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Martin Plencner,1,2,* Barbora East,3,* Zbynek Tonar,4 Martin Otáhal,5 Eva Prosecká,1,2 Michala Rampichová,2,6 Tomáš Krejčí,3 Andrej Litvinec,2,7 Matej Buzgo,2,6 Andrea Míčková,1,2,6 Alois Nečas,8 Jirí Hoch,3 Evžen Amler1,2,9 1Institute of Biophysics, Second Faculty of Medicine, Charles University in Prague, Prague, 2Laboratory of Tissue Engineering, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, 3Department of Surgery, Second Faculty of Medicine, Charles University in Prague, Prague, 4Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Pilsen, 5Department of Anatomy and Biomechanics, Faculty of Physical Education and Sport, Charles University in Prague, Prague, 6University Center for Energy Efficient Buildings, Czech Technical University in Prague, Buštehrad, 7Department of Breeding and Zoohygiene of Laboratory Animals, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, 8Department of Surgery and Orthopedics, Small Animal Clinic, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Science Brno, Central European Institute of Technology, Brno, 9Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic *These authors contributed equally to this work Abstract: Incisional hernia affects up to 20% of patients after abdominal surgery. Unlike other types of hernia, its prognosis is poor, and patients suffer from recurrence within 10 years of the operation. Currently used hernia-repair meshes do not guarantee success, but only extend the recurrence-free period by about 5 years. Most of them are nonresorbable, and these implants can lead to many complications that are in some cases life-threatening. Electrospun nanofibers of various polymers have been used as tissue scaffolds and have been explored extensively in the last decade, due to their low cost and good biocompatibility. Their architecture mimics the natural extracellular matrix. We tested a biodegradable polyester poly-Ԑ-caprolactone in the form of nanofibers as a scaffold for fascia healing in an abdominal closure-reinforcement model for prevention of incisional hernia formation. Both in vitro tests and an experiment on a rabbit model showed promising results. Keywords: nanofibers, growth factors, surgical mesh, hernia regeneration, in vivo

Cytoskeletal mechanics is a field that heavily relies on mathematical models to interpret experimental data related to forces and deformations. In this paper, we present a novel mathematical model designed specifically for analysing the mechanical properties of liposomes, which serve as model systems for studying biological membranes. Our model takes into account various factors such as stretching, bending, and contact adhesion during atomic force microscopy (AFM) indentation using a spherical tip. By applying our model to liposomes, we demonstrate that these structures exhibit nonlinear behaviour characterized by low stiffness at small deformations. Furthermore, we find that the mechanical response of liposomes is influenced by their size. Additionally, we observe that the presence of adhesion energy contributes to the generation of negative tip forces upon initial contact.

Martin Kralovic,1,2 Michal Vjaclovsky,3 Zbynek Tonar,4 Martina Grajciarova,4 Jana Lorenzova,5 Martin Otahal,6 Alois Necas,5 Jiri Hoch,3,7 Evzen Amler1,2 1Quality of Indoor Environment, University Centre for Energy Efficient Buildings, Czech Technical University in Prague, Bustehrad, Czech Republic; 2Department of Biophysics, Second Medical Faculty, Charles University in Prague, Prague, Czech Republic; 3Department of Surgery, Motol University Hospital, Prague, Czech Republic; 4Department of Histology and Embryology and Biomedical Centre, Faculty of Medicine in Pilsen, Charles University, Prague, Czech Republic; 5Section of Small Animal Diseases, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Brno, Czech Republic; 6Department of Natural Sciences, Faculty of Biomedical Engineering in Kladno, Czech Technical University in Prague, Prague, Czech Republic; 7Department of Surgery, Second Medical Faculty, Charles University in Prague, Prague, Czech RepublicCorrespondence: Martin Kralovic, Quality of Indoor Environment, University Centre for Energy Efficient Buildings, Czech Technical University in Prague, Trinecka 1024, Bustehrad, 273 43, Czech Republic, Tel +420 224 356 701, Email martin.kralovic@cvut.czBackground: A current topic of ma jor interest in regenerative medicine is the development of novel materials for accelerated healing of sutures, and nanofibers seem to be suitable materials for this purpose. As various studies have shown, nanofibers are able to partially substitute missing extracellular matrix and to stimulate cell proliferation and differentiation in sutures. Therefore, we tested nanofibrous membranes and cryogenically fractionalized nanofibers as potential materials for support of the healing of intestinal anastomoses in a rabbit model.Materials and Methods: We compared cryogenically fractionalized chitosan and PVA nanofibers with chitosan and PVA nanofiber membranes designed for intestine anastomosis healing in a rabbit animal model. The anastomoses were biomechanically and histologically tested.Results: In strong contrast to nanofibrous membranes, the fractionalized nanofibers did show positive effects on the healing of intestinal anastomoses in rabbits. The fractionalized nanofibers were able to reach deep layers that are key to increased mechanical strength of the intestine. Moreover, fractionalized nanofibers led to the formation of collagen-rich 3D tissue significantly exceeding the healing effects of the 2D flat nanofiber membranes. In addition, the fractionalized chitosan nanofibers eliminated peritonitis, significantly stimulated anastomosis healing and led to a higher density of microvessels, in addition to a larger fraction of myofibroblasts and collagen type I and III. Biomechanical tests supported these histological findings.Conclusion: We concluded that the fractionalized chitosan nanofibers led to accelerated healing for rabbit colorectal anastomoses by the targeted stimulation of collagen-producing cells in the intestine, the smooth muscle cells and the fibroblasts. We believe that the collagen-producing cells were stimulated both directly due to the presence of a biocompatible scaffold providing cell adhesion, and indirectly, by a proper stimulation of immunocytes in the suture.Keywords: cryogenic grinding, electrospinning, colorectal anastomoses, microvessels, collagen

Infraglottic needle/cannula insertion and surgical approaches to the trachea are the last resort choices of providing a patent airway, oxygenation and ventilation in patients where conventional techniques have failed. The main indication, especially in anaesthesia, is "can not intubate, can not oxygenate" situation. Infraglottic approaches may be the primary technique of providing patent airways in facial trauma, tumours, swelling, or in military medicine. Teaching and regular training on cadavers or models are key elements in managing these life-saving techniques, especially because their real frequency is extremely low. This review article discusses individual techniques – cricoid puncture, cricothyrotomy and bougie-assisted cricothyrotomy, their implementation, teaching, advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Barbora East,1,2 Martin Plencner,3,4 Martin Kralovic,1,3,5 Michala Rampichova,3 Vera Sovkova,1,3,5 Karolina Vocetkova,1,3,5 Martin Otahal,6,7 Zbynek Tonar,8,9 Yaroslav Kolinko,8,9 Evzen Amler,1,3,5 Jiri Hoch1,10 1Second Medical Faculty, Charles University in Prague, Prague, Czech Republic; 2Third Department of Surgery, Motol Faculty Hospital, First Medical Faculty, Charles University in Prague, Prague, Czech Republic; 3Institute of Experimental Medicine, The Czech Academy of Sciences, Prague, Czech Republic; 4The Czech Academy of Sciences, Institute of Physiology, Prague, Czech Republic; 5University Centre of Energy Efficient Buildings, Czech Technical University in Prague, Bustehrad, Czech Republic; 6Department of Anatomy and Biomechanics, Faculty of Physical Education, Charles University in Prague, Prague, Czech Republic; 7Department of Natural Sciences, Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic; 8Department of Histology and Embryology, 9Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Pilsen, Czech Republic; 10Surgery Department, Motol Faculty Hospital, Second Medical Faculty, Charles University in Prague, Prague, Czech Republic Purpose: Incisional hernia repair is an unsuccessful field of surgery, with long-term recurrence rates reaching up to 50% regardless of technique or mesh material used. Various implants and their positioning within the abdominal wall pose numerous long-term complications that are difficult to treat due to their permanent nature and the chronic foreign body reaction they trigger. Materials mimicking the 3D structure of the extracellular matrix promote cell adhesion, proliferation, migration, and differentiation. Some electrospun nanofibrous scaffolds provide a topography of a natural extracellular matrix and are cost effective to manufacture.Materials and methods: A composite scaffold that was assembled out of a standard polypropylene hernia mesh and poly-ε-caprolactone (PCL) nanofibers was tested in a large animal model (minipig), and the final scar tissue was subjected to histological and biomechanical testing to verify our in vitro results published previously.Results: We have demonstrated that a layer of PCL nanofibers leads to tissue overgrowth and the formation of a thick fibrous plate around the implant. Collagen maturation is accelerated, and the final scar is more flexible and elastic than under a standard polypropylene mesh with less pronounced shrinkage observed. However, the samples with the composite scaffold were less resistant to distracting forces than when a standard mesh was used. We believe that the adverse effects could be caused due to the material assembly, as they do not comply with our previous results.Conclusion: We believe that PCL nanofibers on their own can cause enough fibroplasia to be used as a separate material without the polypropylene base, thus avoiding potential adverse effects caused by any added substances. Keywords: nanofibers, hernia, mesh, PCL, minipig, biomechanical, large animal

Cell mechanics are a biophysical indicator of cell state, such as cancer metastasis, leukocyte activation, and cell cycle progression. Atomic force microscopy (AFM) is a widely used technique to measure cell mechanics, where the Young modulus of a cell is usually derived from the Hertz contact model. However, the Hertz model assumes that the cell is an elastic, isotropic, and homogeneous material and that the indentation is small compared to the cell size. These assumptions neglect the effects of the cytoskeleton, cell size and shape, and cell environment on cell deformation. In this study, we investigated the influence of cell size on the estimated Young's modulus using liposomes as cell models. Liposomes were prepared with different sizes and filled with phosphate buffered saline (PBS) or hyaluronic acid (HA) to mimic the cytoplasm. AFM was used to obtain the force indentation curves and fit them to the Hertz model. We found that the larger the liposome, the lower the estimated Young's modulus for both PBS-filled and HA-filled liposomes. This suggests that the Young modulus obtained from the Hertz model is not only a property of the cell material but also depends on the cell dimensions. Therefore, when comparing or interpreting cell mechanics using the Hertz model, it is essential to account for cell size.

Low-volume lung injury encompasses local concentration of stresses in the vicinity of collapsed regions in heterogeneously ventilated lungs. We aimed to study the effects on ventilation and perfusion distributions of a sequential lateral positioning (30°) strategy using electrical impedance tomography imaging in a porcine experimental model of early acute respiratory distress syndrome (ARDS). We hypothesized that such strategy, including a real-time individualization of positive end-expiratory pressure (PEEP) whenever in lateral positioning, would provide attenuation of collapse in the dependent lung regions. A two-hit injury acute respiratory distress syndrome experimental model was established by lung lavages followed by injurious mechanical ventilation. Then, all animals were studied in five body positions in a sequential order, 15 min each: Supine 1; Lateral Left; Supine 2; Lateral Right; Supine 3. The following functional images were analyzed by electrical impedance tomography: ventilation distributions and regional lung volumes, and perfusion distributions. The induction of the acute respiratory distress syndrome model resulted in a marked fall in oxygenation along with low regional ventilation and compliance of the dorsal half of the lung (gravitational-dependent in supine position). Both the regional ventilation and compliance of the dorsal half of the lung greatly increased along of the sequential lateral positioning strategy, and maximally at its end. In addition, a corresponding improvement of oxygenation occurred. In conclusion, our sequential lateral positioning strategy, with sufficient positive end-expiratory pressure to prevent collapse of the dependent lung units during lateral positioning, provided a relevant diminution of collapse in the dorsal lung in a porcine experimental model of early acute respiratory distress syndrome., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Mlček, Borges, Otáhal, Alcala, Hladík, Kuriščák, Tejkl, Amato and Kittnar.)

Real-time effects of changing body position and positive end-expiratory pressure (PEEP) on regional lung overdistension and collapse in individual patients remain largely unknown and not timely monitored. The aim of this study was to individualize PEEP in supine and prone body positions seeking to reduce lung collapse and overdistension in mechanically ventilated patients with coronavirus disease (COVID-19)-induced acute respiratory distress syndrome (ARDS). We hypothesized that prone positioning with bedside titrated PEEP would provide attenuation of both overdistension and collapse. In this prospective observational study, patients with COVID-19-induced ARDS under mechanical ventilation were included. We used electrical impedance tomography (EIT) with decremental PEEP titration algorithm (PEEP EIT-titration ), which provides information on regional lung overdistension and collapse, along with global respiratory system compliance, to individualize PEEP and body position. PEEP EIT-titration in supine position followed by PEEP EIT-titration in prone position were performed. Immediately before each PEEP EIT-titration , the same lung recruitment maneuver was performed: 2 min of PEEP 24 cmH 2 O and driving pressure of 15 cmH 2 O. Forty-two PEEP EIT-titration were performed in ten patients (21 pairs supine and prone positions). We have found larger % of overdistension along the PEEP titration in prone than supine position (P = 0.042). A larger % of collapse along the PEEP titration was found in supine than prone position (P = 0.037). A smaller respiratory system compliance was found in prone than supine position (P < 0.0005). In patients with COVID-19-induced ARDS, prone body position, when compared with supine body position, decreased lung collapse at low PEEP levels, but increased lung overdistension at PEEP levels greater than 10 cm H 2 O.Trial registration number: NCT04460859., (© 2022. The Author(s).)

Background: Targeted temperature management is recommended for patients after cardiac arrest, but the supporting evidence is of low certainty., Methods: In an open-label trial with blinded assessment of outcomes, we randomly assigned 1900 adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause to undergo targeted hypothermia at 33°C, followed by controlled rewarming, or targeted normothermia with early treatment of fever (body temperature, ≥37.8°C). The primary outcome was death from any cause at 6 months. Secondary outcomes included functional outcome at 6 months as assessed with the modified Rankin scale. Prespecified subgroups were defined according to sex, age, initial cardiac rhythm, time to return of spontaneous circulation, and presence or absence of shock on admission. Prespecified adverse events were pneumonia, sepsis, bleeding, arrhythmia resulting in hemodynamic compromise, and skin complications related to the temperature management device., Results: A total of 1850 patients were evaluated for the primary outcome. At 6 months, 465 of 925 patients (50%) in the hypothermia group had died, as compared with 446 of 925 (48%) in the normothermia group (relative risk with hypothermia, 1.04; 95% confidence interval [CI], 0.94 to 1.14; P = 0.37). Of the 1747 patients in whom the functional outcome was assessed, 488 of 881 (55%) in the hypothermia group had moderately severe disability or worse (modified Rankin scale score ≥4), as compared with 479 of 866 (55%) in the normothermia group (relative risk with hypothermia, 1.00; 95% CI, 0.92 to 1.09). Outcomes were consistent in the prespecified subgroups. Arrhythmia resulting in hemodynamic compromise was more common in the hypothermia group than in the normothermia group (24% vs. 17%, P<0.001). The incidence of other adverse events did not differ significantly between the two groups., Conclusions: In patients with coma after out-of-hospital cardiac arrest, targeted hypothermia did not lead to a lower incidence of death by 6 months than targeted normothermia. (Funded by the Swedish Research Council and others; TTM2 ClinicalTrials.gov number, NCT02908308.)., (Copyright © 2021 Massachusetts Medical Society.)

Background: Among the challenges for personalizing the management of mechanically ventilated patients with coronavirus disease (COVID-19)-associated acute respiratory distress syndrome (ARDS) are the effects of different positive end-expiratory pressure (PEEP) levels and body positions in regional lung mechanics. Right-left lung aeration asymmetry and poorly recruitable lungs with increased recruitability with alternating body position between supine and prone have been reported. However, real-time effects of changing body position and PEEP on regional overdistension and collapse, in individual patients, remain largely unknown and not timely monitored. The aim of this study was to individualize PEEP and body positioning in order to reduce the mechanisms of ventilator-induced lung injury: collapse and overdistension., Methods: We here report a series of five consecutive mechanically ventilated patients with COVID-19-associated ARDS in which sixteen decremental PEEP titrations were performed in the first days of mechanical ventilation (8 titration pairs: supine position immediately followed by 30° targeted lateral position). The choice of lateral tilt was based on X-Ray. This targeted lateral position strategy was defined by selecting the less aerated lung to be positioned up and the more aerated lung to be positioned down. For each PEEP level, global and regional collapse and overdistension maps and percentages were measured by electrical impedance tomography. Additionally, we present the incidence of lateral asymmetry in a cohort of forty-four patients., Results: The targeted lateral position strategy resulted in significantly smaller amounts of overdistension and collapse when compared with the supine one: less collapse along the PEEP titration was found within the left lung in targeted lateral (P = 0.014); and less overdistension along the PEEP titration was found within the right lung in targeted lateral (P = 0.005). Regarding collapse within the right lung and overdistension within the left lung: no differences were found for position. In the cohort of forty-four patients, ventilation inequality of > 65/35% was observed in 15% of cases., Conclusions: Targeted lateral positioning with bedside personalized PEEP provided a selective attenuation of overdistension and collapse in mechanically ventilated patients with COVID-19-associated ARDS and right-left lung aeration/ventilation asymmetry., Trial Registration: Trial registration number: NCT04460859.

Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt besteht.

Incisional hernia affects up to 20% of patients after abdominal surgery. Unlike other types of hernia, its prognosis is poor, and patients suffer from recurrence within 10 years of the operation. Currently used hernia-repair meshes do not guarantee success, but only extend the recurrence-free period by about 5 years. Most of them are nonresorbable, and these implants can lead to many complications that are in some cases life-threatening. Electrospun nanofibers of various polymers have been used as tissue scaffolds and have been explored extensively in the last decade, due to their low cost and good biocompatibility. Their architecture mimics the natural extracellular matrix. We tested a biodegradable polyester poly-ε-caprolactone in the form of nanofibers as a scaffold for fascia healing in an abdominal closure-reinforcement model for prevention of incisional hernia formation. Both in vitro tests and an experiment on a rabbit model showed promising results.

The aim of the study was to document soft tissue vascularization of the lateral heel on cadavers and, therefore, to indirectly demonstrate the importance to perform perfectly precise incisions, in order to prevent ischemic complications. Sections of 8 human lower limb cadavers were performed in cooperation with the Anatomical Institute of the MU Medical Faculty in Brno, according to current common standards for anatomical preparations. In successive steps, cutaneous and subcutanous covers of the lateral ankle, malleolar and heel regions were preparated. Final branches of the individual arteries were followed and the authors aimed to demonstrate their vascular arcade consisting of anastomosis of the lateral calcaneal artery--LCA (a branch of a. peronea)--which is a clinical term for rami calcaneares laterales, ventrolateral tarsal arteries--LTA (a branch of a. dorsalis pedis) and lateral malleolar artery branching off medially--LMA (a branch of a. tibialis ant.). The course of the arteries and their location is related to a reference point--a lateral tip of the lateral ankle. The investigators found out that all three arteries, as well as the arterial arch, had standard courses. The course of the arch defines the outline of the lateral extensive incision during osteosynthesis in calcaneal fractures, which lies fairly close to the lateral outline of this vascular arcade. Incorrect performance of the incision results, invitably, in serious ischemic complications. Open reduction and internal fixation of intraarticular calcaneal fractures has become a standard surgical method. Correct indication, good timing and saving open reduction, internal fixation using arthroscopy and early mobilization are the prerequisites to prevent further postoperative complications and to achieve complete healing of the fracture. Considering the demandingness of these fractures treatment and their rare incidence, their management should be centred in specialized traumatological clinics.