Buckling forces and the wavy folds between pleural epithelial cells.

Cell shapes in tissues are affected by the biophysical interaction between cells. Tissue forces can influence specific cell features such as cell geometry and cell surface area. Here, we examined the 2-dimensional shape, size, and perimeter of pleural epithelial cells at various lung volumes. We demonstrated a 1.53-fold increase in 2-dimensional cell surface area and a 1.43-fold increase in cell perimeter at total lung capacity compared to residual lung volume. Consistent with previous results, close inspection of the pleura demonstrated wavy folds between pleural epithelial cells at all lung volumes. To investigate a potential explanation for the wavy folds, we developed a physical simulacrum suggested by D'Arcy Thompson in On Growth and Form. The simulacrum suggested that the wavy folds were the result of redundant cell membranes unable to contract. To test this hypothesis, we developed a numerical simulation to evaluate the impact of an increase in 2-dimensional cell surface area and cell perimeter on the shape of the cell-cell interface. Our simulation demonstrated that an increase in cell perimeter, rather than an increase in 2-dimensional cell surface area, had the most direct impact on the presence of wavy folds. We conclude that wavy folds between pleural epithelial cells reflects buckling forces arising from the excess cell perimeter necessary to accommodate visceral organ expansion.

United States-Based Colorectal Cancer Surgical Trials Lack Representation and Adequate Reporting of Racially and Ethnically Diverse Participants: Systematic Review and Regression Analysis.

BACKGROUND: Despite the established National Institute of Health Revitalization Act, which aims to include ethnic and racial minority representation in surgical trials, racial and ethnic enrollment disparities persist. OBJECTIVE: To assess the proportion of patients from minority races and ethnicities that are included in colorectal cancer surgical trials and reporting characteristics. DATA SOURCES: Search was performed using MEDLINE (Ovid), Embase, Web of Science, and Cochrane Central. STUDY SELECTION: Inclusion criteria included 1) trials performed in the United States between January 1, 2000, and May 30, 2022; 2) patients with colorectal cancer diagnosis; and 3) surgical intervention, technique, or postoperative outcome. Trials evaluating chemotherapy, radiotherapy, or other nonsurgical interventions were excluded. INTERVENTIONS: Pooled proportion and regression analysis was performed to identify the proportion of patients by race and ethnicity included in surgical trials and the association of year of publication and funding source. MAIN OUTCOME MEASURES: Proportion of trials reporting race and ethnicity and proportion of participants by race and ethnicity included in surgical trials. RESULTS: We screened 10,673 unique publications, of which 80 were examined in full text. Fifteen studies met our inclusion criteria. Ten (66.7%) trials did not report race, 3 reported races as a proportion of White participants only, and 3 reported 3 or more races. There was no description of ethnicity in 11 (73.3%) trials, with 2 describing "non-Caucasian" as ethnicity and 2 describing only Hispanic ethnicity. Pooled proportion of White participants was 81.3%, of Black participants was 6.2%, of Asian participants was 3.6%, and of Hispanic participants was 3.5%. LIMITATIONS: A small number of studies was identified that reported racial or ethnic characteristics of their participants. CONCLUSIONS: Both race and ethnicity are severely underreported in colorectal cancer surgical trials. To improve outcomes and ensure the inclusion of vulnerable populations in innovative technologies and novel treatments, reporting must be closely monitored.

Topography of pleural epithelial structure enabled by en face isolation and machine learning.

Pleural epithelial adaptations to mechanical stress are relevant to both normal lung function and parenchymal lung diseases. Assessing regional differences in mechanical stress, however, has been complicated by the nonlinear stress-strain properties of the lung and the large displacements with ventilation. Moreover, there is no reliable method of isolating pleural epithelium for structural studies. To define the topographic variation in pleural structure, we developed a method of en face harvest of murine pleural epithelium. Silver-stain was used to highlight cell borders and facilitate imaging with light microscopy. Machine learning and watershed segmentation were used to define the cell area and cell perimeter of the isolated pleural epithelial cells. In the deflated lung at residual volume, the pleural epithelial cells were significantly larger in the apex (624 ± 247 µm2 ) than in basilar regions of the lung (471 ± 119 µm2 ) (p < 0.001). The distortion of apical epithelial cells was consistent with a vertical gradient of pleural pressures. To assess epithelial changes with inflation, the pleura was studied at total lung capacity. The average epithelial cell area increased 57% and the average perimeter increased 27% between residual volume and total lung capacity. The increase in lung volume was less than half the percent change predicted by uniform or isotropic expansion of the lung. We conclude that the structured analysis of pleural epithelial cells complements studies of pulmonary microstructure and provides useful insights into the regional distribution of mechanical stresses in the lung.

General Surgery Trainee Cases Over Time: Postgraduate Year Matters.

BACKGROUND: Trainees and attending surgeons alike have concerns about resident and fellow operative volume/breadth, competency, and overall readiness for practice. This is an important topic within surgical graduate medical education. Our goal was to analyze the change in general surgery trainee operative experience over time by postgraduate year. METHODS: Institutional operative records from two corresponding three-month time periods in 2009 and 2018 at the residency program's main hospital site were reviewed. Cases assisted on by general, vascular, or thoracic surgery trainees were included. The number of cases per level, combination of trainees in each case, and categories of cases were compared over time. RESULTS: There were 1940 cases in 2009 and 1967 cases in 2018 over the respective time periods. The distribution of trainees was different (P < .001), with a similar number of PGY-1 and fellow cases, a decrease in PGY-2 and PGY-5 cases, and an increase in PGY-3 and PGY-4 cases. The number of cases with two trainees, double scrubbed cases, increased from 19.6% to 26.8% (P < .001). In addition, there were differences in the resident years that double scrubbed cases together, an increase in robotic and endovascular surgery, and a decrease in open cases. CONCLUSIONS: This analysis of cases shows that resident operative volume over approximately a decade has been largely preserved, with some change in the distribution of cases based on trainee level, an increase in cases with more than one trainee, and a rise of minimally invasive surgery with a corresponding decrease in open cases.

Kinetics of Pectin Biopolymer Facial Erosion Characterized by Fluorescent Tracer Microfluidics.

Pectin is a plant-derived heteropolysaccharide that has been implicated in drug development, tissue engineering, and visceral organ repair. Pectin demonstrates remarkable biostability in a variety of physiologic environments but is biodegradable in water. To understand the dynamics of pectin biodegradation in basic environments, we developed a microfluidics system that facilitated the quantitative comparison of pectin films exposed to facial erosion. Pectin biodegradation was assessed using fluorescein tracer embedded in pectin, trypan blue quenching of released fluorescence, and highly sensitive microfluorimetry. The microfluidic perfusate, delivered through 6 um-pore synthetic membrane interface, demonstrated nonlinear erosion of the pectin film; 75% of tracer was released in 28 h. The microfluidics system was used to identify potential modifiers of pectin erosion. The polyphenolic compound tannic acid, loaded into citrus pectin films, demonstrated a dose-dependent decrease in pectin erosion. Tannic acid had no detectable impact on the physical properties of citrus pectin including adhesivity and cohesion. In contrast, tannic acid weakened the burst strength and cohesion of pectins derived from soy bean and potato sources. We conclude that facial erosion may explain the biostability of citrus pectin on visceral organ surfaces as well as provide a useful method for identifying modifiers of citrus pectin biodegradation.