Effect Of Pressure Application Research Articles

Cyclic pressure induced decellularization of porcine descending aortas

The demand for decellularized xenogeneic tissues used in reconstructive heart surgery has increased over the last decades. Complete decellularization of longer and tubular aortic sections suitable for clinical application has not been achieved so far. The present study aims at analyzing the effect of pressure application on decellularization efficacy of porcine aortas using a device specifically designed for this purpose. Fresh porcine descending aortas of 8 cm length were decellularized using detergents. To increase decellularization efficacy, detergent treatment was combined with pressure application and different treatment schemes. Quantification of penetration depth as well as histological staining, scanning electron microscopy, and tensile strength tests were used to evaluate tissue structure. In general, application of pressure to aortic tissue does neither increase the decellularization success nor the penetration depth of detergents. However, it is of importance from which side of the aorta the pressure is applied. Application of intermittent pressure from the adventitial side does significantly increase the decellularization degree at the intimal side (compared to the reference group), but had no influence on the penetration depth of SDC/SDS at both sides. Although the present setup does not significantly improve the decellularization success of aortas, it is interesting that the application of pressure from the adventitial side leads to improved decellularization of the intimal side. As no adverse effects on tissue structure nor on mechanical properties were observed, optimization of the present protocol may potentially lead to complete decellularization of larger aortic segments.Graphical

Interactive effect of post-harvest processing method, roasting degree, and brewing method on coffee metabolite profiles

Our study aims to characterize metabolite profiles, varying by major determinants in brewed coffee as follows: three post-harvest processing, three roasting degrees, and two brewing methods for C. arabicacv. Geisha. The major discriminant factor was the roasting degree, explaining 58.84% of the total variance of metabolite profiles. Despite a lesser degree of influence, specific metabolite profiles were retained in temperature-based brewing (Light, 11.11%; Medium, 12.01%; Dark, 22.15%) and post-harvest processing (Light, 35.29%; Medium, 29.64%; Dark, 22.03%), respectively. The effect of pressure application on the coffee metabolome was significant only for the light roasted beans (9.88%). Of note, the post-harvest processing method was featured by norharman (anaerobic), pimelic acid (natural), and xanthine (washed). In addition, our study proposed novel compounds, DiHOMEs, associated with potential health benefits, which will step-up the coffee values and suggest future direction of the development of coffee processing.

An Evaluation of Different 3D Cultivation Models on Expression Profiles of Human Periodontal Ligament Fibroblasts with Compressive Strain.

The effects of compressive strain during orthodontic treatment on gene expression profiles of periodontal ligament fibroblasts (PDLFs) have mostly been studied in 2D cell culture. However, cells behave differently in many aspects in 3D culture. Therefore, the effect of pressure application on PDLFs in different 3D structures was investigated. PDLFs were either conventionally seeded or embedded into different 3D structures (spheroids, Mebiol® gel, 3D scaffolds) and exposed to compressive force or incubated without pressure. For one 3D scaffold (POR), we also tested the effect of different compressive forces and application times. Expression of an angiogenic gene (VEGF), a gene involved in extracellular matrix synthesis (COL1A2), inflammatory genes (IL6, PTGS2), and genes involved in bone remodelling (OPG, RANKL) were investigated by RT–qPCR. Depending on the used 3D cell culture model, we detected different effects of compressive strain on expression profiles of PDLFs. COL1A2 was downregulated in all investigated 3D culture models. Angiogenetic and proinflammatory genes were regulated differentially between models. In 3D scaffolds, regulation of bone-remodelling genes upon compressive force was contrary to that observed in 3D gels. 3D cell culture models provide better approximations to in vivo physiology, compared with conventional 2D models. However, it is crucial which 3D structures are used, as these showed diverse effects on the expression profiles of PDLFs during mechanical strain.

Intra-operative nasal compression after lateral osteotomy to minimize post-operative Peri-orbital ecchymosis and edema

IntroductionPost-operative periorbital ecchymosis and edema following rhinoplasty is a well-known sequela of surgery. Unfortunately, this can be a source of distress for patients, resulting in a longer post-operative recovery time and a delayed return to work. Trauma caused by lateral osteotomies is likely the most significant cause of periorbital edema and ecchymosis in rhinoplasty. There have been various strategies proposed to minimize swelling and ecchymosis with varying success rates and accompanied risks. Intraoperative nasal compression is one potential strategy that may reduce post-operative edema and ecchymosis with minimal risk.ObjectiveTo determine whether applying direct lateral nasal pressure intraoperatively immediately after performing lateral osteotomies reduces visible post-operative edema and ecchymosis.MethodsA prospective, randomized blinded study on consecutive patients undergoing rhinoplasty with lateral osteotomies was conducted in a single academic tertiary care medical center. Each of the participants were randomized into direct pressure application post-lateral osteotomies on the right or the left hand side. Intra-operatively, direct lateral nasal pressure was performed on the pre-determined side for 5 min timed by stopwatch after osteotomy. Post-operatively, standard photographs were taken of the patient on post-operative days 1, 3, and 7. These photographs were then shown to 20 blinded-physicians and the degree of ecchymosis and edema was graded using a previously published scale.ResultsA total of 16 patients were included in this study. Based on our blinded-grading, 11 of the 16 patients had a clear global improvement in the degree of peri-orbital post-operative edema and ecchymosis with compression post lateral osteotomies. Based on the 3 blinded expert reviewers, Periorbital ecchymosis was significantly decreased on the ipsilateral side of pressure application in 10 of the 16 patients, and periorbital edema was significantly decreased in 13 of the 16 patients. The differential degree in periorbital ecchymosis was most pronounced on post-operative day 7. Patient factors such as gender, age, skin color, history of nasal trauma, side of pre-operative nasal deviation, and smoking status did not have a significant influence on the effect of pressure application post lateral osteotomies.ConclusionsApplication of direct continual lateral nasal pressure intraoperatively after performing lateral osteotomies can help reduce post-operative edema and ecchymosis up to post-operative day 7. This may lead to an overall improved appearance and subsequently an improved post-operative experience for the patient. Although the effect may be variable to some degree, this is an intervention with no additional risks involved and thus can be used in a safe manner.

Effect of Pressure Application by Sphygmomanometer on Spasticity in Post Stroke Hemiplegic Patients

Effect of Pressure Application by Sphygmomanometer on Spasticity in Post Stroke Hemiplegic Patients

RegentK and Physiotherapy-Electrodermal Mapping.

BackgroundWithin this study, a new system which measures and analyzes electrical skin impedance in 48 channels within a 2.5 × 3.5 cm matrix is used in rehabilitation medicine for the first time.MethodsElectrodermal activity was measured in 20 patients before and after two different non-surgical treatments of a completely ruptured anterior cruciate ligament. The first treatment, RegentK, was developed by Mohamed Khalifa, the second is a standard physiotherapy.ResultsThe patients in the two groups were age-matched, and all demographic data showed no significant differences. It was interesting that electrodermal activity was significantly decreased only after RegentK.ConclusionWe conclude that not only local effects of pressure application are responsible for these results, rather as yet unknown neurovegetative mechanisms have to be taken into consideration.

Microstructural Investigations of Ultra-High Performance Concrete Obtained by Pressure Application within the First 24 Hours of Hardening

In this study, the effect of pressure application (0–50 MPa) to fresh concrete right after casting and during the first 24 hours of hardening has been examined. Supplementary cementitious materials in a form of silica fume, nanosilica and ground quartz sand were used. The aim of pressure application was to reduce porosity, thus improving concrete mechanical properties. Considerable reduction in porosity and a subsequent increase in compressive strength reaching the level of Ultra-High Performance Concrete (UHPC) were achieved. Mechanical and physical properties were tested and gas sorption porosimetry, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), as well as scanning electron microscopy (SEM) were used for material characterization.

Short-term pressure induced suppression of the short-latency response: a new methodology for investigating stretch reflexes

During experiments involving ischemic nerve block, we noticed that the short-latency response (SLR) of evoked stretches in m. soleus decreased immediately following inflation of a pneumatic cuff surrounding the lower leg. The present study aimed to investigate this short-term effect of pressure application in more detail. Fifty-eight healthy subjects were divided into seven protocols. Unilateral stretches were applied to the calf muscles to elicit a SLR, and bilateral stretches to evoke a subsequent medium-latency response (MLR). Furthermore, H-reflexes and sensory nerve action potentials (SNAPs) were recorded. Additionally, stretches were applied with different velocities and amplitudes. Finally, the SLR was investigated during hopping and in two protocols that modified the ability of the muscle-tendon complex distal to the cuff to stretch. All measurements were performed with deflated and inflated cuff. Results of the protocols were as follows: 1) inflation of the cuff reduced the SLR but not the MLR; 2) the H-reflex, the M-wave, and, 3) SNAPs of n. tibialis remained unchanged with deflated and inflated cuff; 4) the SLR was dependent on the stretch velocity with deflated and also inflated cuff; 5 and 6) the reduction of the SLR by the cuff was dependent on the elastic properties of the muscle-tendon complex distal to the cuff; and 7) the cuff reduced the SLR during hopping. The present results suggest that the cuff did not affect the reflex arc per se. It is proposed that inflation restricted stretch of the muscles underlying the cuff so that most of the length change occurred in the muscle-tendon complex distal to the cuff. As a consequence, the muscle spindles lying within the muscle may be less excited, resulting in a reduced SLR. Due to its applicability in functional tasks, the introduced method can be a useful tool to study afferent feedback in motor control.

Induction of the matrix metalloproteinase-2 activation system in arteries by tensile stress. Involvement of the p38 MAP-kinase pathway

Matrix metalloproteinases (MMPs) play an important role in vascular remodeling and cardiovascular diseases by degrading extracellular matrix. Regulation of MMPs can be mediated by mitogen-activated protein kinases (MAPKs). Effects of pressure application on the proteolytic activity of MMP-2 and MAPK pathways were investigated in an organ culture of porcine muscular arteries. Inhibition of MAPKs (ERK1/2 and p38 MAPK) was carried out to prove their effects on MMP-2 activation. After tensile stress, activity and gene expression of MMP-2 were increased ( p<0.05) as shown by gelatinase assays and real-time PCR. Whereas protein expression of MMP-2 and TIMP-2 showed no changes, its regulator MT1-MMP decreased in Western blot ( p<0.001) and immunohistochemistry. In addition, p38 and ERK1/2 were activated (p38, p<0.05; ERK1/2, p<0.001) by pressure. After inhibition of p38 and ERK1/2 with SB203580 or PD98059, only the inhibition of the p38 pathway had an inhibitory effect on MMP-2 gelatinolytic activity. Tensile stress activates the MMP-2 system in muscular arterial walls. This mechanical signal is mediated by p38 MAPK and can be attenuated by blocking the p38 signal pathway. The regulation of the vascular gelatinolytic system by MAP kinases suggests a therapeutic option against cardiovascular diseases at the level of MAPK signal transduction.

Effect of pressure application on microstructure evolution in a composite of Fe–Al alloy and CrMo steel

The effect of pressure applied by hot isostatic press (HIP) on microstructure evolution during diffusion bonding was studied using a couple composed of an Fe–Al alloy (Fe–Al) and CrMo steel (CrMo). Columnar grains are formed from the joint interface to the CrMo side irrespective of pressure application. The average length of the columnar grains of the couple bonded with pressure was shorter than that of the couple bonded without pressure. For the couple bonded with pressure, the microstructure of the CrMo side beyond the columnar grains exhibits fine facets with acicular precipitates of Fe 3C. Further, strong hardening is found in this region. The application of pressure retards the aluminum diffusion from Fe–Al to CrMo. The growth rate of the columnar grain with respect to bonding time deviated from the parabolic law. These effects of the pressure application on the microstructure evolution are due to the suppression of aluminum diffusion and retardation of transformation during bonding.

Effect of Pressure Application by HIP on Microstructure Evolution during Diffusion Bonding

The effect of pressure application by hot isostatic press (HIP) during diffusion bonding on microstructure evolution and bonding strength was studied using a couple of an Fe–Al alloy (Fe–Al) and CrMo steel (CrMo). Columnar microstructure evolution from the joint interface to the CrMo side is suppressed and aluminum diffusion from Fe–Al to CrMo is retarded with pressure application. Refined microstructure with fine precipitates is observed in the CrMo side beyond the columnar grains of the couple bonded with pressure. The application of pressure decreases the bonding strength and the strain to failure. It is concluded that the application of pressure provides microstructure refinement and strong hardening in the CrMo side of the couple, although it is not beneficial for bonding strength.

Rat atriopeptin III alters hypothalamic neuronal activity

The effect of pressure application of rat atriopeptin III on extracellularly recorded action potentials of 39 hypothalamic neurons was studied in chloral hydrate-anesthetized male rats. Thirteen of these neurons were histologically located within the boundaries of the paraventricular nucleus. Atriopeptin III was a potent inhibitor of the spontaneous activity of 5 (38%) of these neurons and increased the spontaneous activity of one (8%) other neuron (7 paraventricular neurons were unresponsive to atriopeptin III). Neurons not located within the paraventricular nucleus responded similarly to pressure application of atriopeptin III. Twenty-seven percent (n=7) were inhibited and 12% (n=3) were excited while the remaining 16 (61%) neurons were unresponsive to atriopeptin III. Similar applications of an inactive fragment of atriopeptin III (amino acid sequence 18–28) did not alter the spontaneous activity of any neuron (n=6). These results illustrate that atriopeptin III, an atrial peptide which is also present in the brain, can alter the spontaneous activity of hypothalamic neurons. This provides additional evidence for central activity of this peptide.

Effects of high hydrostatic pressure on normal and neoplastic rat cells in culture.

Four types of rat cells in culture were exposed to hydrostatic pressures in the range 1-1,500 bar. Each applied pressure was constant for half an hour. The morphological effects of pressure application were studied by phase contrast microscopy, and mortality was measured by total cell counts and the trypan blue exclusion test. Morphological changes characterized by cell rounding were observed in secondary fetal brain cells and fibroblasts at about 700 bar. In two permanent neoplastic neurogenic cell lines similar changes occurred at 1,000 to 1,100 bar. When approximately 50% of the cells were rounded, mortality began to increase, as compared with controls. This was gradual in secondary cells and comparatively abrupt in the permanent neoplastic lines. Malignant cells in culture may therefore be more resistant to hydrostatic pressure than their normal counterparts.

Raman scattering and local force variations due to transition-element impurities in zinc-sulfide crystals: Effect of pressure application

The results of Raman scattering experiments in zinc-sulfide containing transition-element substitutional impurities (Cr, Mn, Fe, Co, Ni) are reported at different pressures up to 40 kbar. Numerical calculations of these impurity-induced Raman intensities are also made on the basis of Green's-function theory by applying a very simple model of the impurity-host bonding and lattice phonons from an eleven-parameter rigid-ion model (RIM11). The theoretical analysis is made possible by the recent determination of a set of force parameters in terms of RIM11 for any pressure. The calculated results provide very good correspondence with all the experimental data. It is shown that the features observed in the Raman spectra of the above crystals may be interpreted as a series of resonant modes due to the weakening of the impurity-sulfur bonds by about 20%. It is demonstrated that pressure application is a very useful tool in the assignment of the defect modes, and that a calculation of the entire defect Raman spectrum is important for an unambiguous evaluation of the local force variations. Furthermore, the advantage of simultaneously dealing with a series of similar impurities is pointed out. A monotonic evolution of the local force variations is found when going through the series of impurities, which is tentatively correlated with the variable number of the $3d$ electrons contributing to the impurity-sulfur orbitals.