Background: Radiofibrosis of breast tissue compromises breast reconstruction by interfering with tissue viability and healing. Autologous fat transfer may reduce radiotherapy-related tissue injury, but graft survival is compromised by the fibrotic microenvironment. Elevated expression of receptor for hyaluronan-mediated motility (RHAMM; also known as hyaluronan-mediated motility receptor, or HMMR) in wounds decreases adipogenesis and increases fibrosis. The authors therefore developed RHAMM peptide mimetics to block RHAMM profibrotic signaling following radiation. They propose that this blocking peptide will decrease radiofibrosis and establish a microenvironment favoring adipose-derived stem cell survival using a rat mammary fat pad model. Methods: Rat mammary fat pads underwent a one-time radiation dose of 26 Gy. Irradiated (n = 10) and nonirradiated (n = 10) fat pads received a single intramammary injection of a sham injection or peptide NPI-110. Skin changes were examined clinically. Mammary fat pad tissue was processed for fibrotic and adipogenic markers using quantitative polymerase chain reaction and immunohistochemical analysis. Results: Clinical assessments and molecular analysis confirmed radiation-induced acute skin changes and radiation-induced fibrosis in rat mammary fat pads. Peptide treatment reduced fibrosis, as detected by polarized microscopy of picrosirius red staining, increased collagen ratio of 3:1, reduced expression of collagen-1 crosslinking enzymes lysyl-oxidase, transglutaminase 2, and transforming growth factor β1 protein, and increased adiponectin, an antifibrotic adipokine. RHAMM was expressed in stromal cell subsets and was downregulated by the RHAMM peptide mimetic. Conclusion: Results from this study predict that blocking RHAMM function in stromal cell subsets can provide a postradiotherapy microenvironment more suitable for fat grafting and breast reconstruction.
Initial assessment and triage of burns is guided by the American Burn Association criteria for referral to a burn centre. These criteria are sensitive but not specific, and can potentially lead to over-triage and “unnecessary” clinic visits. We are a Level 1 trauma centre with burn subspecialty care, and due to the COVID-19 pandemic, referrals to our multidisciplinary outpatient burn clinic required triaging for virtual care appointments. In order to improve the triage process, we retrospectively reviewed our outpatient burn clinic referrals over a 2-year period 2018-2019, for adherence to American Burn Association criteria. We collected data pertaining to patient and burn characteristics, as well as treatment outcome, to characterize referrals not requiring an in-person appointment. Of the 244 patients referred, 73% met the referral criteria, with 45% of these patients being healed at first visit and 14.6% requiring surgical management. Mean time from injury to first visit was 9.7 days (mode 6), and average number of visits was 2. Overall, mean burn size was 2%, with the majority of injuries being partial thickness (71%), located in the hand or extremity (77%). There was fairly equal distribution of contact (36%), flame (21%), and scald (26%) burns. This study highlights the non-specific nature of the American Burn Association referral criteria. We found that paediatric and hand burns in particular were over-triaged and lead to “unnecessary” appointments. This information is useful to help adjust referral criteria and to guide triaging of appointments with the evolution of telehealth and virtual care.
Hydraulic systems that are operated outdoors during winter can be exposed to extreme low temperatures. Low temperature thickening of the hydraulic fluid can increase power consumption, cause pump cavitation, and stall system actuation. In this study, the response time and power consumption of a hydraulic vehicle restraint system that is used outdoors year-round was evaluated at low temperatures. This safety device incorporated proximity switches that triggered a machine “fault” when the time delay between the locked and unlocked positions exceeded 8 seconds. Straight- and multi-grade ISO VG 32 and 46 fluids were compared in the device. The multi-grade oils were able to function at a lower temperature without faulting. The effect of system operating conditions and fluid properties on pump input power was evaluated. The input power was determined from measurements of pump rotational frequency and torque. Pump torque increased as the oil temperature decreased. As a result, low-temperature operating conditions resulted in a higher system power requirements. An empirical model was developed to investigate the effects of turbulent and laminar flow conditions on the hydraulic system power requirements. A comparison of model standard errors revealed that viscosity-dependent laminar losses had a greater impact on system performance than density-dependent turbulent losses. Since the viscosity coefficients of the fluids were very high at the test temperature, it was theorized that pressure drop in the hydraulic lines was affecting system response. Hydraulic system simulations were conducted via Automation Studio. Cylinder retraction velocities were evaluated with larger ID cap- and rod-side hoses. Increasing the cap-side hose diameter enhanced the low temperature performance of the system. Changes to the rod-side hose had minimal effect. These results provide new insights for system design and the formulation of hydraulic fluids used in extreme low temperature operations.
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