Electric pulses used in electroporation-based treatments have been shown to affect the excitability of muscle and neuronal cells. However, understanding the interplay between electroporation and ...electrophysiological response of excitable cells is complex, since both ion channel gating and electroporation depend on dynamic changes in the transmembrane voltage (TMV). In this study, a genetically engineered human embryonic kidney cells expressing Na
1.5 and K
2.1, a minimal complementary channels required for excitability (named S-HEK), was characterized as a simple cell model used for studying the effects of electroporation in excitable cells. S-HEK cells and their non-excitable counterparts (NS-HEK) were exposed to 100 µs pulses of increasing electric field strength. Changes in TMV, plasma membrane permeability, and intracellular Ca
were monitored with fluorescence microscopy. We found that a very mild electroporation, undetectable with the classical propidium assay but associated with a transient increase in intracellular Ca
, can already have a profound effect on excitability close to the electrostimulation threshold, as corroborated by multiscale computational modelling. These results are of great relevance for understanding the effects of pulse delivery on cell excitability observed in context of the rapidly developing cardiac pulsed field ablation as well as other electroporation-based treatments in excitable tissues.
Zdravljenje atrijske fibrilacije (AF) je hitro razvijajoče se področje kardiologije, pri katerem smo priča stalnemu razvoju različnih oblik tehničnih izboljšav in multidisciplinarnega pristopa. Poleg ...iskanja najprimernejšega ablacijskega načina za učinkovito in varno izoliranje pljučnih ven poskušamo razumeti navidezno kaotičen mehanizem prevajanja akcijskega potenciala med samo aritmijo. Pri razumevanju nastanka AF se je uveljavila predvsem hipoteza o sprožilcih in vzdrževalcih AF. AF sprožajo prezgodnji utripi, ki večinoma izvirajo iz pljučnih ven, vzdržujejo pa jo lokalna področja z upočasnjenim prevajanjem akcijskega potenciala, ki se pretežno nahajajo na področju izraščanja pljučnih ven iz levega preddvora. Kljub številnim novim pristopom pa je izoliranje pljučnih ven s katetrsko ablacijo še vedno temelj invazivnega zdravljenja AF.
Abstract Background Tumor cells can die via immunogenic cell death pathway, in which damage-associated molecular pattern molecules (DAMPs) are released from the cells. These molecules activate cells ...involved in the immune response. Both innate and adaptive immune response can be activated, causing a destruction of the remaining infected cells. Activation of immune response is also an important component of tumor treatment with electrochemotherapy (ECT) and irreversible electroporation (IRE). We thus explored, if and when specific DAMPs are released as a consequence of electroporation in vitro . Materials and methods In this in vitro study, 100 μs long electric pulses were applied to a suspension of Chinese hamster ovary cells. The release of DAMPs – specifically: adenosine triphosphate (ATP), calreticulin, nucleic acids and uric acid was investigated at different time points after exposing the cells to electric pulses of different amplitudes. The release of DAMPs was statistically correlated with cell permeabilization and cell survival, e.g. reversible and irreversible electroporation. Results In general, the release of DAMPs increases with increasing pulse amplitude. Concentration of DAMPs depend on the time interval between exposure of the cells to pulses and the analysis. Concentrations of most DAMPs correlate strongly with cell death. However, we detected no uric acid in the investigated samples. Conclusions Release of DAMPs can serve as a marker for prediction of cell death. Since the stability of certain DAMPs is time dependent, this should be considered when designing protocols for detecting DAMPs after electric pulse treatment.
Gerževič, M, Strojnik, V, and Jarm, T. Differences in muscle activation between submaximal and maximal 6-minute rowing tests. J Strength Cond Res 25(9)2470-2481, 2011—This study aimed to establish ...the differences in muscle activation between a 6-minute simulated race (all-out test) and a submaximal (blood lactate LA concentration 4 mmol·L) 6-minute effort (submax test) on a rowing ergometer. Eleven healthy, well-trained subjects performed the submax test followed after 1-hour rest by the all-out test. Surface electromyographic (sEMG) signal of muscles gastrocnemius medialis (GC), rectus femoris (RF), vastus lateralis (VL), biceps femoris, gluteus maximus (GM), erector spinae (ES), lower latissimus dorsi (LD_lo), upper latissimus dorsi (LD_up), brachioradialis (BR) and biceps brachii (BB), and other biomechanical, biochemical, and respiratory parameters were monitored during rowing. During the all-out test, the subjects covered a longer distance with larger average power output, higher stroke frequency, LA concentration, and oxygen consumption compared to the submax test (p < 0.05). During the submax test, the average rectified values (ARVs) of sEMG signal increased significantly only in the RF and LD_lo muscles. During the all-out test, the ARVs of the RF, VL, and GM muscles increased (p < 0.05), whereas the MDFs of the RF, ES, and LD_lo muscles decreased (p < 0.05). Compared to the submax test, the ARVs of the GC, RF, VL, LD_lo, LD_up, and BB muscles were significantly higher during the all-out test. However, only for the RF muscle, the all-out test resulted in a significantly lower MDF value compared to the submax test. The most involved muscles that would need special attention in training seem to be the leg and shoulder girdle extensors and arm flexors but not the trunk and hip extensors.
The purpose of this study was to investigate postocclusive hyperemic response using near infrared spectroscopy (NIRS) and transcutaneous oximetry (TcpO2). Five minute arterial occlusion on the calf ...muscle was performed in six healthy volunteers (mean age 29, range 23-34 years, mean TcpO2 at rest 53 mm Hg, range 47-58 mmHg, and ankle brachial index between 1 and 1.2). Oxygen partial pressure at rest, oxygen consumption (VO2) during ischemia, recovery times and resaturation rates after arterial occlusion were determined and new parameters for evaluation of the level of vascular disorders of lower limbs are suggested. The reproducibility of the signals was studied by repeating the same protocol on each subject four to six times. Repeated measurements showed no significant difference among trials, indicating that the measurements were reproducible. The mean values of the coefficient of variability for suggested parameters varied between 6% and 30% (mean value 17%). Interindividual variations of parameters are higher and can be explained by differences in fat/muscle ratio and in the measured tissue volume of the NIRS signal. Simultaneous measurements of NIRS and TcpO2 showed different responses to ischemic conditions, due to the different physiological levels of oxygen assessment. The combined use of both methods yields deeper insight into conditions of blood flow and tissue oxygenation.
The effectiveness of electrochemotherapy of tumors (ECT) and of irreversible electroporation ablation (IRE) depends on different mechanisms and delivery protocols. Both therapies exploit the ...phenomenon of electroporation of the cell membrane achieved by the exposure of the cells to a series of high-voltage electric pulses. Electroporation can be fine-tuned to be either reversible or irreversible, causing the cells to either survive the exposure (in ECT) or not (in IRE), respectively. For treatment of tissues located close to the heart (e.g., in the liver), the safety of electroporation-based therapies is ensured by synchronizing the electric pulses with the electrocardiogram. However, the use of ECT and IRE remains contraindicated for patients with implanted cardiac pacemakers if the treated tissues are located close to the heart or the pacemaker. In this study, two questions are addressed: can the electroporation pulses interfere with the pacemaker; and, can the metallic housing of the pacemaker modify the distribution of electric field in the tissue sufficiently to affect the effectiveness and safety of the therapy?
The electroporation pulses induced significant changes in the pacemaker ventricular pacing pulse only for the electroporation pulses delivered during the pacing pulse itself. No residual effects were observed on the pacing pulses following the electroporation pulses for all tested experimental conditions. The results of numerical modeling indicate that the presence of metal-encased pacemaker in immediate vicinity of the treatment zone should not impair the intended effectiveness of ECT or IRE even when the casing is in direct contact with one of the active electrodes. Nevertheless, the contact between the casing and the active electrode should be avoided due to significant tissue heating at the site of the other active electrode for the IRE protocol and may cause the pulse generator to fail to deliver the pulses due to excessive current draw.
The observed effects of electroporation pulses delivered in close vicinity of the pacemaker or its electrodes do not indicate adverse consequences for either the function of the pacemaker or the treatment outcome. These findings should contribute to making electroporation-based treatments accessible also to patients with implanted cardiac pacemakers.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The first clinical studies on the use of electrochemotherapy to treat liver tumours that were not amenable to surgery or thermal ablation techniques have recently been published. However, there is ...still a lack of data on the effects of electrochemotherapy on normal liver tissue. Therefore, we designed a translational animal model study to test whether electrochemotherapy with bleomycin causes clinically significant damage to normal liver tissue, with emphasis on large blood vessels and bile ducts. We performed electrochemotherapy with bleomycin or delivered electric pulses alone using a potentially risky treatment strategy in eight pigs. Two and seven days after treatment, livers were explanted, and histological analysis was performed. Blood samples were collected before treatment and again before euthanasia to evaluate blood biomarkers of liver function and systemic inflammatory response. We found no thrombosis or other clinically significant damage to large blood vessels and bile ducts in the liver. No clinical or laboratory findings suggested impaired liver function or systemic inflammatory response. Electrochemotherapy with bleomycin does not cause clinically significant damage to normal liver tissue. Our study provides further evidence that electrochemotherapy with bleomycin is safe for treatment of patients with tumours near large blood vessels in the liver.
Electrogene therapy combines administration of plasmid DNA into tissue followed by local application of electric pulses. In electrogene therapy with interleukin-12 (IL-12), different routes of ...administration, different doses of plasmid DNA and different protocols for delivery of electric pulses were evaluated in numerous preclinical studies. Antitumor effectiveness was tested in different types of primary tumors, distantly growing tumors and induced metastases. Intratumoral IL-12 electrogene therapy has been proved to be very effective in local tumor control, having also a systemic effect. Intramuscular and peritumoral IL-12 electrogene therapy had also a pronounced systemic effect and when combined with other treatment strategies resulted in tumor cures. Antitumor effectiveness of IL-12 electrogene therapy is due to the induction of adaptive immunity and innate resistance and anti-angiogenic action. Translation of preclinical studies into clinical trials in human and veterinary oncology has started with encouraging results that would hopefully lead to further investigation of this therapy, also in combination with other cancer treatment modalities.
The aim of this study was to evaluate muscle fatigue in upper body muscles during 100-m all-out front crawl. Surface electromyogram (EMG) was collected from the pectoralis major, latissimus dorsi and ...triceps brachii muscles of 11 experienced swimmers. Blood lactate concentration level increased to 14.1 ± 2.9 mmol l
−1
5 min after the swim. The velocity, stroke length and stroke rate calculated based on video analysis decreased by 15.0, 5.8 and 7.4%, respectively, during the swim. EMG amplitude of the triceps and the lower part of the latissimus muscles increased, whilst the mean power frequency (MNF) of all muscles significantly decreased by 20–25%. No significant differences in the relative MNF decrease were observed amongst the muscles; however, the differences in the rate of the MNF decrease between the lower part of the latissimus and the triceps brachii muscles were found (
P
< 0.05). The time of rest between the muscle activation of the two consecutive arm strokes at the end of swimming was extended (
P
< 0.05). It was concluded that 100-m all-out crawl induced significant fatigue with no evident differences amongst the analysed muscles.
Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced ...increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D μm2/s) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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