Tissue Tension Research Articles

Rho Flares Repair Local Tight Junction Leaks

Tight junctions contribute to epithelial barrier function by selectively regulating the quantity and type of molecules that cross the paracellular barrier. Experimental approaches to evaluate the effectiveness of tight junctions are typically global, tissue-scale measures. Here, we introduce Zinc-based Ultrasensitive Microscopic Barrier Assay (ZnUMBA), which we used in Xenopus laevis embryos to visualize short-lived, local breaches in epithelial barrier function. These breaches, or leaks, occur as cell boundaries elongate, correspond to visible breaks in the tight junction, and are followed by transient localized Rho activation, or Rho flares. We discovered that Rho flares restore barrier function by driving concentration of tight junction proteins through actin polymerization and ROCK-mediated localized contraction of the cell boundary. We conclude that Rho flares constitute a damage controlmechanism that reinstates barrier function when tight junctions become locally compromised because of normally occurring changes in cell shape and tissue tension.

Selective inhibition of the FcεRI-induced de novo synthesis of mediators by an inhibitory receptor.

Selective inhibition of the FcεRI-induced de novo synthesis of mediators by an inhibitory receptor.

Getting into shape: tissue tension drives oriented cell divisions duringorganogenesis.

The shapes and architecture of the organs in the animal body develop through complex coordination of cell shape change, cell migration, and cell proliferation. Finegan et al (2019) use the simple model of the Drosophila ovary and elongation of each egg chamber to explore this process. They find that a gradient of myosin‐driven tension exists along the axis of organ elongation and that this orients the division of the constituent cells. This and other recent work highlight how tissue‐level tension plays a key role in regulating tissue architecture.

P4HA1 is a new regulator of the HIF-1 pathway in breast cancer.

Hypoxia-Inducible Factor (HIF)-1 is a transcription factor that plays the key role in response to low oxygen concentrations, or hypoxia. Activation of the HIF-1 pathway is not only crucial for normal tissue development and function, but also involved in disease progression, such as cancer. Cancer cells proliferate rapidly in solid tumors, and thus, solid tumors consume much more oxygen and nutrients than normal tissue and generate oxygen tension. It is well established that oxygen tension in solid tumor tissue induces the aberrant activation of the HIF-1 pathway, and subsequently promotes angiogenesis and tumor progression. Breast cancer is a heterogeneous disease and can be classified into luminal, Her2 positive, and triple negative (TNBC) subtypes base on ER/PR and Her2 expression in the breast cancer tissue. HIF-1 activation is observed in all breast cancer subtypes; interestingly, the HIF-1 pathway is hyperactivated in TNBCs compared to other subtypes. The differential activation of the HIF-1 pathway in breast cancer subtypes suggests that oxygen-independent pathways may be involved in HIF-1 regulation during TNBC progression. However, these pathways have not been well-characterized. We demonstrate that collagen proly 4 hydroxylase 1 (P4H1) induces HIF-1α expression at the protein level by modulating α-ketoglutarate (α-KG) and succinate levels. These results reveal a novel link between collagen hydroxylation and activation of the HIF-1 pathway and unveil a new HIF-1 regulation mechanism in TNBC.

Does bone cement influence soft tissue balancing in total knee arthroplasty?

BackgroundSoft tissue tension significantly affects the function of total knee arthroplasties. This study aims to evaluate if there is a difference in soft tissue tension, comparing trails to cemented definitive components in TKA. MethodsWe prospectively compared femorotibial compartment pressures before and after cement fixation of the components in 40 primary TKA. Femorotibial pressures were measured in the medial and lateral compartment with the knee in 10°, 45°, and 90° of flexion (six measurements per TKA), and the difference in pressure between both compartments was calculated in the three positions. ResultsThe median femorotibial pressures were not significantly different following cement fixation. There was, however, a change in the difference between medial and lateral compartment pressures after cement fixation. The difference between both compartment pressures decreases after cement fixation. This difference is statistically significant only with the knee in 10° of flexion; mean (IQR) pressures change from 8.5 (five to 14) pounds to six (2.25–10) pounds (P = 0.01). ConclusionCompartment pressures in TKA do not significantly change after cement fixation. The number of TKA that qualifies as ‘balanced’ increases after cement fixation, predominantly because the differences between the medial and lateral compartment pressures decrease.

Application of mathematical modeling methods in the evaluation of severity of ischemic stroke in patients with arterial hypertension

To study the possibility of applying methods of mathematical modeling in assessing the severity of ischemic stroke in patients with arterial hypertension. The study included 80 patients with ischemic stroke. Blood pressure was measured. Transcutaneous polarography was used to measure the oxygen tension in tissues. Measurements of gas composition of the blood and thickness of the intima-media complex were performed. The level of stable metabolites of nitric oxide in the blood was determined. Measurement of endothelin-1 in the blood was performed by enzyme immunoassay. NIHSS scale was administered to assess the neurological status. Patients were divided into 3 groups according to the degree of neurological deficit. The control group consisted of 10 people without signs of vascular pathology. An increase in the neurological deficit was accompanied by an increase in the level of endothelin-1, a decrease in the level of stable metabolites of nitric oxide, and a reduction in tissue oxygenation. Discriminative functions were developed for each group of patients using discriminant analysis based on the data obtained in the study. The most statistically significant were two signs: the level of systolic blood pressure and the content of stable metabolites of nitric oxide in the blood. Thus, the imbalance in the indices of endothelium-dependent mechanisms of vascular tone regulation reflect the severity of the condition in ischemic stroke. The method of discriminant analysis allows the creation of sufficiently reliable mathematical models that can have practical significance, and can be used as a method of clarifying the severity of the condition in the acute period of ischemic stroke.

The suprapubic deepithelialized inferiorly based random flap designed to fill the tissue deficiency at supraumbilical area to prevent the concave deformity in abdominoplasty

<br><b>Introduction:</b> The most critical tissue in abdominoplasty is the midsagittal part of the supraumbilical region with the highest risk of hemodynamic disturbance. Here, the skin is also thinner compared to the neighboring lateral tissues. This may result in postoperative suprapubic depression. <b>Methods:</b> An easy technique is designed to prevent this suprapubic depression. While making the transverse incision, deepithelialized suprapubic flap is kept in place attached to the suprapubic region. The medial supraumbilical deficient tissue is brought down with the abdominoplasty flap and lowered over the deepithelialized suprapubic flap. <b>Results:</b> Follow-up with the patients is between 1 month and 2 years. We have no longer observed any concave deformity. <b>Discussion:</b> Another technique described in the literature designed to prevent the concave deformity is deepithelization of the tongue of tissue projecting from the lower end of the abdominal flap and folding this back to double up the thickness of fat in this area. Nevertheless, the median distal end of the abdominal flap is hemodynamically the poorest part of the flap. Preparing deepithelialized tongue and folding it back raises the vascular insufficiency risk. Suturing the upper edge and the sides of the supraumbilical flap to deep tissues of the abdominal flap distribute the tissue tension to deeper parts, thus reduce the incision tension with reduced scar tension at the midline. <b>Conclusion:</b> The suprapubic random flap is an assurance for prevention of concave deformity and helps to reduce the tension of transverse incision at the midline, thus may reduce the risk of scar formation.<br>

Effect of Physical Methods of Lymphatic Drainage on Postexercise Recovery of Mixed Martial Arts Athletes.

Physical methods are reported to be important for accelerating skeletal muscle regeneration, decreasing muscle soreness, and shortening of the recovery time. The aim of the study was to assess the effect of the physical methods of lymphatic drainage (PMLD) such as manual lymphatic drainage (MLD), the Bodyflow (BF) therapy, and lymphatic drainage by deep oscillation (DO) on postexercise regeneration of the forearm muscles of mixed martial arts (MMA) athletes. Eighty MMA athletes aged 27.5 ± 6.4 years were allocated to 4 groups: MLD, the BF device, DO therapy, and the control group. Blood flow velocity in the cephalic vein was measured with the ultrasound Doppler velocity meter. Maximal strength of the forearm muscles (Fmax), muscle tissue tension, pain threshold, blood lactate concentration (LA), and activity of creatine kinase were measured in all groups at rest, after the muscle fatigue test (post-ex) and then 20 minutes, 24, and 48 hours after the application of PMLD. The muscle fatigue test reduced Fmax in all subjects, but in the groups receiving MLD, DO, and BF significantly higher Fmax was observed at recovery compared with post-ex values. The application of MDL reduced the postexercise blood LA and postexercise muscle tension. The lymphatic drainage methods, whether manual or using electro-stimulation and DO, improve postexercise regeneration of the forearm muscles of MMA athletes. The methods can be an important element of therapeutic management focused on optimizing training effects and reducing the risk of injuries of the combat sports athletes.

Evaluation of sutureless mesh repair for inguinal hernia: A prospective study

Background and Aims: Hernias are among the oldest known affliction of humankind. Many procedures have been developed till date to minimize or abolish tissue tension during repair of inguinal hernia. In present study we aimed to evaluate sutureless mesh repair for inguinal hernia. Material and methods: The present study was conducted on 50 consecutive male patients between 20-50 years of age and having uncomplicated inguinal hernia. Patients were operated upon using sutureless mesh repair technique. During the follow up patients were evaluated in terms of post-operative complications, hospital stay, operative time and recurrence if any. Results: We found that mean operative time was 39.36 (2.96) minutes and mean total duration of stay in hospital was 1.06 days. There were no complications in the immediate period. At one week postoperatively, seroma formation, wound infection and scrotal swelling were seen in 3 (6%) cases, 2 (4%) cases and 1 (2%) case respectively. Conclusion: Sutureless tension free mesh repair for the treatment of inguinal hernia cases is an effective technique in terms of decreased time of operative procedure and hospital stay, and decreased postoperative complications.

THE EFFECT OF A TOURNIQUET ON INTRAOPERATIVE SOFT TISSUE BALANCE IN CAS TOTAL KNEE ARTHROPLASTY

Background: The acquirement of appropriate soft tissue balancing and accurate alignment is an essential procedure in total knee arthroplasty (TKA). Gap balancing affects the final knee kinematics , and inadequate correction of soft tissue imbalances is considered an important factor for early TKA failure. During total knee arthroplasty (TKA), tourniquets are widely used to provide clear visualization of the tissue. The aim of the present study was to evaluate the effect of a tourniquet on intraoperative soft tissue balance in CAS total knee arthroplasty. Method: In this prospective cohort study , patients were eligible for inclusion when they were scheduled for primary CAS TKA due to osteoarthritis , age between 50 and 75 years. Exclusion criteria were severe cardiac complaints , severe pulmonary disorders, Body Mass Index(BMD) &gt; 35,severe coagulation disorder. Thirty knees operated by TKA using a navigation-assisted system (KICK system, DuPuy) were evaluated the soft tissue tension and compared between the tourniquet released and the tourniquet inflated in full extension (0°) and at 90° knee flexion. Result: In total, 30 consecutive patients undergoing CAS TKA met the inclusion criteria. There were differences but not statistically significant in terms of soft tissue tension in knee full extension medial side (p=0.616) , knee, full extension lateral side(p=0.780) , 90° knee flexion medial side (p=0.573) and 90° knee flexion lateral side (p=0.163) Conclusion: Our preliminary results showed that tourniquet application during CAS TKA did not significantly affect the soft tissue balance.

Studying YAP-Mediated 3D Morphogenesis Using Fish Embryos and Human Spheroids.

The transcription coactivator, Yes-associated protein (YAP), which is a nuclear effector of the Hippo signaling pathway, has been shown to be a mechano-transducer. By using mutant fish and human 3D spheroids, we have recently demonstrated that YAP is also a mechano-effector. YAP functions in three-dimensional (3D) morphogenesis of organ and global body shape by controlling actomyosin-mediated tissue tension. In this chapter, we present a platform that links the findings in fish embryos with human cells. The protocols for analyzing tissue tension-mediated global body shape/organ morphogenesis in vivo and ex vivo using medaka fish embryos and in vitro using human cell spheroids represent useful tools for unraveling the molecular mechanisms by which YAP functions in regulating global body/organ morphogenesis.

Application of transcutaneous oxygen pressure in scar assessment

To review the application and research progress of transcutaneous oxygen pressure (TcPO 2) in scar assessment. The original articles about scar and TcPO 2 were reviewed and analyzed. Hypoxia environment plays an important role in the progression of scar tissue. TcPO 2 can accurately reflect the oxygen tension of scar tissue, which is of great significance in the assessment of scar maturity, the guidance of scar treatment, and the study of correlations between hypoxia and the progression of scar. TcPO 2 measurement is important in the study of scar evaluation, treatment, and correlation between hypoxia and scar formation.

Stromal protein βig-h3 reprogrammes tumour microenvironment in pancreatic cancer

ObjectivePancreatic cancer is associated with an abundant stromal reaction leading to immune escape and tumour growth. This massive stroma drives the immune escape in the tumour. We aimed to study...

Development of Methods and Techniques to Visualize Mechanical Tension in Embryos Using Genetically Encoded Fluorescent Mechanosensors

Lately, the growing body of quantitative data has provided evidence of the importance of mechanical forces in embryogenesis. The study of spatial and temporal distribution of mechanical tension in the course of embryogenesis is one of the most important problems of modern developmental biology. Development of genetically encoded fluorescent mechanosensors allowed their application in an intravital study of mechanical tension in developing embryos via noninvasive techniques. The possibility of applying fluorescent mechanosensors based on vinculin and C-cadherin to visualize mechanical tension in tissues of Gallus and Xenopus embryos was studied. The methods to express and detect these proteins, as well as process the resulting images, were elaborated. The best results were obtained using Xenopus embryos and the vinculin-based mechanosensor.

Can Freehand Elastosonography Be an Alternative to Renal Scintigraphy in Pediatric Vesicoureteral Reflux Cases?

Detecting renal scar is important in pediatric patients with vesicoureteral reflux (VUR) for deciding on treatment option. The aim of this study is to detect whether freehand elastosonography technique could be an alternative to dimercaptosuccinic acid (DMSA) scan in determining renal scar formation. Between November 2015 and April 2016, 25 VUR patients, age ranging from 3 to 17 years admitted to our clinic, had urinary ultrasound and elastosonography, and data of approximately 147 renal region were recorded. Data were upper, middle, and lower pole renal parenchymal thickness and echogenicities obtained by ultrasound and these poles strain target (ST), strain reference (SR), and strain index (SI) values obtained by freehand elastosonography. DMSA scan data (differential function and upper, middle, and lower pole parenchymal scar formation) were recorded. Scar formation and more than 10% reduction in differential function in renal scan were statistically higher in renal regions in which parenchymal thinning and echogenicity increase was detected by ultrasound. There was no elastosonographic data difference between renal units with and without differential function decrease. Also, there was no elastosonographic data difference between renal units with and without scar formation. In this study, we could not find any significant difference in term of tissue tension values (ST and SI) measured by freehand elastosonography between renal units with and without scar formation in renal scan.

Mechanical behaviors of tension and relaxation of tongue and soft palate: Experimental and analytical modeling

This study is to characterize mechanical properties of uniaxial tension and stress relaxation responses of muscle tissues of tongue and soft palate. Uniaxial tension test and stress relaxation test on 39 fresh tissue samples from four five-month-old boars (65 ± 15 kg) are conducted. Firstly, the rationality of the samples’ dimension design and experimenal data measurement is validated by one-way ANOVA F-type test. Mechanical properties, including stress-strain relationship and stress relaxation characteristic, are then investigated in details to show the nonlinear behaviors of the tissue samples clearly. Finally, a constitutive model of representing the mechanical properties is formulated within the nonlinear integral representation framework proposed by Pinkin and Rogers, and corresponding material parameters are fitted to the experimental data based on the Levenberg-Marquardt minimization algorithm. The results of the fitting comparison prove that the formulated constitutive model can capture the observed nonlinear behaviors of the muscle tissue samples in both the axial tension and stress relaxation experiments.

PL-012 Effect of hypoxic resistance training on the regulation of muscle mass and phenotype

Objective Hypoxia is a state of lowered oxygen tension in tissue that can be created by environmental or pathological conditions. Whatever the origin of hypoxia, different tissues will adapt acutely and/or chronically to deal with this reduction in oxygen availability. Hypoxia has recently emerged as a particularly efficient stimulus to stimulate muscle cell proliferation and accretion of muscle mass and hypoxic resistance training has become popular amongst athletes as it is thought to favor muscle accretion. However, the molecular mechanisms are largely unknown. &#x0D; Methods To determine those molecular mechanisms, 19 volunteers participated to 12 sessions of resistance training spread over 4 weeks whether in normoxia (n=9) or in hypoxia (n=10, FiO213.5% corresponding to 3500m altitude). Each session consisted in 6 sets of 10 repetitions of a one-leg extension exercise at 80% of one repetition maximum (1-RM). Blood and muscle samples in each leg were taken before and after the 4-week training period. Fiber types were determined by immunohistochemistry based on myosin heavy chain isotypes. Blood saturation (SpO2, pulsoximetry) and tissue saturation index (TSI, near-infrared spectroscopy) were monitored during the exercise sessions. &#x0D; Results Muscle thickness determined by ultrasound was increased by 7% in normoxia only (p=0.04). The 1-RM was increased in both groups but the increase was higher in hypoxia (+34%) than in normoxia (+24%) (p=0.02). In average, SpO2stayed around 98-99% in normoxia and around 93-94% in hypoxia during each set of contractions. No difference in TSI between normoxia and hypoxia was measured, which averaged 60% before starting muscle contractions and 40% during muscle contractions. A trend towards a shift in fiber type from type I to type IIa was observed in normoxia (p&lt;0.09) but not in hypoxia. Fiber area was not modified by any condition. &#x0D; Conclusions In summary, 4 weeks of hypoxic resistance training induced a larger increase in 1-RM compared to normoxic resistance training, independently of muscle hypertrophy or any change in fiber type. Further investigation should determine whether metabolic or molecular changes may explain this potentiation of maximal muscle force by hypoxia.

Evaluating tensile damage of brain tissue in intracerebral hemorrhage based on strain energy.

Intracerebral hemorrhage (ICH) may lead to physical and pathological damage and has been a focus of research for decades. Evaluating tensile damage caused by deformation in ICH is an important component of damage assessment for correct diagnosis and treatment. Traditional research on ICH paid little attention to quantified brain tissue damage resulting from mechanical factors, and only a few reported the mechanical properties of damaged brain tissue. The aim of the present study was to present an effective method that is able to evaluate the tissue damage degree in ICH, based on strain energy function. Two finite element analysis (FEA) models were analyzed: A three-dimensional (3D) model for tissue's tension experiment and a two-dimensional (2D) model for brain tissue's deformation in ICH. The polynomial fitting function of stress vs. stretch curve, which was derived from previous reports, was used in the FEA as the constitutive function of brain tissue. The present study demonstrated that white matter could be regarded as hyperelastic material when stretch was <1.343, and with stretch increasing, tissue injury exacerbated when stretch was >1.343. The strain energy loss was not linear in this process, and Neo-Hookean and Ogden model's results demonstrated a similar change in trend, but a difference in quantity. The results from 2D and 3D simulation, respectively, demonstrated the degree of damage according to the above dividing criteria and the possible distribution of tissue damage after ICH ictus. An analytical model from a biomechanical perspective for white matter injury in ICH may facilitate to improve clinical diagnosis and treatment.

Evidence-based intraoperative microbreak activities for reducing musculoskeletal injuries in the operating room.

Neuromusculoskeletal pain and fatigue have been self-reported by over 70% surgeons who perform minimally invasive surgery (MIS). These problems can become impairments impacting surgical performance, patient outcomes, and career longevity. Human factors engineering has identified microbreaks coupled with activities as a viable strategy to counteract known physical, cognitive, and environmental stressors as well as mitigate neuromusculoskeletal (NMS) problems for workers in office and manufacturing domains. Develop a novel set of intraoperative surgical microbreaks activities tailored for MIS surgeons to mitigate surgery-induced neuromusculoskeletal fatigue and pain. Using NSM problems identified by practitioners and literature, a clinician determined causes and solutions and ranked them based on literature and clinical expertise. Solutions were incorporated into synchronized activities that addressed overarching goals and multiple tissues. The resulting activities, translating contemporary science in clinical physical medicine and rehabilitation practice and tissue biomechanics, specifically address the overarching goals of: 1) posture correction; 2) normalization of tissue tension and soft tissue mobility/gliding; and 3) relaxation/stress reduction. Surgeons can perform the activities in approximately one minute inside the sterile field. Movements encompassing multiple requirements and engaging multiple body segments are combined to provide an efficient and effective intervention to the target tissues.

AIP1 and cofilin ensure a resistance to tissue tension and promote directional cell rearrangement

In order to understand how tissue mechanics shapes animal body, it is critical to clarify how cells respond to and resist tissue stress when undergoing morphogenetic processes, such as cell rearrangement. Here, we address the question in the Drosophila wing epithelium, where anisotropic tissue tension orients cell rearrangements. We found that anisotropic tissue tension localizes actin interacting protein 1 (AIP1), a cofactor of cofilin, on the remodeling junction via cooperative binding of cofilin to F-actin. AIP1 and cofilin promote actin turnover and locally regulate the Canoe-mediated linkage between actomyosin and the junction. This mechanism is essential for cells to resist the mechanical load imposed on the remodeling junction perpendicular to the direction of tissue stretching. Thus, the present study delineates how AIP1 and cofilin achieve an optimal balance between resistance to tissue tension and morphogenesis.