α-Actinin-1 promotes activity of the L-type Ca2+ channel Cav 1.2.

The L-type Ca2+ channel CaV 1.2 governs gene expression, cardiac contraction, and neuronal activity. Binding of α-actinin to the IQ motif of CaV 1.2 supports its surface localization and postsynaptic targeting in neurons. We report a bi-functional mechanism that restricts CaV 1.2 activity to its target sites. We solved separate NMR structures of the IQ motif (residues 1,646-1,664) bound to α-actinin-1 and to apo-calmodulin (apoCaM). The CaV 1.2 K1647A and Y1649A mutations, which impair α-actinin-1 but not apoCaM binding, but not the F1658A and K1662E mutations, which impair apoCaM but not α-actinin-1 binding, decreased single-channel open probability, gating charge movement, and its coupling to channel opening. Thus, α-actinin recruits CaV 1.2 to defined surface regions and simultaneously boosts its open probability so that CaV 1.2 is mostly active when appropriately localized.

Outcomes After Implant-Based Breast Reconstruction Following the National Institution of a Ban on Bacitracin Irrigation.

BACKGROUND: The use of irrigation with bacitracin-containing solution is common among surgeons, as it was widely thought to have antibacterial properties and prevent postoperative infection. Current literature, however, suggests that antibiotic-containing irrigation confers little added benefit. On January 31, 2020, the Food and Drug Administration instituted a ban on bacitracin-containing irrigation for operative use. This study aimed to determine whether bacitracin has a beneficial effect on postoperative infection rates by analyzing infection rates before and after the Food and Drug Administration ban on bacitracin irrigation. METHODS: A single-institution retrospective chart review was conducted. Eligible patients underwent implant-based breast reconstruction after mastectomy from October 1, 2016, to July 31, 2022. Procedure date, reconstruction type, patient comorbidities, use of bacitracin irrigation, postoperative infection, and secondary outcomes were collected. Univariate and multivariable logistic regression analyses were performed. RESULTS: A total of 188 female patients were included in the study. Bacitracin use did not protect against infection in univariate or multivariable analysis. Age greater than 50 years was associated with an increased risk of postoperative infection ( P = 0.0366). The presence of comorbidities, smoker status, neoadjuvant therapy treatment before surgery, implant placement, and laterality were all not significantly associated with postoperative infection development. CONCLUSIONS: The results of this study demonstrate a lack of association between bacitracin use and postoperative infection. Additional research into the optimal antibiotic for perioperative irrigation is needed, as bacitracin is not encouraged for use.

Contextualizing the Impact of Pop Culture on Breast Implant Illness and its Medical Relevance.

INTRODUCTION: Despite a lack of data demonstrating causation, there is growing concern over breast implants and systemic illness. This study examines the impact of rising public interest in breast implant illness (BII) and its implications on breast implant removals (BIR). METHODS: A Google Trends (GT) analysis of each year between 2010 and 2022 was performed globally, and then separately for the United States alone (US), using the search terms "capsular contracture," "breast implant illness," and "breast implant(s) removal". Linear regression was performed to determine significant correlations. Data on BII-related Facebook advocacy groups, relevant pop culture events, numbers of BIR surgeries, and number of BII-related publications were collected and analyzed alongside GT data to determine relevance. RESULTS: For global GT, there was a significant relationship between "breast implant illness" and "breast implant(s) removal" in 2016 (R2=0.62, ß =0.33, p<0.01), 2020 (R2=0.53, ß =0.23, p=0.01), and 2022 (R2=0.60, ß =0.44, p=0.01). In the US, 2016 (R2=0.53, ß =1.75, p=0.01) 2018 (R2=0.61, ß =1.93, p<0.01) and 2020 (R2=0.72, ß=0.91, p<0.01) were significant. In 2020, "capsular contracture" and "breast implant(s) removal" was significant in the US (R2=0.58, ß=0.4, p=0.01). In 2016, Facebook was the platform for the largest BII advocacy group and in 2020 YouTube was the platform for the first BII documentary and TEDx talk. From 2010 to 2020, PubMed publications containing "ASIA" and "BII" increased 24-fold and ASPS reports on BIR rose 70%. CONCLUSION: This study suggests that BII is a topic of global concern and has implications on both academic medicine and clinical practice. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Physiological Functions of Bacterial "Multidrug" Efflux Pumps.

Bacterial multidrug efflux pumps have come to prominence in human and veterinary pathogenesis because they help bacteria protect themselves against the antimicrobials used to overcome their infections. However, it is increasingly realized that many, probably most, such pumps have physiological roles that are distinct from protection of bacteria against antimicrobials administered by humans. Here we undertake a broad survey of the proteins involved, allied to detailed examples of their evolution, energetics, structures, chemical recognition, and molecular mechanisms, together with the experimental strategies that enable rapid and economical progress in understanding their true physiological roles. Once these roles are established, the knowledge can be harnessed to design more effective drugs, improve existing microbial production of drugs for clinical practice and of feedstocks for commercial exploitation, and even develop more sustainable biological processes that avoid, for example, utilization of petroleum.

Public Perception of Ideal Areola Proportions.

BACKGROUND: In breast reconstruction, mastopexy, and breast reduction procedures, surgeons make decisions about the resulting areola size, and this significantly impacts the overall aesthetic result. Despite the importance of these decisions, little is known about the general population's preferences for areola size. The objective of this study was to survey the global population to better understand the public's perceptions of ideal areola dimensions. METHODS: A survey was developed with 9 different composite diagrams of a female torso (every combination of 3 breast widths and 3 waist widths). In each composite diagram, 6 different areola sizes were shown (areola-to-breast diameter ranging from 1:12 to 6:12). The survey was distributed via the Amazon Mechanical Turk digital platform, and respondents' demographics (sex, age, race/ethnicity, country, and state if located in the United States) and preferences for the most aesthetically pleasing size in each composite diagram were recorded. RESULTS: Among 2259 participants, with 1283 male (56.8%) and 976 female (43.2%), most participants were between 25 and 34 years old (1012, 44.8%), were from the United States (1669, 73.9%), and identified as White (1430, 63.3%). With 9 breast width and waist width combinations, the respondents were most likely to prefer the 2:12 (32.9%) areola-to-breast ratio ( P < 0.0001). The second most commonly preferred ratio was 3:12 (30.6%) ( P < 0.0001). Gender subgroup analysis showed that women preferred middle-range ratios, such as 2:12, 3:12, and 4:12 ( P < 0.0001). Meanwhile, men were more likely to prefer extreme ratios of 1:12 or 6:12 ( P < 0.0001). Across almost all races/ethnicities, 2:12 was significantly the most popular, except among American Indian/Alaskan Native and Middle Eastern where 3:12 was the most preferred ( P < 0.0001). Within the top 6 countries (United States, India, Brazil, Italy, Canada, United Kingdom), the United States, India, and Italy preferred 2:12, and Brazil, Canada, and the United Kingdom preferred 3:12 ( P < 0.0001). CONCLUSIONS: This study provides the first objective data on public impressions of the ideal areola proportions and can serve as a guide for surgical decision making in breast reconstruction and reshaping procedures.

Periumbilical Anatomy of Scarpa's Fascia: Rationale Behind a "Modified Scarpa's" Abdominal Closure Technique.

BACKGROUND: Intraoperative observation of Scarpa's fascia (SF) has suggested attenuation in the periumbilical region. This study's purpose was to objectively evaluate SF anatomy in the periumbilical region and assess clinical outcomes of a novel, modified SF closure technique of transverse abdominal wall incisions that only reapproximates SF where it is definitively present. METHODS: Women were identified who had undergone abdominal magnetic resonance (MR) angiography before their abdominal-based autologous breast reconstruction that used the modified SF closure technique. Statistical analysis of SF presentation on the MR images was performed. Intraoperative measurements from dissected panniculectomy specimens were used to validate MR analysis. Donor site complications were recorded in patients undergoing modified SF closure. RESULTS: Sixty-six patients were included in the retrospective MR imaging analysis; this revealed an average attenuation of SF of 4.7 cm (SEM = 0.25 cm), 4.5 cm (SEM = 0.23 cm), 4.6 cm (SEM = 0.23 cm), and 4.2 cm (SEM = 0.22 cm) to the left of, right of, cranial to, and caudal to the umbilicus, respectively. The mean surface area of radiologic SF absence was 56.3 cm 2 (SEM = 3.57 cm 2 ). There was a significant difference in SF presentation based on patient age ( P = 0.013) and body mass index ( P = 0.005). Five of the 66 patients (7.6%) experienced abdominal closure site complications. CONCLUSIONS: This study objectively confirms that there is attenuation of SF in the periumbilical region, describes a novel SF closure technique, and provides evidence to support its adoption when closing transverse abdominal wall incisions.

Short-chain diamines are the physiological substrates of PACE family efflux pumps.

Acinetobacter baumannii has rapidly emerged as a major cause of gram-negative hospital infections worldwide. A. baumannii encodes for the transport protein AceI, which confers resistance to chlorhexidine, a widely used antiseptic. AceI is also the prototype for the recently discovered proteobacterial antimicrobial compound efflux (PACE) family of transport proteins that confer resistance to a range of antibiotics and antiseptics in many gram-negative bacteria, including pathogens. The gene encoding AceI is conserved in the core genome of A. baumannii, suggesting that it has an important primordial function. This is incongruous with the sole characterized substrate of AceI, chlorhexidine, an entirely synthetic biocide produced only during the last century. Here we investigated a potential primordial function of AceI and other members of the PACE family in the transport of naturally occurring polyamines. Polyamines are abundant in living cells, where they have physiologically important functions and play multifaceted roles in bacterial infection. Gene expression studies revealed that the aceI gene is induced in A. baumannii by the short-chain diamines cadaverine and putrescine. Membrane transport experiments conducted in whole cells of A. baumannii and Escherichia coli and also in proteoliposomes showed that AceI mediates the efflux of these short-chain diamines when energized by an electrochemical gradient. Assays conducted using 8 additional diverse PACE family proteins identified 3 that also catalyze cadaverine transport. Taken together, these results demonstrate that short-chain diamines are common substrates for the PACE family of transport proteins, adding to their broad significance as a novel family of efflux pumps.

Objective Comparison of FDA-Approved Breast Implant Products in the USA: 5-Year Update.

BACKGROUND: There are currently four companies offering FDA-approved breast implants: Allergan, Sientra, Mentor, and Ideal Implant. In 2015, our paper "Objective Comparison of Commercially Available Breast Implant Devices" sought to provide a unique conceptual framework to better understand the similarities and differences between FDA-approved breast implant products and tissue expanders. This paper uses the same variables, such as fill material, shape, relative dimensions, and surface coating, to aid understanding of both the surgical trainee and the operating surgeon of what devices each company offers, with a focus on how the market has evolved over the ensuing 5 years. METHODS: The product catalogs of each FDA-approved company were carefully explored to determine the current available breast implants and tissue expanders. Subsequently, flow charts were created to provide a clear and objective survey of each companies' offerings, highlighting where there are overlap and deficiencies, and where there has been contraction or growth. RESULTS: Disruptions to the industry, including both technological innovation and the recognition of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), have caused a significant shift in the details of the available permanent breast implants, breast tissue expanders, sizers, and warranty programs. CONCLUSION: As it has been in 2015, company jargon and brand names continue to make it challenging to discern the similarities and differences between company devices and programs. This project remained independent of any company's funding, support, or input, making it a uniquely objective and informative survey of the current breast implant market that should assist surgeons in decision-making regarding the breast implant procedures. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Meta-Fish-Lib: A generalised, dynamic DNA reference library pipeline for metabarcoding of fishes.

The accuracy and reliability of DNA metabarcoding analyses depend on the breadth and quality of the reference libraries that underpin them. However, there are limited options available to obtain and curate the huge volumes of sequence data that are available on public repositories such as NCBI and BOLD. Here, we provide a pipeline to download, clean and annotate mitochondrial DNA sequence data for a given list of fish species. Features of this pipeline include (a) support for multiple metabarcode markers; (b) searches on species synonyms and taxonomic name validation; (c) phylogeny assisted quality control for identification and removal of misannotated sequences; (d) automatically generated coverage reports for each new GenBank release update; and (e) citable, versioned DOIs. As an example we provide a ready-to-use curated reference library for the marine and freshwater fishes of the U.K. To augment this reference library for environmental DNA metabarcoding specifically, we generated 241 new MiFish-12S sequences for 88 U.K. marine species, and make available new primer sets useful for sequencing these. This brings the coverage of common U.K. species for the MiFish-12S fragment to 93%, opening new avenues for scaling up fish metabarcoding across wide spatial gradients. The Meta-Fish-Lib reference library and pipeline is hosted at https://github.com/genner-lab/meta-fish-lib.

Anatomy, Exposure, and Preparation of Recipient Vessels in Microsurgical Head and Neck Reconstruction.

Successful microvascular reconstruction of head and neck defects requires the ability to safely identify, isolate, and utilize recipient vessels. To date, however, a comprehensive review of the anatomy and techniques relevant to the available anatomic regions has not been undertaken. This review covers the relevant clinical anatomy of the anterior triangle, posterior triangle, submandibular region, intraoral region, preauricular region, chest, and arm, taking particular care to highlight the structures that are crucial to identify while performing each dissection. Finally, a step-by-step technique for safely dissecting the recipient vessels at each site is provided.

Microsurgery Training in the Digital Era: A Systematic Review of Accessible Digital Resources.

INTRODUCTION: Significant variation exists in microsurgery training resources provided across plastic surgery residency programs, and dedicated microsurgery courses can be logistically difficult to access (cost, location, protected time, etc). Widespread use of personal digital technology has facilitated the emergence of resources that enable easily accessible microsurgical training through digital modalities that augment traditional training. The authors sought to conduct the first systematic review of all such resources. METHODS: A systematic review of MEDLINE, PubMed Central, and EMBASE was performed according to Preferred Reporting Items for Systematic Review and Meta-analysis guidelines to identify articles describing easily accessible microsurgery training resources. Additional searches on Google, the iOS application store, the Google Play store, and YouTube were conducted using comparable search terms. RESULTS: Nineteen articles describing easily accessible digital microsurgery training resources were identified, which included 9 interactive and 10 passive training resources. Interactive resources included methods for using smartphones, tablets, and computers to provide magnification for microsurgical skill training. Passive resources included training videos, educational forums, and 3-dimensional anatomical models. Google search revealed an additional interactive, commercially available device for positioning a smartphone above a microsurgical training platform. iOS Store and Google Play search revealed 5 passive training applications with tutorials and technique videos. YouTube search revealed 146 videos on microsurgical technique and training models from 19 users with verifiable affiliations. CONCLUSIONS: In contrast to costly and variable microsurgical courses and laboratories, digital technology gives trainees the opportunity to learn about and practice microsurgical techniques in any setting at any time and can serve as a valuable adjunct to traditional training modalities.

Microsurgery Fellows' Impression of Clinical and Educational Offerings during Fellowship Year.

BACKGROUND: Acquisition of microsurgical skill and clinical knowledge is the primary goal of a microsurgery fellowship. There has yet to be any comprehensive reporting in the literature of how American microsurgery fellows viewed their curricula and training at the conclusion of their fellowship year. METHODS: An anonymous, electronic survey was developed and distributed to all 2016 to 2017 microsurgery fellows (n = 37) at the U.S.-based microsurgery fellowship programs (n = 23). Qualitative questions were assessed using either a Likert-type scale of 1 (not at all) to 5 (very), multiple choice, or free response. RESULTS: Twenty-six of 37 fellows (70%) responded to the survey. Respondents reported a mean of 14.4 lectures offered, with a range of 0 to 100. Dry laboratory simulation training was formally incorporated into 32% of microsurgery fellowships and live animal simulation training was formally incorporated into 12%. The median number of free deep inferior epigastric perforator flap cases performed was 112.5, ranging from 60 to 230. A majority felt that an organized microsurgical educational curriculum would be "beneficial," with 42% reporting that an organized microsurgery curriculum would be "very beneficial." Twenty-six of the respondents (100%) said that they would choose to do a microsurgery fellowship again if given the choice. CONCLUSION: Respondent data show that microsurgery fellows are satisfied with training, clinical experience is variable but adequate, educational experiences and opportunities vary from program to program, simulation skills training are perceived to be underutilized, and a program-organized microsurgery curriculum is believed to be advantageous to optimize development of technical and clinical skills.

How to Optimize Prepectoral Breast Reconstruction.

Prepectoral breast reconstruction has become a popular method of postmastectomy breast reconstruction due to its numerous benefits in properly selected patients. Prepectoral reconstruction, as compared with retropectoral position, offers the advantage of leaving the pectoralis muscle undisturbed and in its original anatomic position, resulting in significantly decreased acute and chronic pain, improved upper extremity strength and range of motion, and avoidance of animation deformity. The use of acellular dermal matrices (ADMs) allows for precise control of the breast pocket, resulting in aesthetic outcomes and high patient satisfaction. ADMs have the added benefit of reducing capsular contracture, especially in the setting of postmastectomy radiation therapy. Although prepectoral breast reconstruction is effective, the breast implant is placed closer to the skin flap with less vascularized soft tissue coverage. Therefore, optimizing outcomes in prepectoral breast reconstruction requires careful patient selection, intraoperative mastectomy flap evaluation, and perioperative surgical algorithms specific to prepectoral reconstruction.

Fusogens: Chemical Agents That Can Rapidly Restore Function After Nerve Injury.

BACKGROUND: Restoring function after nerve injury remains one of medicine's greatest challenges. The current approach of epineurial coaptation does not address the fundamental insult at the molecular level: a discontinuity in the axonal membranes. Membrane fusion is possible through agents collectively called chemical fusogens, which are heterogeneous in structure and mechanism of action. We sought a unifying system for classifying fusogens to better understand their role in cell fusion. MATERIALS AND METHODS: We conducted a comprehensive literature review to identify the most commonly cited chemical fusogens, their structures, mechanisms of actions, and clinical applications to date. We identified seven chemical fusogens (polyethylene glycol, chitosan, dextran sulfate, n-nonyl bromide, calcium, sodium nitrate, and H-α-7), which have each been studied to different extents in protoplasts, animals, and humans. RESULTS: Chemical fusogens achieve cell fusion by one of two ways: bringing cells in close enough proximity to each other so the inherent fluidity of the phospholipid membrane allows for their rearrangement or modifying the surface charges of the membranes to diminish repellent charges. Sowers initially put forth a classification system that identified these agents as cell aggregators and membrane modifiers, respectively. We adapted this classification system in the setting of axonal membrane fusion and hypothesized that the most effective approach to axonal membrane repair is likely combination of both. CONCLUSIONS: Chemical fusogens could be grouped into two mechanistic categories-cell aggregators and membrane modifiers. For axonal membrane fusion, a combination of both mechanisms can significantly contribute to advancing outcomes in peripheral nerve repair via a chemical-surgical intervention.

Microbial expression systems for membrane proteins.

Despite many high-profile successes, recombinant membrane protein production remains a technical challenge; it is still the case that many fewer membrane protein structures have been published than those of soluble proteins. However, progress is being made because empirical methods have been developed to produce the required quantity and quality of these challenging targets. This review focuses on the microbial expression systems that are a key source of recombinant prokaryotic and eukaryotic membrane proteins for structural studies. We provide an overview of the host strains, tags and promoters that, in our experience, are most likely to yield protein suitable for structural and functional characterization. We also catalogue the detergents used for solubilization and crystallization studies of these proteins. Here, we emphasize a combination of practical methods, not necessarily high-throughput, which can be implemented in any laboratory equipped for recombinant DNA technology and microbial cell culture.

Molecular mechanism of ligand recognition by membrane transport protein, Mhp1.

The hydantoin transporter Mhp1 is a sodium-coupled secondary active transport protein of the nucleobase-cation-symport family and a member of the widespread 5-helix inverted repeat superfamily of transporters. The structure of Mhp1 was previously solved in three different conformations providing insight into the molecular basis of the alternating access mechanism. Here, we elucidate detailed events of substrate binding, through a combination of crystallography, molecular dynamics, site-directed mutagenesis, biochemical/biophysical assays, and the design and synthesis of novel ligands. We show precisely where 5-substituted hydantoin substrates bind in an extended configuration at the interface of the bundle and hash domains. They are recognised through hydrogen bonds to the hydantoin moiety and the complementarity of the 5-substituent for a hydrophobic pocket in the protein. Furthermore, we describe a novel structure of an intermediate state of the protein with the external thin gate locked open by an inhibitor, 5-(2-naphthylmethyl)-L-hydantoin, which becomes a substrate when leucine 363 is changed to an alanine. We deduce the molecular events that underlie acquisition and transport of a ligand by Mhp1.

Production of membrane proteins for characterisation of their pheromone-sensing and antimicrobial resistance functions.

Despite the importance of membrane proteins in cellular processes, studies of these hydrophobic proteins present major technical challenges, including expression and purification for structural and biophysical studies. A modified strategy of that proposed previously by Saidijam et al. (2005) and others, for the routine expression of bacterial membrane proteins involved in environmental sensing and antimicrobial resistance (AMR), is proposed which results in purification of sufficient proteins for biophysical experiments. We report expression successes amongst a collection of enterococcal vancomycin resistance membrane proteins: VanTG, VanTG-M transporter domain, VanZ and the previously characterised VanS (A-type) histidine protein kinase (HPK). Using the same strategy, we report on the successful amplification and purification of intact BlpH and ComD2 HPKs of Streptococcus pneumoniae. Near-UV circular dichroism revealed both recombinant proteins bound their pheromone ligands BlpC and CSP2. Interestingly, CSP1 also interacted with ComD. Finally, we evaluate the alternative strategy for studying sensory HPKs involving isolated soluble sensory domain fragments, exemplified by successful production of VicKESD of Enterococcus faecalis VicK. Purified VicKESD possessed secondary structure post-purification. Thermal denaturation experiments using far-UV CD, a technique which can be revealing regarding ligand binding, revealed that: (a) VicKESD denaturation occurs between 15 and 50 °C; and (b) reducing conditions did not detectably affect denaturation profiles suggesting reducing conditions per se are not directly sensed by VicKESD. Our findings provide information on a modified strategy for the successful expression, production and/or storage of bacterial membrane HPKs, AMR proteins and sensory domains for their future crystallisation, and ligand binding studies.

Major shifts in Amazon wildlife populations from recent intensification of floods and drought.

In the western Amazon Basin, recent intensification of river-level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high-water seasons, and a drought occurred during the 2010 low-water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km2 ) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish.