scholarly journals Analysis of Radiofrequency Lesions in Egg Whites in Vitro Produced by Application of the Tew Electrode for Different Temperatures and Times

2015 ◽  
Vol 20 (6) ◽  
pp. 316-320 ◽  
Author(s):  
Young Suk Kwon ◽  
So Young Lim ◽  
Jong Ho Kim ◽  
Ji Su Jang ◽  
Chul Ho Kim ◽  
...  
Keyword(s):  
Distal Radius ◽  
Mixed Model ◽  
Glass Container ◽  
Lesion Size ◽  
External Radius ◽  
Internal Radius ◽  
S 100 ◽  
Different Temperatures ◽  
Radiofrequency Lesions

BACKGROUND: Understanding the size and shape of radiofrequency lesions is important to reduce side effects when applied to patients.OBJECTIVES: To investigate the radiofrequency lesions produced by the application of the Tew electrode for different temperatures and times.METHODS: The white from a fresh hen’s egg was placed in a rectangular glass container and warmed to 37°C. After immersion of the Tew electrode in the egg white, radiofrequency lesions were produced at 65°C, 70°C, 75°C, 80°C, 85°C and 90°C. For each temperature, photographs were taken at 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s and 120 s. The size of the lesion was measured at each temperature and time. A mixed model was used to analyze the data.RESULTS: The size of the lesion increased with increasing temperature and time. There were statistically significant differences in the size of the internal radius between the 65°C and 70°C groups and the 70°C and 75°C groups, as well as in the 70°C and 75°C groups in the size of the external radius and the 60°C to 80°C groups in the size of the distal radius. The maximum lesion size was produced at 90°C and 120 s, and was 1.06±0.16 mm in internal radius, 0.37±0.15 mm in external radius, 0.39±0.04 mm in distal radius.CONCLUSION: The Tew electrode produces lesions following the contour of the tip, and the internal radius is larger than the external and distal radius. The best combination of temperature and time for lesioning using the Tew electrode is 80°C, for 60 s to 90 s.

Deep Brain Stimulator Electrodes Used for Lesioning: Proof of Principle

Neurosurgery ◽  
2001 ◽  
Vol 49 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Michael Y. Oh ◽  
Mojgan Hodaie ◽  
Seong Ho Kim ◽  
Ahmed Alkhani ◽  
Anthony E. Lang ◽  
...  
Keyword(s):  
Subthalamic Nucleus ◽  
Lesion Size ◽  
Therapeutic Benefit ◽  
Ethical Review ◽  
Deep Brain Stimulator ◽  
Implanted Electrodes ◽  
Radiofrequency Lesions ◽  
The Right ◽  
Deep Brain

Abstract OBJECTIVE Patients with chronically implanted deep brain stimulator (DBS) electrodes can encounter complications requiring hardware removal. We assessed the safety and efficacy of using implanted DBS electrodes to create a therapeutic lesion before their removal. METHODS Revision or removal of the DBS electrodes was required in two patients who had previously undergone DBS implantation. We conducted a series of in vitro experiments to confirm that the DBS electrodes could be used to generate radiofrequency lesions and to assess the relationship between radiofrequency parameters and lesion size. With this information, and with the approval of the hospital ethical review board, implanted electrodes were used to create incremental radiofrequency lesions in the thalamus in one patient and in the subthalamic nucleus in another. The procedures were performed under local anesthesia with contiguous contacts of the DBS lead connected to the active and reference sites of the RF generator to create a bipolar lesion. RESULTS A 51-year-old man with essential tremor and a thalamic DBS required repeated battery changes secondary to tolerance and high voltage demands. Rather than replacing the battery, a radiofrequency thalamotomy was performed by using the existing left DBS electrode. At the 6-month follow-up examination, successful lesioning provided near complete tremor control. A second patient, a 50-year-old man with Parkinson's disease who had undergone bilateral subthalamic deep brain stimulation, developed skin erosion over the DBS hardware. A subthalamic nucleus lesion was made through the right DBS electrode. Lesion position and size were confirmed with magnetic resonance imaging. CONCLUSION Lesions can be made through chronically implanted DBS electrodes in a safe, graded fashion and can produce therapeutic benefit.

Radiofrequency Energy and Electrode Proximity Influences Stereoelectroencephalography-Guided Radiofrequency Thermocoagulation Lesion Size: An In Vitro Study with Clinical Correlation

2018 ◽  
Vol 15 (4) ◽  
pp. 461-469 ◽  
Author(s):  
Michael D Staudt ◽  
Sarita Maturu ◽  
Jonathan P Miller
Keyword(s):  
Focal Epilepsy ◽  
Intractable Epilepsy ◽  
High Energy ◽  
Lesion Size ◽  
Magnetic Resonance Images ◽  
Low Energy ◽  
Radiofrequency Energy ◽  
Radiofrequency Thermocoagulation ◽  
Radiofrequency Lesions

Abstract BACKGROUND Radiofrequency thermocoagulation of epileptogenic foci via stereoelectroencephalography (SEEG) electrodes has been suggested as a treatment for medically intractable epilepsy, but reported outcomes have been suboptimal, possibly because lesions generated using conventional high-energy radiofrequency parameters are relatively small. OBJECTIVE To describe a technique of delivering low energy across separate SEEG electrodes in order to create large confluent radiofrequency lesions. METHODS The size and configuration of radiofrequency lesions using different radiofrequency intensity and interelectrode distance was assessed in egg whites. Magnetic resonance images (MRI) from 3 patients who had undergone radiofrequency lesion creation were evaluated to determine the contribution of lesion intensity and electrode separation on lesion size. Electroencephalography, MRI, and clinical data were assessed before and after lesion creation. RESULTS Both in Vitro and in Vivo analysis revealed that less energy paradoxically produced larger lesions, with the largest possible lesions produced when radiofrequency power was applied for long duration at less than 3 W. Linear separation of electrodes also contributed to lesion size, with largest lesions produced when electrodes were separated by a linear distance of between 5 and 12 mm. Clinical lesions produced using these parameters were large and resulted in improvement in interictal and ictal activity. CONCLUSION Radiofrequency lesions produced using low-energy delivery between SEEG electrodes in close proximity can produce a large lesion. These findings might have advantages for treatment of focal epilepsy.

Impact of power and contact force in ablation-index guided radiofrequency lesions in an in vitro model

EP Europace ◽  
2021 ◽  
Vol 23 (Supplement_3) ◽  
Author(s):  
C Lozano-Granero ◽  
E Franco Diez ◽  
R Matia Frances ◽  
A Hernandez-Madrid ◽  
I Sanchez Perez ◽  
...  
Keyword(s):  
Contact Force ◽  
Lesion Size ◽  
Public Institution ◽  
Lesion Volume ◽  
Lesion Depth ◽  
Lower Index ◽  
Ablation Index ◽  
Radiofrequency Lesions ◽  
Size And Morphology

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Electrophisiology Section of the Spanish Society of Cardiology Introduction. Lesion Size Index (LSI) and Ablation Index (AI) are markers of lesion quality that incorporate power, contact force (CF), and time in a weighted formula to estimate lesion size. Although accurate predicting lesion depth in-vitro, their precision in lesion size estimation has not been well established for certain power and CF settings. Purpose. We conducted an experimental ex-vivo study to analyse the effect of power and CF in size and morphology of ablation lesions in a porcine heart model. Methods. 24 sets of 10 perpendicular epicardial radiofrequency applications were performed with two commercially available catheters (TactiCath, Sensor Enabled; and SmartTouch) on porcine left ventricle submerged in 37ºC saline, combining different power (25, 30, 35, 40, 50 and 60W) and CF (10 and 20g) settings, and aiming at a lower (LSI/AI of 5/400) or higher (LSI/AI of 6/550) index. After each application, lesions were cross-sectioned and measured. Results. 480 lesions were performed. For a given target index and CF, significant differences in lesion volume and depth with different power settings were observed with both catheters. Regarding lesion volume, statistically significant differences were observed with all CF and LSI targets with TactiCath, except for 10 g and LSI 5 (10 g and LSI 5, p = 0.4134; 10 g and LSI 6, p < 0.0001; 20 g and LSI 5, p < 0.0001; 20 g and LSI 6, p < 0.0001). The same occurred for SmartTouch, showing statistically significant differences with all CF and AI targets, except for 20 g and AI 550 (10 g and AI 400, p = 0.0001; 10 g and AI 550, p < 0.0001; 20 g and AI 400, p < 0.0001; 20 g and AI 550, p = 0.001). Similar differences could be found in lesion depth with each catheter. Globally, lesions performed with 50 and 60W were significantly smaller and shallower than those performed with 35 or 40W (figure). Regarding CF, catheters behaved differently: lesions performed with 10g were smaller and shallower than those performed with 20g with Tacticath, while being bigger and deeper with SmartTouch. In a side-by-side comparison, lesions performed with TactiCath were smaller and shallower than those performed with SmartTouch when applying a lower CF of 10g, both when targeting a lower index objective (volume: 41.8 ± 54.3mm3 vs 158.3 ± 33.2mm3, p < 0.0001; depth: 2 ± 1.7mm vs 4.6 ± 0.5mm, p < 0.0001) or a higher index objective (volume: 103.1 ± 56.5mm3 vs 280 ± 54mm3, p < 0.0001; depth: 4 ± 1.1mm vs 5.8 ± 0.5mm, p < 0.0001). However, lesions with TactiCath were bigger and deeper when applying a higher CF of 20g aiming at a lower index objective (volume: 123.8 ± 39.9mm3 vs 89.7 ± 29.4mm3, p < 0.0001; depth: 4 ± 0.8mm3 vs 3.6 ± 0.5mm, p < 0.0001). No statistically significant difference was observed when applying a higher CF of 20g aiming at a higher index objective. Conclusions. Size and morphology of index-guided radiofrequency lesions varied significantly with different power and CF settings, highlighting the importance of achieving a good CF in any ablation procedure. Abstract Figure. Box-plot of lesion volume

The Effect of Volarly Angulated Distal Radius Fractures on Forearm Rotation: In Vitro Biomechanical Study

2015 ◽  
Vol 04 (S 01) ◽  
Author(s):  
Masao Nishiwaki ◽  
Mark Welsh ◽  
Louis Ferreira ◽  
James Johnson ◽  
Graham King ◽  
...  
Keyword(s):  
Distal Radius ◽  
Biomechanical Study ◽  
Distal Radius Fractures ◽  
Radius Fractures ◽  
Forearm Rotation

scholarly journals Effect of temperature, CO2 and O2 on motility and mobility of Anisakidae larvae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aiyan Guan ◽  
Inge Van Damme ◽  
Frank Devlieghere ◽  
Sarah Gabriël
Keyword(s):  
Enzymatic Digestion ◽  
Infected Fish ◽  
Effect Of Temperature ◽  
Video Recordings ◽  
Different Temperatures ◽  
Semi Solid ◽  
Zoonotic Parasites ◽  
The Impact ◽  
Phosphate Buffered Saline

AbstractAnisakidae, marine nematodes, are underrecognized fish-borne zoonotic parasites. Studies on factors that could trigger parasites to actively migrate out of the fish are very limited. The objective of this study was to assess the impact of different environmental conditions (temperature, CO2 and O2) on larval motility (in situ movement) and mobility (migration) in vitro. Larvae were collected by candling or enzymatic digestion from infected fish, identified morphologically and confirmed molecularly. Individual larvae were transferred to a semi-solid Phosphate Buffered Saline agar, and subjected to different temperatures (6 ℃, 12 ℃, 22 ℃, 37 ℃) at air conditions. Moreover, different combinations of CO2 and O2 with N2 as filler were tested, at both 6 °C and 12 °C. Video recordings of larvae were translated into scores for larval motility and mobility. Results showed that temperature had significant influence on larval movements, with the highest motility and mobility observed at 22 ℃ for Anisakis spp. larvae and 37 ℃ for Pseudoterranova spp. larvae. During the first 10 min, the median migration of Anisakis spp. larvae was 10 cm at 22 ℃, and the median migration of Pseudoterranova spp. larvae was 3 cm at 37 ℃. Larval mobility was not significantly different under the different CO2 or O2 conditions at 6 °C and 12 ℃. It was concluded that temperature significantly facilitated larval movement with the optimum temperature being different for Anisakis spp. and Pseudoterranova spp., while CO2 and O2 did not on the short term. This should be further validated in parasite-infected/spiked fish fillets.

scholarly journals Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans

BioControl ◽  
2021 ◽  
Author(s):  
Mudassir Iqbal ◽  
Maha Jamshaid ◽  
Muhammad Awais Zahid ◽  
Erik Andreasson ◽  
Ramesh R. Vetukuri ◽  
...  
Keyword(s):  
Root Rot ◽  
Fungal Pathogens ◽  
Aureobasidium Pullulans ◽  
Grey Mould ◽  
Lesion Size ◽  
Plant Diseases ◽  
Crown Rot ◽  
Whole Plants

AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.

EXTRAHEPATIC AND EXTRARENAL RENIN INACTIVATION IN THE DOG

1974 ◽  
Vol 60 (2) ◽  
pp. 217-222
Author(s):  
R. FAGARD ◽  
E. FOSSION ◽  
M. CAMPFORTS ◽  
A. AMERY
Keyword(s):  
Blood Vessels ◽  
Pulmonary Circulation ◽  
Plasma Renin ◽  
Glass Container ◽  
Plasma Renin Concentration ◽  
Vascular Beds ◽  
Extrarenal Renin

SUMMARY It was demonstrated previously that renin disappears quickly from the circulation after nephrectomy in the hepatectomized dog. In the present study the plasma renin concentration (PRC) was measured in the efferent and afferent blood vessels of several vascular beds (pulmonary circulation, splanchnic region, spleen, both inferior limbs and pelvis, head) in the anhepatic and in the anhepatic and anephric dog in order to investigate extrarenal and extrahepatic renin inactivation. However, no significant arteriovenous differences in PRC could be traced. The blood of these dogs kept in vitro at 37 °C in a glass container showed no decline in PRC within 3 h of removal. Therefore no specific extrahepatic and extrarenal renin-inactivating mechanism was found which could explain the rapid disappearance of renin from the blood in vivo in the anhepatic and anephric dog.

scholarly journals Eudragit S-100 coated sodium alginate microspheres of naproxen sodium: Formulation, optimization and in vitro evaluation / Alginatne mikrosfere naproksen natrija obložene Eudragitom S-100: Priprava, optimizacija i in vitro vrednovanje

2012 ◽  
Vol 62 (4) ◽  
pp. 529-545 ◽  
Author(s):  
Anuj Chawla ◽  
Pooja Sharma ◽  
Pravin Pawar
Keyword(s):  
Drug Release ◽  
Sodium Alginate ◽  
Naproxen Sodium ◽  
Drug Loading ◽  
Size Analysis ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
S 100 ◽  
Eudragit S 100

The aim of the study was to prepare site specific drug delivery of naproxen sodium using sodium alginate and Eudragit S-100 as a mucoadhesive and pH-sensitive polymer, respectively. Core microspheres of alginate were prepared by a modified emulsification method followed by cross-linking with CaCl2, which was further coated with the pH dependent polymer Eudragit S-100 (2.5 or 5 %) to prevent drug release in the upper gastrointestinal environment. Microspheres were characterized by FT-IR spectroscopy, X-ray diffraction, differential scanning calorimetry and evaluated by scanning electron microscopy, particle size analysis, drug loading efficiency, in vitro mucoadhesive time study and in vitro drug release study in different simulated gastric fluids. Stability studies of the optimized formulation were carried out for 6 months. SEM images revealed that the surface morphology was rough and smooth for core and coated microspheres, respectively. Core microspheres showed better mucoadhesion compared to coated microspheres when applied to the mucosal surface of freshly excised goat colon. The optimized batch of core microspheres and coated microspheres exhibited 98.42 ± 0.96 and 95.58 ± 0.74 % drug release, respectively. Drug release from all sodium alginate microsphere formulations followed Higuchi kinetics. Moreover, drug release from Eudragit S-100 coated microspheres followed the Korsmeyer-Peppas equation with a Fickian kinetics mechanism. Stability study suggested that the degradation rate constant of microspheres was minimal, indicating 2 years shelf life of the formulation.

scholarly journals A complex control region of the mouse rRNA gene directs accurate initiation by RNA polymerase I.

1985 ◽  
Vol 5 (3) ◽  
pp. 554-562 ◽  
Author(s):  
K G Miller ◽  
J Tower ◽  
B Sollner-Webb
Keyword(s):  
Initiation Site ◽  
Rrna Gene ◽  
Sufficient Information ◽  
Reaction Conditions ◽  
Cell Extracts ◽  
S 100 ◽  
Initiation Reaction ◽  
Polymerase I

To determine the size and location of the mouse rDNA promoter, we constructed systematic series of deletion mutants approaching the initiation site from the 5' and 3' directions. These templates were transcribed in vitro under various conditions with S-100 and whole-cell extracts. Surprisingly, the size of the rDNA region that determines the level of transcription differed markedly, depending on the reaction conditions. In both kinds of cell extracts, the apparent 5' border of the promoter was at residue ca. -27 under optimal transcription conditions, but as reaction conditions became less favorable, the 5' border moved progressively out to residues -35, -39, and -45. The complete promoter, however, extends considerably further, for under other nonoptimal conditions, we observed major effects of promoter domains extending in the 5' direction to positions ca. -100 and -140. In contrast, the apparent 3' border of the mouse rDNA promoter was at residue ca. +9 under all conditions examined. We also show that the subcloned rDNA region from -39 to +9 contains sufficient information to initiate accurately and that the region between +2 and +9 can influence the specificity of initiation. These data indicate that, although the polymerase I transcription factors recognize and accurately initiate with only the sequences downstream of residue -40, sequences extending out to residue -140 greatly favor the initiation reaction; presumably, this entire region is involved in rRNA transcription in vivo.

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