Citations

Abstract Natural prokaryotic gene repression systems often exploit DNA looping to increase the local concentration of gene repressor proteins at a regulated promoter via contributions from repressor proteins bound at distant sites. Using principles from the Escherichia coli lac operon we design analogous repression systems based on target sequence-programmable Transcription Activator-Like Effector dimer (TALED) proteins. Such engineered switches may be valuable for synthetic biology and therapeutic applications. Previous TALEDs with inducible non-covalent dimerization showed detectable, but limited, DNA loop-based repression due to the repressor protein dimerization equilibrium. Here, we show robust DNA loop-dependent bacterial promoter repression by covalent TALEDs and verify that DNA looping dramatically enhances promoter repression in E. coli. We characterize repression using a thermodynamic model that quantitates this favorable contribution of DNA looping. This analysis unequivocally and quantitatively demonstrates that optimized TALED proteins can drive loop-dependent promoter repression in E. coli comparable to the natural LacI repressor system. This work elucidates key design principles that set the stage for wide application of TALED-dependent DNA loop-based repression of target genes.

Background: Mohs micrographic surgery (MMS) is a promising treatment modality for melanoma in situ (MIS). However, variations in surgical technique limit the generalizability of existing data and may impede future study of MMS in clinical trials. Methods: A modified Delphi method was selected to establish consensus on optimal MMS techniques for treating MIS in future clinical trials. The Delphi method was selected due to the limited current data, the wide range of techniques used in the field, and the intention to establish a standardized technique for future clinical trials. A literature review and interviews with experienced MMS surgeons were performed to identify dimensions of the MMS technique for MIS that (1) likely impacted costs or outcomes of the procedure, and (2) showed significant variability between surgeons. A total of 8 dimensions of technical variation were selected. The Delphi process consisted of 2 rounds of voting and commentary, during which 44 expert Mohs surgeons across the United States rated their agreement with specific recommendations using a Likert scale. Results: Five of eight recommendations achieved consensus in Round 1. All 3 of the remaining recommendations achieved consensus in Round 2. Techniques achieving consensus in Round 1 included the use of a starting peripheral margin of ≤5 mm, application of immunohistochemistry, frozen tissue processing, and resecting to the depth of subcutaneous fat. Consensus on the use of Wood’s lamp, dermatoscope, and negative tissue controls was established in Round 2. Conclusions: This study generated 8 consensus recommendations intended to offer guidance for Mohs surgeons treating MIS. The adoption of these recommendations will promote standardization to facilitate comparisons of aggregate data in multicenter clinical trials.

Abstract Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy that presents with highly heterogenous clinical syndromes. We perform cross-sectional data-driven discovery of independent patterns of brain atrophy and hypometabolism across the entire PSP spectrum. We then use these patterns to predict specific clinical features and to assess their relationship to phenotypic heterogeneity. We included 111 patients with PSP (60 with Richardson syndrome and 51 with cortical and subcortical variant subtypes). Ninety-one were used as the training set and 20 as a test set. The presence and severity of granular clinical variables such as postural instability, parkinsonism, apraxia and supranuclear gaze palsy were noted. Domains of akinesia, ocular motor impairment, postural instability and cognitive dysfunction as defined by the Movement Disorders Society criteria for PSP were also recorded. Non-negative matrix factorization was used on cross-sectional MRI and fluorodeoxyglucose-positron emission tomography (FDG-PET) scans. Independent models for each as well as a combined model for MRI and FDG-PET were developed and used to predict the granular clinical variables. Both MRI and FDG-PET were better at predicting presence of a symptom than severity, suggesting identification of disease state may be more robust than disease stage. FDG-PET predicted predominantly cortical abnormalities better than MRI such as ideomotor apraxia, apraxia of speech and frontal dysexecutive syndrome. MRI demonstrated prediction of cortical and more so sub-cortical abnormalities, such as parkinsonism. Distinct neuroanatomical foci were predictive in MRI- and FDG-PET-based models. For example, vertical gaze palsy was predicted by midbrain atrophy on MRI, but frontal eye field hypometabolism on FDG-PET. Findings also differed by scale or instrument used. For example, prediction of ocular motor abnormalities using the PSP Saccadic Impairment Scale was stronger than with the Movement Disorders Society Diagnostic criteria for PSP oculomotor impairment designation. Combination of MRI and FDG-PET demonstrated enhanced detection of parkinsonism and frontal syndrome presence and apraxia, cognitive impairment and bradykinesia severity. Both MRI and FDG-PET patterns were able to predict some measures in the test set; however, prediction of global cognition measured by Montreal Cognitive Assessment was the strongest. MRI predictions generalized more robustly to the test set. PSP leads to neurodegeneration in motor, cognitive and ocular motor networks at cortical and subcortical foci, leading to diverse yet overlapping clinical syndromes. To advance understanding of phenotypic heterogeneity in PSP, it is essential to consider data-driven approaches to clinical neuroimaging analyses.

ObjectiveTo identify characteristics of patients who have poor improvement in symptoms following surgical management of Zenker Diverticulum (ZD).MethodsProspective, multicenter cohort study of all individuals enrolled in the Prospective OUtcomes of Cricopharyngeus Hypertonicity (POUCH) Collaborative who underwent surgical repair of ZD between August 2017 and January 2024. Patient demographics, esophagrams, and the 10‐item Eating Assessment Tool (EAT‐10) pre‐ and post‐procedure were obtained from a REDCap database. t‐tests, Wilcoxon rank sum tests, Chi‐square or Fisher's exact tests were used to compare the characteristics. Patients with <50% improvement in their EAT‐10 scores were deemed surgical nonresponders (SNRs). Those with ≥50% improvement in their EAT‐10 scores were deemed surgical responders (SRs).ResultsA total of 184 patients were prospectively followed after undergoing either open or endoscopic surgical management. Twenty‐two patients (12%) were deemed SNRs. Preoperative presence of a hiatal hernia was statistically significant characteristic between the SNRs (63.6%) and SRs (32.1%) (p = 0.004). Size of the ZD and history of previous ZD surgery was not a significant characteristic. The length of stay and complication rate were not statistically different between the groups.ConclusionCoexistent esophageal pathology may lead to poor symptomatic improvement following ZD surgery. Preoperative workup of other esophageal disorders is recommended to detect likely SNRs. For SNRs, further esophageal workup may be necessary to evaluate for other esophageal causes related to poor symptomatic improvement following ZD surgery.Level of Evidence3 Laryngoscope, 134:4897–4902, 2024

Cartilage injuries can present in a diverse setting of anatomic locations, with varying severity, and can impact athletes of all ages and competition levels. Moreover, the timing of when an injury presents introduces an additional dimension to treatment decision-making. Frequently, the level of competition, in conjunction with career trajectory and short-term and long-term athlete goals, will dictate whether a temporary or definitive treatment strategy is ideal. Although indicating the correct therapeutic regimen may prove challenging, understanding the athlete-specific considerations can be essential to meeting the goals of the athlete and other stakeholders involved in the athlete’s career. The purpose of this review is to comprehensively present the deliberations a treating physician must consider in managing cartilage injuries within a spectrum of athletic levels ranging from youth to professional levels, with a secondary focus on the presentation of temporizing treatment strategies and associated outcomes.

Abstract Shoulder arthroscopy is a versatile method for treating a variety of shoulder pathologies in a minimally invasive manner. Typically, it is performed with the patient positioned in a beach‐chair or lateral decubitus position with the latter being conventionally preferred for shoulder instability work given the use of traction and creation of a distracted joint. This allows ideal visualization and accessibility of the anterior, inferior, and posterior aspects of the glenoid, labrum, and axillary pouch. Despite the apparent advantages, the lateral decubitus position comes with its own technical challenges. Many of these may stem from surgeon training, experience, and level of familiarity with the positioning and arthroscopic view. This Technical Note demonstrates a reproducible and teachable method for efficient and effective diagnostic shoulder arthroscopy in the lateral decubitus position, along with presenting its associated advantages and disadvantages. Technique Video video See video under supplementary data.

The use of single-stranded oligodeoxynucleotide (ssODN) along with CRISPR–Cas9-mediated double-strand breaks (DSB) is one of the most commonly deployed methods for introducing genetic alterations, but this approach has notable limitations. Recognizing this, we have developed a protocol article that provides a step-by-step process of donorguide, a covalent fusion of trans-activating CRISPR RNA (tracrRNA) and ssODN. Donorguide has the potential to enhance the introduction of specific genetic alterations (insertion, deletion, and substitution) at a DSB, improving homology-directed repair methods from zebrafish in vivo to human cells in vitro . We also explored and discuss the impact of increasing the length of donorguide homology arms in zebrafish.