Impedance Analysis of Tissues in nsPEF Treatment for Cancer Therapy

Nanosecond pulsed electric field (nsPEF) for cancer therapy is characterized by applications of high voltage pulses with low pulsed energy to induce non-thermal effects on tissues such as tumor ablation. It nonthermally treats tissues via electroporation. Electroporation is the increase in permeabilization of a cell membrane due to the application of high pulsed electric field. The objective of this study was to investigate the effect of nsPEF on tissue by monitoring the tissue’s impedance in real-time. Potato slices (both untreated and electroporated), and tumors extracted from female BALBc mice were studied. 100ns, 1-10kV pulses were applied to the tissues using a four-pin electrode at a pulse repetition frequency of 3Hz. The impedance change during the treatment was recorded by a custom made V-I monitor, and a network analyzer measured the impedance before and after treatment over a frequency range of 100kHz to 30MHz. In addition, system calibration was conducted to ensure the accuracy of the measurements. This includes determination of the attenuation offered by the V-I monitor measured to be 60dB and the cell constant K which represents the geometry of the four-pin electrode measured to be 0.8453����−1 (±0.02cm). Results show that the impedance of tissue reduced with increasing number of pulses and voltage applied, up to 44.4% and 22.3% decrease in the impedance of potato and tumor tissues were respectively observed. Also, the impedance values were higher at lower frequencies compared to those at higher frequencies. This is due to the high resistance of the membrane at low frequencies

The production of OH in a nanosecond pulsed helium plasma jet impinging on water, saline, or pigskin

Applications of plasma-induced biological effects via reactive oxygen and nitrogen species (RONS) make the non-thermal atmospheric-pressure plasma jets an appealing tool in biomedical fields. The presence of biological materials, especially as part of the electrode circuit, may change the plasma properties and impact on the production of RONS at the plasma-biomaterial interface. Effects of biomaterials on the production of hydroxyl radicals (OH) in a nanosecond pulsed, atmospheric-pressure plasma jet were investigated using a needle-to-plate electrode configuration with water, phosphate-buffered saline (PBS), or pigskin covering the ground plate. Driven by 200 ns, 7 kV pulses at 1 kHz, a helium plasma jet was generated between the hollow needle electrode and the biomaterial. Temporally resolved UV-visible imaging showed that the use of pigskin slowed down the streamer head propagation, whereas a more pronounced surface ionization wave was developed on the surface when water was used. The highest OH(A-X) emission above the biomaterial surface was observed using the PBS-covered electrode plate comparing to water or pigskin. Spatiotemporally resolved laser-induced fluorescence (LIF) showed that more OH was produced in the region near the needle electrode for both water and PBS, and the use of pigskin resulted in least OH production overall. In addition, measurements of H2O2 production in the liquid were used to determine the OH concentration in the vicinity of the biomaterial and agreed well with the relative OH-LIF measurements obtained at the gas-liquid interface for water and PBS

Microstructural Evaluation of Aluminium Alloy A365 T6 in Machining Operation

The optimum cutting parameters such as cutting depth, feed rate, cutting speed and magnitude of the cutting force for A356 T6 was determined concerning the microstructural detail of the material. Novel test analyses were carried out, which include mechanical evaluation of the materials for density, glass transition temperature, tensile and compression stress, frequency analysis and optimisation as well as the functional analytic behaviour of the samples. The further analytical structure of the particle was performed, evaluating the surface luminance structure and the profile structure. The cross-sectional filter profile of the sample was extracted, and analyses of Firestone curve for the Gaussian filter checking the roughness and waviness profile of the structure on aluminium alloy A356T6 is proposed. A load cell dynamometer was used to measure different parameters with the combination of a conditioning signal system, a data acquisition system and a computer with visualised software. This allowed recording the variations of the main cutting force throughout the mechanised pieces under different cutting parameters. A carbide inserted tool with triangular geometry was used. The result shows that the lowest optimum cutting force is 71.123 N at 75 m/min cutting speed, 0.08 mm/rev feed rate and a 1.0 mm depth of cut. The maximum optimum cutting force for good surface finishing is 274.87 N which must be at a cutting speed of 40 m/min, 0.325 mm/rev feed rate and the same 1.0 mm depth of cut

Trials and Tribulations of Humanizing Mice for Cancer Research

Cancers are aggressive, evasive, and ruthless killers, claiming millions of lives every year. Cancers are heterogeneous and there is often no single, clearly defined problem as they harness and manipulate a multitude of fundamental mechanisms at the very essence of life. To investigate these mechanisms and vet potential interventive therapies, humanized mice offer a unique model as a prelude to the use of nanosecond pulse stimulation (NPS), a pulse power technology applying nanosecond duration, high electric field pulses, to ablate human tumors. Immunodeficient mouse strains, NSG and NSG-SGM3, were engrafted with human immune cells and human tumors, which would allow us to study the effects of NPS therapy on the human tumor and the human immune system, albeit not without trials and tribulations. Here we show that mice engrafted with human cord blood CD34+ hematopoietic stem cells (hCD34+ HSC) lack consistency in expansion and chimerism, or variety of immune cell types. Unfortunately, mice that developed the human immune system rejected the human tumors without treatment, while mice that rejected the immune system developed the human tumors. Therefore, we had mice with human immune systems and no tumor to treat, and mice with tumors to treat yet no immune system to study. In non-humanized mice, NPS induced complete tumor death in the patient derived mammary cancer xenograft (PDX) model, but not in the MDA-MB-231 VIM-RFP mammary cancer cell-derived xenograft (CDX) model. The absence of NPS elimination of the CDX is the only known NPS cancer failure and requires further study.https://digitalcommons.odu.edu/gradposters2021_gradschool/1000/thumbnail.jp

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Research Photo: Evaluation of Electric Property Changes in Cancer Cells in Vitro Induced by Cold Plasma and Electric Field Treatment

Research photo for Evaluation of Electric Property Changes in Cancer Cells in Vitro Induced by Cold Plasma and Electric Field Treatmenthttps://digitalcommons.odu.edu/bioelectrics-2021retreat-images/1001/thumbnail.jp

Synergistic Effect of Nanopulse and Cold Plasma in Pancreatic Cancer

Pancreatic adenocarcinoma is a highly aggressive malignancy with disease-related mortality almost equaling its incidence. The notorious resistance of pancreatic cancer not only to conventional cytotoxic therapies but also to almost all targeted agents developed to date continues to puzzle the oncological community and represents one of the biggest hurdles to reduce the death toll from this ominous disease. Currently, we have been focusing on developing nanosecond electric pulse or nano-pulse (NP) technology for cancer therapy. However, due to the demand for high electric fields, all currently available designs of NP delivery systems are only able to treat tumors with small sizes (4-7 mm). To solve this problem, we propose a combination of NP with non-thermal plasma or cold plasma (CP) to treat large tumors. Our hypothesis is that the synergistic effect between NP and CP-produced reactive plasma species can be utilized to treat large tumors with sizes relevant to human cancer. First, the dose-dependent cytotoxicity of NP or CP to Pan02 pancreatic cancer cells was examined by cells treated with different doses of NP or CP. Second, we selected one specific dose of NP for further combination evaluation. The combination treatment was carried out either by treating cells with NP first then CP, or CP first then NP. The synergistic effect was assessed with cell viability and impedance measurement. Our results showed that NP at a very low dose can sensitize cancer cells that will then be killed by CP. Our future goals are to develop a prototype engineering system for both NP and CP delivery to tumor tissue, to evaluate the synergistic effect of NP and CP in vitro and in vivo, and to explore the potential molecular mechanisms of the synergistic effect of NP and CP

Evaluation of Electric Property Changes in Cancer Cells in Vitro Induced by Cold Plasma and Electric Field Treatment

Nonthermal atmospheric pressure plasma jet (APPJ) is a promising method for medical applications, especially in the treatment of tumors in vitro. Its main mechanism of action is it induces temporary or permanent damage to tissue known as reversible electroporation (RE) and irreversible electroporation (IRE), respectively. It has been previously shown that APPJ treatment reduces the proliferation of cancer cells, reduces the size of the tumor, and induces oxidative stress in cancer cells that can lead to the death of the cells via apoptosis [1]. Furthermore, nanosecond pulsed electric field (nsPEF) has equally been reported to cause increase in permeability of cell membrane and/or oxidative stress on cells, which is accompanied with a decrease in the impedance of the cells. It is found that the impedance of compromised or dying cells are different, typically lower than healthy cells [2]. It is therefore possible to analyze the electrical properties of the cells before, during and after treatment to better monitor the treatment outcome on the cells in real time. Here, we report the conductivity change of pancreatic cancer cells (Pan02) in response to the treatment of 200-ns, 9 kV pulsed plasma jet, 60-ns, 50 kV/cm nsPEF and the combination in vitro. The dosage dependence is evaluated by varying the treatment time of the plasma, and pulse numbers of the nsPEF, followed by the comparison of the impedance change of the monolayer Pan02 cells. [1] C. Jiang et al., Synergistic Effects of an Atmospheric-Pressure Plasma Jet and Pulsed Electric Field on Cells and Skin, in IEEE Transactions on Plasma Science. 49(11) (2021). [2] E. Oshin, S. Guo, and C. Jiang “Determining Tissue Conductivity in Tissue Ablation by Nanosecond Pulsed Electric Fields,” Bioelectrochemistry. 143 (2022)

Nano-Pulse Treatment Overcomes the Immunosuppressive Tumor Microenvironment to Elicit In Situ Vaccination Protection against Breast Cancer

We previously reported that nano-pulse treatment (NPT), a pulsed power technology, resulted in 4T1-luc mammary tumor elimination and a strong in situ vaccination, thereby completely protecting tumor-free animals against a second live tumor challenge. The mechanism whereby NPT mounts effective antitumor immune responses in the 4T1 breast cancer predominantly immunosuppressive tumor microenvironment (TME) remains unanswered. In this study, orthotopic 4T1 mouse breast tumors were treated with NPT (100 ns, 50 kV/cm, 1000 pulses, 3 Hz). Blood, spleen, draining lymph nodes, and tumors were harvested at 4-h, 8-h, 1-day, 3-day, 7-day, and 3-month post-treatment intervals for the analysis of frequencies, death, and functional markers of various immune cells in addition to the suppressor function of regulatory T cells (Tregs). NPT was verified to elicit strong in situ vaccination (ISV) against breast cancer and promote both acute and long-term T cell memory. NPT abolished immunosuppressive dominance systemically and in the TME by substantially reducing Tregs, myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs). NPT induced apoptosis in Tregs and TAMs. It also functionally diminished the Treg suppression capacity, explained by the downregulation of activation markers, particularly 4-1BB and TGFβ, and a phenotypic shift from predominantly activated (CD44+CD62L−) to naïve (CD44−CD62L+) Tregs. Importantly, NPT selectively induced apoptosis in activated Tregs and spared effector CD4+ and CD8+ T cells. These changes were followed by a concomitant rise in CD8+CD103+ tissue-resident memory T cells and TAM M1 polarization. These findings indicate that NPT effectively switches the TME and secondary lymphatic systems from an immunosuppressive to an immunostimulatory state, allowing cytotoxic T cell function and immune memory formation to eliminate cancer cells and account for the NPT in situ vaccination