Citations

AbstractThe sliding filament theory explains skeletal muscle fibre force change as a function of length based on the overlap of actin and myosin filaments. Although this length‐tension (LT) relationship has been well investigated in animal models, it is not known whether this microscopic sarcomere LT property can be scaled up five orders of magnitude to explain the LT behaviour of a long human muscle such as the gracilis. The goal of this study is to validate the sarcomere LT curve in humans based on human filament length combined with in vivo experimental data. Intraoperative measurements of maximal tetanic force and muscle‐tendon unit length at four different joint configurations (JC) were obtained from 19 patients undergoing free functioning muscle transfer surgery. With physiologically measured fibre length and estimated sarcomere shortening resulting from tendon compliance, we show that 79.7% variance in isometric force data is explained by a simple human sarcomere LT model. This study demonstrates that the human whole muscle LT relationship can be modelled by the sliding filament theory given patient‐specific fibre length, filament length, tendon compliance and sarcomere shortening. imageKey points Whole human gracilis muscle isometric length‐tension relationships were measured in the operating room. Grouped whole muscle raw length‐tension curves showed no obvious form. The width of each experimental length‐tension curve was highly variable across subjects and used to predict fibre length (serial sarcomere number). After whole muscle length‐tension curves were normalized to each patient's serial sarcomere number, the whole human muscle length‐tension curve was well predicted by the sliding filament theory.

Abstract RATIONALE: Chronic lower respiratory diseases (CLRD) confer higher risks from respiratory viral infections, hence CLRD patients are prioritized for influenza, pneumococcal, and COVID-19 vaccination. Nonetheless, vaccine deferral and declination remain common. Given that COVID-19 vaccination is particularly polarizing, and attitudes toward it may differ from other vaccines, we assessed COVID-19 vaccination behaviors and attitudes in adults with versus without CLRD and/or smoking history, which is strongly associated with CLRD risk. METHODS: We pooled data from 10 cohorts participating in the Collaborative Cohort of Cohorts for COVID-19 Research (C4R) that collected pre-pandemic data on self-reported physician diagnosis of asthma or COPD. C4R assessed COVID-19 vaccination status through three waves of standardized questionnaires (2020-2022, 2021-2023, 2023-2024). Prompt COVID-19 vaccination was defined as self-report of receiving at least one COVID-19 vaccine by May 1, 2021. Cumulative COVID-19 vaccine count was self-reported on the Wave 3 Questionnaire. Vaccine attitudes and receipt of influenza and/or pneumococcal vaccines were self-reported on the Wave 1 or 2 Questionnaire. Age-adjusted Poisson regression was used to test associations of vaccination behaviors with CLRD and smoking status at the most recent pre-pandemic exam. RESULTS: Of 20,034 participants (pre-pandemic COPD, 9.3%; asthma, 11.7%; current smoking, 13.4%; former smoking, 36.3%), 64.2% reported prompt COVID-19 vaccination. Among the subset of 10,626 participants completing the Wave 3 Questionnaire in 2023-24, the median COVID-19 vaccine count was 3 (Q1:2, Q3:4). Compared to participants without CLRD, prompt vaccination was more likely in those with asthma (RR=1.04, 95%CI:1.01-1.07, p=0.008) and less likely with COPD (RR=0.94, 95%CI:0.91-0.98, p=0.001), but there were no differences in doses for asthma and COPD. Compared to never smokers, former smoking participants were more likely to receive prompt vaccination (RR=1.11, 95%CI:1.08-1.13, p<0.0001) and more vaccine doses (RR=1.03, 95%CI:1.01-1.05, p=0.015); conversely, current smoking was inversely associated with prompt vaccination (RR=0.94, 95%CI:0.91-0.97, p=0.001) and was associated with fewer doses (RR=0.93, 95%CI:0.89-0.96, p<0.0001). Participants with CLRD versus without CLRD were more likely to report receiving influenza and pneumococcal vaccines, but they were more likely to believe that vaccines are unsafe or ineffective (figure). CONCLUSIONS: COPD was associated with lower likelihood of prompt COVID-19 vaccination. Current smoking was associated with both lower likelihood of prompt COVID-19 vaccination and a lower number of COVID-19 vaccine doses by 2023-24. These associations may be partly attributed to negative vaccine attitudes and beliefs. How the COVID-19 pandemic may have influenced vaccine behaviors and attitudes merits additional study.

Abstract RATIONALE: Deferral and declination of the COVID-19 vaccine is correlated with many factors, including different health guidelines and difficulties accessing the vaccine. In the US, COVID-19 vaccines were made available in tranches of clinical risk starting in December 2020 and were available to all adults on April 19, 2021. In the post-pandemic period, repeating COVID-19 vaccination with updated formulations is broadly recommended. Given that the public health impact of vaccine allocation strategies depends on public acceptance of vaccination, we aimed to evaluate demographic, clinical and social correlates of (1) receiving at least one COVID-19 vaccine by May 1, 2021 (prompt vaccination) and (2) the total number of vaccine doses received (vaccine count) through 2023-2024. METHODS: The Collaborative Cohort of Cohorts for COVID-19 Research (C4R) is a prospective observational meta-cohort study comprising 14 extant NIH-funded population-based cohorts. C4R assessed COVID-19 vaccination using three waves of standardized questionnaires (2020-2021, 2021-2023, 2023-2024). Prompt vaccination was defined by participant self-report of vaccination before May 1, 2021; participants vaccinated after May1, 2021 were classified as non-prompt; participants with missing vaccination information were excluded. Vaccine count was defined by self-report on the 2023-2024 wave Questionnaire. Demographic, clinical and social factors were classified by self-report and/or objective measures from the most recent pre-pandemic cohort exam. Poisson models regressed either prompt vaccination or vaccine count on pre-pandemic factors. RESULTS: Of 17,866 participants (mean age, 6713 years; 60.1% female; 42.1% non-Hispanic White, 22.0% Black, 28.9% Hispanic/Latino, 3.4% American Indian, 2.3% South Asian, 1.4% East Asian), 11,481 (64.3%) reported prompt vaccination. Of the subset of 14,529 participants completing the Wave 3 questionnaire, the median vaccine count in 2023-24 was 3 (Q1, 2; Q3 4). Likelihood of prompt vaccination was higher with greater age, income, and education and with history of diabetes and hypertension; prompt vaccination was less likely with male sex, current smoking, and non-White race and ethnicity (table). Similar associations were observed with respect to vaccine count (table). CONCLUSIONS: In a diverse C4R cohort community-based sample, earlier and greater COVID-19 vaccination was associated with older age and several clinical comorbidities; in contrast, later and lesser vaccine uptake was observed among historically marginalized groups. Whether disparities in COVID-19 vaccination could contribute to disparities in post-COVID-19 conditions merits further investigation.

Abstract IntroductionFungal infections, particularly in the Midwest, can often be asymptomatic and may mimic primary lung cancer. This case illustrates pulmonary histoplasmosis in an 80-year-old woman with a history of lung cancer highlighting the diagnostic challenges presented when both conditions coexist.Case SummaryAn 80-year-old woman (prior smoking history of 47-pack-years) with synchronous lung cancers (poorly differentiated non-small cell carcinoma with squamous differentiation in the left lower lobe and squamous cell carcinoma in the right lower lobe) previously underwent radiation therapy to both lesions. She was admitted for shortness of breath and cough and was initially diagnosed with pneumonia based on CT findings. Despite multiple courses of antibiotics, her symptoms persisted over 2 months, improving only temporarily with a short course of prednisone. A follow-up CT revealed increasing confluent thick-walled cavitation in the posterior right upper lobe and superior segment of the right lower lobe concerning for cavitating/necrotizing pneumonia versus possible cancer progression. A PET-CT scan (Fig.1A) showed significant FDG uptake in the right upper lobe lesion and mild uptake in mediastinal lymph nodes complicating the differentiation between cancer and infection. Bronchoscopy with biopsy of an endobronchial lesion in the posterior segment of right lower lobe revealed necrotizing granulomatous inflammation (Fig.1B) with GMS stain showing the presence of fungal organisms suggestive of histoplasmosis. Histoplasma PCR from bronchoalveolar lavage was also positive. She was subsequently started on antifungal therapy for a planned one-year treatment course. DiscussionHigh positron emission tomography (PET) avidity in chest imaging is often linked to aggressive tumors but can also indicate benign conditions such as fungal infections. A “flip-flop sign” on PET imaging, where nodal activity surpasses that of a lung nodule, is typically seen in benign lung lesions, particularly fungal infections. However, infections and inflammatory conditions may also show high PET avidity mimicking malignancy. Endobronchial lesions, common in lung cancer, are less frequently associated with infections. In patients with a history of cancer, active lung infection, and PET-avid lesions without the flip-flop sign, invasive testing is usually required to differentiate between infection and malignancy. In this case, our patient with a history of lung cancer and a PET-avid lung lesion was found to have pulmonary histoplasmosis after invasive testing highlighting the need for comprehensive evaluation.ConclusionThis case emphasizes the importance of considering fungal infections in the differential diagnosis of PET-avid pulmonary lesions, particularly in patients with a history of malignancy.

Abstract Rationale: SARS-CoV-2 infection may be associated with new or worsening respiratory symptoms that, if persistent, may contribute to “Long COVID.” Research is needed on the prevalence and risk determinants of Long COVID and related respiratory symptoms in adults with and without pre-existing obstructive lung disease or smoking history. Methods: C4R is a prospective, observational study that collected information on SARS-CoV-2 infection using standardized methods across 14 NIH-funded cohorts. The third wave of C4R questionnaires, administered June 2023 to January 2025, assessed self-reported Long COVID via the question, “Do you think that you are experiencing, or have ever experienced, what has been called “long COVID,” or symptoms related to COVID at least a month after your infection?” Questionnaires also assessed the presence (vs absence) of 22 symptoms that have been linked to Long COVID, including cough, shortness of breath, and post-exertional malaise. Pre-pandemic obstructive lung disease (COPD or asthma) and smoking status (ever/never) were harmonized from self-reported data collected at the most recent pre-pandemic cohort exam. Poisson regression was used to assess prevalence ratios (PRs) adjusting for age, sex, BMI, education, and pre-pandemic hypertension, diabetes, cardiovascular disease, and depressive symptoms. PRs for respiratory symptoms were tested according to self-reported Long COVID and history of non-hospitalized or hospitalized infection; effect modification by pre-pandemic lung disease and smoking was assessed by multiplicative interaction terms and in fully stratified models. Results: Among 23,434 questionnaire respondents, 1,484 (6.3%) self-reported Long COVID, including 246/1,262 (19.5%) with pre-pandemic lung disease and 664/4,018 (16.5%) with smoking history. The adjusted PR for Long COVID was 1.17 (95%CI:0.99-1.39;P=0.06) comparing participants with/without lung disease and 1.17 (95%CI:1.04-1.32;P=0.01) comparing participants with/without smoking history. Respiratory symptoms were more prevalent in those with self-reported Long COVID, as well as in those with a history of hospitalized or non-hospitalized infection (Table). Associations were generally stronger in participants without pre-pandemic lung disease (p-interaction<0.05 for all comparisons). Respiratory symptoms were also more prevalent with a history of repeated, and pre-Omicron infections, and were less prevalent among participants vaccinated prior to their first infection; findings were similar even after excluding participants with self-reported Long COVID. Conclusions: Long COVID is common, particularly in adults with pre-existing COPD or asthma or smoking history. Long COVID and history of SARS-CoV-2 infection, including non-hospitalized infections, was associated with greater respiratory symptom burden. Whether SARS-CoV-2 infection or Long COVID are associated with development or progression of obstructive lung diseases warrants future studies.

Abstract RATIONALE: Chronic kidney disease (CKD) is common in the general population and is associated with inflammation and compromised immune function. Since these mechanisms are hypothesized to promote severe COVID-19, we tested associations of pre-pandemic CKD with incident COVID-19 hospitalization or death in a large, multi-ethnic, US general population-based meta-cohort of adults. METHODS: Data were harmonized and pooled from 9 NIH-funded longitudinal cohorts participating in the Collaborative Cohort of Cohorts for COVID-19 Research (C4R). CKD was classified by KDIGO 2024 CKD guideline (Low Risk, Moderately Increased Risk, High Risk, Very High Risk) using pre-pandemic urinary albumin-to-creatinine ratio (uACR) and estimated glomerular filtration rate using creatinine (eGFRcr). Incident COVID-19 hospitalization or death was ascertained over 2020−2023 via self-report and active surveillance, with medical record adjudication in a subset. In our primary analysis, we assessed associations between CKD stages and incident COVID-19 hospitalization or death. A secondary analysis examined joint association of CKD stages and the number of comorbidities (obesity, hypertension, diabetes, and cardiovascular disease) with the severe COVID-19. Multivariable hazard ratios (HRs) were estimated by cause-specific Cox regression, adjusting for socio-demographics and smoking. RESULTS: Among 26,039 multi-ethnic adult participants (mean age 66.1±14.8, 60.6 % female, 28.6% Whites, 3.2% Asians, 20.6% Blacks, 41.3% Hispanics, 6.3% American Indians) with a median follow-up of 550 days since the onset of the pandemic (baseline: March 1, 2020), there were 734 incident COVID-19 hospitalizations or deaths. The mean time since CKD markers were measured before the baseline was 6.5 years. The cumulative incidence of severe COVID-19 was 2.3, 3.5, 6.5, and 7.3% across CKD risk stages, and similar patterns were observed within variant types (Figure 1). Compared to participants with Low Risk of CKD, there was a graded increased hazards of severe COVID-19 across CKD stages, with HRs (95% CIs) of 1.27 (1.03−1.55) for Moderately Increased Risk, 2.33 (1.77−3.06) for High Risk, and 2.72 (1.89−3.92) for Very High Risk. In a joint analysis, both increased CKD risk and a higher number of comorbidities were associated with a higher risk of severe COVID-19, showing the highest HR of 12.29 (5.75−26.27) in Very High Risk individuals with four comorbidities compared to Low Risk individuals with none. CONCLUSIONS: Higher CKD stages were associated with a greater risk of COVID-19 hospitalization or death and the risk is substantially heightened with additional comorbidities. These results suggest that adults with CKD and related comorbidities may merit enhanced COVID-19 risk mitigation.

Abstract Rational: Talc pleurodesis is an effective intervention for preventing recurrent pleural effusions and pneumothoraces, particularly in non-surgical candidates. Due to its efficacy and safety, it is recommended as the most effective sclerosant for pleurodesis. However, in some cases, the initial pleurodesis fails, necessitating a repeat procedure. The efficacy of repeat talc pleurodesis after an initial failure is an area that requires further exploration. This study explores the safety and efficacy of repeat talc pleurodesis among patients who did not respond to the initial intervention. Methods: This retrospective study analyzed hospitalized patients who underwent 4g talc slurry pleurodesis from 2019 to 2024, focusing on demographics, comorbidities, initial pleurodesis failure, and recurrence rates. Pleurodesis failure was identified by lung sliding, recurrent effusion, or pneumothorax during the same hospitalization. The primary outcome was recurrence post-discharge, assessed by pleural effusion or pneumothorax within 180 days post-repeat pleurodesis. Results: This study included 94 patients (52.1% male, 47.9% female) with a mean age of 67.6. Among them, 79 (84%) received a single 4g dose of talc, while 15 (16%) received multiple 4g talc doses for initial pleurodesis. Recurrence occurred in 20 (25.3%) of the single-dose group and 1 (6.7%) of the multiple-dose group within 180 days, though the difference was not statistically significant (p=0.112). Recurrence-free rates were 93.6% at 30 days, 85.1% at 90 days, and 77.7% at 180 days. Of the 20 patients with recurrence after a single 4g dose of talc, 8 (40%) underwent repeat pleurodesis, with only one recurrence requiring surgical intervention. Additionally, there was no recurrence after repeat talc pleurodesis in the one patient with recurrence after receiving multiple 4g talc doses for initial pleurodesis. No associations were found between recurrence rates and factors like gender (p=0.213) or comorbidities (emphysema, COPD, lung malignancy). Chest pain was a common complaint, but no cases of respiratory distress were reported post-pleurodesis. Conclusion: The efficacy of initial talc pleurodesis (77.7%-93.6%) in this cohort aligns with existing literature. Multiple-dose talc pleurodesis effectively prevented recurrence in 93.3% of patients, with no reported respiratory distress. Additionally, repeat talc pleurodesis was successful in 87.5% of those with recurrence after an initial single 4g dose. These findings support multiple-dose talc pleurodesis and repeat talc pleurodesis as safe and effective options for preventing recurrence post-initial failure and post-repeat talc pleurodesis, respectively. Although no significant recurrence predictors were identified, future research could focus on patient-specific factors to enhance treatment selection and optimize outcomes.

Abstract A 77-year-old female with history of a right lower lobe adenocarcinoma (pT1a, pN0) underwent right lower lobectomy in August 2023, which subsequently was complicated by a bronchopleural fistula at the level of the right lower lobe bronchial stump. This led to a chronic hydropneumothorax, including a fungal empyema requiring placement of a 14-French thoracostomy tube and prolonged antimicrobial treatment over the next year. In June 2024 she underwent bronchoscopy, with application of argon plasma coagulation (APC) to cauterize the immediate area abutting the bronchopleural fistula and Gore VBX stent placement from the bronchus intermedius to the right middle lobe bronchus, bypassing the right lower lobe bronchial stump. There was no air leak immediately after that procedure and she continued with a 14-French thoracostomy tube in place for empyema drainage. Unfortunately, within the next 10 days the stent migrated requiring replacement. About a month later in July, 2024 the second stent was removed and revealed a persistent defect at the level of the bronchial stump with no apparent regression in size relative to the images captured prior to the initial bronchial stent placement. Under the expanded access pathway, a size 5 Spiration endobronchial valve was placed within the fistula in the right lower lobe bronchial stump (Figure 1). At the conclusion of the bronchoscopy procedure, a recruitment maneuver was performed while the suction on the thoracostomy tube was briefly increased to -40 cm H2O suction and no air leak was evident. The next CT chest 2 weeks later showed substantial improvement of the right hydropneumothorax. The air leak never returned and the thoracostomy tube was removed once the fluid drainage became negligible. The patient's dyspnea gradually improved and she was able to wean off supplemental oxygen. A follow-up CT chest 3 months later demonstrated a very small residual right pleural effusion with no gas component and stable positioning of the endobronchial valve. The multidisciplinary team involved in the patient's care intend to maintain the endobronchial valve in position indefinitely.

Abstract Rationale: Airway-stenosing disease is a significant clinical problem in multiple populations. While the immediate endoscopic and clinical response to bronchoscopic interventions are high, rates of clinically significant recurrence are elevated, and often require multiple and frequent reinterventions. Newer strategies to prevent recurrence of central and proximal airway stenosis are needed. Methods: Retrospective review of bronchoscopic balloon bronchoplasties performed at the Mayo Clinic utilizing paclitaxel coated balloons (PCB) in 2023-2024 for recurrent airway stenosis. IN.PACT Admiral and AV balloons (sizes 5-12 mm, 3.5 mcg/mm2 paclitaxel dose) were used with an inflation time of 2-3 minutes. Procedural success was defined as <50% airway stenosis or resolution of the procedural indication. Reintervention was considered only if a therapeutic bronchoscopy was subsequently required to address the same lesion treated with PCB. Only patients with follow-ups >90 days were included in the reintervention inter-procedural time analysis. Results: Thirty-three procedures were performed in 18 patients. Seventeen (51%) for lung transplantation-associated stenosis (29% anastomotic/perianastomotic, 76% lobar and segmental stenoses), 8 (24%) for granulomatous polyangiitis-associated stenosis, 3 for postintubation tracheal stenosis and 2 for chemical/pill injury. Eighteen cases (54%) utilized an additional dilation modality (12 non-coated balloon dilation, 4 rigid dilation), 5 spray cryotherapy, 6 other ablative therapies (4 CO2-laser, 2 electrocautery cuts), and 6 received an airway stent during the same procedure. 57% percent of interventions occurred in the lobar, 27% mainstem/bronchus intermedius, 9% tracheal, 7% segmental airways. Thirty-one (93%) cases had a satisfactory initial endoscopic result. The median number of bronchoscopic therapeutic interventions required before the use pf PCB was 5 (IQR 2.5-11.5), which significantly decreased to 0.1 (IQR 0-1, range 0-9) after PCB (p <0.001). The reintervention-free survival significantly increased after PCB dilation from a median 35 days (IQR 28.7-80.5) to 132 days (IQR 64-197; p=0.004). Twenty-one cases required subsequent bronchoscopies, sixteen (76%) of which demonstrated improvement in lesion severity when compared to the results of prior interventions. Only 16 (48%) required therapeutically addressing the same lesion. Only 2 minor complications occurred (6%, self-limited bleeding and unplanned admission), none related to paclitaxel use. Six-month mortality was 3% from an unrelated cause. Conclusions: The locoregional antiproliferative effects of paclitaxel show promise in preventing recurrence, minimizing the need for repeat procedures, and extending intervals between interventions in patients with recurrent, predominantly benign airway stenosis. Its use is feasible, safe, and future research is warranted, particularly comparing PCB with the currently available strategies.