A Parametric Study Delineating Irreversible Electroporation from Thermal Damage Based on a Minimally Invasive Intracranial Procedure

Background  

Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating.     

Influence of Metal of the Applicator on the Dose Distribution during Brachytherapy

This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tandem, differences among measurement, MCNPX calculation and treatment planning system results are <5%. For dose distribution in water with the presence of the ovoid, the MCNPX result agrees with the measurement. But the doses calculated from treatment planning system are overestimated by up to a factor of 4. This is due to the shielding effect of the metal materials in the applicator not being considered in the treatment planning system. This result suggests that the treatment planning system should take into account corrections for the metal materials of the applicator in order to improve the accuracy of the radiation dose delivered.     

The Effects of Irreversible Electroporation on the Achilles Tendon: An Experimental Study in a Rabbit Model

Background

To evaluate the potential effects of irreversible electroporation ablation on the Achilles tendon in a rabbit model and to compare the histopathological and biomechanical changes between specimens following electroporation ablation and radiofrequency ablation.

Methods

A total of 140 six-month-old male New Zealand rabbits were used. The animals were randomly divided into two groups, 70 in the radiofrequency ablation group and 70 in the electroporation group. In situ ablations were applied directly to the Achilles tendons of rabbits using typical electroporation (1800 V/cm, 90 pulses) and radiofrequency ablation (power control mode) protocols. Histopathological and biomechanical evaluations were performed to examine the effects of electroporation ablation and radiofrequency ablation over time.

Results

Both electroporation and radiofrequency ablation produced complete cell ablation in the target region. Thermal damage resulted in tendon rupture 3 days post radiofrequency ablation. In contrast, electroporation-ablated Achilles tendons preserved their biomechanical properties and showed no detectable rupture at this time point. The electroporation-ablated tendons exhibited signs of recovery, including tenoblast regeneration and angiogenesis within 2 weeks, and the restoration of their integral structure was evident within 12 weeks.

Conclusions

When applying electroporation to ablate solid tumors, major advantage could be that collateral damage to adjacent tendons or ligaments is minimized due to the unique ability of electroporation ablation to target the cell membrane. This advantage could have a significant impact on the field of tumor ablation near vital tendons or ligaments.     

Influence of Electroporation Conditions on Transfection of Muscle Fibers in Vivo

This study is a survey of in vivo experiments on transfection of laboratory mouse muscle fibers by electoporation using an original device generating electric impulses. Transfection efficiency proved to depend on DNA dose and the number of electric impulses. It can be increased significantly by electroporation at varying pulse burst polarity. At both direct electrode application to muscles and electroporation through the skin, the muscle fiber transfection was more efficient under electroporation conditions much milder than those usually reported. The use of electroporation method for gene therapy of Duchenne muscular dystrophy is discussed.     

Elucidating the Irreversible Mechanism and Voltage Hysteresis in Conversion Reaction for High‐Energy Sodium–Metal Sulfide Batteries

Irreversible electrochemical behavior and large voltage hysteresis are commonly observed in battery materials, in particular for materials reacting through conversion reaction, resulting in undesirable round‐trip energy loss and low coulombic efficiency. Seeking solutions to these challenges relies on the understanding of the underlying mechanism and physical origins. Here, this study combines in operando 2D transmission X‐ray microscopy with X‐ray absorption near edge structure, 3D tomography, and galvanostatic intermittent titration techniques to uncover the conversion reaction in sodium–metal sulfide batteries, a promising high‐energy battery system. This study shows a high irreversible electrochemistry process predominately occurs at first cycle, which can be largely linked to Na ion trapping during the first desodiation process and large interfacial ion mobility resistance. Subsequently, phase transformation evolution and electrochemical reaction show good reversibility at multiple discharge/charge cycles due to materials' microstructural change and equilibrium. The origin of large hysteresis between discharge and charge is investigated and it can be attributed to multiple factors including ion mobility resistance at the two‐phase interface, intrinsic slow sodium ion diffusion kinetics, and irreversibility as well as ohmic voltage drop and overpotential. This study expects that such understandings will help pave the way for engineering design and optimization of materials microstructure for future‐generation batteries.     

金属对金属全髋关节置换术后体内金属离子对机体的影响

金属对金属全髋假体由于其具有良好的活动度因而被广泛应用全髋关节置换,但是由于金属对金属全髋假体置换术后可以产生大量的钴铬金属离子而使机体内血液尿液中金属离子水平升高,而金属离子水平升高后可能会对机体产生不利影响,本文就金属对金属全髋假体置换术后对机体的影响作一综述。     

金属对金属全髋关节置换术后体内金属离子对机体的影响

金属对金属全髋假体由于其具有良好的活动度因而被广泛应用全髋关节置换,但是由于金属对金属全髋假体置换术后可以产生大量的钴铬金属离子而使机体内血液尿液中金属离子水平升高,而金属离子水平升高后可能会对机体产生不利影响,本文就金属对金属全髋假体置换术后对机体的影响作一综述。     

药物涂层支架与金属裸支架治疗ST段抬高型心肌梗死的临床价值比较

目的:评价药物涂层支架(DES)与金属裸支架(BMS)在急性心肌梗死患者中应用的安全性和有效性。方法:选择2003年1月-2010年12月,在我院确诊的急性ST段抬高型心肌梗死(STEMI)167例患者,其中使用BMS 65例,DES 102例。对比分析两组患者住院期间和出院后1年内的主要心血管或脑血管事件(MAACE)的发生情况及支架内血栓形成的发生率。结果:至随访结束,BMS组有1例患者猝死,5例出现复发心绞痛。DES组有1例突发急性左心衰后死亡,1例复发心绞痛和1例发生亚急性支架内血栓。结论:DES应用于STEMI具有较好的安全性,其术后MAACE发生率较BMS低。     

DNA对电穿孔转染效率的影响

以外源红细胞生成素cDNA的表达产物为指标,研究了运载DNA和重组表达质粒的构象对电穿孔转染CHO细胞的效率的影响.结果250mg/L的运载DNA可使外源基因表达水平提高3倍;线性化质粒DNA比超螺旋DNA更适合于用电穿孔方法获得永久表达.这一结果提示,运载DNA的存在和质粒DNA的线性化对提高电穿孔转染CHO细胞的效率是必须的.     

DNA对电穿孔转染效率的影响研究

以外源红细胞生成素eDNA的表达产物为指标,研究了运载DNA和重组表达质粒的构象对电穿孔转染CHO细胞的效率的影响。结果250μg/ml的运载DNA可使外源基因表达水平提高3倍;线性化质粒DNA比超螺旋DNA更适合于用电穿孔方法获得永久表达。这一结果提示,运载DNA的存在和质粒DNA的线性化对提高电穿孔转染CHO细胞的效率是必需的。     

药物涂层支架与金属裸支架治疗ST段抬高型心肌梗死的临床价值比较

目的：评价药物涂层支架（DES）与金属裸支架（BMS）在急性心肌梗死患者中应用的安全性和有效性。方法：选择2003年1月-2010年12月,在我院确诊的急性sT段抬高型心肌梗死（STEMI）167例患者,其中使用BMS65例,DES102例。对比分析两组患者住院期间和出院后1年内的主要心血管或脑血管事件（MAACE）的发生情况及支架内血栓形成的发生率。结果：至随访结束,BMS组有1例患者猝死,5例出现复发心绞痛。DES组有1例突发急性左心衰后死亡,1例复发心绞痛和1例发生亚急性支架内血栓。结论：DES应用于STEMI具有较好的安全性,其术后MAACE发生率较BMS低。     

The Influence of Mineral Matrices on the Thermal Behavior of Glycine

On the Hadean–Early Archean Earth, the first islands must have provided hot and dry environments for abiotically formed organic molecules. The heat sources, mainly volcanism and meteorite impacts, were also available on Mars during the Noachian period. In recent work simulating this scenario, we have shown that neat glycine forms a black, sparingly water-soluble polymer (“thermomelanoid”) when dry-heated at 200 °C under pure nitrogen. The present study explores whether relevant minerals and mineral mixtures can change this thermal behavior. Most experiments were conducted at 200 or 250 °C for 2 or 7 days. The mineral matrices used were phyllosilicates (Ca-montmorillonites SAz-1 and STx-1, Na-montmorillonite SAz-1-Na, nontronite NAu-1, kaolinite KGa-1), salts (NaCl, NaCl-KCl, CaCl₂, artificial sea salt, gypsum, magnesite), picritic basalt, and three Martian regolith simulants (P-MRS, S-MRS, JSC Mars-1A). The main analytical method employed was high-performance liquid chromatography (HPLC). Glycine intercalated in SAz-1 and SAz-1-Na was well protected against thermomelanoid formation and sublimation at 200 °C: after 2 days, 95 and 79 %, respectively, had either survived unaltered or been transformed into the cyclic dipeptide (DKP) and linear peptides up to Gly₆. The glycine survival rate followed the order SAz-1?>?SAz-1-Na?>?STx-1?≈?NAu-1?>?KGa-1. Very good protection was also provided by artificial sea salt (84 % unaltered glycine after 200 °C for 7 days). P-MRS promoted the condensation up to Gly₆, consistent with its high phyllosilicate content. The remaining matrices were less effective in preserving glycine as such or as peptides.     

Irreversible Electroporation Ablation (IRE) of Unresectable Soft Tissue Tumors: Learning Curve Evaluation in the First 150 Patients Treated

Background

Irreversible electroporation (IRE) is a novel technology that uses peri-target discrete probes to deliver high-voltage localized electric current to induce cell death without thermal-induced coagulative necrosis. “Learnability” and consistently effective results by novice practitioners is essential for determining acceptance of novel techniques. This multi-center prospectively-collected database study evaluates the learning curve of IRE.

Methods

Analysis of 150 consecutive patients over 7 institutions from 9/2010-7/2012 was performed with patients treated divided into 3 groups A (1^st 50 patients treated), B (2^nd 50) and C (3^rd 50 patients treated) chronologically and analyzed for outcomes.

Results

A total of 167 IRE procedures were performed, with a majority being liver(39.5%) and pancreatic(35.5%) lesions. The three groups were similar with respect to co-morbidities and demographics. Group C had larger lesions (3.9vs3cm,p=0.001), more numerous lesions (3.2vs2.2,p=0.07), more vascular invasion(p=0.001), underwent more associated procedures(p=0.001) and had longer operative times(p<0.001). Despite this, they had similar complication and high-grade complication rates(p=0.24). Attributable morbidity rate was 13.3%(total 29.3%) and high-grade complications were seen in 4.19%(total 12.6%). Pancreatic lesions(p=0.001) and laparotomy(p=0.001) were associated with complications.

Conclusion

The review represents that single largest review of IRE soft tissue ablation demonstrating initial patient selection and safety. Over time, complex treatments of larger lesions and lesions with greater vascular involvement were performed without a significant increase in adverse effects or impact on local relapse free survival. This evolution demonstrates the safety profile of IRE and speed of graduation to more complex lesions, which was greater than 5 cases by institution. IRE is a safe and effective alternative to conventional ablation with a demonstrable learning curve of at least 5 cases to become proficient.     

Some Thermal Requirements of Fiddler Crabs of the Temperate and Tropical Zones and Their Influence on Geographic Distribution

Thermal stress is one environmental parameter that has greatlyinfluenced the migration of crustaceans from the sea to land.Since a greater number of species of terrestrial crabs are foundin the tropics than in the temperate zone, comparative studiesof the influence of temperature on latitudinally separated populationswere undertaken. Two tropical species, U. rapax and U. thayeri,may occur as far north as St. Augustine, Florida, or, followinga severe winter, may be rare north of Cape Kennedy. The lethaleffect of the low temperatures recorded during one severe winter(1957–58) is supported by laboratory studies in whichLD₅₀, deaths occurred in 4.5 days at 10°C for U. rapax acclimatedto 18°C. The experiment demonstrates that U. rapax cannotacclimate to and survive low temperatures. This contrasts markedlywith the situation in semi-terrestrial crabs of the temperatezone, which are able to acclimate to cold. The distribution of Uca around Cape Cod Bay correlates wellwith the coastal hydrographic thermal gradient and supportsPassano's suggestion that temperatures below 20° may belimiting as they inhibit proecdysis in U. pugnax. Such an inhibitionis found experimentally in U. pugilator and in the tropicalspecies, U. rapax. It is hypothesized that a shift in the thermodynamicsof the processes underlying molting has not occurred in Ucaof the temperate zone. The paucity of semi-terrestrial Brachyurain the temperate zone may be due to the failure of many speciesto evolve capacity-adaptations to carry out all requisite lifeprocesses at temperatures below 20°, or the resistance-adaptationsnecessary to survive the low temperatures of winter.     

Thermal Energy and the Origin of Life

Life has evolved on Earth with electromagnetic radiation (light), fermentable organic molecules, and oxidizable chemicals as sources of energy. Biological use of thermal energy has not been observed although heat, and the thermal gradients required to convert it into free energy, are ubiquitous and were even more abundant at the time of the origin of life on Earth. Nevertheless, Earth-organisms sense thermal energy, and in suitable environments may have gained the capability to use it as energy source. It has been proposed that the first organisms obtained their energy by a first protein named pF₁ that worked on a thermal variation of the binding change mechanism of today's ATP sythase enzyme. Organisms using thermosynthesis may still live where light or chemical energy sources are not available. Possible suitable examples are subsurface environments on Earth and in the outer Solar System, in particular the subsurface oceans of the icy satellites of Jupiter and Saturn.     

The Influence of Water Depth on Energy Availability for Ducks

Habitat management and planning strategies for nonbreeding ducks are focused on providing enough energy to support a desired number of individuals. Therefore, regional estimates of energy availability for nonbreeding ducks are required to determine if sufficient habitat exists for them. I used core sampling to estimate food and energy density in 6 types of water bodies (i.e., actively and passively managed emergent wetlands, playas, small and large reservoirs, and sloughs) in northeastern Colorado, USA, during 3 sampling occasions throughout 2 nonbreeding seasons, 2015–2016 and 2016–2017. Also, I used precise depth measurements to estimate the percentage of each site that was shallow enough to facilitate feeding by dabbling ducks as a way to correct overall energy density to reflect availability to ducks. Emergent wetlands contained the greatest food and energy density, followed by playas and sloughs, and reservoirs contained little food or energy. Fall depletion of food was greatest in actively managed emergent wetlands and spring depletion was greatest in sloughs and passively managed emergent wetlands. Mean percentage of passively managed emergent wetlands, actively managed emergent wetlands, small reservoirs, large reservoirs, and sloughs shallower than 50 cm was 37%, 77%, 10%, 4%, and 83%, respectively. Incorporating these estimates into the energetic carrying capacity model developed by the Playa Lakes Joint Venture for eastern Colorado resulted in a 54% decrease in overall duck energy day estimates, which is below what is needed to support population goals. This research identifies the need for additional wetland restoration in eastern Colorado to meet energy requirements of nonbreeding ducks and provides information to conservation planners to make more informed decisions about the extent and location of wetland restoration activities. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Ex Vivo and In Silico Feasibility Study of Monitoring Electric Field Distribution in Tissue during Electroporation Based Treatments

Magnetic resonance electrical impedance tomography (MREIT) was recently proposed for determining electric field distribution during electroporation in which cell membrane permeability is temporary increased by application of an external high electric field. The method was already successfully applied for reconstruction of electric field distribution in agar phantoms. Before the next step towards in vivo experiments is taken, monitoring of electric field distribution during electroporation of ex vivo tissue ex vivo and feasibility for its use in electroporation based treatments needed to be evaluated. Sequences of high voltage pulses were applied to chicken liver tissue in order to expose it to electric field which was measured by means of MREIT. MREIT was also evaluated for its use in electroporation based treatments by calculating electric field distribution for two regions, the tumor and the tumor-liver region, in a numerical model based on data obtained from clinical study on electrochemotherapy treatment of deep-seated tumors. Electric field distribution inside tissue was successfully measured ex vivo using MREIT and significant changes of tissue electrical conductivity were observed in the region of the highest electric field. A good agreement was obtained between the electric field distribution obtained by MREIT and the actual electric field distribution in evaluated regions of a numerical model, suggesting that implementation of MREIT could thus enable efficient detection of areas with insufficient electric field coverage during electroporation based treatments, thus assuring the effectiveness of the treatment.     

The Transformation of the Unicellular Alga Chlamydomonas reinhardtii by Electroporation

The cell wall–lacking mutant CW-15 of the unicellular green alga Chlamydomonas reinhardtii was transformed by electroporation using plasmid pCTVHyg, which was constructed with the hygromycin phosphotransferase genehpt as the selective marker and the Tn₅ transposon of Escherichia coli under the control of the virus SV40 early gene promoter. Under optimal conditions (10⁶ mid-exponential cells/ml; electric field strength 1 kV/cm; and pulse length 2 ms), the transformation yielded 10³ Hyg^R transformants per 10⁶ recipient cells. The exogenous DNA integrated into the nuclear genome of Ch. reinhardtii was persistently inherited through more than 350 cell generations. The advantages of this system for the transformation ofCh. reinhardtii with heterologous genes are discussed.     

The Influence of Defoliation on the Distribution of Assimilates in Lolium multiflorum Lam

Autoradiographs were made of plants of Lolium multiflorum Lam.after ¹⁴CO₂ had been fixed by selected leaves. The results showedthat labelled compounds were not translocated to other tillersbut were moved to the whole root system. This pattern of distributionwas changed when all or some of the tillers on the plant weredefoliated. Where a single undefoliated tiller remained, itinitially supplied the cut tillers with ¹⁴C-containing products,thus reintegrating a system of apparently independent tillers.When all the tillers were partially defoliated, labelled compoundswere no longer translocated to the root system. A further experimentsuggested that root reserves were not mobilized for regrowthfollowing defoliation. These results are discussed in termsof the integration of a grass plant in the vegetative state.