Contractile cells can reorganize fibrous extracellular matrices and form dense tracts of fibers between neighboring cells. These tracts guide the development of tubular tissue structures and provide paths for the invasion of cancer cells. Here, we studied the mechanisms of the mechanical plasticity of collagen tracts formed by contractile premalignant acinar cells and fibroblasts. Using fluorescence microscopy and second harmonic generation, we quantified the collagen densification, fiber alignment, and strains that remain within the tracts after cellular forces are abolished. We explained these observations using a theoretical fiber network model that accounts for the stretch-dependent formation of weak cross-links between nearby fibers. We tested the predictions of our model using shear rheology experiments. Both our model and rheological experiments demonstrated that increasing collagen concentration leads to substantial increases in plasticity. We also considered the effect of permanent elongation of fibers on network plasticity and derived a phase diagram that classifies the dominant mechanisms of plasticity based on the rate and magnitude of deformation and the mechanical properties of individual fibers. Plasticity is caused by the formation of new cross-links if moderate strains are applied at small rates or due to permanent fiber elongation if large strains are applied over short periods. Finally, we developed a coarse-grained model for plastic deformation of collagen networks that can be employed to simulate multicellular interactions in processes such as morphogenesis, cancer invasion, and fibrosis.

Objectives: Radiographers are key patient-facing healthcare professionals involved in many aspects of patient care. The working patterns and professional practice of the radiography workforce (RW) has been altered during the COVID-19 pandemic. This survey aimed to assess the impact of the pandemic on radiography practice in the United Kingdom (UK). Methods: An online cross-sectional survey of the UK RW was performed (March 25th to April 26th, 2020). The survey sought information regarding 1. Demographics 2. Impact of the pandemic on professional practice 3. Infection prevention/control and 4. COVID-19 related stress. Data collected was analysed using the Statistical Package for Social Sciences (v.26). Results: A total of 522 responses were received, comprising n = 412 (78.9%) diagnostic and n = 110 (21.1%) therapeutic RW categories from across the UK. 12.5% (65/522) of the respondents were redeployed. Redeployment did not appear to contribute (p = 0.31) to work-related stress. However, fear of contracting the infection and perceived inadequate personal protective equipment (PPE) were identified as key contributors to stress during the study period. Compared to the therapeutic RW, a significantly higher proportion of the diagnostic RW identified fear of being infected as a major stressor (166/412 (40.3%) vs 30/110 (27.3%), p = 0.01). Conclusion: This survey has demonstrated changes to clinical practice, in particular to working patterns, service delivery and infection prevention and control were key contributors to workplace-related stress during the pandemic. Advances in knowledge: Timely and adequate staff training and availability of PPE as well as psychosocial support during future pandemics would enhance quality patient and staff safety.

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Background: There is limited data on outcomes in patients with coronavirus disease 2019 in rural United States (US). This study aimed to describe the demographics, and outcomes of hospitalized Covid-19 patients in rural Southwest Georgia. Methods: Using electronic medical records, we analyzed data from all hospitalized Covid-19 patients who either died or survived to discharge between 2 March 2020 and 6 May 2020. Results: Of the 522 patients, 92 died in hospital (17.6%). Median age was 63 years, 58% were females, and 87% African-Americans. Hypertension (79.7%), obesity (66.5%) and diabetes mellitus (42.3%) were the most common comorbidities. Males had higher overall mortality compared to females (23 v 13.8%). Immunosuppression [odds ratio (OR) 3.6; (confidence interval (CI): 1.52-8.47, p¼.003)], hypertension (OR 3.36; CI:1.3-8.6, p¼.01), age !65 years (OR 3.1; CI:1.7-5.6, p<.001) and morbid obesity (OR 2.29; CI:1.11-4.69, p¼.02), were independent predictors of in-hospital mortality. Female gender was an independent predictor of decreased in-hospital mortality. Mortality in intubated patients was 67%. Mortality was 8.9% in <50 years, compared to 20% in !50 years. Conclusions: Immunosuppression, hypertension, age ! 65 years and morbid obesity were independent predictors of mortality, whereas female gender was protective for mortality in hospitalized Covid-19 patients in rural Southwest Georgia. KEY MESSAGES1. Patients hospitalized with Covid-19 in rural US have higher comorbidity burden. 2. Immunosuppression, hypertension, age ! 65 years and morbid obesity are independent predictors of increased mortality. 3. Female gender is an independent predictor of reduced mortality.