Biomechanics of parasite migration within hosts.

The dissemination of protozoan and metazoan parasites through host tissues is hindered by cellular barriers, dense extracellular matrices, and fluid forces in the bloodstream. To overcome these diverse biophysical impediments, parasites implement versatile migratory strategies. Parasite-exerted mechanical forces and upregulation of the host's cellular contractile machinery are the motors for these strategies, and these are comparably better characterized for protozoa than for helminths. Using the examples of the protozoans, Toxoplasma gondii and Plasmodium, and the metazoan, Schistosoma mansoni, we highlight how quantitative tools such as traction force and reflection interference contrast microscopies have improved our understanding of how parasites alter host mechanobiology to promote their migration.

Minimally Required Personal Protective Equipment during Local Anesthesia Surgery in COVID-19: A Simulation Study.

In the era of the coronavirus disease 2019 (COVID-19) pandemic, surgeons and medical staff are often at a high risk of infection in the operating room, especially when the patient is spontaneously breathing. In this study, we examined the minimum requirements for personal protective equipment with double surgical masks to potentially reduce unnecessary waste of supplies. Methods: Two mannequins were each connected to a test lung machine simulating a surgeon and patient with spontaneous breathing. An aerosol generator containing severe acute respiratory syndrome coronavirus 2 virion particle substitutes was connected to the patient mannequin. The sampling points for the target molecules were set at different distances from the patient mannequin and sent for multiplex quantitative polymerase chain reaction analysis. Three clinical scenarios were designed, which differed in terms of the operating room pressure and whether a fabric curtain barrier was installed between the mannequins. Results: Analysis of the multiplex quantitative polymerase chain reaction results showed that the cycle threshold (Ct) value of the target molecule increased as the distance from the aerosol source increased. In the negative-pressure operating room, the Ct values were significantly increased at all sample points compared with the normal pressure room setting. The Ct value sampled at the surgeon mannequin wearing double face masks was significantly increased when a cloth curtain barrier was set up between the two mannequins. Conclusion: Double surgical masks provide elementary surgeon protection against COVID-19 in a negative pressure operating room, with a physical barrier in place between the surgeon and patient who is spontaneously breathing during local anesthesia or sedated surgery.

Hydroxychloroquine on the Pulmonary Vascular Diseases in Interstitial Lung Disease: Immunologic Effects, and Virus Interplay.

To investigate the effects of hydroxychloroquine (HCQ) drug use on the risk of pulmonary vascular disease (PVD) in an interstitial lung disease cohort (ILD cohort, ILD+ virus infection), we retrospectively enrolled the ILD cohort with HCQ (HCQ users, N = 4703) and the ILD cohort without HCQ (non-HCQ users, N = 4703) by time-dependence after propensity score matching. Cox models were used to analyze the risk of PVD. We calculated the adjusted hazard ratios (aHRs) and their 95% confidence intervals (CIs) for PVD after adjusting for sex, age, comorbidities, index date and immunosuppressants, such as steroids, etc. Compared with the HCQ nonusers, in HCQ users, the aHRs (95% CIs) for PVD were (2.24 (1.42, 3.54)), and the women's aHRs for PVD were (2.54, (1.49, 4.35)). The aHRs based on the days of HCQ use for PVD of 28−30 days, 31−120 days, and >120 days were (1.27 (0.81, 1.99)), (3.00 (1.81, 4.87)) and (3.83 (2.46, 5.97)), respectively. The medium or long-term use of HCQ or young women receiving HCQ were associated with a higher aHR for PVD in the ILD cohort. These findings indicated interplay of the primary immunologic effect of ILD, comorbidities, women, age and virus in the HCQ users.

Cyclic Mechanical Stresses Alter Erythrocyte Membrane Composition and Microstructure and Trigger Macrophage Phagocytosis.

Red blood cells (RBCs) are cleared from the circulation when they become damaged or display aging signals targeted by macrophages. This process occurs mainly in the spleen, where blood flows through submicrometric constrictions called inter-endothelial slits (IES), subjecting RBCs to large-amplitude deformations. In this work, RBCs are circulated through microfluidic devices containing microchannels that replicate the IES. The cyclic mechanical stresses experienced by the cells affect their biophysical properties and molecular composition, accelerating cell aging. Specifically, RBCs quickly transition to a more spherical, less deformable phenotype that hinders microchannel passage, causing hemolysis. This transition is associated with the release of membrane vesicles, which self-extinguishes as the spacing between membrane-cytoskeleton linkers becomes tighter. Proteomics analysis of the mechanically aged RBCs reveals significant losses of essential proteins involved in antioxidant protection, gas transport, and cell metabolism. Finally, it is shown that these changes make mechanically aged RBCs more susceptible to macrophage phagocytosis. These results provide a comprehensive model explaining how physical stress induces RBC clearance in the spleen. The data also suggest new biomarkers of early "hemodamage" and inflammation preceding hemolysis in RBCs subjected to mechanical stress.

Advanced preoperative three-dimensional planning decreases the surgical complications of using large-for-size grafts in pediatric living donor liver transplantation.

BACKGROUND: Using "large-for-size" liver graft, graft-to-recipient weight ratio (GRWR) ≥4%, has been debated in pediatric liver transplantation due to possible graft compartment after abdomen closure. Meticulous preoperative evaluation with three-dimensional (3D) techniques may prevent these problems. This study compared the safety of large-for-size grafts in pediatric living donor liver transplantation (PLDLT) during the eras with or without 3D planning. METHODS: We defined the 3D era was after November 2017 due to our first implication of 3D printing for surgical planning and subsequently developing a 3D simulation implanting model. From November 2004 to July 2021, we enrolled 30 PLDLT patients with body weight (BW) < 10 kg and categorized them into conventional group: GRWR ≥4% before the 3D era (n = 9), 3D group: GRWR ≥4% in the 3D era (n = 8), and control group: GRWR <4% (n = 13). We followed and compared their clinical outcomes. RESULTS: The 3D group had the lowest BW and the highest graft volume reduction rate, with all receiving modified left lateral segments (LLS), such as reduced LLS (n = 2), hyperreduced LLS (n = 5), and segment 2 monosegment (n = 1). Overall postoperative complications were similar in conventional and control groups but significantly lower in the 3D group (OR 0.06, 95% CI 0.006-0.70, p = 0.025). However, all groups had similar graft and patient survival at 1, 2, and 4 years. CONCLUSION: Advanced preoperative 3D planning can decrease post-transplant complications and increase the safety of large-for-size grafts in PLDLT. LEVEL OF EVIDENCE: Type of study: Retrospective comparative study; Evidence level: Level III.

Biomechanical interactions of Schistosoma mansoni eggs with vascular endothelial cells facilitate egg extravasation.

The eggs of the parasitic blood fluke, Schistosoma, are the main drivers of the chronic pathologies associated with schistosomiasis, a disease of poverty afflicting approximately 220 million people worldwide. Eggs laid by Schistosoma mansoni in the bloodstream of the host are encapsulated by vascular endothelial cells (VECs), the first step in the migration of the egg from the blood stream into the lumen of the gut and eventual exit from the body. The biomechanics associated with encapsulation and extravasation of the egg are poorly understood. We demonstrate that S. mansoni eggs induce VECs to form two types of membrane extensions during encapsulation; filopodia that probe eggshell surfaces and intercellular nanotubes that presumably facilitate VEC communication. Encapsulation efficiency, the number of filopodia and intercellular nanotubes, and the length of these structures depend on the egg's vitality and, to a lesser degree, its maturation state. During encapsulation, live eggs induce VEC contractility and membranous structures formation in a Rho/ROCK pathway-dependent manner. Using elastic hydrogels embedded with fluorescent microbeads as substrates to culture VECs, live eggs induce VECs to exert significantly greater contractile forces during encapsulation than dead eggs, which leads to 3D deformations on both the VEC monolayer and the flexible substrate underneath. These significant mechanical deformations cause the VEC monolayer tension to fluctuate with the eventual rupture of VEC junctions, thus facilitating egg transit out of the blood vessel. Overall, our data on the mechanical interplay between host VECs and the schistosome egg improve our understanding of how this parasite manipulates its immediate environment to maintain disease transmission.

Statins Reduce Hepatocellular Carcinoma Risk in Patients with Chronic Kidney Disease and End-Stage Renal Disease: A 17-Year Longitudinal Study.

Hepatocellular carcinoma (HCC) is the most common cancer in end-stage renal disease (ESRD) patients in Taiwan. Whether statin therapy associated with the HCC risk in hyperlipidemic patients with chronic kidney disease (CKD) and ESRD is unclear. Using population-based insurance claim data from Taiwan, we identified from hyperlipidemic patients taking statins or not (677,364 versus 867,707) in 1999-2015. Among them, three pairs of propensity score matched statin and non-statin cohorts were established by renal function: 413,867 pairs with normal renal function (NRF), 46,851 pairs with CKD and 6372 pairs with ESRD. Incidence rates of HCC were compared, by the end of 2016, between statin and non-statin cohorts, between hydrophilic statins (HS) and lipophilic statins (LS) users, and between statin-ezetimibe combination therapy (SECT) and statin monotherapy (SM) users. The HCC incidence increased progressively from NRF to CKD and ESRD groups, was lower in the statin cohort than in the non-statin cohort, with the differences of incidence per 10,000 person-years increased from (7.77 vs. 21.4) in NRF group to (15.8 vs. 37.1) in CKD group to (19.1 vs. 47.8) in ESRD group. The incidence increased with age, but the Cox method estimated hazard ratios showed a greater statin effectiveness in older patients. Among statin users, the HCC incidence was lower in HS users than in LS users, and lower in SECT users than in SM users, but the difference was significant only in the NRF group. Hyperlipidemic patients with CKD and ESRD receiving statins are at reduced HCC risks; the treatment effectiveness is superior for HS users than for LS users, and for SECT users than for SM users, but not significant.

Needle-Probe Optical Coherence Tomography for Real-Time Visualization of Veress Peritoneal Needle Placement in a Porcine Model: A New Safety Concept for Pneumoperitoneum Establishment in Laparoscopic Surgery.

The safe establishment of pneumoperitoneum is a critical step in all laparoscopic surgeries. A closed pneumoperitoneum is usually obtained by inserting a Veress needle into the peritoneal cavity. However, there is no definite measure to visually confirm the position of the Veress needle tip inside the peritoneal cavity. This study aimed to describe a method of real-time visual detection of peritoneal placement of the Veress needle using an incorporated optical coherence tomography (OCT) probe in a porcine model. A 14-gauge Veress needle was incorporated with a miniature fiber probe to puncture the piglet's abdominal wall into the peritoneal cavity. A total of 80 peritoneal punctures were attempted in four piglets. For each puncture, continuous two-dimensional OCT images of the abdominal wall were acquired for real-time visual detection of the needle placement into the peritoneal cavity. Characteristic OCT image patterns could be observed during the puncturing process, especially a deep V-shaped concave pattern before the peritoneum puncture, which was a crucial feature. A statistical difference in the OCT signal standard deviation value also indicated the differentiability of images between the peritoneum and extra-peritoneal tissue layers. A success rate of 97.5% could be achieved with the guidance of the OCT images. OCT images translate the blind closed technique of peritoneal access into a visualized procedure, thus improving peritoneal access safety.

Safety and long-term outcomes of early liver transplantation for pediatric methylmalonic acidemia patients.

BACKGROUND: LT is a treatment option for MMA patients, but renal function impairment is one of the long-term concerns. The aim of this study was to evaluate the outcomes of early LT in these patients. METHODS: A total of 11 MMA mut-type patients (including 10 mut0 cases and 1 mut-case) who received LT in our institute were reviewed. Their metabolic profiles were compared between the pre/post-transplant periods. Their immunosuppressant and renal function changes after transplantation were assessed. RESULTS: After a mean follow-up of 97.5 ± 38.4 months, there were two deaths, and the actual survival rate was 81.8%. Their metabolic profiles had improved (mean blood ammonia level 366.8 ± 105.5 vs. 53.1 ± 17.4 µg/dl, p < .001; C3/C2 ratio 2.68 ± 0.87 vs. 0.73 ± 0.22, p = .003; mean urine MMA level 920.5 ± 376.6 vs. 196.2 ± 85.4, p = .067), and hospital stays were decreased (78.8 ± 74.5 vs. 7.4 ± 7.0 days/year, p = .009) after transplantation. The mean age at transplant was 1.81 ± 2.02 years old, and nine of these patients received LT before the age of 1.5 years old (early LT). Under prospective immunosuppressant dose reduction, three of these early LT patients discontinued the drug and were sustained for more than 5 years. Most of the patients had a preserved renal function, and no patient is currently on dialysis. CONCLUSIONS: In addition to the improvement in the metabolic parameters, early LT in MMA patients may allow for a dose reduction of the immunosuppressant, and the patient's renal function could be preserved in the long term.

Factors associated with postoperative respiratory conditions and critical outcomes on pediatric liver transplantation: A single-center experience.

BACKGROUND: Orthotopic liver transplantation (OLT) is an established therapeutic option for pediatric end-stage liver disease (PELD). The postoperative respiratory conditions of OLT recipients may be associated with subsequent clinical outcomes including length of stay (LOS) in the pediatric intensive care unit (PICU). This study aimed to characterize the postoperative respiratory conditions, associated factors, and outcomes after pediatric OLT. METHODS: Clinical data of children receiving OLT from July 2014 to July 2020 were retrospectively collected. Postoperative respiratory conditions were defined as time to extubation, significant pleural effusion, and initial postoperative PaO2/FiO2 ratio. Logistic and multiple regressions were applied to analyze the associations among clinical factors, postoperative respiratory conditions, and clinical outcomes. RESULTS: Twenty-two patients with median age of 1.4-year-old (range: 25 days to 12 years old) were analyzed. Mortality within 28 days was 4.5% and median LOS in the PICU was 18 days. Of 22 patients, 11 patients (50.0%) were extubated over 24 hours after surgery, and 8 patients (36.4%) required drainage for pleural effusions. Longer LOS in the PICU were noted in patients extubated over 24 hours (p = 0.008), complicated with significant pleural effusions (p = 0.02) after surgery, and having low initial postoperative PaO2/FiO2 (<300 mmHg) (p = 0.001). Among clinical factors, massive intraoperative blood transfusion (>40 mL/kg) was significantly associated with prolonged intubations, significant pleural effusions, low initial postoperative PaO2/FiO2, and prolonged LOS in the PICU (>14 days). The initial postoperative PaO2/FiO2 significantly depended on age, disease severity (PELD score), and whether the patient received massive intraoperative blood transfusion. CONCLUSION: Pediatric patients of OLT with poor postoperative respiratory conditions including low initial PaO2/FiO2 ratio, extubation over 24 hours or significant pleural effusions have longer LOS in the PICU, and the requirement of massive intraoperative transfusion was a risk factor for both poor postoperative respiratory conditions and prolonged LOS in the PICU.

A novel homemade simulator for training and assessing competency of totally implantable venous access port implantation via venous cutdown.

Total implantable venous access port (TIVAP) by cephalic vein cutdown (CVCD) is one of the first procedures surgery residents can be performed independently under supervision. There is currently a lack of affordable simulators for teaching and assessing TIVAP competency to improve patient safety. A panel of 10 experts divided the TIVAP by CVCD procedure into 9 steps. A homemade, low-cost ($3 USD) simulator was then designed for practicing standardized procedural steps in the context of a simulation-based mastery learning course. Residents were given a simulator for at-home practice and completed a survey evaluating the simulator and their learning experience. Twenty-eight first-year surgery residents participated in the course and completed the survey. They were highly satisfied with the simulator (mean score = 8.7 of 10) and generally agreed with its anatomical appearance and functional fidelity. They also appreciated the educational value of using this simulator to learn and practice basic techniques and procedural steps. Our novel, homemade simulator of CVCD TIVAP implantation is a cost-effective way of achieving procedural competence of a basic operation for inexperienced surgery residents. We envision the same principle can be applied to other procedures to enhance resident education.

The interplay between matrix deformation and the coordination of turning events governs directed neutrophil migration in 3D matrices.

Neutrophils migrating through extravascular spaces must negotiate narrow matrix pores without losing directional movement. We investigated how chemotaxing neutrophils probe matrices and adjust their migration to collagen concentration ([col]) changes by tracking 20,000 cell trajectories and quantifying cell-generated 3D matrix deformations. In low-[col] matrices, neutrophils exerted large deformations and followed straight trajectories. As [col] increased, matrix deformations decreased, and neutrophils turned often to circumvent rather than remodel matrix pores. Inhibiting protrusive or contractile forces shifted this transition to lower [col], implying that mechanics play a crucial role in defining migratory strategies. To balance frequent turning and directional bias, neutrophils used matrix obstacles as pivoting points to steer toward the chemoattractant. The Actin Related Protein 2/3 complex coordinated successive turns, thus controlling deviations from chemotactic paths. These results offer an improved understanding of the mechanisms and molecular regulators used by neutrophils during chemotaxis in restrictive 3D environments.

Elucidating the Biomechanics of Leukocyte Transendothelial Migration by Quantitative Imaging.

Leukocyte transendothelial migration is crucial for innate immunity and inflammation. Upon tissue damage or infection, leukocytes exit blood vessels by adhering to and probing vascular endothelial cells (VECs), breaching endothelial cell-cell junctions, and transmigrating across the endothelium. Transendothelial migration is a critical rate-limiting step in this process. Thus, leukocytes must quickly identify the most efficient route through VEC monolayers to facilitate a prompt innate immune response. Biomechanics play a decisive role in transendothelial migration, which involves intimate physical contact and force transmission between the leukocytes and the VECs. While quantifying these forces is still challenging, recent advances in imaging, microfabrication, and computation now make it possible to study how cellular forces regulate VEC monolayer integrity, enable efficient pathfinding, and drive leukocyte transmigration. Here we review these recent advances, paying particular attention to leukocyte adhesion to the VEC monolayer, leukocyte probing of endothelial barrier gaps, and transmigration itself. To offer a practical perspective, we will discuss the current views on how biomechanics govern these processes and the force microscopy technologies that have enabled their quantitative analysis, thus contributing to an improved understanding of leukocyte migration in inflammatory diseases.

The feasibility of medial segment graft in pediatric liver transplantation revisited by three-dimensional printing.

BACKGROUND: The medial segment as a mono-segmental graft was proposed to increase the donor pool for pediatric liver transplantation, but to date, there has been no published case. This study aims to revisit the feasibility of procuring the medial segment graft (MSG) by three-dimensional (3D) printing and ex vivo procedures performed on explanted diseased livers to overcome the gap between theory and clinical implementation. METHODS: From October 2004 to December 2016, we retrospectively analyzed preoperative computed tomography, magnetic resonance cholangiopancreatography, and intraoperative cholangiography images of our previous live liver donors and identified the indicated anatomy for the MSG, then materialized by 3D printing models to simulate the engraftment. Furthermore, we practiced the procurement procedures on selected explanted diseased livers. RESULTS: Among 291 analyzed livers, 96 livers (33%) met the arterial criteria for MSG, and two-thirds of them had ideal portal branches for reconstruction. The proposed right border of the MSG was the Cantlie's line, and the left edge was the right side of the umbilical fissure. The mean estimated volume of the MSG was 234 ± 54 ml. Besides, we suggest implanting the MSG as an auxiliary partial graft in an inverted vertical position or a standalone graft with right-side rotation in the right subphrenic space. CONCLUSION: The procurement of the MSG is feasible based on our results. However, due to the novelty of the procedure, we suggest that the first attempted case of MSG should be implanted as an auxiliary partial graft to maximize patient safety. LEVEL OF EVIDENCE: Type of study: Case series with no comparison groups EVIDENCE LEVEL: Level IV.

Living donor liver transplantation for small infants aged less than 6 months: The experience of a single institute.

PURPOSE: Liver transplantation (LT) for small infants < 6 months old is rare but becoming common as perioperative care improves. In Taiwan, living donor LT (LDLT) has expanded indications but is rarely performed for this age group because of unfavorable outcomes in the literature. We evaluated LDLT outcomes of patients <6 months old. METHODS: We identified infants < 6 months old undergoing LDLT between 2004 and 2019 at our hospital. Variables related to recipients, donors, surgeries, and outcomes were analyzed. RESULTS: Nine patients were identified. Indications for LT were biliary atresia (n = 2), Alagille syndrome (n = 1), protein C deficiency (n = 1), and acute liver failure (n = 5), including two patients with neonatal hemochromatosis, one with herpes simplex hepatitis, one with giant cell hepatitis with autoimmune hemolytic anemia, and one with hemophagocytic lymphohistiocytosis. Median age and weight at LT were 129 days and 4.8 kg, respectively. Graft types included left lateral segment (LLS, n = 4), hyper-reduced LLS (n = 4), and monosegment (n = 1). The median graft-to-recipient weight ratio was 4%. The median follow-up period was 14 months (range, 8 days to 127 months) with two mortalities, and two patients were totally weaned off immunosuppressants. Adjuvant therapies were required for patients with giant cell hepatitis and hemophagocytosis. Preoperative reconstructive imaging for estimating graft thickness facilitated surgical planning. CONCLUSION: Although LDLT is difficult to perform for small infants, outcomes are favorable and mainly dependent on underlying causes in addition to technical innovations.

Complete and durable response to immune checkpoint inhibitor in a patient with refractory and metastatic hepatoblastoma.

We herein report the case of a girl with PRETEXT III hepatoblastoma (HB) developing recurrent lung metastases despite multiple chemotherapy regimens, aggressive tumor excision, multiple lung metastasectomies, and autologous peripheral blood stem cell transplantation. High tumor mutation burden (TMB) was identified through targeted next-generation sequencing, and pembrolizumab was administered post-operatively as a last resort. A complete and sustained response to the immune checkpoint inhibitor was achieved for 22 months. Although the majority of HB have a low TMB, immune checkpoint inhibitor therapy may be useful for patients with refractory HBs with a high TMB.

Mechanical competition triggered by innate immune signaling drives the collective extrusion of bacterially infected epithelial cells.

Intracellular pathogens alter their host cells' mechanics to promote dissemination through tissues. Conversely, host cells may respond to the presence of pathogens by altering their mechanics to limit infection. Here, we monitored epithelial cell monolayers infected with intracellular bacterial pathogens, Listeria monocytogenes or Rickettsia parkeri, over days. Under conditions in which these pathogens trigger innate immune signaling through NF-κB and use actin-based motility to spread non-lytically intercellularly, we found that infected cell domains formed three-dimensional mounds. These mounds resulted from uninfected cells moving toward the infection site, collectively squeezing the softer and less contractile infected cells upward and ejecting them from the monolayer. Bacteria in mounds were less able to spread laterally in the monolayer, limiting the growth of the infection focus, while extruded infected cells underwent cell death. Thus, the coordinated forceful action of uninfected cells actively eliminates large domains of infected cells, consistent with this collective cell response representing an innate immunity-driven process.

Elongated neutrophil-derived structures are blood-borne microparticles formed by rolling neutrophils during sepsis.

Rolling neutrophils form tethers with submicron diameters. Here, we report that these tethers detach, forming elongated neutrophil-derived structures (ENDS) in the vessel lumen. We studied ENDS formation in mice and humans in vitro and in vivo. ENDS do not contain mitochondria, endoplasmic reticulum, or DNA, but are enriched for S100A8, S100A9, and 57 other proteins. Within hours of formation, ENDS round up, and some of them begin to present phosphatidylserine on their surface (detected by annexin-5 binding) and release S100A8-S100A9 complex, a damage-associated molecular pattern protein that is a known biomarker of neutrophilic inflammation. ENDS appear in blood plasma of mice upon induction of septic shock. Compared with healthy donors, ENDS are 10-100-fold elevated in blood plasma of septic patients. Unlike neutrophil-derived extracellular vesicles, most ENDS are negative for the tetraspanins CD9, CD63, and CD81. We conclude that ENDS are a new class of bloodborne submicron particles with a formation mechanism linked to neutrophil rolling on the vessel wall.

Bronchial Dieulafoy's Disease in Children: A Case Report and Review of Literature.

Dieulafoy's disease is a rare vascular lesion characterized by presence of large aberrant arteries within the submucosa of gastrointestinal tract or respiratory tract with a potential to cause life-threatening hemorrhage. Treatment includes bronchoscopy ablation, angiographic embolization or surgery. We report management of 7-year old girl with Dieulafoy's disease in the airway who presented with recurrent hemoptysis. Bronchial angiography revealed multiple feeding vessels to the lesion. Considering the potential risk of recurrence with embolization, sleeve resection of bronchus offered complete resolution. This case demonstrates the usefulness of bronchial angiography as part of multi-faceted approach before surgery in the management of Dieulafoy's disease.