The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Elfed Lewis - One of the best experts on this subject based on the ideXlab platform.
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intra Tissue Pressure measurement in ex vivo liver undergoing laser ablation with fiber optic fabry perot probe
Sensors, 2016Co-Authors: Daniele Tosi, Paola Saccomandi, Emiliano Schena, Dineshbabu Duraibabu, Sven Poeggel, Gabriel Leen, Elfed LewisAbstract:We report the first-ever intra-Tissue Pressure measurement performed during 1064 nm laser ablation (LA) of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI) miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm). Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal Pressure levels range from 1.9 kPa to 71.6 kPa. Different Pressure evolutions have been recorded, as Pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal Pressure detection in liver undergoing LA: the successful detection of intra-Tissue Pressure may be a key asset for improving LA, as Pressure levels have been correlated to scattered recurrences of tumors by different studies.
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intra Tissue Pressure measurement in ex vivo liver undergoing laser ablation with fiber optic fabry perot probe
Sensors, 2016Co-Authors: Daniele Tosi, Paola Saccomandi, Emiliano Schena, Dineshbabu Duraibabu, Sven Poeggel, Gabriel Leen, Elfed LewisAbstract:We report the first-ever intra-Tissue Pressure measurement performed during 1064 nm laser ablation (LA) of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI) miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm). Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal Pressure levels range from 1.9 kPa to 71.6 kPa. Different Pressure evolutions have been recorded, as Pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal Pressure detection in liver undergoing LA: the successful detection of intra-Tissue Pressure may be a key asset for improving LA, as Pressure levels have been correlated to scattered recurrences of tumors by different studies.
P Preti - One of the best experts on this subject based on the ideXlab platform.
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Effect of valsartan addition to amlodipine on ankle oedema and subcutaneous Tissue Pressure in hypertensive patients
Journal of Human Hypertension, 2007Co-Authors: R Fogari, A Zoppi, G Derosa, A Mugellini, P Lazzari, A Rinaldi, E Fogari, P PretiAbstract:The aim of this study was to assess the effect of valsartan addition to amlodipine on ankle foot volume (AFV) and pretibial subcutaneous Tissue Pressure (PSTP), two objective measures of ankle oedema. After a 4-week placebo period, 80 grade 1–2 hypertensive patients (diastolic blood Pressure (DBP)>90 mm Hg and 140 mm Hg) were randomized to amlodipine 10 mg or valsartan 160 mg or amlodipine 10 mg plus valsartan 160 mg for 6 weeks according to an open-label, blinded end point, crossover design. At the end of the placebo period and of each treatment period, blood Pressure, AFV and PSTP were evaluated. AFV was measured using the principle of water displacement. PSTP was assessed connecting the subcutaneous pretibial interstitial environment with a water manometer. Both amlodipine and valsartan monotherapy significantly reduced SBP (−16.9 and –14.5 mm Hg, respectively, P
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effect of valsartan addition to amlodipine on ankle oedema and subcutaneous Tissue Pressure in hypertensive patients
Journal of Human Hypertension, 2007Co-Authors: R Fogari, A Zoppi, G Derosa, A Mugellini, P Lazzari, A Rinaldi, E Fogari, P PretiAbstract:The aim of this study was to assess the effect of valsartan addition to amlodipine on ankle foot volume (AFV) and pretibial subcutaneous Tissue Pressure (PSTP), two objective measures of ankle oedema. After a 4-week placebo period, 80 grade 1-2 hypertensive patients (diastolic blood Pressure (DBP)>90 mm Hg and 140 mm Hg) were randomized to amlodipine 10 mg or valsartan 160 mg or amlodipine 10 mg plus valsartan 160 mg for 6 weeks according to an open-label, blinded end point, crossover design. At the end of the placebo period and of each treatment period, blood Pressure, AFV and PSTP were evaluated. AFV was measured using the principle of water displacement. PSTP was assessed connecting the subcutaneous pretibial interstitial environment with a water manometer. Both amlodipine and valsartan monotherapy significantly reduced SBP (-16.9 and -14.5 mm Hg, respectively, P<0.01 vs baseline), and DBP (-12.9 and -10.2 mm Hg, respectively, P<0.01 vs baseline) but the reduction was greater with the combination (-22.9 mm Hg for SBP, P<0.01 vs monotherapy; -16.8 mm Hg for DBP, P<0.01 vs monotherapy). Amlodipine monotherapy significantly increased both AFV (+23%, P<0.01 vs baseline) and PSTP (+75.5%, P<0.001 vs baseline) whereas valsartan monotherapy did not influence them. As compared to amlodipine alone, the combination produced a less marked increase in AFV (+6.8%, P<0.01 vs amlodipine) and PSTP (+23.2%, P<0.001 vs amlodipine). Ankle oedema was clinically evident in 24 patients with amlodipine and in six patients with the combination. These results suggest that angiotensin receptor blockers partially counteract the microcirculatory changes responsible for calcium channel blockers induced oedema formation.
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Effect of benazepril addition to amlodipine on ankle oedema and subcutaneous Tissue Pressure in hypertensive patients
Journal of human hypertension, 2003Co-Authors: R Fogari, A Zoppi, A Mugellini, A Rinaldi, G.d. Malamani, Alessandro Vanasia, P PretiAbstract:The aim of this study was to evaluate the effect of benazepril addition to amlodipine antihypertensive treatment on ankle-foot volume (AFV) and pretibial subcutaneous Tissue Pressure (PSTP), two objective measures of ankle oedema. A total of 32 mild to moderate essential hypertensives (DBP>90 and
Daniele Tosi - One of the best experts on this subject based on the ideXlab platform.
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intra Tissue Pressure measurement in ex vivo liver undergoing laser ablation with fiber optic fabry perot probe
Sensors, 2016Co-Authors: Daniele Tosi, Paola Saccomandi, Emiliano Schena, Dineshbabu Duraibabu, Sven Poeggel, Gabriel Leen, Elfed LewisAbstract:We report the first-ever intra-Tissue Pressure measurement performed during 1064 nm laser ablation (LA) of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI) miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm). Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal Pressure levels range from 1.9 kPa to 71.6 kPa. Different Pressure evolutions have been recorded, as Pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal Pressure detection in liver undergoing LA: the successful detection of intra-Tissue Pressure may be a key asset for improving LA, as Pressure levels have been correlated to scattered recurrences of tumors by different studies.
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intra Tissue Pressure measurement in ex vivo liver undergoing laser ablation with fiber optic fabry perot probe
Sensors, 2016Co-Authors: Daniele Tosi, Paola Saccomandi, Emiliano Schena, Dineshbabu Duraibabu, Sven Poeggel, Gabriel Leen, Elfed LewisAbstract:We report the first-ever intra-Tissue Pressure measurement performed during 1064 nm laser ablation (LA) of an ex vivo porcine liver. Pressure detection has been performed with a biocompatible, all-glass, temperature-insensitive Extrinsic Fabry-Perot Interferometry (EFPI) miniature probe; the proposed methodology mimics in-vivo treatment. Four experiments have been performed, positioning the probe at different positions from the laser applicator tip (from 0.5 mm to 5 mm). Pressure levels increase during ablation time, and decrease with distance from applicator tip: the recorded peak parenchymal Pressure levels range from 1.9 kPa to 71.6 kPa. Different Pressure evolutions have been recorded, as Pressure rises earlier in proximity of the tip. The present study is the first investigation of parenchymal Pressure detection in liver undergoing LA: the successful detection of intra-Tissue Pressure may be a key asset for improving LA, as Pressure levels have been correlated to scattered recurrences of tumors by different studies.
Brian W. Pogue - One of the best experts on this subject based on the ideXlab platform.
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Collagen Complexity Spatially Defines Microregions of Total Tissue Pressure in Pancreatic Cancer
Scientific Reports, 2017Co-Authors: Michael D. Nieskoski, Marvin M. Doyley, Kayla Marra, Jason R. Gunn, P. Jack Hoopes, Tayyaba Hasan, B. Stuart Trembly, Brian W. PogueAbstract:The poor efficacy of systemic cancer therapeutics in pancreatic ductal adenocarcinoma (PDAC) is partly attributed to deposition of collagen and hyaluronan, leading to interstitial hypertension collapsing blood and lymphatic vessels, limiting drug delivery. The intrinsic micro-regional interactions between hyaluronic acid (HA), collagen and the spatial origins of mechanical stresses that close off blood vessels was investigated here. Multiple localized Pressure measurements were analyzed with spatially-matched histochemical images of HA, collagen and vessel perfusion. HA is known to swell, fitting a linear elastic model with total Tissue Pressure (TTP) increasing above interstitial fluid Pressure (IFP) directly with collagen content. However, local TTP appears to originate from collagen area fraction, as well as increased its entropy and fractal dimension, and morphologically appears to be maximized when HA regions are encapsulated by collagen. TTP was inversely correlated with vascular patency and verteporfin uptake, suggesting interstitial hypertension results in vascular compression and decreased molecular delivery in PDAC. Collagenase injection led to acute decreases in total Tissue Pressure and increased drug perfusion. Large microscopic variations in collagen distributions within PDAC leads to microregional TPP values that vary on the hundred micron distance scale, causing micro-heterogeneous limitations in molecular perfusion, and narrows viable treatment regimes for systemically delivered therapeutics.
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separation of solid stress from interstitial fluid Pressure in pancreas cancer correlates with collagen area fraction
Journal of Biomechanical Engineering-transactions of The Asme, 2017Co-Authors: Michael D. Nieskoski, Marvin M. Doyley, Kayla Marra, Jason R. Gunn, Tayyaba Hasan, Stephen C Kanick, Stephen P Pereira, Stuart B Trembly, Brian W. PogueAbstract:: 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.
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Shear modulus is a good surrogate for total Tissue Pressure: Preliminary studies with a xenograft pancreatic cancer tumor model
The Journal of the Acoustical Society of America, 2017Co-Authors: Marvin M. Doyley, Hexuan Wang, Michael D. Nieskoski, Brian W. PogueAbstract: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...
R. Ethier - One of the best experts on this subject based on the ideXlab platform.
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Spinal cord distraction: an in vitro study of length, tension, and Tissue Pressure
Journal of spinal disorders, 1991Co-Authors: Peter Jarzem, Mark Filiaggi, D.j. Doyle, R. Ethier, John P. Kostuik, C H TatorAbstract:Since the Scoliosis Research Society released a report on cord injury related to Harrington rod instrumentation for scoliosis, little has been published on the pathophysiology of this disorder. Dolan et al. (4) described diminished cord blood flow associated with spinal distraction in a cat model, but failed to demonstrate its cause. In this article, we describe a series of in vitro experiments performed on dog and sheep cadaver spinal cords. Controlled distractive forces were applied to spinal cords while monitoring both cord interstitial Pressure and cord elongation. A close (Ravg = 0.986) correlation was noted between applied tensile forces and cord interstitial Pressure. At 1,000-g loads, the average Tissue Pressure obtained was 29.5 cm H2O, ranging from 17 to 47 cm H2O. However, it was noted that the cord demonstrated nonlinear tensile elastic properties that appeared exponential in the range examined. These properties are consistent with those described for collagen-containing compounds. We conclude that spinal cord distraction is capable of generating cord Tissue Pressures that could cause a spinal cord compartment syndrome and thereby seriously impair spinal cord blood flow causing spinal cord injury.
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Length, Tension And Tissue Pressure Relationships During Spinal Cord Distraction: An In-vitro Study
[1990] Proceedings of the Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1Co-Authors: P.f. Jarzern, Mark Filiaggi, D.j. Doyle, R. EthierAbstract:Spinal distraction during surgical procedures is a well-known cause of paresis. To determine whether the decreased blood flow noted in experimental distraction injury is related to elevated Tissue Pressures, we examined the in-vitro relationship of spinal cord tensile load, Tissue Pressure, and strain. We noted a linear relationship between tensile load and Tissue Pressure. Tissue Pressures as high as 25 mmHg were possible with loads of 1250 gm. We conclude that cord distraction may cause Tissue Pressure elevations that may arrest microvascular circulation.