scholarly journals Exploiting Tissue Dielectric Properties to Shape Microwave Thermal Ablation Zones

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3960
Author(s):  
Anna Bottiglieri ◽  
Giuseppe Ruvio ◽  
Martin O’Halloran ◽  
Laura Farina
Keyword(s):  
Adipose Tissue ◽  
Dielectric Properties ◽  
Thermal Ablation ◽  
Ex Vivo ◽  
Reference Scenario ◽  
Target Tissue ◽  
Ablation Zone ◽  
Dielectric Characterization ◽  
Clinical Scenarios ◽  
Tissue Target

The dielectric characterization of tissue targets of microwave thermal ablation (MTA) have improved the efficacy and pre-procedural planning of treatment. In some clinical scenarios, the tissue target lies at the interface with an external layer of fat. The aim of this work is to investigate the influence of the dielectric contrast between fat and target tissue on the shape and size of the ablation zone. A 2.45 GHz monopole antenna is placed parallel to an interface modelled by fat and a tissue characterized by higher dielectric properties and powered at 30 and 60 W for 60 s. The performances of MTA are numerically investigated considering different interface scenarios (i.e., different widths of fat layer, shifts in the antenna alignment) and a homogeneous reference scenario. Experiments (N = 10) are conducted on ex vivo porcine tissue to validate the numerical results. Asymmetric heating patterns are obtained in the interface scenario, the ablation zone in the target tissue is two-fold to ten-fold the size of the zone in the adipose tissue, and up to four times larger than the homogenous scenario. The adipose tissue reflects the electromagnetic energy into the adjacent tissue target, reducing the heating in the opposite direction.

scholarly journals Frequency and average gray-level information for thermal ablation status in ultrasound B-Mode sequences

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Jens Ziegle ◽  
Alfredo Illanes ◽  
Axel Boese ◽  
Michael Friebe
Keyword(s):  
Thermal Ablation ◽  
Ex Vivo ◽  
Cell Damage ◽  
Potential Temperature ◽  
Image Sequences ◽  
Target Tissue ◽  
Gray Level ◽  
Porcine Liver ◽  
Time Frequency ◽  
Average Gray Level

AbstractDuring thermal ablation in a target tissue the information about temperature is crucial for decision making of successful therapy. An observable temporal and spatial temperature propagation would give a visual feedback of irreversible cell damage of the target tissue. Potential temperature features in ultrasound (US) B-Mode image sequences during radiofrequency (RF) ablation in ex-vivo porcine liver were found and analysed. These features could help to detect the transition between reversible and irreversible damage of the ablated target tissue. Experimental RF ablations of ex-vivo porcine liver were imaged with US B-Mode imaging and image sequences were recorded. Temperature was simultaneously measured within the liver tissue around a bipolar RF needle electrode. In the B-Mode images, regions of interest (ROIs) around the centre of the measurement spots were analysed in post-processing using average gray-level (AVGL) compared against temperature. The pole of maximum energy level in the time-frequency domain of the AVGL changes was investigated in relation to the measured temperatures. Frequency shifts of the pole were observed which could be related to transitions between the states of tissue damage.

scholarly journals Restoring Perivascular Adipose Tissue Function in Obesity Using Exercise

2021 ◽  
Author(s):  
Sophie N Saxton ◽  
Lauren K Toms ◽  
Robert G Aldous ◽  
Sarah B Withers ◽  
Jacqueline Ohanian ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Contractile Function ◽  
Ex Vivo ◽  
Vascular Complications ◽  
Electrical Field Stimulation ◽  
Organic Cation Transporter ◽  
Nervous Stimulation ◽  
Perivascular Adipose Tissue ◽  
Contractile Effect ◽  
Organic Cation Transporter 3

AbstractPurposePerivascular adipose tissue (PVAT) exerts an anti-contractile effect which is vital in regulating vascular tone. This effect is mediated via sympathetic nervous stimulation of PVAT by a mechanism which involves noradrenaline uptake through organic cation transporter 3 (OCT3) and β3-adrenoceptor-mediated adiponectin release. In obesity, autonomic dysfunction occurs, which may result in a loss of PVAT function and subsequent vascular disease. Accordingly, we have investigated abnormalities in obese PVAT, and the potential for exercise in restoring function.MethodsVascular contractility to electrical field stimulation (EFS) was assessed ex vivo in the presence of pharmacological tools in ±PVAT vessels from obese and exercised obese mice. Immunohistochemistry was used to detect changes in expression of β3-adrenoceptors, OCT3 and tumour necrosis factor-α (TNFα) in PVAT.ResultsHigh fat feeding induced hypertension, hyperglycaemia, and hyperinsulinaemia, which was reversed using exercise, independent of weight loss. Obesity induced a loss of the PVAT anti-contractile effect, which could not be restored via β3-adrenoceptor activation. Moreover, adiponectin no longer exerts vasodilation. Additionally, exercise reversed PVAT dysfunction in obesity by reducing inflammation of PVAT and increasing β3-adrenoceptor and OCT3 expression, which were downregulated in obesity. Furthermore, the vasodilator effects of adiponectin were restored.ConclusionLoss of neutrally mediated PVAT anti-contractile function in obesity will contribute to the development of hypertension and type II diabetes. Exercise training will restore function and treat the vascular complications of obesity.

scholarly journals Processing and Ex Vivo Expansion of Adipose Tissue-Derived Mesenchymal Stem/Stromal Cells for the Development of an Advanced Therapy Medicinal Product for Use in Humans

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1908
Author(s):  
Anna Labedz-Maslowska ◽  
Agnieszka Szkaradek ◽  
Tomasz Mierzwinski ◽  
Zbigniew Madeja ◽  
Ewa Zuba-Surma
Keyword(s):  
Adipose Tissue ◽  
Medicinal Product ◽  
Stromal Cells ◽  
Manufacturing Process ◽  
Cellular Therapy ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Advanced Therapy Medicinal Product ◽  
Differentiation Potential ◽  
Advanced Therapy

Adipose tissue (AT) represents a commonly used source of mesenchymal stem/stromal cells (MSCs) whose proregenerative potential has been widely investigated in multiple clinical trials worldwide. However, the standardization of the manufacturing process of MSC-based cell therapy medicinal products in compliance with the requirements of the local authorities is obligatory and will allow us to obtain the necessary permits for product administration according to its intended use. Within the research phase (RD), we optimized the protocols used for the processing and ex vivo expansion of AT-derived MSCs (AT-MSCs) for the development of an Advanced Therapy Medicinal Product (ATMP) for use in humans. Critical process parameters (including, e.g., the concentration of enzyme used for AT digestion, cell culture conditions) were identified and examined to ensure the high quality of the final product containing AT-MSCs. We confirmed the identity of isolated AT-MSCs as MSCs and their trilineage differentiation potential according to the International Society for Cellular Therapy (ISCT) recommendations. Based on the conducted experiments, in-process quality control (QC) parameters and acceptance criteria were defined for the manufacturing of hospital exemption ATMP (HE-ATMP). Finally, we conducted a validation of the manufacturing process in a GMP facility. In the current study, we presented a process approach leading to the optimization of processing and the ex vivo expansion of AT-MSCs for the development of ATMP for use in humans.

scholarly journals Finite Element Analysis of the Microwave Ablation Method for Enhanced Lung Cancer Treatment

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3500
Author(s):  
Marija Radmilović-Radjenović ◽  
Martin Sabo ◽  
Marta Prnova ◽  
Lukaš Šoltes ◽  
Branislav Radjenović
Keyword(s):  
Dielectric Properties ◽  
Cancer Cells ◽  
Microwave Ablation ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Surrounding Tissue ◽  
Physical Parameters ◽  
Medical Procedure ◽  
Ablation Zone ◽  
Specific Absorption

Knowledge of the frequency dependence of the dielectric properties of the lung tissues and temperature profiles are essential characteristics associated with the effective performance of microwave ablation. In microwave ablation, the electromagnetic wave propagates into the biological tissue, resulting in energy absorption and providing the destruction of cancer cells without damaging the healthy tissue. As a consequence of the respiratory movement of the lungs, however, the accurate prediction of the microwave ablation zone has become an exceptionally demanding task. For that purpose, numerical modeling remains a primordial tool for carrying out a parametric study, evaluating the importance of the inherent phenomena, and leading to better optimization of the medical procedure. This paper reports on simulation studies on the effect of the breathing process on power dissipation, temperature distribution, the fraction of damage, and the specific absorption rate during microwave ablation. The simulation results obtained from the relative permittivity and conductivity for inflated and deflated lungs are compared with those obtained regardless of respiration. It is shown that differences in the dielectric properties of inflated and deflated lungs significantly affect the time evolution of the temperature and its maximum value, the time, the fraction of damage, and the specific absorption rate. The fraction of damage determined from the degree of tissue injury reveals that the microwave ablation zone is significantly larger under dynamic physical parameters. At the end of expiration, the ablation lesion area is more concentrated around the tip and slot of the antenna, and the backward heating effect is smaller. The diffuse increase in temperature should reach a certain level to destroy cancer cells without damaging the surrounding tissue. The obtained results can be used as a guideline for determining the optimal conditions to improve the overall success of microwave ablation.

Open-Flow Microperfusion of Subcutaneous Adipose Tissue for On-Line Continuous Ex Vivo Measurement of Glucose Concentration

Diabetes Care ◽  
1997 ◽  
Vol 20 (7) ◽  
pp. 1114-1121 ◽  
Author(s):  
Z. Trajanoski ◽  
G. A. Brunner ◽  
L. Schaupp ◽  
M. Ellmerer ◽  
P. Wach ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Glucose Concentration ◽  
Subcutaneous Adipose Tissue ◽  
Ex Vivo ◽  
Open Flow ◽  
On Line ◽  
Subcutaneous Adipose

scholarly journals Effect of Dietary Carbohydrate Type on Serum Cardiometabolic Risk Indicators and Adipose Tissue Inflammatory Markers

2018 ◽  
Vol 103 (9) ◽  
pp. 3430-3438 ◽  
Author(s):  
Huicui Meng ◽  
Nirupa R Matthan ◽  
Susan K Fried ◽  
Silvia Berciano ◽  
Maura E Walker ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Cholesterol Efflux ◽  
Cardiometabolic Risk ◽  
Ex Vivo ◽  
Inflammatory Marker ◽  
Density Lipoprotein ◽  
Hdl Cholesterol ◽  
Risk Indicators ◽  
Dietary Carbohydrate ◽  
Fasting Serum

Abstract Context and Objective Direct comparisons between types of dietary carbohydrate in terms of cardiometabolic risk indicators are limited. This study was designed to compare the effects of an isocaloric exchange of simple, refined, and unrefined carbohydrates on serum cardiometabolic risk indicators, adipose tissue inflammatory markers, and peripheral blood mononuclear cell (PBMC) fractional cholesterol efflux. Design, Participants, and Measures Participants [postmenopausal women and men (N = 11), 65 ± 8 years, body mass index 29.8 ± 3.2 kg/m2, low-density lipoprotein (LDL) cholesterol ≥2.6 mmol/L] were provided with diets (60% energy from total carbohydrate, 15% from protein, 25% from fat) for 4.5 weeks in a randomized crossover design, with 2-week washout periods. The variable component was an isocaloric exchange of simple, refined, or unrefined carbohydrate–containing foods. Serum lipoprotein, glucose, insulin, and inflammatory marker concentrations were measured. Abdominal subcutaneous adipose tissue was aspirated to assess macrophage and inflammatory marker gene expression and ex vivo cytokine secretion, and PBMCs were isolated to assess ex vivo fractional cholesterol efflux. Results Fasting serum LDL and non–high-density lipoprotein (HDL) cholesterol concentrations were higher after the refined compared with simple or unrefined carbohydrate–enriched diets (P < 0.01). Other serum measures, ex vivo fractional cholesterol efflux and adipose tissue gene expression and ex vivo cytokine secretion, were similar between diets. Conclusions Diets enriched in refined compared with simple or unrefined carbohydrate resulted in higher fasting serum LDL and non-HDL cholesterol concentrations but had little effect on other cardiometabolic risk indicators. This small study raises the intriguing possibility that refined carbohydrate may have unique adverse effects on cardiometabolic risk indicators distinct from simple and unrefined carbohydrate.

scholarly journals Dielectric characterization of Plasmodium falciparum -infected red blood cells using microfluidic impedance cytometry

2018 ◽  
Vol 15 (147) ◽  
pp. 20180416 ◽  
Author(s):  
C. Honrado ◽  
L. Ciuffreda ◽  
D. Spencer ◽  
L. Ranford-Cartwright ◽  
H. Morgan
Keyword(s):  
Plasmodium Falciparum ◽  
Dielectric Properties ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Time Course ◽  
Fluorescent Protein ◽  
Clear Understanding ◽  
Infection Cycle ◽  
Dielectric Characterization ◽  
Impedance Cytometry

Although malaria is the world's most life-threatening parasitic disease, there is no clear understanding of how certain biophysical properties of infected cells change during the malaria infection cycle. In this article, we use microfluidic impedance cytometry to measure the dielectric properties of Plasmodium falciparum -infected red blood cells ( i- RBCs) at specific time points during the infection cycle. Individual parasites were identified within i- RBCs using green fluorescent protein (GFP) emission. The dielectric properties of cell sub-populations were determined using the multi-shell model. Analysis showed that the membrane capacitance and cytoplasmic conductivity of i- RBCs increased along the infection time course, due to membrane alterations caused by parasite infection. The volume ratio occupied by the parasite was estimated to vary from less than 10% at earlier stages, to approximately 90% at later stages. This knowledge could be used to develop new label-free cell sorting techniques for sample pre-enrichment, improving diagnosis.

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