis or limbic encephalitis; focal cortical dysplasias; periventricular nodular or other heterotopias; long-term epilepsy associated tumors; gliotic scar, hemosiderin or cavernoma), and non - lesional epilepsy. At professional conferences, we invited neurologists, epileptologists, radiologists, and neuroradiologists to read two out of four MRI sets, one of which was presented with a clinical focus hypothesis. Participants were randomly assigned to MRI sets. Effects of examiners' specialty, duration of training and professional experience on detection rate of epileptogenic lesions were investigated. RESULTS: Fourty-eight neurologists, 22 epileptologists, 20 radiologists and 21 neuroradiologists read 1323 MRI scans. Overall, 613 of 1101 (55.7%) epileptogenic lesions were detected. Long-term epilepsy associated tumors (182/221, 82.4%) were found more frequently than gliotic scar, hemosiderin or cavernoma (157/220, 71.4%), hippocampal sclerosis or limbic encephalitis (141/220, 64.1%), nodular heterotopia (68/220, 30.9%) and focal cortical dysplasias (65/220, 29.5%, p < 0.001). Provision of a focus hypothesis improved the detection of hippocampal sclerosis or limbic encephalitis (86/110, 78.2% vs 55/110, 50%, p < 0.001) and focal cortical dysplasias (40/110, 36.4% vs 25/110, 22.7%, p = 0.037). Neuroradiologists and epileptologists were more likely than radiologists and neurologists to be amongst the most successful readers. In multivariable analysis, type of epileptogenic lesion, specialty of MRI reader, and provision of focus hypothesis predicted correct identification of epileptogenic lesions. CONCLUSIONS: Epileptogenic lesions are often not recognized on MRI even by expert readers. Their detection can be improved by providing a focus hypothesis. These results stress the need for training in the MRI characteristics of epilepsy - specific pathology, and, most importantly, interdisciplinary communication between neurologists/epileptologists and (neuro)radiologists to improve detection of epileptogenic lesions.

Residual breast tissue after robot-assisted nipple sparing mastectomy.

INTRODUCTION: While the long-term oncologic safety of robot-assisted nipple sparing mastectomy (RNSM) remains to be elucidated, histologically detected residual breast tissue (RBT) can be a surrogate for oncologically sound mastectomy. The objective of this study is to determine the presence of RBT after RNSM. METHODS: Between August 2019-January 2020, we completed 5 cadaveric RNSMs. Full thickness biopsies from the mastectomy skin flap were obtained from predefined locations radially around the mastectomy skin envelop and nipple areolar complex to histologically evaluate for RBT. RESULTS: The first case was not technically feasible due to inability to obtain adequate insufflation. Five mastectomy flaps were analyzable. The average mastectomy flap thickness was 2.3 mm (range 2-3 mm) and the average specimen weight was 382.72 g (range 146.9-558.3 g). Of 70 total biopsies, RBT was detected in 11 (15.7%) biopsies. Most common location for RBT was in the nipple-areolar complex, with no RBT detected from the peripheral skin flaps. CONCLUSIONS: In this cadaveric study, RNSM is feasible leaving minimal RBT on the mastectomy flap. The most common location for RBT is in the periareolar location consistent with previous published findings after open NSM. Clinical studies are underway to evaluate the safety of RNSM.