Maja Miletić

The effect of a plasma needle on bacteria in planktonic samples and on peripheral blood mesenchymal stem cells

In this paper, we study the application of a plasma needle to induce necrosis in planktonic samples containing a single breed of bacteria. Two different types of bacteria, Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), were covered in this study. In all experiments with bacteria, the samples were liquid suspensions of several different concentrations of bacteria prepared according to the McFarland standard. The second system studied in this paper was human peripheral blood mesenchymal stem cells (hPB-MSC). In the case of hPB-MSC, two sets of experiments were performed: when cells were covered with a certain amount of liquid (indirect) and when the cell sample was in direct contact with the plasma.Most importantly, the study is made with the aim to see the effects when the living cells are in a liquid medium, which normally acts as protection against the many agents that may be released by plasmas. It was found that a good effect may be expected for a wide range of initial cell densities and operating conditions causing destruction of several orders of magnitude even under the protection of a liquid. It was established independently that a temperature increase could not affect the cells under the conditions of our experiment, so the effect could originate only from the active species produced by the plasma. In the case of those hPB-MSC that were not protected by a liquid, gas flow proved to produce a considerable effect, presumably due to poor adhesion of the cells, but in a liquid the effect was only due to the plasma. Further optimization of the operation may be attempted, opening up the possibility of localized in vivo sterilization.

Epstein-Barr virus infection induces bone resorption in apical periodontitis via increased production of reactive oxygen species

Chronic inflammatory processes in periapical tissues caused by etiological agents of endodontic origin lead to apical periodontitis. Apart from bacteria, two herpesviruses, Epstein-Barr virus (EBV) and Human cytomegalovirus (HCMV) are recognized as putative pathogens in apical periodontitis. Although previous reports suggest the involvement of EBV in the pathogenesis of apical periodontitis, its exact role in periapical bone resorption has not yet been fully elucidated. We hypothesize that EBV infection in apical periodontitis is capable of inducing periapical bone resorption via stimulation of reactive oxygen species (ROS) overproduction. Increased levels of ROS induce expression of receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL). RANKL binding to receptor activator of nuclear factor κB (RANK) present on the surface of preosteoclasts induces their maturation and activation which consequently leads to bone resorption. The potential benefit of antiviral and antioxidant-based therapies in periapical bone resorption treatment remains to be assessed.

Sterilization of bacteria suspensions and identification of radicals deposited during plasma treatment

Abstract In this paper we will present results for plasma sterilization of planktonic samples of two reference strains of bacteria, Pseudomonas aeruginosa ATCC 27853 and Enterococcus faecalis ATCC 29212. We have used a plasma needle as a source of non-equilibrium atmospheric plasma in all treatments. This device is already well characterized by OES, derivative probes and mass spectrometry. It was shown that power delivered to the plasma is bellow 2 W and that it produces the main radical oxygen and nitrogen species believed to be responsible for the sterilization process. Here we will only present results obtained by electron paramagnetic resonance which was used to detect the OH, H and NO species. Treatment time and power delivered to the plasma were found to have the strongest influence on sterilization. In all cases we have observed a reduction of several orders of magnitude in the concentration of bacteria and for the longest treatment time complete eradication. A more efficient sterilization was achieved in the case of gram negative bacteria.

Herpesviruses in Periapical Pathoses: An Updated Systematic Review

Apical periodontitis represents a chronic inflammation and destruction of periradicu‐ lar tissue caused by polymicrobial infection of endodontic origin. The aim of this systematic review was to make an update on findings related to Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) presence in periapical pathoses and to correlate these findings with clinical, histopathological and radiographic features of periapical lesions. Methods were based on the preferred reporting items for systemat‐ ic reviews and meta-analyses (PRISMA) statement. A search was performed using PubMed, Web of Science and SCOPUS. Search key words included the following medical subjects heading terms: (periapical disease OR apical periodontitis OR periapical lesions OR periapical abscess) AND (viruses OR herpesvir*). A manual search involved references from articles retrieved for possible inclusion. The search, evalua‐ tion, and critical appraisal of articles were performed by two independent judges. Collected data were analyzed using the measures of descriptive statistics. The final review has included twenty nine articles related to herpesviral presence periapical pathoses. Qualitative analysis indicated that EBV HCMV, and HHV-8 were the most prevalent species in periapical pathoses. Our findings suggest that there is wide variety of herpesviruses detection rates in periapical pathoses in relation to their clinical, histopathological and radiographic features.

Inhibition of methicillin resistant Staphylococcus aureus by a plasma needle

In numerous recent papers plasma chemistry of non equilibrium plasma sources operating at atmospheric pressure has been linked to plasma medical effects including sterilization. In this paper we present a study of the effectiveness of an atmospheric pressure plasma source, known as plasma needle, in inhibition of the growth of biofilm produced by methicillin resistant Staphylococcus aureus (MRSA). Even at the lowest powers the biofilms formed by inoculi of MRSA of 104 and 105 CFU have been strongly affected by plasma and growth in biofilms was inhibited. The eradication of the already formed biofilm was not achieved and it is required to go to more effective sources.

The Role of Varicella Zoster Virus in the Development of Periapical Pathoses and Root Resorption: A Systematic Review

Introduction Varicella zoster virus (VZV) and subsequent herpes zoster (HZ) infection have been proposed as a causative agent of periapical pathoses and root resorption. This review aimed to identify, synthesize, and present a critical analysis of the available data on the association among VZV, subsequent HZ infection, and the development of periapical pathoses and root resorption and to analyze the level of evidence of available studies. Methods The literature search covered MEDLINE, Science Citation Index Expanded, and Scopus. A qualitative critical appraisal of the included articles was performed. Results The electronic database search yielded 66 hits from PubMed, 73 hits from Web of Science, and 107 from Scopus. Seven case reports and 3 cross‐sectional studies were included in the final review. When summarized, in 7 patients with a history of a previous HZ attack and with no other apparent cause, 23 teeth were diagnosed with apical periodontitis, 8 teeth with internal and 1 tooth with external root resorption. The cross‐sectional studies investigated the presence of VZV DNA in samples of acute apical abscess. The VZV DNA was found only in 2 of 65 samples. Conclusions All studies included in this systematic review had a low level of evidence (4 and 5). Still, the potential role of VZV in the etiopathogenesis of periapical pathoses and root resorption cannot be ruled out. Future investigations should be directed toward the analysis of VZV pathologic effects on pulp blood vessels, which might cause local ischemia and tissue necrosis. HighlightsThe literature search covered MEDLINE, Science Citation Index Expanded, and Scopus.Seven case reports and 3 cross‐sectional studies were included in final review.Only 1 of 7 case reports comprehensively analyzed the association among clinical manifestations of a previous HZ attack, the detection of VZV DNA, and the presence of apical periodontitis and root resorption.All available and included studies in this systematic review had a low level of evidence (4 and 5).A potential role of VZV in the etiopathogenesis of periapical pathoses and root resorption cannot be ruled out.

Herpesviral Infection in Periapical Periodontitis

Purpose of ReviewThis review describes the most recent findings on herpesviral infections and offers current concepts of herpesviral role in the pathogenesis of periapical periodontitis.Recent FindingsThirty articles reported data on herpesviral infection in periapical periodontitis. Epstein-Barr virus and human cytomegalovirus are the most frequently detected herpesviruses in periapical samples. The main hypothesis postulates a bidirectional herpesviral-bacterial relationship in the etiopathogenesis of periapical periodontitis. A high heterogeneity of herpesviruses incidence was registered within the studies, in part, due to various methodological approaches used in laboratory testing, different inclusion criteria, study design, seroprevalence of herpesviruses, and sociodemographic characteristics of investigated populations.SummaryHerpesviruses have been shown to potentially impair local host defense in periapical tissue. Although it has been demonstrated that endodontic pathogenic bacteria are able to reactivate herpesviruses, further, in vitro studies should provide more data on herpesviruses as a factor in the pathogenesis of the periapical pathoses. It is, therefore, necessary to investigate potential benefits of antiviral therapy in well-designed controlled longitudinal studies.