Mapping the unicellular transcriptome of the ascending thoracic aorta to changes in mechanosensing and mechanoadaptation during aging.

Aortic stiffening is an inevitable manifestation of chronological aging, yet the mechano-molecular programs that orchestrate region- and layer-specific adaptations along the length and through the wall of the aorta are incompletely defined. Here, we show that the decline in passive cyclic distensibility is more pronounced in the ascending thoracic aorta (ATA) compared to distal segments of the aorta and that collagen content increases in both the medial and adventitial compartments of the ATA during aging. The single-cell RNA sequencing of aged ATA tissues reveals altered cellular senescence, remodeling, and inflammatory responses accompanied by enrichment of T-lymphocytes and rarefaction of vascular smooth muscle cells, compared to young samples. T lymphocyte clusters accumulate in the adventitia, while the activation of mechanosensitive Piezo-1 enhances vasoconstriction and contributes to the overall functional decline of ATA tissues. These results portray the immuno-mechanical aging of the ATA as a process that culminates in a stiffer conduit permissive to the accrual of multi-gerogenic signals priming to disease development.

B3 Breast Lesions: Positive Predictive Value and Follow-Up on a Large Single-Institution Series.

INTRODUCTION: Lesions of uncertain malignant potential (B3) represent 10% of core needle biopsies (CNBs) or vacuum-assisted breast biopsies (VABBs). Traditionally, B3 lesions are operated on. This study investigated the association between B3 subtypes and malignancy to determine the best management. METHODS: Pre- and postoperative histological reports from 226 patients, who had undergone excisional surgery for B3 lesions, following CNB or VABB, were retrospectively analyzed. The correlation between the CNB/VABB diagnosis and the final pathology was investigated, along with the correlation between malignancy upgrade and the type of mammographic lesion. The positive predictive value (PPV) of malignancy of B3 lesions was calculated by simple logistic regression. Patients without cancer diagnosis underwent a 7-y follow-up. RESULTS: Pathology showed 171 (75.6%) benign and 55 (24.3%) malignant lesions. The PPV was 24.3% (P = 0.043), including 31 (13.7%) ductal carcinomas in situ and 24 (10.6%) invasive carcinomas. The most frequently upgraded lesions were atypical ductal hyperplasia, 34.2% (P = 0.004), followed by lobular intraepithelial neoplasia, 27.5% (P = 0.025). The median diameter of mammographic lesions was 1.5 [0.9-2.5] cm, while for surgical specimens, it was 5 [4-7] cm (P < 0.0001). Mammographic findings and histology showed a significant correlation (P = 0.038). After a 7-y follow-up, 15 (8.9%) patients developed carcinoma, and 7 patients (4%) developed a new B3 lesion. CONCLUSIONS: We can conclude that atypical ductal hyperplasia and lobular intraepithelial neoplasia still require surgery for a significant PPV. Other types that lacked significance or confidence intervals were too wide to draw any conclusion.

Contrast-enhanced mammography in the management of breast architectural distortions and avoidance of unnecessary biopsies.

BACKGROUND: To assess contrast-enhanced mammography (CEM) in the management of BI-RADS3 breast architectural distortions (AD) in digital breast tomosynthesis (DBT). METHODS: We retrospectively reviewed 328 women with 332 ADs detected on DBT between 2017 and 2021 and selected those classified as BI-RADS3 receiving CEM as problem-solving. In CEM recombined images, we evaluated AD's contrast enhancement (CE) according to its presence/absence, type, and size. AD with enhancement underwent imaging-guided biopsy while AD without enhancement follow-up or biopsy if detected in high/intermediate-risk women. RESULTS: AD with enhancement were 174 (52.4%): 72 (41.4%) were malignant lesions, 102 (59.6%) false positive results: 28 (16%) B3 lesions, and 74 (42.5%) benign lesions. AD without enhancement were 158 (47.6%): 26 (16.5%) were subjected to biopsy (1 malignant and 25 benign) while the other 132 cases were sent to imaging follow-up, still negative after two years. CEM's sensitivity, specificity, positive (PPV) and negative predictive values (NPV), and accuracy were 98.63%, 60.62%, 41.38%, 99.37%, and 68.98%. The AUC determined by ROC was 0.796 (95% CI, 0.749-0.844). CONCLUSION: CEM has high sensitivity and NPV in evaluating BI-RADS3 AD and can be a complementary tool in assessing AD, avoiding unnecessary biopsies without compromising cancer detection.

Nonpathogenic E. coli engineered to surface display cytokines as a new platform for immunotherapy.

Given the safety, tumor tropism, and ease of genetic manipulation in non-pathogenic Escherichia coli (E. coli), we designed a novel approach to deliver biologics to overcome poor trafficking and exhaustion of immune cells in the tumor microenvironment, via the surface display of key immune-activating cytokines on the outer membrane of E. coli K-12 DH5α. Bacteria expressing murine decoy-resistant IL18 mutein (DR18) induced robust CD8+ T and NK cell-dependent immune responses leading to dramatic tumor control, extending survival, and curing a significant proportion of immune-competent mice with colorectal carcinoma and melanoma. The engineered bacteria demonstrated tumor tropism, while the abscopal and recall responses suggested epitope spreading and induction of immunologic memory. E. coli K-12 DH5α engineered to display human DR18 potently activated mesothelin-targeting CAR NK cells and safely enhanced their trafficking into the tumors, leading to improved control and survival in xenograft mice bearing mesothelioma tumor cells, otherwise resistant to NK cells. Gene expression analysis of the bacteria-primed CAR NK cells showed enhanced TNFα signaling via NFkB and upregulation of multiple activation markers. Our novel live bacteria-based immunotherapeutic platform safely and effectively induces potent anti-tumor responses in otherwise hard-to-treat solid tumors, motivating further evaluation of this approach in the clinic.

Pre-pectoral breast reconstruction with tissue expander entirely covered by acellular dermal matrix: feasibility, safety and histological features resulting from the first 64 procedures.

Background: Reconstructive options that can be used following conservative mastectomy, skin-, nipple-sparing and skin-reducing mastectomies, allow a remarkable variety of safe methods to restore the natural shape and aesthetics of the breast mound. In case of two-stage breast reconstruction, tissue expanders (TEs) are usually placed in a subpectoral position. The purpose of this retrospective cohort study is to evaluate the feasibility and safety of two-step reconstruction with TE in pre-pectoral position covered by acellular dermal matrix (ADM). Methods: Between March 2021 and May 2023, at the Azienda Ospedaliero Universitaria Careggi, University of Florence, 55 patients with BRCA 1/2 mutations or early breast cancer underwent conservative mastectomy with immediate pre-pectoral reconstruction using TE covered with ADM, followed by a second surgery with replacement of the expander with definitive prosthesis. Demographic, oncological, and histological data along with surgical complications were recorded. Results: A total of 64 conservative mastectomies were performed. In 2 patients (3.1%) complications were found that required reintervention and, in both cases, the TE had to be removed. Two patients developed hematoma and one patient developed seroma. Two patients showed wound dehiscence, both healed after conservative treatment and without implant exposure. No case of necrosis of the skin or nipple-areola complex has been observed, neither of capsular contracture. Capsule formed around TE was populated with cells and blood vessels and showed a thin area of synovial metaplasia. Conclusions: In selected cases it may be more cautious to perform a two-stage breast reconstruction after radical breast surgery by means of TEs. The placement of TEs in pre-pectoral position combines the excellent aesthetic and functional results of the pre-pectoral philosophy with a quite safer and more prudent two-step approach. Our experience reports optimistic results: the ADM covering the TE is seen successfully integrating during tissue expansion and becoming a vascularised new self-tissue. Complications rates are low and such ADM-assisted two-stage pre-pectoral reconstructive technique is a safe, practical, and reproducible method.

Assessment of Left Lung Remodeling With Magnetic Resonance Imaging in a Murine Model Following Exposure to Douglas Fir Smoke.

Wildland firefighters (WLFFs) experience lung function decline due to occupational exposure to fire smoke. WLFFs typically do not wear respiratory personal protective equipment, and if they do, it is a simple bandana, which is not effective at filtering smoke. To pinpoint the biological underpinnings of abnormal respiratory function following 3-7 years of WLFF service, we exposed mice to Douglas fir smoke (DFS) over 8 weeks. Following exposure, we assessed changes in lung structure through Magnetic Resonance Imaging (MRI) and histological analysis, which was supported by immunohistochemistry staining. With MRI, we found that the signal decay time, T2*, from ultrashort echo time (UTE) images was significantly shorter in mice exposed to DFS compared to air controls. In addition, the variation in T2* was more heterogeneously distributed throughout the left lung in DFS-exposed mice, compared to air controls. As confirmed by histological analysis, shorter T2* was caused by larger parenchyma airspace sizes and not fibrotic remodeling. Destruction of the alveolar spaces was likely due to inflammation, as measured by an influx of CD68+ macrophages and destruction due to enhanced neutrophil elastase. In addition, measurements of airspace dimensions from histology were more heterogeneously distributed throughout the lung, corroborating the enhanced relative dispersion of T2*. Findings from this study suggest that the decline in lung function observed in WLFFs may be due to emphysema-like changes in the lung, which can be quantified with MRI.

Impact of Wildfires on Cardiovascular Health.

Wildfire smoke (WFS) is a mixture of respirable particulate matter, environmental gases, and other hazardous pollutants that originate from the unplanned burning of arid vegetation during wildfires. The increasing size and frequency of recent wildfires has escalated public and occupational health concerns regarding WFS inhalation, by either individuals living nearby and downstream an active fire or wildland firefighters and other workers that face unavoidable exposure because of their profession. In this review, we first synthesize current evidence from environmental, controlled, and interventional human exposure studies, to highlight positive associations between WFS inhalation and cardiovascular morbidity and mortality. Motivated by these findings, we discuss preventative measures and suggest interventions to mitigate the cardiovascular impact of wildfires. We then review animal and cell exposure studies to call attention on the pathophysiological processes that support the deterioration of cardiovascular tissues and organs in response to WFS inhalation. Acknowledging the challenges of integrating evidence across independent sources, we contextualize laboratory-scale exposure approaches according to the biological processes that they model and offer suggestions for ensuring relevance to the human condition. Noting that wildfires are significant contributors to ambient air pollution, we compare the biological responses triggered by WFS to those of other harmful pollutants. We also review evidence for how WFS inhalation may trigger mechanisms that have been proposed as mediators of adverse cardiovascular effects upon exposure to air pollution. We finally conclude by highlighting research areas that demand further consideration. Overall, we aspire for this work to serve as a catalyst for regulatory initiatives to mitigate the adverse cardiovascular effects of WFS inhalation in the community and alleviate the occupational risk in wildland firefighters.

The Fbn1 gene variant governs passive ascending aortic mechanics in the mgΔlpn mouse model of Marfan syndrome when superimposed to perlecan haploinsufficiency.

Introduction: Ascending thoracic aortic aneurysms arise from pathological tissue remodeling that leads to abnormal wall dilation and increases the risk of fatal dissection/rupture. Large variability in disease manifestations across family members who carry a causative genetic variant for thoracic aortic aneurysms suggests that genetic modifiers may exacerbate clinical outcomes. Decreased perlecan expression in the aorta of mgΔlpn mice with severe Marfan syndrome phenotype advocates for exploring perlecan-encoding Hspg2 as a candidate modifier gene. Methods: To determine the effect of concurrent Hspg2 and Fbn1 mutations on the progression of thoracic aortopathy, we characterized the microstructure and passive mechanical response of the ascending thoracic aorta in female mice of four genetic backgrounds: wild-type, heterozygous with a mutation in the Fbn1 gene (mgΔlpn), heterozygous with a mutation in the Hspg2 gene (Hspg2+/-), and double mutants carrying both the Fbn1 and Hspg2 variants (dMut). Results: Elastic fiber fragmentation and medial disarray progress from the internal elastic lamina outward as the ascending thoracic aorta dilates in mgΔlpn and dMut mice. Concurrent increase in total collagen content relative to elastin reduces energy storage capacity and cyclic distensibility of aortic tissues from mice that carry the Fbn1 variant. Inherent circumferential tissue stiffening strongly correlates with the severity of aortic dilatation in mgΔlpn and dMut mice. Perlecan haploinsufficiency superimposed to the mgΔlpn mutation curbs the viability of dMut mice, increases the occurrence of aortic enlargement, and reduces the axial stretch in aortic tissues. Discussion: Overall, our findings show that dMut mice are more vulnerable than mgΔlpn mice without an Hspg2 mutation, yet later endpoints and additional structural and functional readouts are needed to identify causative mechanisms.

Vascular Remodeling During Late-Gestation Pregnancy: An In-Vitro Assessment of the Murine Ascending Thoracic Aorta.

Maternal mortality due to cardiovascular disease is a rising concern in the U.S. Pregnancy triggers changes in the circulatory system, potentially influencing the structure of the central vasculature. Evidence suggests a link between a woman's pregnancy history and future cardiovascular health, but our understanding remains limited. To fill this gap, we examined the passive mechanics of the murine ascending thoracic aorta during late gestation. By performing biaxial mechanical testing on the ascending aorta, we were able to characterize the mechanical properties of both control and late-gestation tissues. By examining mechanical, structural, and geometric properties, we confirmed that remodeling of the aortic wall occurred. Morphological and mechanical properties of the tissue indicated an outward expansion of the tissue, as reflected in changes in wall thickness (∼12% increase) and luminal diameter (∼6% increase) at its physiologically loaded state in the pregnant group. With these geometric adaptations and despite increased hemodynamic loads, pregnancy did not induce significant changes in the tensile wall stress at the similar physiological pressure levels of the pregnant and control tissues. The alterations also included reduced intrinsic stiffness in the circumferential direction (∼18%) and reduced structural stiffness (∼26%) in the pregnant group. The observed vascular remodeling maintained the elastic stored energy of the aortic wall under systolic loads, indicating preservation of vascular function. Data from our study of pregnancy-related vascular remodeling will provide valuable insights for future investigations of maternal cardiovascular health.

E-cigarette aerosol exposure effect on bone biomechanical properties in murine models.

Numerous studies have shown the detrimental health effects of tobacco smoking on bone volume and strength in human and animal models. Little is known regarding the impacts of e-cigarettes, a form of smoke-less nicotine intake, despite their growing population of users. This study uses murine models to evaluate the effects of exposure to e-cigarette aerosols (JUUL) on bone structure and strength through micro-CT imaging and mechanical testing. JUUL mice had more trabecular bone in thickness and volume, yet lower ultimate stress and modulus values in the cortical bone than the control mice. These outcomes suggest that, although vaping can result in a higher bone volume, this bone is weaker than average. E-cigarettes should be examined more closely regarding adolescence and long-term consequences on skeletal health.

Age is superior to aortopathy phenotype as a predictor of aortic mechanics in patients with bicuspid valve.

OBJECTIVES: Bicuspid aortic valve (BAV) aortopathy is defined by 3 phenotypes-root, ascending, and diffuse-based on region of maximal aortic dilation. We sought to determine the association between aortic mechanical behavior and aortopathy phenotype versus other clinical variables. METHODS: From August 1, 2016, to March 1, 2023, 375 aortic specimens were collected from 105 patients undergoing elective ascending aortic aneurysm repair for BAV aortopathy. Planar biaxial data (191 specimens) informed constitutive descriptors of the arterial wall that were combined with in vivo geometry and hemodynamics to predict stiffness, stress, and energy density under physiologic loads. Uniaxial testing (184 specimens) evaluated failure stretch and failure Cauchy stress. Boosting regression was implemented to model the association between clinical variables and mechanical metrics. RESULTS: There were no significant differences in mechanical metrics between the root phenotype (N = 33, 31%) and ascending/diffuse phenotypes (N = 72, 69%). Biaxial testing demonstrated older age was associated with increased circumferential stiffness, decreased stress, and decreased energy density. On uniaxial testing, longitudinally versus circumferentially oriented specimens failed at significantly lower Cauchy stress (50th [15th, 85th percentiles]: 1.0 [0.7, 1.6] MPa vs 1.9 [1.3, 3.1] MPa; P < .001). Age was associated with decreased failure stretch and stress. Elongated ascending aortas were also associated with decreased failure stress. CONCLUSIONS: Aortic mechanical function under physiologic and failure conditions in BAV aortopathy is robustly associated with age and poorly associated with aortopathy phenotype. Data suggesting that the root phenotype of BAV aortopathy portends worse outcomes are unlikely to be related to aberrant, phenotype-specific tissue mechanics.

Longitudinal versus circumferential biomechanical behavior of the aneurysmal ascending aorta.

OBJECTIVES: We evaluate the independent effects of patient and aortic tissue characteristics on biaxial physiologic mechanical metrics in aneurysmal and nonaneurysmal tissues, and uniaxial failure metrics in aneurysmal tissue, comparing longitudinal and circumferential behavior. METHODS: From February 2017 to October 2022, 382 aortic specimens were collected from 134 patients; 268 specimens underwent biaxial testing, and 114 specimens underwent uniaxial testing. Biaxial testing evaluated Green-Lagrange transition strain and low and high tangent moduli. Uniaxial testing evaluated failure stretch, Cauchy stress, and low and high tangent moduli. Longitudinal gradient boosting models were implemented to estimate mechanical metrics and covariates of importance. RESULTS: On biaxial testing, nonaneurysmal tissue was less deformable and exhibited a lower transition strain than aneurysmal tissue in the longitudinal (0.18 vs 0.30, P < .001) and circumferential (0.25 vs 0.30, P = .01) directions. Older age and increasing ascending aortic length contributed most to predicting transition strain. On uniaxial testing, longitudinal specimens failed at lower stretch (1.4 vs 1.5, P = .003) and Cauchy stress (1.0 vs 1.9 kPa, P < .001) than circumferential specimens. Failure stretch and Cauchy stress were most strongly associated with tissue orientation and decreased sharply with older age. Age, ascending aortic length, and tissue thickness were the most frequent covariates predicting mechanical metrics across 10 prediction models. CONCLUSIONS: Age was the strongest predictor of mechanical behavior. After adjusting for age, nonaneurysmal tissue was less deformable than aneurysmal tissue. Differences in longitudinal and circumferential mechanics contribute to tissue dysfunction and failure in ascending aneurysms. This highlights the need to better understand the effects of age, ascending aortic length, and thickness on clinical aortic behavior.

Design and Characterization of a Multistage Peptide-Based Vaccine Platform to Target Mycobacterium tuberculosis Infection.

The complex immunopathology ofMycobacterium tuberculosis(Mtb) is one of the main challenges in developing a novel vaccine against this pathogen, particularly regarding eliciting protection against both active and latent stages. Multistage vaccines, which contain antigens expressed in both phases, represent a promising strategy for addressing this issue, as testified by the tuberculosis vaccine clinical pipeline. Given this approach, we designed and characterized a multistage peptide-based vaccine platform containing CD4+ and CD8+ T cell epitopes previously validated for inducing a relevant T cell response against Mtb. After preliminary screening, CFP10 (32-39), GlfT2 (4-12), HBHA (185-194), and PPE15 (1-15) were selected as promising candidates, and we proved that the PM1 pool of these peptides triggered a T cell response in Mtb-sensitized human peripheral blood mononuclear cells (PBMCs). Taking advantage of the use of thiol-maleimide chemoselective ligation, we synthesized a multiepitope conjugate (Ac-CGHP). Our results showed a structure-activity relationship between the conjugation and a higher tendency to fold and assume an ordered secondary structure. Moreover, the palmitoylated conjugate (Pal-CGHP) comprising the same peptide antigens was associated with an enhanced cellular uptake in human and murine antigen-presenting cells and a better immunogenicity profile. Immunization study, conducted in BALB/c mice, showed that Pal-CGHP induced a significantly higher T cell proliferation and production of IFNγ and TNFα over PM1 formulated in the Sigma Adjuvant System.

Biomechanical remodeling of the murine descending thoracic aorta during late-gestation pregnancy.

With the rise in maternal mortality rates and the growing body of epidemiological evidence linking pregnancy history to maternal cardiovascular health, it is essential to comprehend the vascular remodeling that occurs during gestation. The maternal body undergoes significant hemodynamic alterations which are believed to induce structural remodeling of the cardiovascular system. Yet, the effects of pregnancy on vascular structure and function have not been fully elucidated. Such a knowledge gap has limited our understanding of the etiology of pregnancy-induced cardiovascular disease. Towards bridging this gap, we measured the biaxial mechanical response of the murine descending thoracic aorta during a normotensive late-gestation pregnancy. Non-invasive hemodynamic measurements confirmed a 50% increase in cardiac output in the pregnant group, with no changes in peripheral blood pressure. Pregnancy was associated with significant wall thickening ( ∼14%), an increase in luminal diameter ( ∼6%), and material softening in both circumferential and axial directions. This expansive remodeling of the tissue resulted in a reduction in tensile wall stress and intrinsic tissue stiffness. Collectively, our data indicate that an increase in the geometry of the vessel may occur to accommodate for the increase in cardiac output and blood flow that occurs in pregnancy. Similarly, wall thickening accompanied by increased luminal diameter, without a change in blood pressure may be a necessary mechanism to decrease the tensile wall stress, and avoid pathophysiological events following late gestation.

Breast Lesions of Uncertain Malignant Potential (B3) and the Risk of Breast Cancer Development: A Long-Term Follow-Up Study.

Breast lesions of uncertain malignant potential (B3) are frequently diagnosed in the era of breast cancer (BC) screening and their management is controversial. They are generally removed surgically, but some international organizations and guidelines for breast research suggest follow-up care alone or, more recently, propose vacuum-assisted excision (VAE). The risk of upgrade to BC is known, but very little data exist on its role as risk factor for future BC development. We analyzed 966 B3 lesions diagnosed at our institution, 731 of which had long-term follow-up available. Surgical removal was performed in 91%, VAE in 3.8%, and follow-up in 5.2% of cases. The B3 lesions included flat epithelial atypia (FEA), atypical ductal hyperplasia (ADH), lobular intraepithelial neoplasia (LIN), atypical papillary lesions (PLs), radial scars (RSs), and others. Overall, immediate upgrade to BC (invasive or in situ) was 22.7%. After long-term follow-up, 9.2% of the patients were diagnosed with BC in the same or contralateral breast. The highest risk was associated with ADH diagnosis, with 39.8% of patients upgraded and 13.6% with a future BC diagnosis (p < 0.0001). These data support the idea that B3 lesions should be removed and provide evidence to suggest annual screening mammography for women after a B3 diagnosis because their BC risk is considerably increased.

Lengthwise regional mechanics of the human aneurysmal ascending thoracic aorta.

The prognosis of patients undergoing emergency endovascular repair of ascending thoracic aortic aneurysm (ATAA) depends on defect location, with root disease bearing worse outcomes than proximal or distal aortopathy. We speculate that a spatial gradient in aneurysmal tissue mechanics through the length of the ascending thoracic aorta may fuel noted survival discrepancies. To this end, we performed planar biaxial testing on 153 root, proximal, and distal segments of ATAA samples collected from 80 patients receiving elective open surgical repair. Following data averaging via surface fitting-based interpolation of strain-controlled protocols, we combined in-vitro and in-vivo measurements of loads and geometry to resolve inflation-extension kinematics and evaluate mechanical metrics of stress, stiffness, and energy at consistent deformation levels. Representative (averaged) experimental data and simulated in-vivo conditions revealed significantly larger biaxial stiffness at the root compared to either proximal or distal tissues, which persisted as the entire aorta stiffened during aging. Advancing age further reduced biaxial stretch and energy storage, a measure of aortic function, across all ATAA segments. Importantly, age emerged as a stronger predictor of tissue mechanics in ATAA disease than either bicuspid aortic valve or connective tissue disorders. Besides strengthening the general understanding of aneurysmal disease, our findings provide specifications to customize the design of stent-grafts for the treatment of ATAA disease. Optimization of deployment and interaction of novel endovascular devices with the local native environment is expected to carry significant potential for improving clinical outcomes. STATEMENT OF SIGNIFICANCE: Elucidating the lengthwise regional mechanics of ascending thoracic aortic aneurysms (ATAAs) is critical for the design of endovascular devices tailored to the ascending aorta. Stent-grafts provide a less invasive alternative to support the long-term survival of ATAA patients ineligible for open surgical repair. In this study, we developed a numerical framework that combines semi-inverse constitutive and forward modeling with in-vitro and in-vivo data to extract mechanical descriptors of ATAA tissue behavior at physiologically meaningful deformation. Moving distally from the aortic root to the first ascending aortic branch, we observed a progressive decline in biaxial stiffness. Furthermore, we showed that aging leads to reduced aortic function and is a stronger predictor of mechanics than either valve morphology or underlying syndromic disorder.

Ex vivo biaxial load testing analysis of aortic biomechanics demonstrates variation in elastic energy distribution across the aortic zone zero.

OBJECTIVES: We hypothesized that tissue characteristics vary significantly along zone zero, which may be reflected by regional differences in stored elastic energy. Our objectives were to (1) characterize the regional variation in stored elastic energy within tissues of the aortic zone zero and (2) identify the association between this variation and patient characteristics. METHODS: From February 2018 to January 2021, 123 aortic tissue samples were obtained from the aortic root and proximal and distal ascending aortas of 65 adults undergoing elective ascending aorta replacement. Biaxial biomechanics testing was performed to obtain tissue elastic energy at the inflection point and compared with patient demographics and preoperative computed tomography imaging. Coefficient models were fit using B-spline to interrogate the relationship among elastic energy, region, and patient characteristics. RESULTS: Mean elastic energy at inflection point was 24.3 ± 15.6 kJ/m3. Elastic energy increased significantly between the root and proximal, and root and distal ascending aorta and decreased with increasing age. Differences due to history of connective tissue disorder and bicuspid aortic valve were significant but diminished when controlled for other patient characteristics. Among covariates, age and region were found to be the most important predictors for elastic energy. CONCLUSIONS: Aortic tissue biomechanical metrics varied across regions and with patient characteristics within the aortic zone zero. Assessment of endovascular outcomes in the ascending aorta must closely consider the region of deployment and variable tissue qualities along the length of the landing zone. Regional variation in tissue characteristics should be incorporated into existing patient-specific models of aortic mechanics.

Prolonged smoldering Douglas fir smoke inhalation augments respiratory resistances, stiffens the aorta, and curbs ejection fraction in hypercholesterolemic mice.

While mounting evidence suggests that wildland fire smoke (WFS) inhalation may increase the burden of cardiopulmonary disease, the occupational risk of repeated exposure during wildland firefighting remains unknown. To address this concern, we evaluated the cardiopulmonary function in mice following a cumulative exposure to lab-scale WFS equivalent to a mid-length wildland firefighter (WLFF) career. Dosimetry analysis indicated that 80 exposure hours at a particulate concentration of 22 mg/m3 yield in mice the same cumulative deposited mass per unit of lung surface area as 3600 h of wildland firefighting. To satisfy this condition, male Apoe-/- mice were whole-body exposed to either air or smoldering Douglas fir smoke (DFS) for 2 h/day, 5 days/week, over 8 consecutive weeks. Particulate size in DFS fell within the respirable range for both mice and humans, with a count median diameter of 110 ± 20 nm. Expiratory breath hold in mice exposed to DFS significantly reduced their minute volume (DFS: 27 ± 4; Air: 122 ± 8 mL/min). By the end of the exposure time frame, mice in the DFS group exhibited a thicker (DFS: 109 ± 3; Air: 98 ± 3 µm) and less distensible (DFS: 23 ± 1; Air: 28 ± 1 MPa-1) aorta with reduced diastolic blood augmentation capacity (DFS: 53 ± 2; Air: 63 ± 2 kPa). Cardiac magnetic resonance imaging further revealed larger end-systolic volume (DFS: 14.6 ± 1.1; Air: 9.9 ± 0.9 µL) and reduced ejection-fraction (DFS: 64.7 ± 1.0; Air: 75.3 ± 0.9 %) in mice exposed to DFS. Consistent with increased airway epithelium thickness (DFS: 10.4 ± 0.8; Air: 7.6 ± 0.3 µm), airway Newtonian resistance was larger following DFS exposure (DFS: 0.23 ± 0.03; Air: 0.20 ± 0.03 cmH2O-s/mL). Furthermore, parenchyma mean linear intercept (DFS: 36.3 ± 0.8; Air: 33.3 ± 0.8 µm) and tissue thickness (DFS: 10.1 ± 0.5; Air: 7.4 ± 0.7 µm) were larger in DFS mice. Collectively, mice exposed to DFS manifested early signs of cardiopulmonary dysfunction aligned with self-reported events in mid-career WLFFs.

Respiratory mechanics following chronic cigarette smoke exposure in the Apoe[Formula: see text] mouse model.

Even though cigarette smoking (CS) has been on the decline over the past 50 years, it is still the leading cause of preventable premature death in the United States. Preclinical models have investigated the cardiopulmonary effects of CS exposure (CSE), but the structure-function relationship in the respiratory system has not yet been fully explored. To evaluate these relationships, we exposed female apolipoprotein E-deficient (Apoe[Formula: see text]) mice to mainstream CS ([Formula: see text]) for 5 days/week over 24 weeks with room air as a control (AE, [Formula: see text]). To contextualize the impact of CSE, we also assessed the natural aging effects over 24 weeks of air exposure (baseline, [Formula: see text]). Functional assessments were performed on a small animal mechanical ventilator (flexiVent, SCIREQ), where pressure-volume curves and impedance data at four levels of positive end-expiratory pressure ([Formula: see text]) and with increasing doses of methacholine were collected. Constant phase model parameters ([Formula: see text]: Newtonian resistance, H: coefficient of tissue elastance, and G: coefficient of tissue resistance) were calculated from the impedance data. Perfusion fixed-left lung tissue was utilized for quantification of parenchyma airspace size and tissue thickness, airway wall thickness, and measurements of elastin, cytoplasm + nucleus, fibrin, and collagen content for the parenchyma and airways. Aging caused the lung to become more compliant, with an upward-leftward shift of the pressure-volume curve and a reduction in all constant phase model parameters. This was supported by larger parenchyma airspace sizes, with a reduction in cell cytoplasm + nucleus area. Airway walls became thinner, even though low-density collagen content increased. In contrast, CSE caused a downward-rightward shift of the pressure-volume curve along with an increase in H, G, and hysteresivity ([Formula: see text]). Organ stiffening was accompanied by enhanced airway hyper-responsiveness following methacholine challenge. Structurally, parenchyma airspaces enlarged, as indicated by an increase in equivalent airspace diameter ([Formula: see text]), and the septum thickened with significant deposition of low-density collagen along with an influx of cells. Airway walls thickened due to deposition of both high and low-density collagen, infiltration of cells, and epithelial cell elongation. In all, our data suggest that CSE in female Apoe[Formula: see text] mice reduces respiratory functionality and causes morphological alterations in both central and peripheral airways that results in lung stiffening, compared to AE controls.

Aortic diameter is a poor predictor of aortic tissue failure metrics in patients with ascending aneurysms.

OBJECTIVES: There is growing consensus that aortic diameter is a flawed predictor of aortic dissection risk. We hypothesized that aortic tissue metrics would be better predicted by clinical metrics other than aortic diameter. Our objectives were to (1) characterize circumferential aortic failure stress and stretch as a result of aortic size and patient demographics, and (2) identify the influence of bicuspid aortic valve on failure metrics. METHODS: From February 2018 to January 2021, 136 aortic tissue samples were obtained from 86 adults undergoing elective ascending aorta repair. Uniaxial biomechanical testing to failure, defined as a full-thickness central tear, was performed to obtain tissue failure stress and failure stretch and compared with clinical data and preoperative computed tomography imaging. The relationships among aortic diameter, patient demographics, and failure metrics were assessed using random forest regression models. RESULTS: Median failure stress was 1.46 (1.02-1.94) megapascals, and failure stretch was 1.36 (1.27-1.54). Regression models correlated moderately with failure stress (R2 = 0.557) and highly with failure stretch (R2 = 0.806). Failure stress decreased with increasing age, lower body mass index, thicker tissue, and tricuspid aortic valves, whereas failure stretch was most highly correlated with age. Aortic area-to-height index outperformed aortic diameter in all models. CONCLUSIONS: Aneurysmal ascending aortic tissue failure metrics correlated with available clinical metrics. Greater tissue thickness, older age, and tricuspid aortic valve morphology outperformed aortic diameter, warranting further investigation into the role of a patient-specific multifactorial dissection risk assessment over aortic diameter as a sole marker of aortic tissue integrity.