Tissue Pressure Research Articles

L-arginine Attenuates Hypobaric Hypoxia-Induced Increase in Ornithine Decarboxylase 1

Chronic hypoxia-induced pulmonaryhypertension and vascular remodeling have been shown to be associated with ornithine decarboxylase 1 (ODC1). However, few animal studies have investigated the role of ODC1 in acute hypoxia. We investigated ODC1 gene expression, morphologic and functional changes, and the effect of L-arginine as an attenuator in lung tissues of rats exposed to acute hypobaric hypoxia at a simulated altitude of 6000 m. Sprague-Dawley rats exposed to simulated hypobaric hypoxia (6000 m) for 24, 48, or 72 hours were treated with L-arginine(L-arginine group, 20 mg/100 g intraperitoneal; n=15) or untreated (non-L-arginine group, n=15). Control rats (n=5) were maintained at 2260 m in a normal environment for the same amount of time but were treated without L-arginine. The mean pulmonary artery pressure was measured by PowerLab system. The morphologic and immunohistochemical changes in lung tissue were observed under a microscope. The mRNA and protein levels of ODC1 were measured by real-time polymerase chain reaction and Western-blot, respectively. Hypobaric hypoxia induced pulmonary interstitial hyperemia and capillary expansion in the lungs of rats exposed to acute hypoxia at 6000 m. The mean pulmonary artery pressure and the mRNA and protein levels of ODC1 were significantly increased, which could be attenuated by treatment with L-arginine. L-arginine attenuates acute hypobaric hypoxia-induced increase in mean pulmonary artery pressure and ODC1 gene expression in lung tissues of rats. ODC1 gene contributes to the development of hypoxic pulmonary hypertension.

Blood vessel tortuosity selects against evolution of aggressive tumor cells in confined tissue environments: A modeling approach.

Cancer is a disease of cellular regulation, often initiated by genetic mutation within cells, and leading to a heterogeneous cell population within tissues. In the competition for nutrients and growth space within the tumors the phenotype of each cell determines its success. Selection in this process is imposed by both the microenvironment (neighboring cells, extracellular matrix, and diffusing substances), and the whole of the organism through for example the blood supply. In this view, the development of tumor cells is in close interaction with their increasingly changing environment: the more cells can change, the more their environment will change. Furthermore, instabilities are also introduced on the organism level: blood supply can be blocked by increased tissue pressure or the tortuosity of the tumor-neovascular vessels. This coupling between cell, microenvironment, and organism results in behavior that is hard to predict. Here we introduce a cell-based computational model to study the effect of blood flow obstruction on the micro-evolution of cells within a cancerous tissue. We demonstrate that stages of tumor development emerge naturally, without the need for sequential mutation of specific genes. Secondly, we show that instabilities in blood supply can impact the overall development of tumors and lead to the extinction of the dominant aggressive phenotype, showing a clear distinction between the fitness at the cell level and survival of the population. This provides new insights into potential side effects of recent tumor vasculature normalization approaches.

Reply: Effects of Negative-Pressure Wound Therapy on Primary Closed Defects after Superficial Circumflex Iliac Artery Perforator Flap Harvest: Randomized Controlled Study

Sir: We thank the authors for their interest in our article.1 Recently, incisional negative-pressure wound therapy has been used to enhance healing for surgical incisions in patients with a high risk of wound dehiscence. As shown in this article, the application of negative-pressure wound therapy has many benefits. However, before applying negative-pressure wound therapy to patients, clinicians need to know the limited benefits and possible complications by understanding the physics and physiology of the therapy. The following are answers to your questions. First, it became a common belief that when using negative-pressure wound therapy dressing, tissue pressure increases proportional to the amount of negative pressure applied.2,3 The additional tissue pressure, with a pressure setting of −150 mmHg with continuous pressure mode, was +2 to 10 mmHg in noncircumferential wounds. This increased tissue pressure has a minimal effect on healthy tissues. However, in ischemic wounds and tissues with compromised perfusion, tissue perfusion might be jeopardized. There are many clinical reports of minimizing the tissue pressure increase by using a lower pressure setting.4–6 In these cases, lowering the pressure to −50 mmHg over the incisional wound can be an option. However, our series involves healthy donor sites and furthermore uses the cyclic mode to minimize the chance of possible tissue ischemia caused by the compression effect. This compression, in our hands, is enough to give the tie-over bolster fixation effect. This will minimize shearing of the skin and thus allow faster healing and reduce seroma/hematoma formation as shown in the article. Second, using the Jackson-Pratt drain is within good practice when closing a wound with dead space. By maintaining the negative pressure of the drain, hematoma collection will be minimized. One cannot compare the effect of the drain to the negative-pressure wound therapy applied on the skin because it is used for different purposes. The negative-pressure wound therapy over the skin will improve perfusion of the skin and play a role in fixation. If one were to see the fluid drain to the negative-pressure wound therapy system, it would mean that either the Jackson-Pratt drain was not functioning or secure closure of the skin was not performed. Third, the PeriScan PIM 3 System does not use a probe but rather uses a 785-nm, 70-mW laser (Perimed AB, Stockholm, Sweden) to calculate the blood perfusion of the closed margin. The measurement is performed immediately after the dressing is removed. DISCLOSURE Dr. Hong and Dr. Suh are consultants for Daewoong Pharmaceutical Company. No financial support was received regarding this study. Hyunsuk Peter Suh, M.D., Ph.D.Min Young Jang, R.N.Joon Pio (Jp) Hong, M.D., Ph.D., M.M.M.Seoul Asan Medical CenterUniversity of Ulsan College of MedicineSeoul, Republic of Korea

Use of Noncontact Low-Frequency Ultrasound in Deep Tissue Pressure Injury: A Retrospective Analysis.

The purpose of this study was to examine the effect of noncontact low-frequency ultrasound (NLFU) on deep tissue pressure injury (DTPI), both hospital-acquired and those present on admission (POA). Retrospective, descriptive study. Medical records from 44 adult patients with a DTPI treated with NLFU were reviewed; 22 had a hospital-acquired DTPI (HADTPI) and 22 had DTPI POA. Their mean age was 71.3 ± 16.3 years (mean ± SD); 52% were male. The study setting was a 318-bed community hospital in the Mid-Atlantic region of the United States. Data were collected from the medical records including demographic and relevant clinical characteristics, DTPI measurements, and DTPI evolution/resolution. Data were summarized and examined using descriptive statistics (eg, frequencies and percentages and means and standard deviations). Differences between groups were examined using paired t tests or the Mann-Whitney U test and the chi-square test as appropriate. In addition, the heel DTPI subgroup (N = 8) was examined separately due to the small sample size. All patients with HADTPI and DTPI POA treated with NLFU exhibited a statistically significant decrease in injury size from initiation to discontinuation of NLFU therapy (24.6 cm vs 14.4 cm, P = .02). No statistically significant difference in wound resolution was found between HADTPI versus DTPI POA (27% vs 18%, P = .47). Mean size of both HADTPI and DTPI POA decreased significantly from 15.9 to 13.4 cm (P = .045) by NLFU therapy. Wounds were classified as resolved at completion of treatment in 23% (10 out of 44) of all treated patients. Of all patients with the potential to be resolved (not discharged early or expired) 63% (10 out of 16) had wounds classified as resolved. Study findings suggest that NLFU is a viable and promising treatment option for both HADTPI and DTPI POA. Future studies are needed to confirm these results and to examine efficacy and feasibility of DTPI across care settings.

Tissue growth pressure drives early blood flow in the chicken yolk sac.

Understanding how molecular and physical cues orchestrate vascular morphogenesis is a challenge for developmental biology. Only little attention has been paid to the impact of mechanical stress caused by tissue growth on early blood distribution. Here we study the peripheral accumulation of blood in the chicken embryonic yolk sac, which precedes sinus vein formation. We report that blood accumulation starts before heart-induced blood circulation. We hypothesized that the driving force for the primitive blood flow is a growth-induced gradient of tissue pressure in the yolk sac mesoderm. Therefore, we studied embryos in which heart development was arrested after 2 days of incubation, and found that yolk sac growth and blood peripheral accumulation still occurred. This suggests that tissue growth is sufficient to initiate the flow and the formation of the sinus vein, whereas heart contractions are not required. We designed a simple mathematical model which makes explicit the growth-induced pressure gradient and the subsequent blood accumulation, and show that growth can indeed account for the observed blood accumulation. This study shows that tissue growth pressure can drive early blood flow, and suggests that the mechanical environment, beyond hemodynamics, can contribute to vascular morphogenesis. Developmental Dynamics 246:573-584, 2017. © 2017 Wiley Periodicals, Inc.

Outcome Calculations Based on Nursing Documentation in the First Generation of Electronic Health Records in the Netherlands.

Previous studies regarding nursing documentation focused primarily on documentation quality, for instance, in terms of the accuracy of the documentation. The combination between accuracy measurements and the quality and frequencies of outcome variables such as the length of the hospital stay were only minimally addressed. An audit of 300 randomly selected digital nursing records of patients (age of >70 years) admitted between 2013-2014 for hip surgery in two orthopaedic wards of a general Dutch hospital was conducted. Nursing diagnoses: Impaired tissue perfusion (wound), Pressure ulcer, and Deficient fluid volume had significant influence on the length of the hospital stay. Nursing process documentation can be used for outcome calculations. Nevertheless, in the first generation of electronic health records, nursing diagnoses were not documented in a standardized manner (First generation 2010-2015; the first generation of electronic records implemented in clinical practice in the Netherlands).

Compartment Syndrome- Controversies and where are we Today

AbstractCompartment Syndrome in Orthopedic practice is a night mare and has to be diagnosed and treated as an emergency to save the function of the limb. Importance of different criteria of early diagnosis, compartment pressure measurement and immediate fasciotomy are the controversies even today. The review emphasizes the importance of these concerns. Definition Compartment syndrome occurs due to an increased interstitial tissue pressure inside a closed 1 space especially in an osseo-fascial compartment , should be treated as an acute emergency.

Effect of hyperbaric oxygen on BDNF-release and neuroprotection: Investigations with human mesenchymal stem cells and genetically modified NIH3T3 fibroblasts as putative cell therapeutics.

Hyperbaric oxygen therapy (HBOT) is a noninvasive widely applied treatment that increases the oxygen pressure in tissues. In cochlear implant (CI) research, intracochlear application of neurotrophic factors (NTFs) is able to improve survival of spiral ganglion neurons (SGN) after deafness. Cell-based delivery of NTFs such as brain-derived neurotrophic factor (BDNF) may be realized by cell-coating of the surface of the CI electrode. Human mesenchymal stem cells (MSC) secrete a variety of different neurotrophic factors and may be used for the development of a biohybrid electrode in order to release endogenously-derived neuroprotective factors for the protection of residual SGN and for a guided outgrowth of dendrites in the direction of the CI electrode. HBOT could be used to influence cell behaviour after transplantation to the inner ear. The aim of this study was to investigate the effect of HBOT on the proliferation, BDNF-release and secretion of neuroprotective factors. Thus, model cells (an immortalized fibroblast cell line (NIH3T3)–native and genetically modified) and MSCs were repeatedly (3 x – 10 x) exposed to 100% oxygen at different pressures. The effects of HBO on cell proliferation were investigated in relation to normoxic and normobaric conditions (NOR). Moreover, the neuroprotective and neuroregenerative effects of HBO-treated cells were analysed by cultivation of SGN in conditioned medium. Both, the genetically modified NIH3T3/BDNF and native NIH3T3 fibroblasts, showed a highly significant increased proliferation after five days of HBOT in comparison to normoxic controls. By contrast, the number of MSCs was decreased in MSCs treated with 2.0 bar of HBO. Treating SGN cultures with supernatants of fibroblasts and MSCs significantly increased the survival rate of SGN. HBO treatment did not influence (increase / reduce) this effect. Secretome analysis showed that HBO treatment altered the protein expression pattern in MSCs.

Demyelinating diseases as a result of cerebral edema?

Due to the elastic properties of the human organs, tissue edema causes an increased tissue pressure. This phenomenon leads to a reduction of blood circulation or ischemia, and thus leads to the hypothesis that tissue edema can be the cause of demyelinating lesions. Even though brain edema occurs in the whole brain, the authors assume that the characteristically focal appearance of demyelinated lesions, for instance of multiple sclerosis plaques, are attributable to anatomical and structural characteristics of the brain. In an experimental section, a balloon inserted into the brain and other organs removed during autopsies produces an increased tissue pressure. This model shows tissue pressure in the vicinity of the balloon up to 80mmHg. The height of the produced pressure varies in different organs and special regions of the brain.The verified pressures in the pons cerebri show that stretched myelinated fiber bundles in outer regions can induce strong pressures in enclosed edematous tissue, as seen in central pontine myelinolysis.The presented experimental results support the hypothesis that demyelinated lesions, as seen in multiple sclerosis, may be caused by increased tissue pressure, or respectively, brain edema.

Shear modulus is a good surrogate for total tissue pressure: Preliminary studies with a xenograft pancreatic cancer tumor model

Pancreatic ductal adenocarcinoma (PDA) is a common and lethal disease, with a 5-year survival rate of less than 6%. The absence of a functional vasculature and the build-up of dense stromal regions impede drug delivery that prevents the disease from being eradicated, even when surgery is combined with chemotherapy. We hypothesize that real-time measurement of total tissue pressure, as related to cancer cell growth and drug delivery, will enable translational research into patient-specific therapies. Since no imaging methods can measure tissue pressure in vivo, we investigated the feasibility of using elastography to provide a surrogate measure of total tissue pressure. Specifically, we performed studies on orthotopically and subcutaneously grown xenograft tumors (n = 20) to assess how the shear modulus of naturally occurring AsPc-1 pancreatic tumors varies with stromal density. The results of this investigation revealed that there is 6 kPa difference between the shear modulus of orthotopically and subcuta...

Separation of Solid Stress From Interstitial Fluid Pressure in Pancreas Cancer Correlates With Collagen Area Fraction.

Elevated total tissue pressure (TTP) in pancreatic adenocarcinoma is often associated with stress applied by cellular proliferation and hydrated hyaluronic acid osmotic swelling; however, the causal roles of collagen in total tissue pressure have yet to be clearly measured. This study illustrates one direct correlation between total tissue pressure and increased deposition of collagen within the tissue matrix. This observation comes from a new modification to a conventional piezoelectric pressure catheter, used to independently separate and quantify total tissue pressure, solid stress (SS), and interstitial fluid pressure (IFP) within the same tumor location, thereby clarifying the relationship between these parameters. Additionally, total tissue pressure shows a direct correlation with verteporfin uptake, demonstrating the impediment of systemically delivered molecules with increased tissue hypertension.

"One-for-All"-Type, Biodegradable Prussian Blue/Manganese Dioxide Hybrid Nanocrystal for Trimodal Imaging-Guided Photothermal Therapy and Oxygen Regulation of Breast Cancer.

Multimodal imaging-guided diagnosis and therapy has been highlighted in the area of theranostic nanomaterials. To provide more suitable theranostic candidates, Prussian blue (PB)/manganese dioxide (MnO2) hybrid nanoparticles (PBMn) smaller than 50 nm are prepared by a one-pot method. MnO2, which is reduced from KMnO4, not only controls the particle size, the optical properties, and the transverse relaxation rate (r2) of PB but also enhances the catalysis efficacy of PB to H2O2 for oxygen generation. PBMn can serve as a photoacoustic imaging (PAI) and longitudinal relaxation (T1) mode magnetic resonance imaging contrast agent (14 times and 1.8 times of the saline-treated group, respectively). Injection of PBMn can regulate the oxygen partial pressure of the tumor tissue from 2.1 ± 0.2 to 9.3 ± 0.4 kPa and rearrange the ratio of oxygenated hemoglobin and deoxygenate hemoglobin inside the tumor, which favor the enhancement of the diamagnetic T2-weighted imaging (T2WI) signal intensity (two times that of the saline-treated group). Furthermore, PBMn-mediated PTT can efficiently inhibit the growth of the MCF-7 tumor in vitro and in vivo. PBMn can serve as a PAI/T1/T2 trimodal contrast agent and in imaging-guided PTT, as well as in the oxygen regulation of the exografted breast cancer.

An MRI investigation of the effects of user anatomy and wheelchair cushion type on tissue deformation

Aim of the studyTissue deformation is recognized as an important risk factor for pressure injuries. This study investigated the effects of anatomy and wheelchair cushion type on tissue deformation. Materials and methodsDirect 3-dimensional tissue deformation response was measured for six participants sitting on six different wheelchair cushions using MR imaging. Two participants had a traumatic spinal cord injury (SCI) within one year of the assessment, two sustained traumatic SCI at least 13 years prior, and two were without SCI. Tissue deformation was quantified using the difference in volume of tissue beneath the ischial tuberosity (IT) between unloaded and loaded (sitting) conditions. ResultsThe participants with SCI tended to have less muscle tissue volume beneath their ITs while sitting compared to participants without SCI. Reductions in muscle and fat volumes in the loaded conditions varied depending on both cushion and participant. Higher interface pressures tended to be associated with lower unloaded tissue thicknesses. ConclusionThe study showed no single cushion type tested produced the lowest amount of tissue deformation across all participants. Individual anatomy and cushion type affect deformation response of tissue and related pressure injury risk.

Biosensor Diagnostic for Congestive Heart Failure via Detection of B‐Type Natriuretic Peptide

We developed an electrochemical DNA (E‐DNA) biosensor for point‐of‐care quantitative determination of B‐type natriuretic peptide (BNP) levels in blood. BNP is a commonly used biomarker for the onset of heart failure conditions, as its secreted levels in the blood correlate with the internal pressure of cardiac tissue, and high levels of BNP are typically found in patients with congestive heart failure. Unfortunately, current tests for BNP are largely based on phlebotomic blood draw followed by ELISA, which requires external testing and eliminates the possibility of point‐of‐care diagnosis. To address this unmet need, we have developed a rapid, convenient biosensor for BNP based on a known DNA aptamer specific to BNP that has been modified and incorporated into an electrochemical readout format. E‐DNA biosensors have been shown to function in unprocessed whole blood and yield quantitative results in less than one drop of blood. When an E‐DNA biosensor binds to its target, a conformational change results in a change in electrical current. Using varied concentrations of BNP in PBS buffer we were able to dose‐response behavior from the biosensor. This data is used as a calibration standard to allow quantitative measurement of unknown concentrations of BNP, which would have useful clinical application. Although optimizations remain, ultimately, the biosensor will measurement of BNP levels in whole blood, offering a new bedside or point‐of‐care way to measure and monitor an important biomarker for diagnosis of heart failure.Support or Funding InformationSupport for this work comes from the Metropolitan State University of Denver Provost's and LAS Dean's offices.

Regulation of Coronary Blood Flow.

The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017.

Spatial landscape of oxygen in and around microvasculature during epileptic events.

Measuring changes in cerebral oxygen in tissue microdomains during epilepsy is important to identify hypoxic potential. Here, using a custom-built two-photon microscopy system, we present microscopic measurements of oxygen partial pressure ([Formula: see text]) in cortical microvessels and tissue of anesthetized mice during 4-aminopyridine (4-AP)-induced epileptic seizures. Investigating epileptic events, we characterized the distribution of the "initial dip" in [Formula: see text] in arterioles, venules, and tissue near the 4-AP injection site. Our results reveal a correlation between the percent change in [Formula: see text] during the "initial dip" and the diameter of nearest arterioles and venules.

Telomere length correlates with disease severity and inflammation in sickle cell disease.

BackgroundTelomeres, the ends of linear chromosomes, shorten during mitotic cell division and erosion may be aggravated by inflammation or proliferative and oxidative stress. As the bone marrow is under hyperproliferative pressure in sickle cell disease and several tissues are submitted to chronic inflammation, this study sought to determine the telomere length of patients with sickle cell disease.MethodsThe mean telomere length was measured in peripheral blood leukocytes by quantitative polymerase chain reaction. The age-adjusted telomere to single copy gene ratio was compared between 91 adult sickle cell disease patients and 188 controls.ResultsSickle cell disease patients had significantly shorter telomeres than the controls (p-value < 0.0001). Moreover, among sickle cell disease genotypes, Hb SS patients had significantly shorter telomeres compared to Hb SC and Hb Sβ patients (p-value < 0.0001). Patients on hydroxyurea also had shorter telomeres in comparison to those off the drug (p-value = 0.02). A positive correlation was observed between telomere length and hemoglobin level (r = 0.3; p-value = 0.004), whereas negative correlations were detected between telomere length and lymphocyte count (r = −0.3; p-value = 0.005) and interleukin-8 serum levels (r = −0.4; p-value = 0.02).ConclusionsThe findings of this study indicate that telomeres are short in sickle cell disease patients and that telomere erosion directly correlates with disease genotype, inflammation markers, and the use of hydroxyurea.

Acute Compartment Syndrome

Acute compartment syndrome is a serious complication of injury. It occurs when raised pressure within a closed osteofascial compartment compromises the circulation and function of tissues within the compartment. Most cases are caused by fracture. The largest group are tibial diaphyseal fractures, followed by soft tissue injury, crush syndrome, distal radial fractures and forearm diaphyseal fractures. Those at risk of developing acute compartment syndrome are young males, patients with bleeding disorders or on anticoagulant therapy and in the upper limb, high energy injury. The clinical symptoms and signs of acute compartment syndrome are pain, stretch pain and neurological abnormality, none of which are constantly present. Since early diagnosis of this condition is of paramount importance compartment monitoring is recommended. The recommended tissue pressure threshold for decompression has been variable through the years but should be related to the patient's blood pressure. A difference of less than 30 mmHg between the diastolic and tissue pressures has been validated clinically and it is recommended that at this level serious consideration should be given to decompression of the affected compartments. Use of this pressure threshold with compartment monitoring has been shown to half the delay to fasciotomy and significantly reduces the late complications of acute compartment syndrome.

Pressure Injury Prevalence and the Rate of Hospital-Acquired Pressure Injury Among Pediatric Patients in Acute Care.

The purpose of this study was to describe the prevalence and rate of hospital-acquired pressure injuries (HAPIs) in pediatric patients. Descriptive, secondary analysis of 2012 data on pressure injuries among pediatric patients from the National Database for Nursing Quality Indicators (NDNQI). The sample included 39,984 patients 1 day to 18 years old from 678 pediatric acute care units (general pediatrics, pediatric critical care, neonatal intensive care, pediatric step-down, and pediatric rehabilitation units) in 271 US hospitals that submitted pressure injury data to the NDNQI for at least 3 quarters during 2012. The pressure injury prevalence was 1.4% and the prevalence of HAPI was 1.1%. The rate of HAPI among males was 1.06%, and the rate among females was 1.14%. HAPI rates were highest among children ages 9 to 18 years (1.6%) and 5 to 8 years (1.4%) and lowest among patients 1 to 30 days of age (0.72%). By unit type, HAPIs were highest among patients in pediatric critical care units (3.7%) and pediatric rehabilitation units (4.6%) and lowest in general pediatrics units (0.57%). Most of the HAPIs were Stage 1 and Stage 2 (65.6%); 14.3% were deep tissue pressure injuries and 10.1% were unstageable pressure injuries. Acutely ill children develop pressure injuries, including HAPI. Study findings provide data on HAPI from a large sample of hospitalized children and by pediatric unit type for comparison purposes.

Intermittent vibration protects aged muscle from mechanical and oxidative damage under prolonged compression

Deep tissue pressure ulcers, a serious clinical challenge originating in the muscle layer, are hardly detectable at the beginning. The challenge apparently occurs in aged subjects more frequently. As the ulcer propagates to the skin surface, it becomes very difficult to manage and can lead to fatal complications. Preventive measures are thus highly desirable. Although the complex pathological mechanisms have not been fully understood, prolonged and excessive physical challenges and oxidative stress are believed to be involved in the ulcer development. Previous reports have demonstrated that oxidative stress could compromise the mechanical properties of muscle cells, making them easier to be damaged when physical challenges are introduced. In this study, we used senescence accelerated (SAMP8) mice and its control breed (SAMR1) to examine the protective effects of intermittent vibration on aged and control muscle tissues during prolonged epidermal compression under 100mmHg for 6h. Results showed that an application of 35Hz, 0.25g intermittent vibration during compression decreased the compression-induced muscle breakdown in SAMP8 mice, as indicated histologically in terms of number of interstitial nuclei. The fact that no significant difference in muscle damage could be established in the corresponding groups in SAMR1 mice suggests that SAMR1 mice could better accommodate the compression insult than SAMP8 mice. Compression-induced oxidative damage was successfully curbed using intermittent vibration in SAMP8 mice, as indicated by 8-OHdG. A possible explanation is that the anti-oxidative defense could be maintained with intermittent vibration during compression. This was supported by the expression level of PGC-1-alpha, catalase, Gpx-1 and SOD1. Our data suggested intermittent vibration could serve as a preventive measure for deep tissue ulcer, particularly in aged subjects.