Search

Plasma medicine refers to the application of nonequilibrium plasmas at approximately body temperature, for therapeutic purposes. Nonequilibrium plasmas are weakly ionized gases which contain charged and neutral species and electric fields, and emit radiation, particularly in the visible and ultraviolet range. Medically-relevant cold atmospheric pressure plasma (CAP) sources and devices are usually dielectric barrier discharges and nonequilibrium atmospheric pressure plasma jets. Plasma diagnostic methods and modelling approaches are used to characterize the densities and fluxes of active plasma species and their interaction with surrounding matter. In addition to the direct application of plasma onto living tissue, the treatment of liquids like water or physiological saline by a CAP source is performed in order to study specific biological activities. A basic understanding of the interaction between plasma and liquids and bio-interfaces is essential to follow biological plasma effects. Charged species, metastable species, and other atomic and molecular reactive species first produced in the main plasma ignition are transported to the discharge afterglow to finally be exposed to the biological targets. Contact with these liquid-dominated bio-interfaces generates other secondary reactive oxygen and nitrogen species (ROS, RNS). Both ROS and RNS possess strong oxidative properties and can trigger redox-related signalling pathways in cells and tissue, leading to various impacts of therapeutic relevance. Dependent on the intensity of plasma exposure, redox balance in cells can be influenced in a way that oxidative eustress leads to stimulation of cellular processes or oxidative distress leads to cell death. Currently, clinical CAP application is realized mainly in wound healing. The use of plasma in cancer treatment (i.e. plasma oncology) is a currently emerging field of research. Future perspectives and challenges in plasma medicine are mainly directed towards the control and optimization of CAP devices, to broaden and establish its medical applications, and to open up new plasma-based therapies in medicine.

Peri-implantitis may result in the loss of dental implants. Cold atmospheric pressure plasma (CAP) was suggested to promote re-osseointegration, decrease antimicrobial burden, and support wound healing. However, the long-term risk assessment of CAP treatment in the oral cavity has not been addressed. Treatment with two different CAP devices was compared against UV radiation, carcinogen administration, and untreated conditions over 12 months. Histological analysis of 406 animals revealed that repeated CAP exposure did not foster non-invasive lesions or squamous cell carcinoma (SCCs). Carcinogen administration promoted non-invasive lesions and SCCs. Molecular analysis by a qPCR screening of 144 transcripts revealed distinct inflammatory profiles associated with each treatment regimen. Interestingly, CAP treatment of carcinogen-challenged mucosa did not promote but instead left unchanged or reduced the proportion of non-invasive lesions and SCC formation. In conclusion, repeated CAP exposure of murine oral mucosa was well tolerated, and carcinogenic effects did not occur, motivating CAP applications in patients for dental and implant treatments in the future.

Purpose Despite all innovations in continuous flow left ventricular assist devices (cfLVAD) wound infections are still leading factors for morbidity and mortality in VAD patients. Over the last years, cold atmospheric plasma (CAP) has been safely and effectively used to treat superficial infections. Thus, in this study we present our results using CAP for the treatment of superficial driveline infections (SDI). Methods We describe a two center experience with 25 patients (21male, 4 female) and 32 treatments, who were implanted between 2012 and 2018 and developed a SDI in the follow up. 17 cases were treated inhospital, 9 in an outpatient clinic and 6 were treated in both. All wounds were treated with CAP (kinPen MED) starting from the day of diagnosis. Results The average number of CAP applications per case was 11.2 times (1-49), median duration of hospital stay due to SDI was 25 days (5-106). 19 cases were additional treated with antibiotics (59%). In 9 cases (28%) occurred an ascending driveline infection (ADI) requiring surgical revision. The 3 month event free survival was 23 cases (72 %). There were no adverse side effects of CAP therapy observed and there were no abnormalities of cfLVAD during CAP treatment. Conclusion In our study we demonstrate that CAP therapy could be effectively and safely applied in cfLVAD patients with SDI. Using CAP 72% of our cases with SDI were prevented from ADI. Future studies have to show if ambulant CAP therapy of superficial cfLVAD wound infections has the potential to prevent progression of infection or to avoid SDI infection at all as prophylactic therapy.

Das neue Gebiet der Plasmamedizin beschaftigt sich mit der medizinischen Anwendung physikalischer, kalter Atmospharendruckplasmen („cold atmospheric plasma“, CAP). Darstellung der wissenschaftlichen Grundlagen der Plasmamedizin und gegenwartiger sowie potenzieller medizinischer Anwendungsmoglichkeiten. Zusammenfassung des aktuellen Stands der praklinischen und der klinischen Forschung unter besonderer Berucksichtigung der CAP-Plasmajet-Quelle kINPen®. Physikalisches Plasma wird auch als 4. Aggregatzustand der Materie bezeichnet. Mit CAP ist es moglich, ein breites Spektrum an Mikroorganismen, einschlieslich multiresistenter Bakterien, sehr effektiv zu inaktivieren, sowie die Regeneration verletzten Gewebes zu stimulieren. Daruber hinaus wurde die Moglichkeit der Induktion des programmierten Zelltods (Apoptose) auch und v. a. in Krebszellen experimentell nachgewiesen. Kalte Atmospharendruckplasmen beeinflussen insbesondere uber temporar und lokal erhohte Konzentrationen von reaktiven Sauerstoff- und Stickstoffspezies in der flussigen Zellumgebung die zellulare Redoxbalance. Die Anwendung von CAP am oder im menschlichen Korper birgt bei bestimmungsgemaser Anwendung keine erhohten Risiken. Gegenwartiger Anwendungsschwerpunkt von CAP sind v. a. die Wundheilung und die Behandlung infektioser Hauterkrankungen. An Einsatzmoglichkeiten in der Krebsbehandlung wird intensiv geforscht. Die Plasmamedizin steht am Anfang eines sehr erfolgversprechenden Wegs in die klinische Anwendung. Das Besondere und Einzigartige der CAP liegt darin, dass die Wirkkomponenten lokal am Ort und nur fur die erforderliche Zeit der Anwendung primar durch einen physikalischen Prozess generiert werden.

Foodborne diseases are often related to the consumption of microbially contaminated fresh produce. Infections occur due to Norovirus, Listeria or Samonella. However, contaminations with Escherichia coli and its pathovar EHEC (enterohemorrhagic Escherichia coli) also result in serious health problems. To reduce/prevent microbial contaminations, cleaning and hygiene of food is indispensible. Due to many disadvantages of the currently used methods, the industry is demanding alternative techniques. One alternative could be the application of physical plasma. As a flexible and highly adaptable tool, it is used in manifold industrial applications. Therefore, three very different non-thermal atmospheric pressure plasma techniques were investigated for their antimicrobial capacity regarding selected food contaminants. All plasma sources applied, resulted in a 3 to 5 log cycle reduction of E. coli K-12 and EHEC O157:H7 within 10 minutes treatment time. The gained results are very promising. Further investigations should handle the influence on food quality and other pathogens.

The ability to produce cold plasma at atmospheric pressure conditions was the basis for the rapid growth of plasma related application areas in biomedicine. Plasma comprises a multitude of active components such as charged particles, electric current, UV radiation, and reactive species which can act synergistically. The antiitch, antimicrobial, and anti-inflammatory effect was already demonstrated in in vivo and in vitro experiments and until now no resistance of pathogens against plasma treatment was observed. The combination of the different active agents and their broad range of positive effects on various diseases, especially easily accessible skin diseases, render plasma quite attractive for applications in medicine. Hence, plasma medicine as an independent and promising medical field has been emerged recently. For medical applications two different types of cold plasma are suitable; indirect (plasma jet, plasma torch) and direct plasma sources (dielectric barrier discharge - DBD). So far, no standards and norms are defined for any of these plasma sources. Also, no convenient criteria for standardization of the quality rating of plasma in the view of dermatological applications exist. Although various cold plasma studies have been performed the results are hardly comparable, as physical parameters of the plasma devices, experimental conditions, and organisms used vary greatly. Therefore, standardized risk analyses are necessary for the assessment of different plasma sources. In this review two plasma sources are described and possible risk factors are discussed to estimate the safety of plasma used as a therapeutic tool in dermatology. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Purpose Despite all innovations in continuous flow left ventricular assist devices (cfLVAD) wound infections are still leading factors for morbidity and mortality in VAD patients. Over the last years, cold atmospheric plasma (CAP) has been safely and effectively used to treat superficial infections. Thus, in this study we used CAP the first time intraoperativly and postoperativly in patients with ascending driveline infections (DI) and device related infections (DRI). Methods We describe a two center experience with nine patients (HVAD n=8; HeartMate III n=1), who were implanted between 08/2013 and 03/2018 and developed a DI or DRI in the follow up. Five patients had an ascending DI, one patient with recurrent ascending DI, one patient had a substernal abscess, one patient had first a sternal abscess and after the follow up an ascending DI and another patient first an ascending DI and after the follow up a subxiphoidal abscess. All wounds were treated with CAP (kinPen MED) starting intraoperatively (n=11), after surgical wound debridement and after wound closure postoperatively during wound dressing. Five wounds were additional treated with vacuum therapy till secondary surgical wound closure. Bacteria specific antibiotic therapy was given for all patients. Results Median time from implantation to device related infections was 18.5 (3 to 60) months. CAP applications was done on average 20 times per wound (6 to 50), median time of CAP therapy was 38.6 (6 to 150) days. In the follow-up after 3 months the healing of 10 wounds was normal. Wound infection recurrence happened in one wound after primarily closure (n=6), and in one wound of a patient with vacuum therapy (n=5). There were no adverse side effects of CAP therapy observed and there were no abnormalities of cfLVAD during CAP treatment. Conclusion In our study we demonstrate that CAP therapy could be effectively and safely applied in cfLVAD patients with device related wound infections. Future studies have to show if early CAP therapy of superficial cfLVAD wound infections has the potential to prevent progression of infection to avoid surgical debridement.

Cold atmospheric pressure plasmas represent a favorable option for the treatment of heat sensitive materials and human or animal tissue. Beneficial effects have been documented in a variety of medical conditions, e.g., in the treatment of chronic wounds. It is assumed that the main mechanism of the plasma's efficacy is mediated by a stimulating dissipation of energy via radiation and/or chemical energy. Although no evidence on undesired side effects of a plasma treatment has yet been presented, skepticism toward the safety of the exposure to plasma is present. However, only little data regarding the mutagenic potential of this new treatment option is available. Accordingly, we investigated the mutagenic potential of an argon plasma jet (kinpen) using different testing systems in accordance with ISO norms and multiple cell lines: a HPRT1 mutation assay, a micronucleus formation assay, and a colony formation assay. Moderate plasma treatment up to 180 s did not increase genotoxicity in any assay or cell type investigated. We conclude that treatment with the argon plasma jet kinpen did not display a mutagenic potential under the test conditions applied and may from this perspective be regarded as safe for the use in biomedical applications.

© 2016 IOP Publishing Ltd. Plasma-liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

The initial adhesion and spreading of cells are crucial factors for the successful performance of a synthetic biomaterial used for cell culture disposables or human medical devices (e.g., implants). Surface properties which allow the control of the attachment of cells are decisive for the acceptance of the provided material. Hence, different surface preparation techniques are used to equip surfaces with functional groups to improve initial surface interactions. In this paper, polystyrene (PS) surfaces were modified by using different nonthermal plasma processes. In particular, low-pressure plasma and atmospheric-pressure plasma were applied to modify surfaces or to deposit thin films on surfaces. Furthermore, the behaviors of human osteoblastic cells with respect to cell viability and cell growth on differently plasma treated PS surfaces are investigated. A comparison is made between plasma-grafted PS and commercially available PS-such as tissue-culture PS and Primaria. The cell studies were accompanied by surface analysis comprising atomic force microscopy, determination of surface energies, and X-ray photoelectron spectroscopy measurements. This work demonstrates that the functionalization of PS substrates by applying low-pressure and atmospheric-pressure plasma processes are equally effective in the improvement of cell attachment and proliferation. Furthermore, it is shown that the enhanced metabolic activity and spreading behavior of osteoblastic cells correlate well with an increase in surface wettability and the introduction of polar oxygen- and/or nitrogen-containing functional groups after plasma treatment.

The research and development of plasma sources, which can be used for therapeutic applications in the new and emerging field of plasma medicine, has gained more and more interest during recent years. These applications require cold nonthermal plasmas operating at atmospheric pressure. Due to the fact that, in general, plasma on or in the human body is a challenge both for medicine and plasma physics, basic research combining experimental physical and biological investigation and modeling is necessary to provide the required knowledge for therapeutic applications. It turned out that each application needs a special tailor-made plasma source, passing a minimum set of physical and biological tests before it can be considered for medical use. In addition to atmospheric-pressure plasma jets, dielectric barrier discharges offer great potential for a variety of medical indications. A new 2-D and even 3-D acting plasma source is introduced, exemplified for a possible decontamination of human extremities or similar tasks. In contradiction to most of today's existing plasma sources with fixed electrodes and nozzles, the prototype uses flexible electrodes to automatically adapt the plasma under equal and stable conditions to nearly all surface structures. First, physical and biological investigations demonstrate the general potential for therapeutic applications on preferably intact skin surfaces.

An atmospheric-pressure argon plasma jet with varying admixtures of molecular oxygen was used to study the etching mechanism of poly(ether ether ketone) (PEEK). Furthermore, a correlation between plasma-based etching processes on PEEK with the generation of chemically reactive plasma species is proposed. The surface analysis was performed by X-ray photoelectron spectroscopy, atomic force microscopy, and surface profilometry which showed a dramatic increase in the content of oxygen functionalities and surface roughness after long-time Ar/O2-plasma treatment. For the plasma diagnostics, two-photon absorption laser-induced fluorescence spectroscopy was applied. The obtained etching mass as well as the surface roughness for different molecular oxygen admixtures revealed a strong dependence on the atomic-oxygen density. Furthermore, the radial surface profile, affected by plasma etching, might be attributed to the distribution of plasma-generated oxygen species in the plasma jet effluent.

The use of plasma for healthcare can be dated back as far as the middle of the 19th century. Only the development of room temperature atmospheric pressure plasma sources in the past decade, however, has opened the new and fast growing interdisciplinary research field of plasma medicine. Three main topics can be distinguished: plasma treated implants, plasma decontamination, and plasmas in medical therapy. Understanding of the plasma sources and the plasma processes involved is still incomplete. With the aim of a more fundamental insight we investigate plasmas in a) functionalization of implants with antimicrobial as well as cell attachment enhancing surfaces b) atmospheric pressure plasmas (APPs) in inactivation of bacteria, decontamination of bottles and food products, as well as medical equipment and c) APPs in medical therapy and their effects on cell viability as a means to finding a plasma “dosage”. The possibilities of an application focused designing of plasma sources will be emphasized. On the example of feed gas humidity and its significant influence the importance of determining and controlling unobvious or hidden parameter is demonstrated (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Summary Background Over the past few years, plasma medicine has become an important field in medical science. Cold plasma has proven anti-inflammatory, antimicrobial and antineoplastic effects. Aim To test the decontamination power of two cold plasma sources [low-temperature atmospheric pressure plasma jet (APPJ) and dielectric barrier discharge plasma (DBD)] in vivo on human fingertips. Methods After 3, 15, 30, 60, 90, 120, 150, 180, 210 and 240 s of spot treatment with the APPJ and DBD, the log reduction factors (RFs) of physiological (PF) and artificially (AF) contaminated flora ( Staphylococcus epidermidis and Micrococcus luteus ) were calculated. The bacterial load was determined after counting. Tolerance (paresthesia, pain and heat) was measured using a numerical rating scale. Findings Both plasma devices led to a significant reduction in PF and AF. The maximum log reduction factors for PF were 1.3 for the DBD at 210 s and 0.8 for the APPJ at 60 s. For AF, the maximum log reduction factors were 1.7 for the DBD at 90 s and 1.4 for the APPJ at 120 s. Treatment with both devices was well tolerated. Conclusion Both the APPJ and DBD were highly effective in eradicating PF and AF from the fingertips of healthy volunteers. No plasma-resistant isolates were observed. Cold plasma appears to have potential for skin disinfection. For hand hygiene purposes, plasma exposure times would need to be reduced significantly by technical means.

Plasma medicine is emerging worldwide, and some promising applications seem to be near the horizon. Direct therapeutic plasma application as the central field of plasma medicine will bring physical plasmas directly on or in a human (or animal) body. Campus PlasmaMed is a research association supported by the German Federal Ministry of Education and Research (BMBF), concentrated in the northeast of Germany and founded to explore promising and safe applications of atmospheric-pressure plasmas in medical therapy based on systematic and interdisciplinary basic research on the interactions of plasma components with living systems. Whereas a broad spectrum of plasma sources dedicated for biomedical applications has been reported during recent years, mainly two basic principles of plasma sources are used in the Campus PlasmaMed: atmospheric-pressure plasma jets and dielectric barrier discharges. A comprehensive assessment of potential risk factors, such as gas temperature, power transfer from plasma to the target, (V)UV radiation emission, or the generation of toxic gases and its release into the adjacencies, which could be dangerous for patients and therapists, has to be done as a basic precondition before any biomedical experiments can be started or a potential therapeutic application can be taken into consideration. Despite the fact that the initial plasma-source characterization and optimization are in the main responsibility of plasma physicists and engineers, potential users from the biomedical field should be integrated as soon as possible to include special needs and constraints for specific applications during early steps of development. This multidisciplinary research cooperation among plasma scientists and engineers on the one side and life scientists and clinicians on the other is one of the main characteristics of the Campus PlasmaMed. Such interdisciplinary cooperation is more than ever required for the characterization of biological effects of plasma sources, which has to be realized by a multistep program, starting with the investigations of plasma-liquid interactions and including a broad spectrum of in vitro tests with cells, as well as cell and tissue cultures up to isolated tissues or organs to be proved finally with animal experiments and clinical trials. Because there are no standardized criteria so far according to which atmospheric-pressure plasma sources can be assessed as to their suitability for medical applications, interdisciplinary results from plasma medical research have to be transferred into rules and standards to guarantee successful and safe practical application, including economic exploitation of plasma-medical research results.

Plasma medicine is an expanding focus and offers new aspects of therapy combining potent physical partial efficacies, like such as ultraviolet, infrared, and reactive species and particles, and nowadays, many successful treatments of different illnesses have been described. Fungal skin and nail infections pose significant therapeutic and economical problems. To test the plasma susceptibility of clinical strains of the most frequently encountered fungal species involved in dermatomycosis, clinical isolates of Trichophyton interdigitale, Trichophyton rubrum, Microsporum canis, and Candida albicans were irradiated by a cold atmospheric pressure plasma jet. Punctual plasma irradiation eradicated fungal growth of all species with the largest inactivation zones with most progress in the first 15 s of treatment, treating C. albicans and least progress in that of , the lowest being M. canis. No isolate exhibited resistance to plasma treatment. Plasma treatment also completely eradicated reproductive fungal elements of T. interdigitale in dandruff of patients with tinea pedis ex vivo and in the environment in contaminated shoes. Accordingly, cold plasma seems suited to antifungal in vivo treatment of fungal skin infections and decontamination of environmental infective material.

A set of minimum standards which have to be adjusted if a plasma source is intended for therapeutic applications has been defined. The main performance parameters of an optimized low-temperature atmospheric pressure plasma source were investigated and controlled. This has been done to discuss global risk factors that have to be avoided during application. By using this minimum standard set of parameters it should become possible to directly compare different atmospheric plasma sources for special biomedical applications and to derive optimum treatment parameters found on different sources and locations. Up to now a strict comparison is mainly done indirectly by investigating the effect of the plasma treatment on the surface. Temperature, thermal load, UV radiation, production of radicals and toxic gases and the resulting biological effects have been investigated to minimize risk factors and to indicate first meaningful parameter ranges (dosages) for therapeutic applications. The mix of these parameters (like mixing a cocktail) has to be adapted individually for each application. For practical use constant energetic conditions at the visible tip of the investigated jet could be observed, therefore it could be recommended to adjust the visible tip of the pen in such a way that it just touches the surface.

Radio-frequency-driven plasma jets in argon at atmospheric pressure have been shown to emit a significant amount of UV and VUV radiation. There is an increasing interest in the use of UV and VUV photons in many fields of research and in industry, in particular for life-science applications. In order to study the antimicrobial effect of plasma-emitted UV and VUV radiation, microbiological tests and plasma diagnostics are combined. In particular, quantitative values of irradiance are estimated. The VUV emission of the plasma jet is dominated by the emission of argon excimer (Ar2). The recorded spectra between 115 and 180 nm also include several atomic emission lines of nitrogen and oxygen. The UV emissions are due to molecular bands of NO, OH, and N2. The best antimicrobial effect is observed by means of direct plasma treatment. UV and VUV emissions have a lower effect, and there is no difference observed between these two components.

Summary Background Over the past few decades, new cold plasma sources have been developed that have the great advantage of operating at atmospheric pressure and at temperatures tolerable by biological material. New applications for these have emerged, especially in the field of dermatology. Recently it was demonstrated that cold atmospheric-pressure plasma positively influences healing of chronic wounds. The potential of cold plasma lies in its capacity to reduce bacterial load in the wound while at the same time stimulating skin cells and therefore promoting wound closure. In recent years, there have been great advances in the understanding of the molecular mechanisms triggered by cold plasma involving signalling pathways and gene regulation in cell culture. Aim To investigate cold plasma-induced effects in ex vivo treated human skin biopsies. Methods Human skin tissue was exposed to cold plasma for different lengths of time, and analysed by immunofluorescence with respect to DNA damage, apoptosis, proliferation and differentiation markers. Results After cold plasma treatment, the epidermal integrity and keratin expression pattern remained unchanged. As expected, the results revealed an increase in apoptotic cells after 3 and 5 min of treatment. Strikingly, an induction of proliferating basal keratinocytes was detected after cold plasma exposure for 1 and 3 min. As these are the cells that regenerate the epidermis, this could indeed be beneficial for wound closure. Conclusion We investigated the effect of cold plasma on human skin by detecting molecules for growth and apoptosis, and found that both processes are dependent on treatment time. Therefore, this approach offers promising results for further applications of cold plasma in clinical dermatology.

A low-pressure mercury vapour discharge tube generating high-intensity ultraviolet (UV) resonance radiation at 254 nm was designed to achieve a nearly simultaneous all-round UV irradiation of products. Testing this ‘universal homogeneous ultraviolet (UHUV) irradiation facility' with suspended Bacillus subtilis spores, resulted in a 10 6 -fold reduction in viable count within 30 s applying irradiation energy of 0.3 mW/cm 2 . Moreover, this irradiation dose reduced the number of immobilized B. subtilis spores on several material surfaces (wood-free paper, aluminium foil, polystyrol, polypropylene, and polyethylene foil) 10 2 –10 4 -fold. To evaluate potential applications of this UHUV irradiation technique under more realistic conditions, dental hand pieces and orthodontic forceps were contaminated by a blood–saliva mix containing Staphylococcus aureus . Under these conditions, a reduction in viable count of 10 5 –10 6 -fold was achieved within 5–15 min, but higher irradiation energy levels up to 13 mW/cm 2 were necessary. Because of its construction, the shape of the newly developed UHUV irradiation device can be adapted to various shapes to achieve a fast and effective antimicrobial treatment.

The development of in vivo working glucose sensors needs two decades, so far. The availability of long term functional implantable biosensors for continuous glucose measurings is a basic prerequisite for the individualized optimum insulin treatment of diabetics. Enzymatic electrochemical sensors are described which realize a functional stability over more than 2 years in vitro, however their function in vivo is limited due to certain bioincompatibility expressed by inflammation of the surrounding tissue, exudates, and immun reactions. The paper reflects an overview concerning different sensor covering materials used as more or less suitable diffusion membranes. From experimental studies in animals and human volunteers conclusions are drawn for further developmental steps of biosensors for in vivo use and for the applicability of glucose sensors for transient diagnostic purposes and as a basis for glucose controlled therapeutic measures. The results demonstrate that further progress aimed at long term biostability of implanted biosensors needs to solve technological problems and the serial production of sensors with really comparable qualities as a prerequisite for clinical trials.

Summary form only given. Atmospheric pressure plasmas are very promising tools for biomedical applications and are expected to bring new therapeutic options in surgery, dentistry and dermatology1,2. Each scope of application requires specific, adapted plasma sources. In most cases, basic geometric criteria can be met by choosing a proper discharge type. Locally active plasmas are easily realized with single corona, jet or micro hollow cathode setups whereas large-area treatments may require arrays of these or the use of dielectric barrier discharges. Although physical modes of action like electric current and field, temperature or non-ionizing radiation may have a specific share in the desired biomedical effect, the plasma should not be irritating, if living tissue has to be treated, especially in veterinary and human medicine.

Summary form only given. Non-thermal atmospheric-pressure plasmas have been developed that will be used for several indications, e.g. also in medicine. Here, living tissues and cells are in focus of plasma treatment, e.g. to improve wound healing or to induce apoptosis and growth arrest in tumour cells. Detailed investigations of plasma-cell interactions are strongly needed. The cell membrane with its embedded proteins is the first target of plasma treatment. Such cell surface molecules as integrins, cadherins or the epidermal growth factor receptor (EGFR) are of importance in wound healing and also for development of cancer metastasis. This study focused on measurement of cell surface molecules on human HaCaT keratinocytes promoting adhesion, migration and proliferation as one important feature of plasma-cell interactions. HaCaT keratinocytes were treated with plasma by a surface dielectric barrier discharge in air. Cell surface molecules were analyzed by flow cytometry 24h after plasma treatment. Besides a reduction of cell viability a significant down regulation of E-cadherin and the EGFR expression was observed. The influence on α2- and β1-integrin was less pronounced and expression of ICAM-1 was not affected. The extent of effects depended on the treatment regimen and the exposure time of cells to the plasma. The two-dimensional culture of HaCaT keratinocytes are proved to be a suitable method of investigating plasma-cell interactions.

The application of non-thermal atmospheric pressure plasma in medicine, especially in dermatology, is a very promising approach to improve the treatment of chronic wounds. This application has to be effective as well as safe. That is why it is important to understand the effects of plasma on living cells and on the genetic information.

Summary form only given. It is well known that plasma treatment results in inactivation of microorganisms in suspension. Furthermore, it is a fact that plasma treatment of water results in acidification and generation of several species. In this study a surface dielectric barrier discharge arrangement was used. Liquids were treated in a lower shell of a petridish, they were non-stirred and have no direct contact with the plasma (distance between liquid surface and plasma arrangement was 5 mm). The plasma was ignited in argon atmosphere with different oxygen admixtures from 1 up to 40 %. The first aim of these investigations was to show the influence of the percentage oxygen admixtures on the inactivation of suspended E. coli by DBD treatment. Therefore E. coli have been suspended in physiological sodium chloride solution to reach a concentration of 107 cfu ml-1. Volumes of 5 ml of this microorganism suspension were plasma treated for 2 min, each, in different argon oxygen atmospheres and the numbers of viable E. coli were estimated and compared in correlation with the percentage oxygen admixtures. Furthermore, after DBD treatment for different times and in different argon oxygen atmospheres of 5 ml distilled water the pH decrease and concentrations of hydrogen peroxide were determined and compared with each other. Based on these results, it was observed that an inactivation maximum of E. coli was at an oxygen admixture of 4-5 % to argon atmosphere. The inactivation of E. coli and the generation of the detected hydrogen peroxide, as well as acidification, are discussed.

This study was aimed at validating the in vitro estimated response characteristics of implanted glucose oxidase/H2O2electrodes with respect to their in vivo function. Mono-exponential non-linear regression analysis of sensor current vs. time curves in response to square alterations in glucose concentration gave response times T95of between 1 and 5 min. Non-primed glucose infusions were applied to dogs with these electrodes implanted subcutaneously. The simultaneously monitored in vivo data were subjected to non-linear regression analysis. The time constants T of increases or decreases after starting or ending the glucose load were (mean ± SEM) 53 ± 10 and 26 ± 4 min (significant difference, p < 0.05) in sensor current, 28 ± 8 and 15 ± 2 min (NS) in whole blood, and 26 ± 5 and 18 ± 2 min (NS) in plasma. The in vivo kinetic patterns of sensors were not related to their in vitro response times. Non-linear regression analysis of in vitro responses of glucose sensors under clearly defined conditions is recommended as a basis for further studies. The physiological delay in the subcutaneous glucose system needs more attention in this field of research.

Foreign-body reaction is an obligatory subsequence of biomaterial implantation whose extent can be determined on the one hand from the implant surface, and on the other through individual factors. This study investigates individual, humoral immune response in LEW.1A rats after repeat i.m. implantation of commercially available polyester vascular prostheses coated with different substances (collagen = G1, gelatin = G2, human serum albumin = G3) as well as from a poly-tetrafluoroethylene control graft prosthesis (G4). Sham procedures in control animals were designated G5. Serum sample Ab detection was performed by enzyme immunoassay employing polymer particles of a non-impregnated polyester prosthesis as a target. In contrast to the G4 & G5 groups, all animals with polyester implants demonstrated a differentiated anti-polymer Ab development (G2 > G3 > Gl). Polymer Ab prevalence was 100% for G2 + G3 on day 22. For Gl it was a maximum of 71.4%. Only G3 revealed a specific Ab reaction to the surface-coating as well as the strongest overall immunological reaction. G4 demonstrated no specific Ab development against polytetrafluoroethylene. Our results have showed a specific immune reaction which varied not only as a result of the applied polymer, but also due to the surface-coating as well as individual factors.

To estimate process parameters for non-thermal methods of antimicrobial inactivation, the half-cycle method is very often used. However, the essential premise of this method of estimation, the independence of microbial inactivation kinetics from the microbial load, seems not to be true. Consequently, the attainment of the sterility assurance level as recommended by the pharmacopoeias by a process which has been validated using the half cycle method is not guaranteed. For the evaluation of such chemo-thermo disinfection processes, the quantification of remaining hepatitis B virus DNA (HBV-DNA) traces on the surface of instruments is a useful tool. An infection can be excluded if a decrese of the HBV-DNA residues on the instruments below the minimum infective dose can be demonstrated. Using the signal amplification technique to detect HBV-DNA on instruments, the safety of any reprocessing procedures can be improved.

Generation of chemical species by atmospheric-pressure plasma treatment of aqueous liquids is a result of reactions at the plasma/gas-liquid interface and subsequent diffusion and convection processes into the liquid volume. Using color forming reactions, acidification as well as generation of nitrite is visualized in the water treated by a surface dielectric barrier discharge under atmospheric conditions in ambient air.

For sterilization processes the pharmacopoeias demand a sterility assurance level (SAL) of 10(-6), i.e. a probability of not more than one viable microorganism among one million sterilized products. This SAL concept is based on the assumption that the inactivation of microorganisms by physical or chemical means generally follows first-order kinetics. In this paper it is demonstrated that this is not absolutely true for non-thermal antimicrobial processes. Using Bacillus subtilis spore test preparations the sporicidal efficacy of gamma and ultraviolet irradiation on the one hand as well as the treatment by glutaraldehyde and hydrogen peroxide containing solutions on the other hand was investigated. A range of mean spore contamination between 10(8) and 10(-2) spores per test item could be supported by experimental data. It was demonstrated that the antimicrobial treatment parameters which are sufficient to reduce a high spore burden were not valid for an adequate reduction of the remaining lower spore burden. It is concluded that any extrapolation of such experimental data to the SAL range as usual in the validation of sterilization process parameters may be not permitted. Possible theoretical explanations of the non-homogeneity of the spore inactivation by non-thermal methods as well as consequences for the safety evaluation of sterilization processes are discussed.

The antimicrobial efficacy as well as the content of preservative agents of six commercially available grapefruit seed extracts were examined. Five of the six extracts showed a high growth inhibiting activity against the test germs Bacillus subtilis SBUG 14, Micrococcus flavus SBUG 16, Staphylococcus aureus SBUG 11, Serratia marcescens SBUG 9, Escherichia coli SBUG 17, Proteus mirabilis SBUG 47, and Candida maltosa SBUG 700. In all of the antimicrobial active grapefruit seed extracts, the preservative benzethonium chloride was detected by thin layer chromatography. Additionally, three extracts contained the preserving substances triclosan and methyl parabene. In only one of the grapefruit seed extracts tested no preservative agent was found. However, with this extract as well as with several self-made extracts from seed and juiceless pulp of grapefruits (Citrus paradisi) no antimicrobial activity could be detected (standard serial broth dilution assay, agar diffusion test). Thus, it is concluded that the potent as well as nearly universal antimicrobial activity being attributed to grapefruit seed extract is merely due to the synthetic preservative agents contained within. Natural products with antimicrobial activity do not appear to be present.

This study was aimed at validating the in vitro estimated response characteristics of implanted glucose oxidase/H2O2 electrodes with respect to their in vivo function. Monoexponential non-linear regression analysis of sensor current vs. time curves in response to square alterations in glucose concentration gave response times T95 of between 1 and 5 min. Non-primed glucose infusions were applied to dogs with these electrodes implanted subcutaneously. The simultaneously monitored in vivo data were subjected to non-linear regression analysis. The time constants T of increases or decreases after starting or ending the glucose load were (mean +/- SEM) 53 +/- 10 and 26 +/- 4 min (significant difference, p less than 0.05) in sensor current, 28 +/- 8 and 15 +/- 2 min (NS) in whole blood, and 26 +/- 5 and 18 +/- 2 min (NS) in plasma. The in vivo kinetic patterns of sensors were not related to their in vitro response times. Non-linear regression analysis of in vitro responses of glucose sensors under clearly defined conditions is recommended as a basis for further studies. The physiological delay in the subcutaneous glucose system needs more attention in this field of research.

The technological potential of non-thermal plasmas for the antimicrobial treatment of heat sensitive materials is well known. Despite a multitude of scientific activities with considerable progress within the last few years, the realization of industrial plasma-based decontamination or sterilization technology remains a great challenge. This may be due to the fact that an antimicrobial treatment process needs to consider all properties of the product to be treated as well as the requirements of the complete procedure, e.g. a reprocessing cycle of medical instruments. The aim of this work is to demonstrate the applicability of plasma-based processes for the antimicrobial treatment on selected heat sensitive products. The strategy is to use modular, selective and miniaturized plasma sources, which are driven at atmospheric pressure and adaptable to the products to be treated.

To elucidate potential influences of the average tissue pO2 on the function of implanted glucose sensors, non-miniaturized polarographic oxygen electrodes and glucose oxidase/H2O2 glucose electrodes were implanted in the subcutaneous tissue of spontaneously breathing normal and diabetic dogs. There was no appreciable run-in phenomenon of oxygen sensors but normally a pronounced initial decrease in current after implantation of glucose sensors. The subcutaneous pO2 amounted to an average of 7 kPa in air-breathing animals with no difference between normal and insulin-dependent diabetic dogs. It showed oscillations of approximately +/- 2 kPa but the mean was stable over the maximum duration of experiments of 16 h. Induced alterations of tissue pO2 between less than 2 and greater than 20 kPa (as verified by measurements of arterial pO2) were not followed by alterations in the current of nearby implanted glucose sensors. It is concluded that the frequently observed instabilities and losses in sensitivity of the system "implanted glucose sensor in situ + tissue glucose compartment" are not caused by alterations in tissue pO2.

A feasible and reliable method of in situ checking and calibration of implanted glucose sensors is required to compensate for alterations in the overall sensitivity of the "sensor plus subcutaneous fluid glucose compartment" system. In a study on nondiabetic dogs, the linear regression analysis of paired plasma glucose/sensor current data is validated as a potential basis of recalibration of intracorporal glucose sensors. These sensors were amperometric glucose oxidase/hydrogen peroxide electrodes of which the in vitro response time to square alterations in the ambient glucose concentration T95 was less than 5 min. The method presented may be incorporated into the data handling system of portable glucose monitors or of miniaturized artificial beta-cells. For its performance, no steady state glycaemia but a minimum alteration in the intracorporal glucose concentration is needed. The latter can be provided both by tests or by fluctuations as they occur spontaneously during the course of the day.