H2A.X Phosphorylation in Oxidative Stress and Risk Assessment in Plasma Medicine.

At serine139-phosphorylated gamma histone H2A.X (γH2A.X) has been established over the decades as sensitive evidence of radiation-induced DNA damage, especially DNA double-strand breaks (DSBs) in radiation biology. Therefore, γH2A.X has been considered a suitable marker for biomedical applications and a general indicator of direct DNA damage with other therapeutic agents, such as cold physical plasma. Medical plasma technology generates a partially ionized gas releasing a plethora of reactive oxygen and nitrogen species (ROS) simultaneously that have been used for therapeutic purposes such as wound healing and cancer treatment. The quantification of γH2A.X as a surrogate parameter of direct DNA damage has often been used to assess genotoxicity in plasma-treated cells, whereas no sustainable mutagenic potential of the medical plasma treatment could be identified despite H2A.X phosphorylation. However, phosphorylated H2A.X occurs during apoptosis, which is associated with exposure to cold plasma and ROS. This review summarizes the current understanding of γH2A.X induction and function in oxidative stress in general and plasma medicine in particular. Due to the progress towards understanding the mechanisms of H2A.X phosphorylation in the absence of DSB and ROS, observations of γH2A.X in medical fields should be carefully interpreted.

Platinum nanoparticles inhibit intracellular ROS generation and protect against cold atmospheric plasma-induced cytotoxicity.

Platinum nanoparticles (PtNPs) have been investigated for their antioxidant abilities in a range of biological and other applications. The ability to reduce off-target cold atmospheric plasma (CAP) cytotoxicity would be useful in Plasma Medicine; however, little has been published to date about the ability of PtNPs to reduce or inhibit the effects of CAP. Here we investigate whether PtNPs can protect against CAP-induced cytotoxicity in cancerous and non-cancerous cell lines. PtNPs were shown to dramatically reduce intracellular reactive species (RONS) production in U-251 MG cells. However, RONS generation was unaffected by PtNPs in medium without cells. PtNPs protect against CAP induced mitochondrial membrane depolarization, but not cell membrane permeabilization which is a CAP-induced RONS-independent event. PtNPs act as potent intracellular scavengers of reactive species and can protect against CAP induced cytotoxicity. PtNPs, showing no significant biocorrosion, may be useful as a catalytic antioxidant for healthy tissue and for protecting against CAP-induced tissue damage.

Efeitos do plasma frio sob pressão atmosférica como adjuvante no controle da periodontite experimental induzida por Aggregatibacter actinomycetemcomitans / Effect of atmospheric pressure cold plasma as adjuvante in the control of experimental periodontitis induced by Aggregatibacter actinomycetemcomitans

A etiopatogenia da doença periodontal é complexa e exige estudos constantes em alternativas terapêuticas que possibilitem seu controle. Aggregatibacter actinomycetemcomitans está associado fortemente à periodontite crônica e à periodontite agressiva. A tecnologia do plasma frio sob pressão atmosférica tem potencial para uso na odontologia, mas sua aplicação na periodontia ainda é pouco explorada. Este estudo teve como objetivo avaliar os efeitos do plasma de baixa temperatura sob pressão atmosférica (PBTPA) como adjuvante no controle da doença periodontal experimental induzida por ligadura, inoculada com A. actinomycetemcomitans, na região cervical do primeiro molar inferior em modelo murino. Inicialmente, foram determinados os parâmetros físicos efetivos para inibição de biofilmes de A. actinomycetemcomitans utilizando cepa padrão American Type Culture Collection ATCC 29523. Foram realizados testes de screening inicial com a verificação da inibição do crescimento por exposição ao PBTPA de A. actinomycetemcomitans semeados em placas de Petri. Posteriormente, foram formados biofilmes em placas de microtitulação e foram determinados os parâmetros físicos efetivos do PBTPA. Foram realizados experimentos in vivo de indução de doença periodontal por A. actinomycetemcomitans em modelo utilizando ligaduras em ratos. A tomografia computadorizada de feixe cônico foi utilizada para avaliar o nível de perda óssea após período experimental. Os resultados mostraram que o PBTPA foi efetivo na eliminação do micro-organismo observado através da formação de halos de inibição nos tempos de 5 e 7, 5 minutos e sobre biofilmes de A. actinomycetemcomitans expostos ao PBTPA no tempo de 5 minutos. Os resultados exibiram diferença estatística significativa (p <0,001) na distância entre a junção esmalte-cemento e a crista óssea alveolar, do grupo tratado com PBTPA em relação ao grupo raspagem e ao grupo controle. Os resultados do presente estudo sugerem o potencial do PBTPA no controle da periodontite induzida, contudo análises adicionais são necessárias(AU)

The etiopathogenesis of periodontal disease is complex requiring constant studies of therapeutic alternatives that enable its control. Aggregatibacter actinomycetemcomitans is strongly associated with chronic periodontitis and aggressive periodontitis. Cold plasma technology under atmospheric pressure has potential for use in dentistry, but its application in periodontics is still not well explored. This study aimed to evaluate the effects of low temperature atmospheric pressure plasma (PBTPA) as an adjuvant in the control of experimental periodontal disease induced by ligature inoculated with A. actinomycetemcomitans in the cervical region of the lower 1st molar in a murine model. Initially, effective physical parameters for inhibition of A. actinomycetemcomitans biofilms were determined using the standard strain American Type Culture Collection ATCC 29523. Initial screening tests were performed to verify growth inhibition after exposure of A. actinomycetemcomitans seeded in Petri dishes to the PBTPA. Subsequently, biofilms were formed on microtiter plates and the effective physical parameters of the PBTPA were determined. In vivo experiments were carried out to induce A. actinomycetemcomitans periodontal disease induced by ligature in a rat model. Cone beam computed tomography was used to assess the level of bone loss after the experimental period. The results showed that PBTPA was effective in eliminating the microorganism observed through the formation of halos inhibition during 5 and 7.5 minutes and in A. actinomycetemcomitans biofilms exposed to PBTPA at 5 minutes. The previous study using PBTPA in 5 minutes did not show cytotoxicity in Vero cells. The results showed a statistically significant difference (p <0.0001) in the distance between the enamel-cement joint and the alveolar bone crest, of the group treated with PBTPA in relation to the scalling group and the control group, confirming the potential of the technique in dentistry(AU)

Tolerability of Six Months Indirect Cold (Physical) Plasma Treatment of the Scalp for Hair Loss.

Androgenetic alopecia (AGA) is a chronic form of hair loss. Cold atmospheric (physical) plasma (CAP) is partly ionized gas with various widely researched effects on living tissues. CAP is an emerging treatment modality in dermatology with uses for chronic leg ulcer, actinic keratosis, warts, and other applications. Its previously demonstrated ability to induce stem cell differentiation in various cell types makes CAP a possible treatment option for AGA. Directly creating CAP on the scalp surface has drawbacks, but indirect CAP treatment—when a CAP-treated liquid is used as topical therapy—offers an alternative. In a clinical pilot study, we treated 14 patients with AGA using the indirect CAP method for three months (4 patients) and six months (10 patients). The indirect CAP treatment was well tolerated and while the primary goal of the study was not to assess efficacy, most patients reported improvement, and the investigator’s assessment also showed improvement in most patients. Our findings create the foundation for longer, extensive trials to systematically assess the efficacy of indirect CAP treatment for AGA. ClinicalTrials.gov: NCT04379752 J Drugs Dermatol. 2020;19(12): doi:10.36849/JDD.2020.5186.

Large-Scale Image Analysis for Investigating Spatio-Temporal Changes in Nuclear DNA Damage Caused by Nitrogen Atmospheric Pressure Plasma Jets.

The effective clinical application of atmospheric pressure plasma jet (APPJ) treatments requires a well-founded methodology that can describe the interactions between the plasma jet and a treated sample and the temporal and spatial changes that result from the treatment. In this study, we developed a large-scale image analysis method to identify the cell-cycle stage and quantify damage to nuclear DNA in single cells. The method was then tested and used to examine spatio-temporal distributions of nuclear DNA damage in two cell lines from the same anatomic location, namely the oral cavity, after treatment with a nitrogen APPJ. One cell line was malignant, and the other, nonmalignant. The results showed that DNA damage in cancer cells was maximized at the plasma jet treatment region, where the APPJ directly contacted the sample, and declined radially outward. As incubation continued, DNA damage in cancer cells decreased slightly over the first 4 h before rapidly decreasing by approximately 60% at 8 h post-treatment. In nonmalignant cells, no damage was observed within 1 h after treatment, but damage was detected 2 h after treatment. Notably, the damage was 5-fold less than that detected in irradiated cancer cells. Moreover, examining damage with respect to the cell cycle showed that S phase cells were more susceptible to DNA damage than either G1 or G2 phase cells. The proposed methodology for large-scale image analysis is not limited to APPJ post-treatment applications and can be utilized to evaluate biological samples affected by any type of radiation, and, more so, the cell-cycle classification can be used on any cell type with any nuclear DNA staining.

Emission of Ultraviolet Radiation from 220 to 280 NM by a Cold Physical Plasma Generating Device.

The generation of cold physical plasma at atmospheric pressure (cold atmospheric plasma: CAP) generates different reactive molecular species as well as radiation in the ultraviolet (UV) range. The therapy of tumor diseases has proven to be a new promising area of application for CAP treatment. With regard to the routine use of CAP in cancer therapy, however, application safety must be ensured both for the patient and for the operator. In this study, the intensity of UVC radiation of the CAP device MiniJet-R (HF Technik, Aachen, Germany) was measured in the range from 220 to 280 nm depending on various device-specific parameters. Depending on the distance to the CAP flame, the UVC intensity reaches values up to 124.5±11 mW m. It should be noted here that the UVC radiation generated by the CAP is emitted in all orientations in the room but is also shielded by the geometry of the handpiece of the CAP device. The device-specific settings for the flow rate of the carrier gas, argon, and the power level at the high-frequency (HF) generator of the CAP device also influence the intensity of the UVC radiation. With regard to the medical use of the CAP device, it can be stated that there is an exposure to UVC radiation, which, depending on the duration of treatment, can also be above the maximum value legally specified in Europe. Shielding components on the CAP device can reduce UVC exposure to the operator as well as adverse side effects to the patient.

Notch signalling is a potential resistance mechanism of progenitor cells within patient-derived prostate cultures following ROS-inducing treatments.

Low Temperature Plasma (LTP) generates reactive oxygen and nitrogen species, causing cell death, similarly to radiation. Radiation resistance results in tumour recurrence, however mechanisms of LTP resistance are unknown. LTP was applied to patient-derived prostate epithelial cells and gene expression assessed. A typical global oxidative response (AP-1 and Nrf2 signalling) was induced, whereas Notch signalling was activated exclusively in progenitor cells. Notch inhibition induced expression of prostatic acid phosphatase (PAP), a marker of prostate epithelial cell differentiation, whilst reducing colony forming ability and preventing tumour formation. Therefore, if LTP is to be progressed as a novel treatment for prostate cancer, combination treatments should be considered in the context of cellular heterogeneity and existence of cell type-specific resistance mechanisms.

Aplicação do plasma de baixa temperatura sob pressão atmosférica no controle de biofilmes e reparo inicial de feridas infectadas / Application of low temperature plasma under atmospheric pressure in biofilm control and wound infected repair initial

O manejo clínico e tratamento das feridas crônicas têm sido considerados grandes desafios nas áreas médicas. Infecções por biofilmes em feridas crônicas afetam milhões de pessoas no mundo a cada ano e muitas mortes ocorrem como consequência. O plasma de baixa temperatura sob pressão atmosférica (LTAPP) é uma mistura gasosa contendo partículas carregadas, radicais livres e radiação. As ações biológicas das espécies reativas geradas concomitantemente, em particular antimicrobiana, anti-inflamatória e indutora de reparação tecidual, mostram-se altamente promissoras dentro do contexto do controle das feridas crônicas. O objetivo deste estudo foi avaliar os efeitos LTAPP frente a biofilmes monoespécie e multiespécies de micro-organismos frequentemente isolados de feridas crônicas. Além disso, objetivou-se avaliar estudar os efeitos citotóxicos e genotóxicos do LTAPP nos parâmetros físicos eficazes para o controle dos biofilmes A seguir, o protocolo eficaz e seguro foi avaliado in vivo utilizando modelo murino e modelo de úlcera dermal em coelhos. O LTAPP foi capaz de reduzir as UFC/mL de biofilmes monoespécie e mutiespécie a partir de 5 minutos de exposição. O LTAPP, nos parâmetros efetivos antibiofilme, apresentou-se seguro para uso em ensaios in vivo, pois não foi cito ou genotóxico. O tratamento com LTAPP levou à maior redução da área da ferida quando comparado ao grupo controle, em ambos os modelos de ferida com infecção polimicrobiana. Redução da resposta inflamatória foi observada no modelo de úlcera dermal no tempo de 8 dias. Não houve evidências de que o LTAPP aumente significativamente a proliferação celular. Com base nos resultados obtidos, conclui-se que o LTAPP acelera o processo de reparação de feridas, porém o mecanismo de ação ainda precisa ser elucidado(AU)

The clinical management and treatment of chronic wounds have been considered one of the main challenges in the medical area. Biofilm infections in chronic wounds affect millions of people worldwide each year and many deaths occur as consequence. LTAPP is a gas containing charged particles, free radicals and radiation. The biological actions of the reactive species generated concomitantly, anti-inflammatory and tissue repair inducing, are highly promising within the context of chronic wound control. The aim of the present project is to evaluate the effects of low temperature plasma under atmospheric pressure (LTAPP) on mono and multispecies biofilms frequently isolated from chronic wounds. The cyto and genotoxic effects of LTAPP in the effective parameters were also assessed. The effective and safe protocol was tested in vivo using a murine model and a rabbit dermal ulcer model. LTAPP was able to reduce significantly the mono and multispecies biofilm after 5 minutes exposure. In the anti-biofilm effective parameters, LTAPP was not cyto or genotoxic. Treatment with LTAPP reduced significantly the wound area when compared to control in both animal models. Anti-inflammatory effect was observed in dermal ulcer model at 8 days. No evidences of increase in cell proliferation caused by LTAPP were noted. According to the results, it could be concluded that LTAPP enhanced the wound repair process, however the mechanism of action must be still elucidated(AU)

Side effects by oral application of atmospheric pressure plasma on the mucosa in mice.

Cold atmospheric pressure plasma (CAP) has been investigated with promising results for peri-implant diseases treatment. However, prior to in-vivo applications of CAP sources in humans, short-term harmful mucosal damage or other unwanted side effects have to be reviewed. 180 male mice (B6C3F1) were divided into twelve treatment groups (n = 15). The right buccal cheek mucosa was treated with CAP. The first and second group each received continuous 10 sec irradiation with 2 different plasma sources (kINPen09, PS-MWM). The third group was treated with the kINPen09 for one minute. Control groups were treated with a corresponding dose of ultraviolet light for 8 seconds or 48 seconds and the other one was left untreated. The animals were weighed before and after treatment. The animals were sacrificed one day or one week after exposure. Stained tissue samples were histologically examined for tissue damage independently by two experienced pathologists. One day after CAP treatment histological analysis showed focal mucosal erosion with superficial ulceration and necrosis accompanied by a mild inflammatory reaction. One week after CAP treatment, the mucosal defects were completely re-epithelialized, associated with remnants of granulation tissue in the stroma irrespective of treatment duration. Furthermore, no cytological atypia was found and no severe weight loss occurred. The control groups did not show any alterations at all. CAP treatment led to a superficial mucosal damage that healed within few days. Nonetheless, further long-term experiments are necessary to exclude undesirable side effects after longer observation time. Particularly, potential carcinogenic effects must be ruled out prior to the application of CAP treatment in daily dental practice.

Harmless effects of argon plasma on caudal fin regeneration and embryogenesis of zebrafish: novel biological approaches for safe medical applications of bioplasma.

The argon plasma jet (Ar-PJ) is widely used in medical fields such as dermatology and dentistry, and it is considered a promising tool for cancer therapy. However, the in vivo effects of Ar-PJ for medical uses have not yet been investigated, and there are no biological tools to determine the appropriate clinical dosages of Ar-PJ. In this study, we used the caudal fin and embryo of zebrafish as novel in vivo tools to evaluate the biosafety of Ar-PJ. Typically, Ar-PJ is known to induce cell death in two-dimensional (2D) cell culture systems. By contrast, no detrimental effects of Ar-PJ were shown in our 3D zebrafish systems composed of 2D cells. The Ar-PJ-treated caudal fins grew by an average length of 0.7 mm, similar to the length of the normally regenerating fins. Remarkably, Ar-PJ did not affect the expression patterns of Wnt8a and ß-Catenin, which play important roles in fin regeneration. In the embryo system, 85% of the Ar-PJ-treated embryos hatched, and the lateral length of these embryos was ~3.3 mm, which are equivalent to the lengths of normal embryos. In particular, vasculogenesis, which is the main cellular process during tissue regeneration and embryogenesis, occurred normally under the Ar-PJ dose used in this study. Therefore, our biosafety evaluation tools that use living model systems can be used to provide an experimental guideline to determine the clinically safe dosage of Ar-PJ.

One Year Follow-Up Risk Assessment in SKH-1 Mice and Wounds Treated with an Argon Plasma Jet.

Multiple evidence in animal models and in humans suggest a beneficial role of cold physical plasma in wound treatment. Yet, risk assessment studies are important to further foster therapeutic advancement and acceptance of cold plasma in clinics. Accordingly, we investigated the longterm side effects of repetitive plasma treatment over 14 consecutive days in a rodent full-thickness ear wound model. Subsequently, animals were housed for 350 days and sacrificed thereafter. In blood, systemic changes of the proinflammatory cytokines interleukin 1ß and tumor necrosis factor α were absent. Similarly, tumor marker levels of α-fetoprotein and calcitonin remained unchanged. Using quantitative PCR, the expression levels of several cytokines and tumor markers in liver, lung, and skin were found to be similar in the control and treatment group as well. Likewise, histological and immunohistochemical analysis failed to detect abnormal morphological changes and the presence of tumor markers such as carcinoembryonic antigen, α-fetoprotein, or the neighbor of Punc11. Absence of neoplastic lesions was confirmed by non-invasive imaging methods such as anatomical magnetic resonance imaging and positron emission tomography-computed tomography. Our results suggest that the beneficial effects of cold plasma in wound healing come without apparent side effects including tumor formation or chronic inflammation.

Nonthermal physical technologies to decontaminate and extend the shelf-life of fruits and vegetables: Trends aiming at quality and safety.

Minimally processed fruits and vegetables are one of the major growing sectors in food industry. This growing demand for healthy and convenient foods with fresh-like properties is accompanied by concerns surrounding efficacy of the available sanitizing methods to appropriately deal with food-borne diseases. In fact, chemical sanitizers do not provide an efficient microbial reduction, besides being perceived negatively by the consumers, dangerous for human health, and harmful to the environment, and the conventional thermal treatments may negatively affect physical, nutritional, or bioactive properties of these perishable foods. For these reasons, the industry is investigating alternative nonthermal physical technologies, namely innovative packaging systems, ionizing and ultraviolet radiation, pulsed light, high-power ultrasound, cold plasma, high hydrostatic pressure, and dense phase carbon dioxide, as well as possible combinations between them or with other preservation factors (hurdles). This review discusses the potential of these novel or emerging technologies for decontamination and shelf-life extension of fresh and minimally processed fruits and vegetables. Advantages, limitations, and challenges related to its use in this sector are also highlighted.

Periodic Exposure of Keratinocytes to Cold Physical Plasma: An In Vitro Model for Redox-Related Diseases of the Skin.

Oxidative stress illustrates an imbalance between radical formation and removal. Frequent redox stress is critically involved in many human pathologies including cancer, psoriasis, and chronic wounds. However, reactive species pursue a dual role being involved in signaling on the one hand and oxidative damage on the other. Using a HaCaT keratinocyte cell culture model, we investigated redox regulation and inflammation to periodic, low-dose oxidative stress after two, six, eight, ten, and twelve weeks. Chronic redox stress was generated by recurrent incubation with cold physical plasma-treated cell culture medium. Using transcriptome microarray technology, we identified both acute ROS-stress responses as well as numerous adaptions after several weeks of redox challenge. We determined a differential expression (2-fold, FDR < 0.01, p < 0.05) of 260 genes that function in inflammation and redox homeostasis, such as cytokines (e.g., IL-6, IL-8, and IL-10), growth factors (e.g., CSF2, FGF, and IGF-2), and antioxidant enzymes (e.g., HMOX, NQO1, GPX, and PRDX). Apoptotic signaling was affected rather modestly, especially in p53 downstream targets (e.g., BCL2, BBC3, and GADD45). Strikingly, the cell-protective heat shock protein HSP27 was strongly upregulated (p < 0.001). These results suggested cellular adaptions to frequent redox stress and may help to better understand the inflammatory responses in redox-related diseases.

The repetitive use of non-thermal dielectric barrier discharge plasma boosts cutaneous microcirculatory effects.

BACKGROUND: Non-thermal atmospheric plasma has proven its benefits in sterilization, cauterization and even in cancer reduction. Furthermore, physical plasma generated by dielectric barrier discharge (DBD) promotes wound healing in vivo and angiogenesis in vitro. Moreover, cutaneous blood flow and oxygen saturation can be improved in human skin. These effects are mostly explained by reactive oxygen species (ROS), but electric fields, currents and ultraviolet radiation may also have an impact on cells in the treated area. Usually, single session application is used. The aim of this study was to evaluate the effects of the repetitive use of cold atmospheric plasma (rCAP) on cutaneous microcirculation. HYPOTHESIS: The repetitive use of non-thermal atmospheric plasma boosts cutaneous microcirculation effects. METHODS: Microcirculatory data was assessed at a defined skin area of the radial forearm of 20 healthy volunteers (17 males, 3 females; mean age 39.1±14.8years; BMI 26.4±4.6kg/m(2)). Microcirculatory measurements were performed under standardized conditions using a combined laser Doppler and photospectrometry system. After baseline measurement, CAP was applied by a DBD plasma device for 90s and cutaneous microcirculation was assessed for 10min. Afterwards, a second session of CAP application was performed and microcirculation was measured for another 10min. Then, the third application was made and another 20min of microcirculatory parameters were assessed. RESULTS: Tissue oxygen saturation and postcapillary venous filling pressure significantly increased after the first application and returned to baseline values within 10min after treatment. After the second and third applications, both parameters increased significantly vs. baseline until the end of the 40-minute measuring period. Cutaneous blood flow was significantly enhanced for 1min after the first application, with no significant differences found during the remainder of the observation period. The second application improved and prolonged the effect significantly until 7min and the third application until 13min. CONCLUSION: These data indicate that the repetitive use of non-thermal atmospheric plasma boosts and prolongs cutaneous microcirculation and might therefore be a potential tool to promote wound healing.

Non-thermal dielectric-barrier discharge plasma damages human keratinocytes by inducing oxidative stress.

The aim of this study was to identify the mechanisms through which dielectric-barrier discharge plasma damages human keratinocytes (HaCaT cells) through the induction of oxidative stress. For this purpose, the cells were exposed to surface dielectric-barrier discharge plasma in 70% oxygen and 30% argon. We noted that cell viability was decreased following exposure of the cells to plasma in a time-dependent manner, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The levels of intracellular reactive oxygen species (ROS) were determined using 2',7'-dichlorodihydrofluorescein diacetate and dihydroethidium was used to monitor superoxide anion production. Plasma induced the generation of ROS, including superoxide anions, hydrogen peroxide and hydroxyl radicals. N-acetyl cysteine, which is an antioxidant, prevented the decrease in cell viability caused by exposure to plasma. ROS generated by exposure to plasma resulted in damage to various cellular components, including lipid membrane peroxidation, DNA breaks and protein carbonylation, which was detected by measuring the levels of 8-isoprostane and diphenyl-1-pyrenylphosphine assay, comet assay and protein carbonyl formation. These results suggest that plasma exerts cytotoxic effects by causing oxidative stress-induced damage to cellular components.

Cold-Plasma Coagulation on the Surface of the Small Bowel Is Safe in Pigs.

INTRODUCTION: Surgical treatment in patients with peritoneal carcinomatosis is often limited by the extent of small bowel involvement. We investigated the results of the application of cold-plasma coagulation on the surface of the small bowel. METHODS: After permission by the federal government of Schleswig-Holstein, 8 female pigs underwent a laparoscopy and cold-plasma coagulation on the small bowel with different energy levels. Cold plasma is generated by high-frequency energy that is directed through helium gas. After 12 to 18 days a laparotomy was done and the abdomen was inspected for peritonitis, fistula, or other pathology. RESULTS: Perioperative morbidity was low with transient diarrhea in 1 pig and loss of appetite for 1 day in another pig. We saw 1 interenteric fistula that was clinically not apparent after accidently prolonged application of cold-plasma coagulation (6 seconds instead of 2 seconds) with the highest energy level of 100 W. We did not observe any mortality. The depth of necrosis after application of different energy levels was dependent on the generator energy. We observed statistically significant differences between the different energy levels (20 W vs 10 W [P = .014], 75 W vs 50 W [P = .011]). The comparison of the necrosis depths after the application of 100 W and 75 W almost reached statistical significance (P = .059). We observed distinct interenteric adhesions as a result of the coagulation. DISCUSSION: The application of cold-plasma coagulation on the surface of vital bowel in pigs is safe. We would recommend against the use of the highest energy level of 100 W before more clinical data are available.

Plasma jet's shielding gas impact on bacterial inactivation.

One of the most desired aims in plasma medicine is to inactivate prokaryotic cells and leave eukaryotic cells unharmed or even stimulate proliferation to promote wound healing. The method of choice is to precisely control the plasma component composition. Here the authors investigate the inactivation of bacteria (Escherichia coli) by a plasma jet treatment. The reactive species composition created by the plasma in liquids is tuned by the use of a shielding gas device to achieve a reactive nitrogen species dominated condition or a reactive oxygen species dominated condition. A strong correlation between composition of the reactive components and the inactivation of the bacteria is observed. The authors compare the results to earlier investigations on eukaryotic cells and show that it is possible to find a plasma composition where bacterial inactivation is strongest and adverse effects on eukaryotic cells are minimized.

Influence of high voltage atmospheric cold plasma process parameters and role of relative humidity on inactivation of Bacillus atrophaeus spores inside a sealed package.

BACKGROUND: Non-thermal plasma has received much attention for elimination of microbial contamination from a range of surfaces. AIM: This study aimed to determine the effect of a range of dielectric barrier discharge high voltage atmospheric cold plasma (HVACP) parameters for inactivation of Bacillus atrophaeus spores inside a sealed package. METHODS: A sterile polystyrene Petri dish containing B. atrophaeus spore strip (spore population 2.3 × 10(6)/strip i.e. 6.36 log10/strip) was placed in a sealed polypropylene container and was subjected to HVACP treatment. The HVACP discharge was generated between two aluminium plate electrodes using a high voltage of 70kVRMS. The effects of process parameters, including treatment time, mode of exposure (direct/indirect), and working gas types, were evaluated. The influence of relative humidity on HVACP inactivation efficacy was also assessed. The inactivation efficacy was evaluated using colony counts. Optical absorption spectroscopy (OAS) was used to assess gas composition following HVACP exposure. FINDINGS: A strong effect of process parameters on inactivation was observed. Direct plasma exposure for 60s resulted in ≥6 log10 cycle reduction of spores in all gas types tested. However, indirect exposure for 60s resulted in either 2.1 or 6.3 log10 cycle reduction of spores depending on gas types used for HVACP generation. The relative humidity (RH) was a critical factor in bacterial spore inactivation by HVACP, where a major role of plasma-generated species other than ozone was noted. Direct and indirect HVACP exposure for 60s at 70% RH recorded 6.3 and 5.7 log10 cycle reduction of spores, respectively. CONCLUSION: In summary, a strong influence of process parameters on spore inactivation was noted. Rapid in-package HVACP inactivation of bacterial spores within 30-60s demonstrates the promising potential application for reduction of spores on medical devices and heat-sensitive materials.

Cold atmospheric plasma devices for medical issues.

Cold atmospheric plasma science is an innovative upcoming technology for the medical sector. The plasma composition and subsequent effects on cells, tissues and pathogens can vary enormously depending on the plasma source, the plasma settings and the ambient conditions. Cold atmospheric plasmas consist of a highly reactive mix of ions and electrons, reactive molecules, excited species, electric fields and to some extent also UV radiation. In the last year, this partly ionized gas has been demonstrated to have a broad antimicrobial activity, while resistance and resistance development are unlikely. Furthermore, recent research has indicated that plasmas also have a strong influence on various cell lines and cell functions, including anticancer properties. This review summarizes the major plasma designs available and their main benefits, as well as assessing possible risks of this new technology.