Furthermore, recent updates on the distribution of eukaryotes and archaea recovered through sterile filtering (herein referred to as filterable fraction) in these environments demand their inclusion in the microbial characterization of AMD systems. In this review, we present a complete overview of the bacterial, archaeal (including filterable fraction), and eukaryotic diversity in these ecosystems, and include a thorough depiction of the metabolism and element cycling in AMD habitats. We also review different metabolic network structures at the organismal level, which is necessary to disentangle the role of each member of the AMD communities described thus far.Acid mine drainage (AMD) emplacements are low-complexity natural systems. Low-pH conditions appear to be the main factor underlying the limited diversity of the microbial populations thriving in these environments, although temperature, ionic composition, total organic carbon, and dissolved oxygen are also considered to significantly influence their microbial life. This natural reduction in diversity driven by extreme conditions was reflected in several studies on the microbial populations inhabiting the various micro-environments present in such ecosystems. Early studies based on the physiology of the autochthonous microbiota and the growing success of  Acid mine drainage (AMD) refers to the acid runoff originating in  abandoned mining areas. The chemical reactions leading to AMD have been described extensively . Microbial macroscopic growth is present in ~30% of the AMD sites characterized globally , and dissolved oxygen (DO) Figure . Such enThe diversity and microbiology in AMD systems have been thoroughly reviewed . Mining sites where AMD habitats have been extensively studied in terms of their microbial ecology include the Tinto River (SW Spain), the Richmond mine in Iron Mountain , Cae Coch (pyrite), and Mynydd Parys (copper) mines in UK, the Carnoulès (lead-zinc) mine in France, the Drei Kronen und Ehrt (pyrite) mine in Germany, and the Los Rueldos mercury mine in NW Spain. Others have been surveyed to generate a descriptive overview of their microbiology , or just sulfur compounds , under oxic conditions. At. ferrooxidans can perform CO2 and atmospheric nitrogen fixation  cycle, has an incomplete tricarboxylic acid cycle (TCA), and is also able to assimilate carbohydrates  genes for carbon fixation were observed to be highly expressed in a naturally occurring population of “Ferrovum” spp., while no nitrogen fixation-associated genes were detected; however, the expression of genes related to urea breakdown and nitrate reduction suggests the utilization of alternative nitrogen resources , Ralstonia sp. , and Acidovorax sp. (Tong Shankou and Yinshan mines)   are also found in acid mine waters . Acidisphaera spp., which are aerobic heterotrophic alphaproteobacteria, have been detected in Japan and in the Roeros mining area in Norway . Among Proteobacteria, both Sphingomonas-like alphaproteobacteria  and Ralstonia-like betaproteobacteria  are present in the Tinto River and Cae Coch mines.) Figure  appears Nitrospirae, the most relevant genus known to inhabit AMD systems is Leptospirillum   and “group II” (L. ferriphilum and “L. rubarum”-related) have optimum growth temperatures of 26–30°C and 30–40°C, respectively. “L. ferrodiazotrophum” (“group III”) is proposed to be responsible for nitrogen fixation in AMD at pH levels below 1.0 in the Iron Mountain mine  has recently been detected via metagenomic data as a minority member in archaea-dominated low-pH biofilms in the Richmond mine  Figure . LeptospActinobacteria (Ferrimicrobium spp. and Acidimicrobium spp.) are microorganisms that commonly thrive in these environments  thrive in relatively moderate acidic mine drainage-impacted environments  appear to thrive preferentially in warm AMD solutions (optimum growth at temperatures ~45°C) , have been detected in the Iron Mountain mine   Figure . SulfobaSome bacteria classified as affiliates of the candidate division TM7 have been detected in waste ore samples (pH 3.0) collected at an AMD site in the Anhui province of China  are chemoorganotrophic or chemolithotrophic organisms that use sulfate as a terminal electron acceptor and constitute a physiologically unique group of microorganisms that couple anaerobic electron transport to ATP synthesis   Table .Candidatus Micrarchaeum acidophilum, Baker et al., Candidatus Parvarchaeum acidophilum, Baker et al., Candidatus Parvarchaeum acidophilus, Baker et al., Thermoplasmatales and ARMAN call into question the existence of an independent life-style. Additional archaeal  16S rRNA sequences from an acidic biofilm collected at the Harz-Mountains  have been deposited in public sequence databases  have been discovered in AMD biofilms developing within the Richmond mine , Excavata (protists) and Opisthokonta taxa. AMD-related Archaeplastida include phototrophic red (Rhodophyceae) and green algae (mainly Chlorophyta); these organisms depend on sunlight and are present in open-air systems, such as the Tinto River (SW Spain). The SAR members present in acidic waters include diatoms , ciliates such as Oxytricha and Vorticella, and cercomonads. Members of Excavata detected in AMDs include Euglena sp. (Euglenozoa), Bodo saltans (flagellate) and the Heterolobosea genera Naegleria and Vahlkampfia. Rotifera and Fungi (Opisthokonta) complete the general set of eukaryotes found in AMD emplacements. The Ascomycota and Basidiomycota fungi are the primary eukaryotic members in sub-surface low-pH biofilms thriving inside the Richmond mine (Iron Mountain)  and the experimental measurement of protein levels (community proteomics or metaproteomics) may be better indicators of the element cycling in environmental samples. However, it is important to point out the limitations resulting from these experimental approaches, including that the activity associated with some sequences might be unclear or incorrectly assigned and that, due to regulatory effects, the experimental measurement of protein levels may not be synonymous with their activity. For all these reasons, experimental validation assays need to be conducted. Whatever the case, both Leptospirillum spp.), while additional carbon intake into the system may depend upon photosynthetic Euglena thriving at the surface of the river. In the As-rich Carnoulès environment, arsenate-resistance mechanisms appear ubiquitously in different members of the community, and proteogenomic signatures for arsenite oxidation and methylation are also present  and some archaea of the genus Ferroplasma (“type I” and “type II”). Possibly, heterotrophic archaea , ARMAN and fungi (mainly Acidomyces richmondensis) are present at higher levels; however, these organisms exhibit low relative abundances in thick biofilms, dominated by Leptospirillum ferriphilum-like bacteria (“group II”)- at late developmental stages. The most complex study of carbon mobilization in AMD systems was performed by Justice et al. (Leptospirillum spp. are responsible for Fe(II) oxidation and carbon assimilation through Leptospirillum ferriphilum-like “group II”   Figure  (Ziegler) Figure .Mendez-Garcia et al.  proposedc, as in Acidithiobacillus ferrooxidans or Leptospirillum ferrooxidans , or organic , in the case of heterotrophic acidophiles . The enzymatic system related to ferric iron reduction remains unknown, but evidence exists of that this process might involve iron reductases , which could be oxidized to sulfite by the periplasmic sulfur dioxygenase . A similar coupling of enzymes is used for the oxidation of the polythionates  by enzymes such as trithionate dehydrogenase (produces thiosulfate), and thiosulfate dehydrogenase . Tetrathionate hydrolysis is performed by tetrathionate hydrolase (TetH), and the produced thiosulfate is oxidized by a thiosulfate quinone oxidoreductase (DoxDA)  oxidizes reduced sulfur compounds directly to sulfate without the formation of sulfite as an intermediate. This system is expressed from over 15 genes that encode various cytochromes and other proteins necessary for the oxidation of reduced sulfur compounds directly to sulfate. The presence of three terminal electron acceptors relates to RISC energy conservation: a bd ubiquinol oxidase , a bo3 oxidase (cyoABCD) and the bc1 complex, and cytochrome c4, encoded by the petII operon   can accumulate in areas where pyrite and other sulfide minerals are oxidized by ferric iron   Figure , is perf) Figure . The keyAcidithiobacillus ferrooxidans  pathway, which might be encoded by two non-identical copies of cysNC  might be performed across the cellular membrane either via an ABC uptake system or the SulP sulfate permease in The main nitrogen transformations occurring at AMD sites include nitrogen fixation, ammonification, nitrification and denitrification.2: Acidithiobacillus ferrooxidans  might also be involved in nitrogen fixation  retrieved from an acidic biofilm at the Richmond mine harbor various genes implicated in nitrogen fixation . Genes flanking this operon  can also be involved in nitrogen fixation  and hao gene, respectively. Leptospirillum spp. of the so-called “group II” and “group III” contain the amoA gene in their metagenomes, but they lack the rest of the operon, which suggests that AmoA might be involved in other activities, such as methane oxidation or/and hydrocarbon degradation . Baeseman et al.  examinedLeptospirillum ferriphilum “group II”-related bacteria was suggested based on the observation of a cytochrome c NapC/NirT family protein involved in respiratory nitrite ammonification. Leptospirillum spp. “group II” and “group III,” which were reported to contain genes for a nitrite/sulfite reductase, are required for assimilatory nitrite ammonification with the end-product, ammonium, being directly channeled into amino acid biosynthesis  and Nir and Nrf (nitrite reductases). In AMD systems, the putative presence of this activity in s Simon, . Once amLeptospirillum ferriphilum-related bacteria (“group II”) have genes encoding three ammonium transporters clustered with the genes encoding nitrogen-regulatory PII proteins. This gene arrangement appears to be highly conserved and suggests that the regulatory proteins are related to ammonium uptake  and a gene encoding a protein that incorporates ammonium into glutamine (the glnA-homologous gene) , and uncultured Leptospirillum spp. (“group IV”)  or the reductive acetyl-CoA pathway (not yet demonstrated).As carbon sources are severely limited in acidic waters, microbial carbon cycling is of great interest in AMD ecosystems. Notably, some typical members of AMD communities contain genes that enable them to fix COAlphaproteobacteria , and the phyla Firmicutes  and Actinobacteria . Facultative metabolism can be observed in the bacteria Acidiphilium acidophilum, Sulfobacillus, Alicyclobacillus and Acidimicrobium ferrooxidans. Obligate heterotrophic archaea in AMD biotopes include the genera Thermoplasma, some Ferroplasma spp., and some Acidiplasma spp. (Euryarchaeota). Crenarchaeal representatives, more common in high-temperature volcanic environments, include obligate heterothrophic members of the genera Sulfolobus and facultative heterotrophic members of Metallosphaera, Sulfurococcus, Acidianus, Sulfurisphaera, and Acidilobus  similar to those from methanogens. Johnson  observed2) is a common product that is generated during microbial metabolic transformations and fermentations, and a number of chemolithotrophs can use it in energy metabolism.Hydrogen , or secondary  consumers within the community. Low-pH conditions favor the development of fungi, which act as decomposers and contribute to carbon recycling Figure . When prThe extent of eukaryotic roles is still unclear for a number of reasons and awaits further studies. First, it is difficult to identify eukaryotic genomic sequences through direct DNA sequencing due to their low cell numbers compared with archaea and bacteria in the majority of AMD habitats. Second, identified species are in some cases extremely divergent from any organism that have been cultured or sequenced  would extend our understanding about the origin and ecological succession of the microbial communities in acidic environments. Additionally, the inference of the role of many detected members belonging to different taxonomic groups  is still unclear, and expansion of this knowledge would result in a more accurate depiction of the microbial ecology in AMD systems.Acid mine drainage triggered by anthropogenic mining activities represents a significant environmental problem. The ecosystems emerging as a result of AMD are extremely acidic and metal-rich, and the associated microbiome is restricted almost entirely to only a few most abundant taxa of specialized bacteria and archaea. These habitats contain unique microorganisms and novel metabolic functions selected to cope with the harsh conditions, some of which, as well as the metabolites they produce, might be of biotechnological relevance. The presence of a filterable archaeal fraction in microbial communities of the AMD necessitates further genomic diversity studies in environments of a similar nature and stimulates the debates regarding the origins of life. Microbial ecology focuses on mechanisms of functioning biological systems and their interaction with the abiotic environment (lithosphere). Therefore, to obtain a general view on how biological systems function, the approaches should be very inclusive.Further efforts should be conducted to more in-depth sequencing and cultivation studies. Only a detailed survey of complete genomes, whose production from metagenomes and single-cells is still technically challenging, will facilitate an accurate prediction of microbial metabolism; in turn, the experimental investigation of physiological traits in pure cultures brings us to a more comprehensive understanding of metabolism of the members of AMD communities and to a full assessment of their biotechnological prospects. Obviously, introducing new isolation approaches to bypass all the difficulties in the cultivation of AMD-related microorganisms  will improve our current knowledge on archaeal and bacterial lineages within AMD habitats, whereas the main attention should be paid to cellular communications and any form of interactions between microbial partners important in natural environments.Finally, a greater effort to culture the individual members of AMD communities and to establish stable low-complexity enrichment cultures to include co-cultures of archaea from the filterable fraction will facilitate new and exciting discoveries in coming years.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Saliva is an important compound produced by the salivary glands and performs numerous functions. Hyposalivation (dry mouth syndrome) is a deleterious condition often resulting from radiotherapy for patients with head and neck cancer, Sjogren’s Syndrome, or as a side effect of certain medications. Hyposalivation negatively affects speaking, mastication, and swallowing in afflicted patients, greatly reducing their quality of life. Current treatments for this pathology include modifying lifestyle, synthetic saliva supplementation, and the utilization of salivary gland stimulants and sialagogues. However, many of these treatments do not address the underlying issues and others are pervaded by numerous side effects. In order to address the shortcomings related to current treatment modalities, many groups have diverted their attention to utilizing tissue engineering and regenerative medicine approaches. Tissue engineering is defined as the application of life sciences and materials engineering toward the development of tissue substitutes that are capable of mimicking the structure and function of their natural analogues within the body. The general underlying strategy behind the development of tissue engineered organ substitutes is the utilization of a combination of cells, biomaterials, and biochemical cues intended to recreate the natural organ environment. The purpose of this review is to highlight current bioengineering approaches for salivary gland tissue engineering and the adult stem cell sources used for this purpose. Additionally, future considerations in regard to salivary gland tissue engineering strategies are discussed. Saliva is a watery substance produced by the salivary glands. It consists of mucus, various electrolytes, glycoproteins, enzymes, and antibacterial compounds such as lysozyme and IgA . In relaCurrent treatments for hyposalivation include symptom management, lifestyle changes, synthetic saliva supplementation, and the utilization of salivary gland stimulants and sialagogues  which stimulate salivary secretion from residual acinar cells , 10. SalThus, development of an alternative treatment to provide a long-term and effective solution solution is imperative . In ordeTissue engineering is defined as the application of life sciences and materials engineering toward the development of tissue substitutes that are capable of mimicking the structure and function of their natural analogues within the body . The genWithin the body, there are three main sources of saliva production: The parotid gland, the submandibular gland, and the sublingual gland. Additionally, there are 800–100 minor salivary glands throughout the oral cavity that produce a small amount of saliva, although, this amount is considerably less than the three major salivary organs .Each of the salivary glands is located in various locations throughout the oral cavity in humans . The parIn terms of their growth and development, each of these organs are formed from two different layers of the three primary embryonic germ layers . The subThe salivary glands of most mammals are made up of three main cell types: serous producing acinar cells, mucous producing acinar cells, and myoepithelial cells . Serous The effects of radiotherapy on salivary gland cells are confounding. Theoretically, saliva producing acinar cells are not predicted to be radiation sensitive due to the fact that they are post-mitotic in nature . HoweverThe purpose of this review is to highlight current bioengineering approaches for salivary gland tissue engineering and the adult stem cell sources used for this purpose. Some of the most currently studied adult derived stem cell populations for the purpose of salivary gland regeneration include salivary gland-derived stem cells (SGSCs), mesenchymal stem cells (MSCs), and human amnion epithelial stem cells (hAECs).Since adult stem cells are generally restricted to cell lineages of the body part of origin, researchers have attempted to use stem cells derived from salivary glands (SGSCs) to reduce hyposalivation and restore natural function . Thus fain vitro[Stem cells from the human parotid gland, removed via lateral parotidectomy, have been isolated and characterized in vitro. Flow cyin vivo recovery of salivary gland function in radiation-damaged rat salivary glands [in vitro experiments confirmed that the SGSCs expressed MSC markers , excluded HSC markers , differentiated into MSC lineages, and could differentiate into amylase-expressing cells. Radiation-induced hyposalivation in rats was generated using an x-ray irradiator and human SGSCs (hSGSCs) were transplanted into the glands. After 60 days, the average saliva flow rate of the irradiation-damaged, hSGSC-treated group was twice that of the PBS-treated, irradiation-damaged group but was still lower than the undamaged group. Treatment with hSGSC was also quantified by measuring the rat body weight over time; the average body weight of hSGSC-treated rats was slightly increased in comparison to the PBS-treated rats.Stem cells isolated from a combination of the human parotid and submandibular glands were revealed to have a certain capacity for y glands . Prior iin vitro characterization of submandibular-derived SGSCs revealed cellular expression of Sca-1, c-Kit, and Musahsi-1 [By using a floating sphere culture, further usahsi-1 . Immunohin vitro results suggest that these sphere-forming cells originate from salivary gland ducts and are able to differentiate into amylase-producing, acinar-like cells. To analyze the stem cell characteristics of these spheres , common stem cell markers  were fluorescently labeled and visualized in culture. Sca-1 and c-Kit expression was seen in excretory duct cells but not acinar cells. Results from the H&E/PAS staining were confirmed by the fluorescent microscopy, which indicated a peak Sca-1 expression at 5 days.The + population, cells were capable of differentiating into acinar cells in vitro and transplantation of a small number of cells (300–1000 per gland) improved saliva production in 69% of irradiated mice in vivo, after 120 days.Intraglandular transplantation of 3-day cultured salispheres into irradiated mice resulted in the formation of ductal structures near the injection site. There was an increase in acinar cell surface area in salisphere-treated mice compared to the untreated group. Ninety days after irradiation, saliva production in salisphere-treated mice was higher than the untreated counterparts and correlated strongly with acinar surface area. After purifying salispheres to a c-KitHowever, a major limitation for SGSC therapy in the treatment of radiation-induced hyposalivation is the difficulty with isolating autologous stem cells from a severely injured gland. To overcome this barrier, a co-culture system of mouse embryonic stem cells (mESCs) and human SG fibroblasts was developed to facilitate differentiation of mESCs to SGSCs . After 1in vitro and in vivo as well as clinical treatment of various diseases [Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into many cell types, including chondrocytes, adipocytes, osteoblasts, acinar cells, and salivary epithelial cells –34. Theidiseases –35. TherTwo studies investigated the role of MSCs as a therapeutic option for treatment of Sjögren’s syndrome (SS), a chronic autoimmune disorder that results in exocrine gland inflammation, impaired salivary function, and lymphocytic infiltrates within the salivary glands , 35. KhaXu et al.  investigSeveral groups explored the effects of MSCs on radiation-induced damage to salivary glands –34. Sumiin vitro and in vivo. After 3 weeks of co-culture (MSCs and acinar cells), about half of the MSCs had differentiated into acinar-like cells, demonstrating MSC differentiation capacity in vitro. Both MSCs and differentiated acinar-like cells significantly increased saliva production, salivary gland weight, and body weight when transplanted into radiation-treated mice; these systemic and local effects indicate salivary gland regeneration. Moreover, after 43 days, transplanted MSCs were found to be integrated into the salivary gland and transdifferentiated into acinar-like cells. Therefore, transplantation of either MSCs or differentiated acinar-like cells may aid regeneration and restore functional salivary glands.Lin et al.  studied Lim et al.  investigTwo studies explored the use of adipose-derived MSCs (AdMSCs) for salivary gland regeneration as these cells are readily available and are known to contribute to angiogenesis and to secrete multiple cytokines and growth factors , 37. Kojin vivo as well as after co-culture in vitro with salivary gland cells. Treatment with hAdMSCs also significantly increased post-stimulation salivary flow rate compared to untreated controls, promoted regeneration of salivary gland cells, and provided protection against radiation damage to cells. These results show that xenogeneic hAdMSCs can migrate through the bloodstream to radiation-damaged salivary glands and promote functional recovery, indicating that hAdMSCs have potential for salivary gland restoration.Lim et al.  investigRecently, much attention has been dedicated towards the study of stem cells derived from placental tissues. Many studies have reported the isolation and identification of various pluripotent and broadly multipotent cell types from umbilical cord blood, amniotic and chorionic membranes, wharton’s jelly, and amniotic fluid –43. In rhAECs are typically derived from the top-most layer of the amniotic membrane via trypsinization of the membrane following its collection during cesarean section. Human amniotic epithelial cells are similar to epithelial cells in the sense that they express common epithelial markers such as cytokeratin 7 (CK7) and are negative for CD44. However, unlike adult epithelial cells, these cells have been demonstrated to express characteristic markers of pluripotent stem cells such as stage specific embryonic antigen-4 (SSEA4), octamer binding protein-4 (oct-4), and Nanog . AdditioIn the first study, hAECs were isolated and co-cultured with submandibular salivary gland acinar cells of sqrague dawley rats using a double-chamber system for 1–2 weeks to induce their differentiation into salivary gland acinar cells . At eachIn a separate study, isolated hAECs were injected into the irradiated glands of mice . The glaOne of the most common treatments for hyposalivation is oral administration of drugs for the stimulation of saliva flow. Muscarinic receptor agonists, such as pilocarpine and cevimeline, have been widely used as orally administered drugs for hyposalivation treatment –51. HoweGene delivery approach has also been considered as a potential therapeutic treatment for hyposalivation. Salivary glands have several advantages for clinical gene delivery . SalivarRecently, bone marrow-derived cells (BMC) mobilization by cytokine stimulation has also been reported for hyposalivation treatment , 76. TheVarious current approaches including the delivery of stem cell and therapeutic molecules such as drugs, genes, and cytokines, hold great promise to overcome the challenge of hyposalivation; however, they provide only partial restoration of the damaged salivary gland and its function. Thus, to achieve the complete functional replacement of lost or damaged tissue, a novel bioengineering approach reconstructing a fully functional organ was proposed , 77, 78.Many bioengineering and adult stem cell therapies for the treatment of hyposalivation are currently being developed and investigated. Most of these treatments rely on the utilization of allogeneic, adult derived stem cells. While many of these therapies are promising, there are still shortcomings that need to be addressed in the future. For example, the role that allogeneic stem cells play in regeneration has been shown to be transient in nature . In thisThe first strategy involves the use of immunoprotective biomaterials intended to isolate the donor stem cells from the recipient’s innate immune cells, yet, allow the diffusion of essential nutrients and oxygen necessary to maintain cellular viability. A few research groups have investigated the use of various biomaterials and configurations for this purpose –87. A prAn alternative solution to the problem of donor cell destruction is to utilize autologous cell populations capable of forming salivary gland acinar cells. In this sense, the ideal cellular source for this purpose is induced pluripotent stem cells (iPSCs). IPSCs, which are derived from adult somatic cells of the patient via reprogramming to express a subset of pluripotency genes and induce an embryonic-like state, would be an ideal candidate for autologous cellular therapy due to enhanced potency and immunological compatibility . HoweverWith regard to the differentiation of various stem cell populations, a majority of studies induce differentiation either by co-culture with isolated salivary gland cells or by injection into the salivary glands of mice. In the future, it would be beneficial to identify and utilize specific growth factors to create an induction media to ease the study of various stem cell types in-vitro and allow for consistency in deriving acinar-like salivary gland cells. Preliminary work has been performed to elucidate some of the conditions necessary to induce the differentiation of progenitor cell populations into salivary gland acinar-like cells. For example, one study found that TGF-b1 inhibited the expression of acinar cell associated genes from mesenchyme progenitors while TGF-bR1 inhibitor increased their expression . FurtherThis paper is intended to provide an up to date review on the current status of salivary gland regeneration for the treatment of xerostomia induced hyposalivation. Overall, it has been demonstrated that tissue engineering approaches utilizing stem cells and biomaterials have the capability to become a viable means to achieve meaningful salivary gland regeneration. However, while preliminary in-vitro, animal, and human clinical studies have yielded promising results, it is clear that additional research is needed before salivary gland regeneration becomes a widespread therapeutic and clinical option.


Essential oils are natural products, derived from aromatic plants, traditionally used all over the world for disinfection, as anti-inflammatory, relaxing, and stimulating substances, and with potential and modern exploitation in clinical medicine. The earliest recorded mention of the techniques and methods used to produce essential oils is believed to be that of Ibn al-Baitar (1188–1248). The chemical composition of these essential oils varies widely depending upon the geographical location, botanical origin, genetics, bacterial endophytes, and extraction techniques. Essential oils are commonly used in food and cosmetic industries. They can be used as natural alternatives to synthetic preparations to prevent and treat infectious diseases. They are used traditionally to treat other diseases like respiratory tract, digestive system, gynecological, andrological, endocrine, cardiovascular, nervous system, and skin infections. Many of them have shown anticancer activities, too.For this special issue we received seventeen papers, confirming the interest shown by the scientific community on a great number of old and new issues still open about essential oil, particularly chemical characterization and standard methods to control quality; human clinical and experimental pharmacology and toxicology of essential oils; safety; pharmacological actions and interactions; new biomedical targets of the biological responses; clinical assays to pharmaceutical products with essential oils in biotechnology; nanotechnology and nanomedicine. We have selected seven papers, with the aim of showing some progress made by the pharmaceutical point of view and the new perspectives of pharmacological research to facilitate their transition into clinical practice. “Hepatoprotective effect of pretreatment with Thymus vulgaris essential oil in experimental model of acetaminophen-induced injury,” R. Grespan et al. investigated the hepatoprotective effect of Thymus vulgaris essential oil on acetaminophen-induced hepatic damage in mice. Thymus vulgaris is used popularly such as its antiseptic, carminative, and antimicrobial effects, and this study is very interesting for new possible clinical applications. The positive results are confirmed by reduction of the serum marker enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), and myeloperoxidase (MPO) and by histopathological analysis. Acute liver damage caused by acetaminophen overdose is a significant clinical problem and could benefit from new therapeutic strategies.In the study “Exploring the anti-Burkholderia cepacia complex activity of essential oils: a preliminary analysis,” I. Maida et al. have checked the ability of the essential oils extracted from six different aromatic plants to inhibit the growth of 18 known species of the Burkholderia cepacia complex (Bcc), an opportunistic human pathogen that can cause severe infection in immunocompromised patients, especially those affected by cystic fibrosis (CF) and who are often resistant to multiple antibiotics. Eugenia caryophyllata, Origanum vulgare, and Thymus vulgaris essential oils were particularly active versus the Bcc strains, including those exhibiting a high degree or resistance to ciprofloxacin, active toward both environmental and clinical strains isolated from CF patients.In the paper entitled “Chemical composition, antioxidant and antimicrobial activities of Thymus capitata essential oil with its preservative effect against Listeria monocytogenes inoculated in minced beef meat” evaluated the preservative effect of Thymus capitata essential oil (TCEO) against Listeria monocytogenes inoculated in minced beef meat. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL, and essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) of TCEO to minced beef significantly reduced the L. monocytogenes population.N. El Abed et al. in the work “Essential oils for complementary treatment of surgical patients: state of the art” S. Stea et al. revised the available literature to determine the effectiveness of aromatherapy in surgical patients . Efficacy studies of lavender or orange and peppermint essential oils, to treat anxiety and nausea, respectively, have shown positive results. Therefore there are encouraging data for the treatment of infections, especially for tea tree oil (TTO). The authors conclude that it is important that the therapeutic use of essential oils be performed in compliance with clinical safety standards.In the paper “Effect of eugenol on cell surface hydrophobicity, adhesion, and biofilm of Candida tropicalis and Candida dubliniensis isolated from oral cavity of HIV-infected patients” S. B. de Paula et al. evaluated the effect of eugenol on the adherence properties and biofilm formation capacity of Candida dubliniensis and Candida tropicalis isolated from the oral cavity of HIV-infected patients. Eugenol showed inhibitory activity against planktonic and sessile cells of Candida spp. Scanning electron microscopy demonstrated that eugenol drastically reduced the number of sessile cells on denture material surfaces. The paper corroborates the effectiveness of eugenol against Candida species other than C. albicans, reinforcing its potential as an antifungal applied to limit both the growth of planktonic cells and biofilm formation on different surfaces.In the article “Essential oils loaded in nanosystems: a developing strategy for a successful therapeutic approach” A. R. Bilia et al. revised the nanoencapsulation of essential oils in drug delivery systems, for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano/microemulsions.In the work “Essential oil of Artemisia annua L.: an extraordinary component with numerous antimicrobial properties” describes the qualitative composition and the antimicrobial activities of essential oil of Artemisia annua L., a medicinal plant from China, well known and used in the treatment of the chloroquine-resistant and cerebral malaria. The essential oil of A. annua is rich in mono- and sesquiterpenes  exciting a lot of antibacterial and antifungal activities: against gram-positive bacteria , gram-negative bacteria , and mycetes . The authors believe that this review will serve to prepare the most appropriate microbiological studies also useful for clinical practice.Lastly, the paper by A. R. Bilia et al. entitledFabio FirenzuoliFabio FirenzuoliVikas JaitakVikas JaitakGyorgyi HorvathGyorgyi HorvathImaël Henri Nestor BassoléImaël Henri Nestor BassoléWilliam N. SetzerWilliam N. SetzerLuigi GoriLuigi Gori


While the modest reduction in the primary composite outcome of myocardial infarction, stroke or cardiovascular death in the EMPA-REG Outcomes trial was welcome, the 30–40% reductions in heart failure hospitalisation (HFH) and cardiovascular and all-cause deaths in patients treated with empagliflozin were highly impressive and unexpected. In this review, we discuss briefly why cardiovascular endpoint trials for new diabetes agents are required and describe the results of the first four such trials to have reported, as a precursor to understanding why the EMPA-REG Outcomes results came as a surprise. Thereafter, we discuss potential mechanisms that could explain the EMPA-REG Outcomes results, concentrating on non-atherothrombotic effects. We suggest that the main driver of benefit may derive from the specific effects of sodium-glucose linked transporter-2 (SGLT2) inhibition on renal sodium and glucose handling, leading to both diuresis and improvements in diabetes-related maladaptive renal arteriolar responses. These haemodynamic and renal effects are likely to be beneficial in patients with clinical or subclinical cardiac dysfunction. The net result of these processes, we argue, is an improvement in cardiac systolic and diastolic function and, thereby, a lower risk of HFH and sudden cardiac death. We also discuss whether other drugs in this class are likely to show similar cardiovascular benefits. Finally, areas for future research are suggested to better understand the relevant mechanisms and to identify other groups who may benefit from SGLT2 inhibitor therapy. Recent epidemiological studies indicate that diabetes approximately doubles cardiovascular risk . It alsoNotably, the results of recent trials comparing intensive glucose control with standard control led to some concern that aggressive lowering of glucose levels in some individuals may increase short-term mortality, as seen in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study , even thThe four trials were not designed as glucose-lowering trials per se since background glucose-lowering medications (other than incretin therapy) were generally allowed to be changed freely in both arms, in line with usual care. DPP-4 inhibitors are glucose-lowering agents that neither increase weight nor cause hypoglycaemia and that have negligible effects on lipids or blood pressure Table . That noThe results of the first two DPP-4 inhibitor trials . One concern was a slight but significant increase in risk of heart failure hospitalisation (HFH) seen with saxagliptin in the SAVOR−TIMI study. EXAMINE also showed a higher risk of HFH ).If we assume that the explanations for the benefit of empagliflozin revolve around its effects principally on diuresis (driven by promoting both glucose and sodium loss) and via blood pressure reductions, then other SGLT2 inhibitors should yield directionally similar outcomes. That noted, available SGLT2 inhibitors have differential specificities for SGLT2 and SGLT1 , the relThe effects of empagliflozin on important secondary endpoints in EMPA-REG Outcomes, namely HFH, cardiovascular and all-cause death, were unexpected. The rapid emergence of these benefits points strongly towards non-atherothrombotic mechanisms, perhaps principally haemodynamic effects. Further mechanistic studies will be needed to identify these mechanisms and further clinical trials of SGLT2 inhibitors in patients with and without heart failure, with and without cardiovascular disease and, potentially, with and without diabetes, will likely ensue. Finally, we will also shortly know whether these findings are common to other drugs in the class. It appears that a new era in diabetes–cardiovascular research has emerged.


Introduction: Little is known about the clerkship  medical students’ knowledge of hand hygiene as the single most important precautionary measure to reduce nosocomial healthcare-associated infections. The aim of this study is to explore the knowledge of, and attitudes towards, hand hygiene practices among fourth-year clerkship medical students at Alfaisal University, College of Medicine, Riyadh, Saudi Arabia.Materials and Methods: A cross-sectional, paper-based, Yes/No formatted questionnaire was administered to explore the students’ knowledge of, and attitudes towards, hand hygiene practices. Data were decoded in Microsoft Excel sheet and presented as numbers and percentages.clostridium difficile infections". Almost all students (93%) agreed to the importance of hand hygiene education in medical curricula and its awareness in healthcare centers. Despite the importance of hand hygiene, only 13% of students reviewed the respective WHO and CDC guidelines before starting their clinical training in the teaching hospital.Results: One hundred and eleven students (n=111/147) participated in the questionnaire (response rate: 76%). Although the majority of students had a fair knowledge of hand hygiene practices, a number of them had some misconceptions. Only 14% of students correctly agreed to the statement: "Traditional hand washing  decreases the number of germs." Furthermore, only 32% of students correctly answered that "hand washing with a regular soap, instead of an antiseptic soap, is better in limiting the transmission of Discussion: The students’ inadequate knowledge about hand hygiene needs to be enriched by well-structured curricular and extra-curricular programs as well as more positive attitudes by healthcare workers. Healthcare-associated infections (HAIs) bear huge burdens on healthcare systems. More precisely, HAIs are associated with lengthy hospitalization, long-term disability, higher microbial drug resistance, increased morbidity, greater mortality, and extra healthcare-related costs . CompliaClerkship  medical students are key players in any healthcare teams and are greatly involved in the delivery of patient care. Moreover, during their clinical training, they rotate in infection-sensitive floors, such as: labor and delivery, intensive care units, neonatal intensive care units, and operating rooms, where greater requirements of sterility and infection control are highly demanded. Despite the significant impact of HAIs on the safety and cost of healthcare systems, priority consideration of HAIs education in pre-clerkship and clerkship medical curricula has yet to be reinforced . As a reHand hygiene is regarded to be the single most central precautionary measure to prevent HAIs . This noLittle is known about the clerkship students’ knowledge of hand hygiene as one of the infection control measures. Exploring medical students’ knowledge of, and attitudes towards, hand hygiene are of high importance to public health policy makers and medical educators. Such exploration is expected to identify the curricular needs and, therefore, can be appropriately incorporated into the pre-clerkship and clerkship medical curricula to equip students with satisfactory knowledge and skills. In the short- and long-term, such curricular incorporation is expected to decrease the rate of nosocomial HAIs that could be caused by clerkship medical students. Although there are a number of reports concerning the knowledge of hand hygiene among medical students in many countries, Saudi Arabia has greatly lagged behind in this aspect -8.The aim of this study is to explore the knowledge of, and attitudes towards, hand hygiene among fourth-year clerkship medical students at Alfaisal University, College of Medicine, Riyadh, Saudi Arabia.A cross-sectional study was conducted during the fall semester of 2014-2015. The participants were fourth-year clerkship medical students enrolled in Alfaisal University, College of Medicine who were entering clinical training at a single teaching hospital in Riyadh, Saudi Arabia. This study was approved by the Institutional Review Board (IRB) of Alfaisal University .Students were requested to complete a paper-based questionnaire. The questionnaire was administered during an academic lecture, and students were given 10 minutes to complete the questionnaire. The questionnaire was administered to explore students’ demographical data as well as their knowledge of, and attitudes towards, hand hygiene.Demographic data included gender and previous attendance of scientific meetings  about hand hygiene. Knowledge of hand hygiene was examined by 18 Yes/No formatted questions; they were scientifically based objective questions and explored information about gloves, antiseptic soaps, and sanitizers as well as hand hygiene concepts and techniques. Attitudes towards hand hygiene were examined by five Yes/No formatted questions; they were opinion-based subjective questions and explored aspects relating to hand hygiene in terms of importance, education, compliance, and role models.The questionnaire was developed based on a literature review (previous studies as well as WHO and CDC guidelines). All questions were peer-reviewed by two public health/infection control healthcare professionals and piloted on a group of students to ensure proper understanding and interpretation of questions.After collecting the responses, data were decoded by using Microsoft Excel sheet . Categorical data were presented as numbers and percentages.One hundred and eleven students (n=111/147) participated in the questionnaire with an overall response rate of 76%. Around 57% and 43% of students were males and females, respectively. Around 7% of students attended previous scientific meetings about hand hygiene.Table Table  [Studies from Saudi Arabia that explored clerkship medical students' knowledge of hand hygiene are limited. To the best of our knowledge, there are only two related studies conducted at Qassim University, College of Medicine, Qassim, Saudi Arabia  and King . Our curOur study endeavored to examine clerkship medical students’ knowledge of, and attitudes towards, hand hygiene as one of the most important infection control measures. It revealed that students’ knowledge of hand hygiene is inadequate. Several students wrongly answered some basic hand hygiene questions. Our results were largely similar to other studies conducted elsewhere in Saudi Arabia -8, IndiaAccording to CDC guidelines on hand hygiene, washing hands with water and regular soap is the best available method to decrease the number of microbes on them in the vast majority of circumstances . In our When water and soap are unavailable — which can be the case in several occasions in healthcare settings — students should look for an alternative, such as hand sanitizers. Students exhibited several major misconceptions regarding the use of hand sanitizers. This can generally be attributed to the students’ lack of knowledge. For example, 69 students (62%) falsely agreed that "Using instant hand sanitizer to quickly wash hands is adequate". Students should recognize the difference between alcohol-based and non-alcohol-based hand sanitizers. For effective killing/elimination of germs, several studies have shown that highly-concentrated alcohol-based hand sanitizers  are more superior to low-concentrated alcohol-based  and non-alcohol-based hand sanitizers -14. The In addition, students should be aware that traditional hand washing  has been demonstrated to be more effective at inactivating and eliminating particular kinds of germs, such as clostridium difficile-associated infections in suspected individuals/patients . This isBesides, students should understand that "on unsoiled hands, an alcohol-based hand rub is recommended over an antiseptic soap for proper hand hygiene", as it is quicker and better endured . Only 42Up to this moment, there are no well-documented and established recommendations for using both hand sanitizers and antiseptic soap to clean hands and achieve hand hygiene. Only 48 students (43%) answered this question correctly.An infection control preventive measure that is worthy of mentioning is the use of medical gloves . AccordiStudents showed appropriate awareness of hand hygiene in terms of indications and techniques. Hand hygiene should be performed before and after each patient encounter  , and 82 It should be noted that the relatively appropriate awareness of hand hygiene in the context of 1) patient encounter, 2) physical examination, and 3) hand washing techniques can be attributed to the intensive pre-clerkship training the students have received in the "Clinical Skills" courses at our college.In our study, students showed positive attitudes towards hand hygiene. More than 90% of the students agreed that "Proper hand hygiene is an important matter to be emphasized in medical curricula and healthcare centers" and that "Improper hand hygiene significantly contributes to a patient’s morbidity and mortality". It is of high significance to spread the awareness about hygiene among undergraduate clerkship medical students as this will be reflected on their behaviors later on when they become professional healthcare providers. Obviously, the higher the level of education/awareness about hand hygiene standards, the more precautions will be taken, and the less ensued nosocomial HAI rates . DespiteSixty-seven students (60%) declared that one of the reasons accounting for their lack of proper hand hygiene is related to absence of living examples  adhering to the hand hygiene guidelines. Previous studies showed that students’ hand hygiene behaviors are substantially influenced by their role models’  behaviors towards hand hygiene -23. MoreOnly 43 students (39%) asserted that they were "educating patients and their families about hand hygiene and its importance". This is a worrisome issue. Clerkship medical students’ roles should evolve from merely "learners" to include "public health advocators", "patient safety ambassadors", and "valuable mentors/roles models" by promoting hand hygiene compliance among patients and healthcare workers, too. These qualities should be cultivated in medical students early in pre-clerkship curricula and strongly reinforced in clerkship clinical training by their teaching physicians.The inadequate knowledge of our students can be attributed to two main factors. First, in our pre-clerkship curriculum  and clinical (clerkship) years is needed . The sigSecond, using the systemic Hand Hygiene Self-Assessment Framework tool can help in generating an analysis of hand hygiene of all healthcare workers at a particular healthcare center . The tooThere are a few limitations to our study. First, the study design was cross-sectional; differing results could have been obtained if another time-frame had been chosen. Second, all questions were Yes/No formatted questions, and accordingly, answers were liable to random correct guessing . Third, the use of opposing statements in subsequent questions of the questionnaire may have forced respondents more towards the guessing mode for answering.Clerkship medical students had some misconceptions about hand hygiene that reflected their inadequate knowledge. Medical educators should design well-structured pre-clerkship and clerkship curricula that guarantee satisfactory knowledge of infection control measures and hand hygiene. Public awareness and creative campaigns about hand hygiene are also encouraged. Developing positive attitudes towards hand hygiene and the students’ compliance to such should be underscored as being essential to clinical practice and reducing the rate of HAIs. Incorporating formal curricular assessments is one plausible method to cultivate this compliance. Students’ adequate knowledge of hand hygiene is expected to decrease the rate of nosocomial HAIs that could be incurred unintentionally or negligibly by the clerkship medical students. Future research projects include exploring students’ perception on barriers towards hand hygiene education and practice as well as exploring the impact of mentoring role models  towards proper hand hygiene.


This type of CNS injury has been previously described in cancer patients treated with common anti-neoplastic drugs such as doxorubicine, carmustine, methotrexate and cyclophosphamide. It seems that all these pharmacological factors promote neuronal death through a final common pathway represented by TNF alpha (tumour necrosis factor). However, as cancer in general is diagnosed more commonly in the aging population, the elderly oncological patient must be treated with great care since aging per se is also impacted by oxidative stress and potentiually by TNF alpha deleterious action on brain parenchyma. In this context, some patients may develop cognitive dysfunction well before the appearance of CICI. In addition, chemotherapy may worsen their cognitive function. Therefore, at the present time, there is an acute need for development of effective therapeutic methods to prevent CICI as well as new methods of early CICI diagnosis.Chemobrain or chemotherapy induced cognitive impairment (CICI) represents a new clinical syndrome characterised by memory, learning and motor function impairment. As numerous patients with cancer are long-term survivors, CICI represent a significant factor which may interfere with their quality of life. However, this entity CICI must be distinguished from other cognitive syndromes and addressed accordingly. At the present time, experimental and clinical research suggests that CICI could be induced by numerous factors including  Chemobrain or chemotherapy induced cognitive impairment (CICI) represents a newly described clinical diagnosis associated with cancer therapy. This neuropsychological syndrome induced by pharmacological agents used in oncological therapy is centred on the gradual cognitive decline of the patients which could range from mild inability in performing some tasks to serious attention and memory problems [problems -3. In faproblems -8.The combination of electroencephalography (EEG) with multimodal neuroimaging  have added to the understanding of the underlying mechanisms of chemotherapy-induced cognitive impairment. Neuroimaging may help uncover a neural basis for the subtle cognitive deficits in cancer patients. However, a serious limitation of functional imaging studies in CICI is the consistent use of small samples .et al. (2014) have evaluated cognitive deficits in breast cancer patients after chemotherapy on quality of life and reported that medical practitioners fail to diagnose and address appropriately this condition as well as the whole array of associated features experienced by the chemotherapy patients including but not limited to calls for help and coping, daily life and survivorship issues [A significant number of experimental and clinical studies have reported neuropsychological symptoms after chemotherapy with platinum compounds, mitotic spindle and proteasome inhibitors as well as interferon alpha and small thyrosine kinase inhibitors ,11. Morep issues . Moreovep issues -18. Therp issues . We assuThe above mentioned abnormal neuropsychological changes correlate with morphological changes recorded by neuro-structural radiological tests. A study investigating structural changes in brain parenchyma in breast chemotherapy patients has reported a time dependent gradual continuous structural damage. In addition, a significant reduction in total brain and grey matter volumes was recorded post-chemotherapy in breast cancer survivors ,17,20. TFunctional magnetic resonance imaging (fMRI) studies investigating changes associated with cerebral blood flow dependent blood oxygenation level (BOLD) have shown that patients with breast cancer have a different CNS activation pattern as compared with healthy controls during declarative memory tasks. More specifically, after therapy with cyclophosphamide, methotrexate, and 5-fluorouracil, their pre-frontal cortex presents with a lower degree of activation during memory formation. The authors report a significantly lower activation in the dorso-lateral and caudal frontal cortex as well as in the pre-motor cortex. The anomalies recorded in the left caudal lateral frontal cortex were positively linked to a superior executive dysfunction but unexpectedly, during recall, cancer patients have a greater level of generalised diffuse activation compared with healthy subjects. ,22. ThesThe mechanisms for chemotherapy induced cognitive changes are unknown, but several mechanisms have been proposed, including the direct neurotoxicity of chemotherapeutic agents, genetic predisposition , oxidative damage, chemotherapy induced peripheral neuropathy, immune dysregulation or shortened telomeres -27 Fig.. HoweverCognitive impairment described in cancer patients is determined by numerous factors. Perhaps the most important is related to the origin and location of the tumour. We can assume that a patient with a primary or metastatic lesion in the CNS could present with neuropsychological changes at an early stage compared with a patient presenting with a tumour located in another organ/system and without brain secondary deposits. Other factors contributing to cognitive dysfunction in cancer are represented by associated diseases especially those requiring anti-depressive and pharmacological therapy for pain. Also, the aging factor must be carefully considered as cancer is encountered in significant numbers in an aging population. In this setting, preliminary changes suggestive of dementia could be already present before cancer development and chemotherapy. Therefore, there is an acute need to separate the cognitive dysfunction induced by chemotherapy (CICI), from those neuropsychological changes induced by aging, co-morbidities and associated therapies.chemotherapy induced cancer impairment (CICI), the oxidative stress represents one of the most common etio-pathological factor leading to significant neurobiological changes. More specifically, the cognitive dysfunction in this setting may be directly promoted by the reactive oxygen species (ROS) generated during chemotherapy. Butterfield DA (2014) [In the realm of A (2014)  reports A (2014) . HoweverA (2014) .Activated oxygen species, especially those that share electronic orbital features with singlet oxygen, are highly reactive, and therefore, the evolutionary adaptation by organisms to make oxygen wholly beneficial has never been complete. Consequently, there are many deleterious effects associated with excessive, activated ROS -35. ProdThe brain is especially susceptible to the assaults perpetrated by ROS. This is because the brain is a big oxygen consumer (20% of the body consumption), causing it to be especially vulnerable to oxidative stress due to its low level of protective antioxidant mechanisms. The brain contains a large amount of polyunsaturated peroxidizable fatty acids along with high levels of iron that act as pro-oxidant and sometimes induces autophagic cell death. In addition, lipid peroxidation leads to the production of toxic compounds such aldehydes or dienals  which may cause in turn, neuronal apoptosis .At DNA level, oxidative modifications may cause rapid depletion of intracellular energy by activating DNA repair enzymes. Energy scarcity after stroke will cause in turn, endonuclease-mediated DNA fragmentation, the key mechanism that leads to DNA damage .It was postulated that CICI represents the ultimate result of synergistic action of several factors including chemotherapy mediated oxidative stress, direct vascular and neurotoxic action of some chemotherapeutic agents as well as inefficient DNA-repair mechanism(s) ,26.through TNF alpha a state of oxidative stress and subsequent CICI are presented below.Oxidative stress derived ROS may be the most important factor promoting CICI and it seems that some patients may have a genetic predisposition to develop this condition. A study conducted in a children diagnosed with acute lymphoblastic leukaemia suggests that cognitive dysfunction after oxidative stress induced by chemotherapy is associated with polymorphisms in three oxidative stress genes, NOS3 894T, SLCO2A1 variant G allele and GSTP1 variant allele . The rolDoxorubicin. Doxorubicin, an anthracycline anti-tumour antibiotic indicated in several types of malignancies, is known to generate intracellular oxygen species as its effects on heart are explained by the ROS synthesis [ynthesis , 43. In ynthesis . Subsequynthesis .In the brain, TNF alpha produces a significant oxidative stress associated with a reduction in glutathione levels, a known anti-oxidant, in parallel with increased levels of glutathione peroxidase and reductase as well as increased glutathione-S-transferase levels. In addition, redox proteomics evaluation suggested a significant CNS oxidative stress induced via TNF alpha production by doxorubicin . AdditioExperimental work conducted in a murine model has revealed that simultaneous administration of the anti-oxidant 2-mercaptoethane sulfonate (MESNA) prevents oxidative damage induced by doxorubicin. More importantly, it seems that MESNA is capable to inhibit the increase in peripheral TNF alpha induced by doxorubicin . A recenCarmustine. Studies conducted in rats have revealed that carmustine induces a major oxidative stress level in the brain parenchyma as well as an impairment of memory and learning processes. Administration of carmustine is associated with a significant increase in plasma TNF alpha and CNS malondialdehyde, a marker indicating significant oxidative stress. Histological evaluation has also shown an over-expressed caspase-3. Remarkably, administration of carmustine in a rat model induces an increased synthesis of metallothionein in hippocampus [pocampus . This isUltimately, it seems that oxidative stress produced by reactive oxygen species (ROS) after carmustine administration, are produced as a result of inhibition of glutathione reductase. Also, ROS species activate c-jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) pathways which finally will promote neurotoxicity .Methotrexate. Methotrexate is a dihydrofolate reductase inhibitor used in the treatment of cancer, including lymphomas and breast cancer. Methotrexate is capable to produce nephrotoxicity subsequent to reactive oxygen species (ROS) formation. The role of oxidative stress in this setting is suggested by an increased level of plasma TNF alpha [NF alpha . ResearcNF alpha . These sNF alpha . RemarkaNF alpha .More information related to the full extent of oxidative stress induced by methotrexate have been revealed by other experiments. In an animal model, it induces lipid peroxidation in the plasma as well as a significant increase in HSP70 and glutathione reduction in several brain regions . ResearcCyclophosphamide. This anti-cancer factor is recommended in various combinations in a wide variety of malignancies. In a standard dosage, it may induce neurotoxicity but administered in a high dosage it may cause confusion and visual blurring [blurring . Rarely,blurring -59.Experimental research has shown that cyclophosphamide administered intra-peritoneally induces a significant oxidative stress in the CNS. This is quantified by an increased level of brain malondialdehyde, a product of lipid peroxidation and oxidation of fatty polyunsaturated acids . It seemInterestingly, administration of Annatto seeds (Bixa orella), linseed oil (Linum usitatissimum) and boron to animal models can counter act the oxidative stress effect induced by cyclophosphamide. However, this has not yet been verified in a clinical setting in patients treated with cyclophosphamide ,62,63. RCancer is a multi-factorial disease acquired as a result of numerous acquired genetic and molecular abnormalities. As more and more people are living longer they are prone to develop these molecular hits which will further result in the development of malignant lesions. However, with the advent of new therapeutic options including chemotherapy, elderly patients diagnosed with cancer are nowadays long-term survivors. As a result of chemotherapy, we can assume that these subjects will sustain a generalised/CNS oxidative stress injury which will induce a more or less severe chemotherapy induced cognitive impairment (CICI)/chemobrain. This needs adequate assessment and therapy as it could interfere significantly with the quality of life of elderly cancer patients including their medical compliance.However, if CICI supervenes on a background of systemic aging, the brain aging factor is of paramount importance as it may accentuate the overall cognitive impairment. Remarkably, both CNS aging and CICI are induced and accelerated by oxidative stress and ROS. Therefore, a thorough understanding of molecular pathways and factors modulating oxidative stress is of paramount importance as it may lead to discovery and synthesis of factors specifically designed to improve cognition, motor function and quality of life in elderly patients with CICI.Fifty years ago, Brody H (1955)  has reitIn aging, neurons and glial cells increase their ability to cope with stress, producing new neurons and glial cells and remodelling neuronal circuits. Increased ROS levels and accumulation of oxidation products derived from nucleic acids, proteins and lipids, may induce mitochondrial dysfunction, perturbation of different metabolic and signalling pathways, cause endothelial damage of brain micro-vessels. Subsequently, these abnormalities are followed by progressive changes in hemodynamic stability predisposing to inflammatory and ischemic changes ,70. OverMoreover, prior to CICI, elderly patients could develop several pathological conditions associated with cognitive decline which are more commonly described in their age group. This population may develop Alzheimer’s disease as a result of complex mutations or any other vascular cerebral condition. The most important vascular entities associated with cognitive impairment are the cerebral atherosclerosis and small vessels disease. In both settings oxidative stress and ROS are the most important pathogenic factors facilitating injury to the vessel wall by accumulation of oxidation products. The natural biology of these pathological conditions is characterised by brain tissue haemorrhages and infarcts which would increase the cognitive impairment. Also Alzheimer’s disease is associated with amyloid angiopathy which could also lead to brain ischemia and subsequent neuronal death, ultimately amplifying cognitive impairment ,74 Fig..Aging or normal senescence is a physiological, multi factorial process modulated epigenetically and characterised by the accumulation of neurotoxic molecules in cells and tissues. It is also characterised by mutations in repair genes and telomere shortening . During The Harman’s hypothesis of free radicals claims that free radicals cause progressive accumulation of oxidative damage to lipids, proteins as well as DNA, promoting cellular damage induced by ROS. More specifically, the ROS attack glial cells and neurons, leading to neuronal damage and apoptosis . AccordiBoth mitochondrial dysfunction and mitochondrial metabolism modulate the process of aging, through several molecular pathways represented by the insulin/IGF-1 signalling (IIS), the target of rapamycin (mTOR) and the respiratory chain. Abnormalities in these molecular pathways will led to an overproduction of ROS . The mitOxidative stress is one putative mechanism underlying chemotherapy-induced cognitive impairment associated with cancer treatment. As a significant number of those receiving chemotherapy are long term survivors this issue could significantly interfere with their quality of life. A special attention should be dedicated to the elderly patient with cancer undergoing chemotherapy. The aging process is associated with morphological and functional changes in the brain which may be also modulated by oxidative stress. Oxidative stress or changes in redox state are implicated in age-related malfunction of the brain. An increase in oxidative stress or decreases in the antioxidant capacity of the brain are key factors involved in neuronal degeneration in the elderly . In addi


Autophagy is a homeostatic process that is highly conserved across different types of mammalian cells. Autophagy is able to relieve tumor cell from nutrient and oxidative stress during the rapid expansion of cancer. Excessive and sustained autophagy may lead to cell death and tumor shrinkage. It was shown in literature that many anticancer natural compounds and extracts could initiate autophagy in tumor cells. As summarized in this review, the tumor suppressive action of natural products-induced autophagy may lead to cell senescence, provoke apoptosis-independent cell death, and complement apoptotic cell death by robust or target-specific mechanisms. In some cases, natural products-induced autophagy could protect tumor cells from apoptotic death. Technical variations in detecting autophagy affect data quality, and study focus should be made on elaborating the role of autophagy in deciding cell fate. In vivo study monitoring of autophagy in cancer treatment is expected to be the future direction. The clinical-relevant action of autophagy-inducing natural products should be highlighted in future study. As natural products are an important resource in discovery of lead compound of anticancer drug, study on the role of autophagy in tumor suppressive effect of natural products continues to be necessary and emerging. Accumulating studies have revealed the role of autophagy as an important cellular homeostatic process. Autophagy, derived from Greek meaning self-eating, is a self-degradative approach to clear intracellular organelles and proteins . It was It was particularly found that the role of autophagy in human cancer is complicated. On one hand, autophagy may be critical in removing stress induced by infection, hypoxia, nutrient deprivation, and metabolic damage. Autophagy-deficient cells are much susceptible to stress and damage to cell genome, leading to easier tumorigenesis in vivo. It was found that chemical carcinogen-induced hepatocarcinoma could be suppressed by enhanced autophagy which removed aggresome and damaged organelles that could lead to DNA double strand break and genome instability , while m Garcinia yunnanensis Hu could suppress autophagy and enhance the antitumor effect of nutrient deprivation. As cancer cell develops autophagy as adaptive mechanism towards nutrient deprivation, inhibition of autophagy may lead to death of the cells [Data was retrieved from publications regarding the regulatory action of natural products on autophagy in cancer cells. Interestingly, almost all the literature refers to the property of natural products in inducing autophagy in cancer. Few studies reported inhibition of autophagy by natural products. Kallifatidis et al. reported that a marine natural compound manzamine A could suppress autophagy in pancreatic cancer cells. Manzamine A could block the fusion of autophagosome and lysosome and abrogate autophagosome turnover . Despitehe cells . However Syzygium samarangense (Blume) Merr. & L.M. Perry (Myrtaceae), presence of autophagy inhibitor 3-MA or siRNA against Beclin-1 or Atg5 could restore proliferation of tumor cells [ Alisma orientale could initiate cell cycle redistribution and autophagy. Blockade of autophagy in Alisol B-treated cancer cells may result in unfolded protein accumulation-related endoplasmic reticulum stress [Previous studies have revealed that natural products may induce autophagy and cell cycle arrest in cancer cells without significant presentation of cell death. Natural compound isolated from Radix Ophiopogon Japonicus named ophiopogonin B could induce both G0/G1 cell cycle arrest and autophagy in lung cancer cells, without significant apoptosis observed . Sustainor cells . A naturor cells . Howeverm stress , which im stress . As retr Peschiera fuchsiaefolia induced tumor cell death dependent on autophagy but not apoptosis [ Geodia japonica could induce autophagy as they could observe neither the altered expression of apoptosis marker Bcl-2 nor the appearance of apoptotic nuclei [ Piper longum L. in the presence of caspase and necrosis inhibitors. It was found that cell death was attenuated when autophagy inhibitor was added to piperlongumine-treated cancer cells [Although many studies have reported that autophagy may be initiated for killing the cells, there is lack of evidence that can be markers and mechanisms of presence of autophagic cell death (ACD). The existence of ACD is therefore under constant criticism, as autophagy is generally observed in dying cells. In this case, autophagy in dying cells may be considered as an automatically raised mechanism for cell survival, even though it is not effective enough to overcome the cellular stress-induced death . Hau et poptosis . Similarpoptosis  and tritpoptosis . The cric nuclei . Howeverc nuclei . Furtherc nuclei . As caspc nuclei . Furtherer cells . Observaer cells . To gainer cells . The use Evodia rutaecarpa could trigger cell death with both autophagy and apoptosis, while the presence of 3-MA reduced the number of dead cells [As autophagy is usually observed in dying cells, argument was raised to criticize the role of autophagy in promoting cell death, which claimed that autophagy might be an accompanying event that occurs after initiation of apoptosis. Despite the fact that the argument appears to be reasonable since autophagy could be regarded as a mechanism to scavenge dysfunctional organelles and proteins during apoptosis, some studies indeed observed that autophagy may contribute to supporting apoptosis. It was massively considered that autophagy may play a supportive role in inducing cell death though Xavier and colleagues found that, in ursolic acid-induced cell death, apoptosis only contributes to a small proportion while autophagic cell death may be the mass . Saiki ead cells . The ind Akebia saponins PA from Dipsacus asperoides. When AGS cells were cotreated with autophagy inhibitor bafilomycin A1, the Akebia saponins A1-triggered caspase-3-dependent apoptosis was decreased; however, autophagy was not affected in cells with caspase-3 inhibitor [The other way by which autophagy may support apoptosis in dying cells with apoptosis is much interesting. Xu et al. examined the relationship between autophagy and apoptosis induced bynhibitor . Inductinhibitor . Since anhibitor . The mecnhibitor .The protective effect of autophagy in natural products-induced cancer cell death could be much more straightforward as the process was naturally regarded as cellular stress clearance.  Magnolia officinalis [ Garcinia yunnanensis Hu could induce the number of autophagosomes; however, blockade of lysosome function was found and p62/SQSTM1 turnover was impaired. In this case, whether oblongifolin C could initiate autophagy remains uncertain and requires further investigation [As a dynamic intracellular process, autophagy is composed of an onset activity, during which autophagosome is formed and fused with lysosome, and an offset activity that facilitates degradation of autophagosome-lysosome complex  . Althougicinalis , celastricinalis , and tanicinalis . As onseicinalis . While iicinalis . Therefoicinalis . It was tigation . Mei et tigation . In additigation . Presenctigation . Genetictigation . It is qAs a cellular response mechanism to internal and external stress, autophagy is regarded as robust but highly conserved across different types of cells including tumor cells . The reg Albatrellus confluens could block the consumption of glucose and ATP generation of cancer cells, as reported by Deng and colleagues, and was able to initiate autophagy. Autophagy is a spontaneous response to energy deprivation in cancer cells [Retrieved studies have revealed that a single natural product may regulate multiple signaling pathways in cancer cells that could mediate onset of autophagy. Expression of molecules that are directly involved in autophagosome formation, such as Beclin-1, Atg5, Atg7, Atg12, and LC3, was altered upon exposure of the compounds as reported by some studies; however, literature majorly focused on signal transduction through various pathways of kinase like Akt/mTOR, Erk1/2, p38 MAPK, AMPK, and JNK. It was shown that some of these pathways might be responsible for the induction of autophagy. Kim et al. found that blockade of JNK pathway by specific inhibitor SP600125, Samsoeum (SEE), extract-triggered autophagy could be attenuated via suppression on expression of autophagy-related proteins Beclin-1 and LC3 . Nonetheer cells . Therefoer cells .α/CHOP was responsible for the interplay between apoptosis and autophagy in bufalin-treated cancer cells [However, study on signaling pathway involved in natural product-induced autophagy may still have significance in elaborating the action of mechanism. For instance, it was found, in different studies, bufalin from Chan-su exhibits both tumor suppressive and cytoprotective autophagy in human cancer cells. The controversial actions of bufalin may be due to the differential effect in inducing changes of signaling pathways. When bufalin was given at lower dose, it may cause endoplasmic reticulum stress, which would initiate autophagy to dispose misfolded proteins, and bufalin-induced autophagy at this dose may elicit protective role to prevent cancer cells from ER stress-induced apoptosis , 111; wher cells . SimilarAutophagy could be either tumor promoting or tumor suppressive. The tumor suppressive effect may be much more clear, as autophagy may facilitate cell cycle arrest and apoptosis or directly induce cell death. The cellular events in cytoprotective action, in which autophagy helps cancer cell to overcome various cellular stresses, are not clearly elucidated in most of the publications. Recycling of nonessential proteins and organelles to overcome the lack of substrates of metabolism that are required for survival of cancer cells under nutrient deprivation may be possibly one of the major cellular events that fosters the cytoprotective action of autophagy. In some of the studies, researchers observed natural products could suppress mTOR pathway, which was considered as a major mechanism in inducing autophagy. In fact, mTOR signaling mediated translational control of protein synthesis and high activity of mTOR signaling in cancer cells was found in different types of cancer cells. mTOR inhibition is in this case not just the way mediating activation of autophagy but an indicator that cancer cell is trying to overcome nutrient deprivation by restricting nascent protein synthesis. Autophagy induction may subsequently contribute to overcoming nutrient deprivation by future recycling the existing proteins. However, due to technical limit in most of the published studies, direct evidence of natural product-induced autophagy in facilitating recycling of cellular substrates in nutrient-depriving cancer cells is not yet available. Moreover, lack of nutrient and oxygen supply, as well as cytotoxic agent treatment, may lead to damage of proteins and organelles in cancer cells, which brings stress to endoplasmic reticulum and mitochondria. The malfunction of endoplasmic reticulum and mitochondria results in release of proapoptotic factors and causes subsequent cancer cell death. The induction of autophagy by natural products may collectively dispose the damaged proteins and organelles and therefore normalize endoplasmic reticulum and mitochondria function. It was recently shown that blockade of autophagy in bufalin-treated HCC cell could potentiate apoptosis, indicating that bufalin-induced autophagy may be involved in normalizing endoplasmic reticulum . UnfortuAs a homeostatic process that responds to cellular stress, autophagy is essential in preventing stress-induced DNA damage and genomic instability . DespiteThe property that natural products could suppress cancers in animal models is quite important for evaluating the druggability of the compounds. More and more autophagy-inducing natural compounds exhibit potent inhibition on tumor growth in vivo. However, although the role of autophagy in determining cancer cell fate could be elaborated on in vitro platform, so far no study could provide compelling evidence showing that in vivo tumor inhibition of natural products involves its regulation on autophagy. This may be due to lack of useful in vivo animal models in which autophagy could be selectively monitored. He and Klionsky reported in vivo monitoring of autophagy in a transgenic GFP-LC3 zebrafish line . Inducti Koelreuteria henryi Dummer and Emblica officinalis [In recent years, many reviews have summarized the synergistic action of natural product in cancer treatment. Many autophagy-inducing natural products, including berberine, curcumin, and resveratrol, could enhance the therapeutic effect of other agents, and this synergistic effect is correlated with induction of autophagy. Peng et al. found that berberine could enhance tumor-killing action of irradiation by inducing autophagic cell death ; curcumiicinalis , 124. ThThe ultimate goal of mentioned studies remains to discover autophagy-inducing natural products with significant clinical efficacy in cancer treatment. However, rare published study has focused on clinical trials of autophagy-inducing natural products. In fact, the clinical role of autophagy in cancer treatment is not yet fully elucidated. However, from the data we collected, it is easy to find some compounds may have been used in some countries as anticancer agents. For example, bufalin injection has been used clinically in some parts of China and has shown some therapeutic action in restricting tumor progression in cancer patients. A phase I pilot study showed that bufalin treatment in HCC patients leads to no significant dose-limiting toxicity and improvement of quality of life . Some naAs a conclusion, recent studies have remarked that autophagy in human cancer cells could be initiated by natural compounds and extracts isolated from anticancer medical plants. Induction of autophagy by natural products may contribute to its tumor suppressive effect by causing cell senescence, inducing apoptosis-independent death, and provoking apoptotic death. Natural products-induced autophagy can also be cytoprotective and cause resistance of cancer cells against death. Higher technical requirement on monitoring autophagy in natural products-treated cancer cells is required to improve study quality in this field. In vivo action of autophagy in mediating tumor regression may be necessary to explore in the future, and significance of synergistic action and clinical relevancy in future studies should be highlighted. Studies in this field will shed light on the development of lead compounds of anticancer drug from autophagy-inducing natural products.


While numerous studies have explored relevant factors of posttraumatic stress disorder (PTSD) symptoms, there have been few joint investigations of trauma severity and trait neuroticism on the development of PTSD symptoms. This study aims to assess the involvement and interrelationship of trauma severity and neuroticism in the expression of PTSD symptoms among adolescents exposed to an accidental explosion.Six hundred and sixty-two adolescents were recruited from a junior middle school closest to the 2013 pipeline explosion site in China and were assessed using the Explosion Exposure Questionnaire, the NEO Five Factor Inventory-Neuroticism Subscale (FFI-N), and the PTSD Checklist-Civilian (PCL-C). A battery of hierarchical multiple regression analyses and two-way ANOVAs were performed to examine the effect of trauma severity and trait neuroticism on adolescent PTSD symptoms.Eighty-seven adolescents (13.1%) showed PTSD symptoms after the pipeline explosion. Correlation analysis showed that all the factors of explosion exposure and trait neuroticism were positively associated with adolescent PTSD symptoms. Being male and younger was linked to lower risk for PTSD symptoms. The regression models identified explosion exposure and neuroticism as independent risk factors for PTSD symptoms, and the interactions between trait neuroticism and trauma exposure  were related to PTSD symptoms.The results highlight the role of trauma exposure and trait neuroticism as risk factors for PTSD symptoms. Therefore, the combination of these two factors should be investigated in clinical settings due to an augmented risk for more severe PTSD symptoms. In the past two decades, destructive events have caused millions of deaths worldwide. Sudden unexpected traumatic accidents, such as hurricanes, tsunamis, earthquakes, mudslides, traffic accidents, airplane crashes, and explosions, have led to a broad range of serious and long-lasting negative physical and psychological consequences for both children and adult survivors. These include internalizing and externalizing psychopathology such as anxiety, depression, posttraumatic stress disorder (PTSD), borderline personality disorder, substance abuse, antisocial behaviors, suicidality, somatic complaints, nightmares, and overall reduced functioning –5.Posttraumatic stress disorder is usually considered the most prevalent psychopathology among juvenile populations exposed to deadly disasters –8. PTSD It has been suggested that individuals exposed to technological accidents would show greater emotional responses than those who experienced natural disasters . In NoveAs mentioned previously, a considerable body of research has examined prevalence rates of PTSD, as well as relevant risk factors, among victims of natural disasters and war-related bombing ,28–33. TEven though stress is a major risk factor for PTSD symptoms, considerable heterogeneity exists in outcomes after stress, and a large proportion of individuals exposed to early-life stresses will not exhibit psychopathological symptoms as adults ,45. TherIt is worth noting that few previous studies have jointly investigated both personality characteristics and trauma severity in relation to PTSD risk factors. Accordingly, the current study will focus on prevalence estimates among adolescents between 10 and 16 years of age, and the involvement and interrelationship of trauma severity and trait neuroticism in the development of PTSD symptoms following explosion-related trauma. Specifically, we hypothesized that: (1) each aspect of trauma severity  would be positively correlated with PTSD symptoms; (2) trait neuroticism would be positively associated with PTSD symptoms; and (3) trauma severity would interact with trait neuroticism, leading to PTSD symptoms in adolescents, and the association between trauma severity and PTSD symptoms would be most pronounced in individuals with high levels of neuroticism.This study was a cross-sectional survey of adolescents exposed to an accidental explosion in China. Each participant was administered a short questionnaire to collect demographic data and a set of self-reported questionnaires one month after the accidental explosion.th and 8th grade) located in east China near the 2013 explosion. This middle school was located closest to the bomb site and some buildings were destroyed and students were moved to another school. The only exclusion criterion for the study was refusal to participate, yielding a response rate of 85%. Finally, data for 662 respondents were complete and suitable for analysis. The demographic characteristics of participants are described in the Results section.Initially, a sample of 788 participants was recruited from a public junior middle school  to 5 (“extremely”) based on the degree to which a respondent had been troubled by a specific symptom during the past month. Total scores are calculated as the mean response across all items, ranging from 17 to 85, with a higher total score representing greater PTSD symptoms. The recommended cutoff point for screening PTSD due to sudden traumatic accidents is set at 38 [PTSD symptoms were assessed using the PTSD Check List-Civilian Version (PCL-C), a self-rated instrument measuring PTSD symptoms, with 17 items corresponding to the symptoms emphasized in the DSM-IV: PTSD Criteria B (re-experiencing), C (avoidance/ numbing), and D  . The reset at 38 . The Chiet at 38 .“strong approval”) to 5 . In the current study, neuroticism was assessed by the Neuroticism subscale. Higher total scores are indicative of greater levels of neuroticism. The NEO-FFI has been shown to have satisfactory construct validity and good internal consistency in general population samples [The NEO Five- Factor Inventory (NEO-FFI) , is a sh samples .SD) of the demographic variables were computed. We utilized the mean of nearby points to substitute for missing data. Interrelations between the main psychosocial variables were tested using Pearson correlation analyses. The association between demographic variables (including age and gender), trauma severity, trait neuroticism, and PTSD symptoms was examined using a set of hierarchical multiple regression analyses. In all analyses, PTSD symptoms were regarded as outcome variables. All independent variables were centered on their respective means in order to reduce the problem of multi-collinearity between main effects and the interaction term, as well as to enhance the predictive power of β weights for interaction terms. Finally, a series of two-way ANOVAs were performed to further illustrate the significant interactions. All tests were two-tailed with P <. 05 representing statistical significance.IBM SPSS Version 21.0 was used for statistical analysis. Data were double entered after careful review for completeness and obvious errors. Descriptive statistics including frequencies, means, and standard deviations . Figs. For better visual conceptualization of the significant interactions, the three indicators of trauma severity and trait neuroticism were dichotomized as high or low using median values. A series of two-way ANOVAs were then performed, including high or low trait neuroticism and one of the three indicators of trauma severity. All main effects and interactions were statistically significant  in the development of PTSD symptoms (controlling for gender and age), using hierarchical regression models. We hypothesized that the interaction between these factors might be associated with PTSD symptoms. The results confirmed our hypotheses, as they indicate that the interaction between trait neuroticism and trauma severity is related to PTSD symptoms, and the association between trauma severity and PTSD symptoms is most pronounced in individuals with high levels of neuroticism. Similar findings were found when we dichotomized trait neuroticism and trauma severity and further explored the main effect and interactions.In the sample of trauma-exposed adolescents, the prevalence of PTSD symptoms was around 13%, which is relatively lower than that found in earlier studies ,54. SpecOur results are consistent with findings of prior studies –61, whicRegarding personality features, we observed a strong association between level of neuroticism and risk of PTSD symptoms, which corroborates the previous findings of Cox et al. (2004)  and PerrSpecifically, we found that the interaction between high trait neuroticism and severe trauma exposure was associated with high PTSD symptom severity. That is, the association between trauma severity and PTSD symptoms is most pronounced in individuals with high levels of neuroticism. This finding is similar to results of previous studies regarding psychopathology. For example, Ormel et al. (2001) found that in the presence of high neuroticism, the depressogenic effect of stressful life events was substantial . BrietzkOur research should be interpreted in light of several limitations. First, in assessing PTSD symptoms, we applied the PCL-C, which is a screening tool rather than a standard clinical diagnostic method; thus, incidence of PTSD was probably somewhat overestimated. Second, retrospective assessment implies potential recall bias regarding exposure to traumatic events and the presence of PTSD symptoms. Also, the assessment of trait neuroticism could have been affected by the occurrence of PTSD symptoms. Future studies are therefore needed to highlight the role of clinical diagnostic measurements when addressing similar issues, to enhance the reliability of the findings among clinicians.Despite these possible limitations, the current study also has several strengths. Above all, our study is among the first investigations, to our knowledge, to report the prevalence of PTSD symptoms in a relatively large sample of adolescent survivors after an accidental explosion; the large sample size lends reliability to the results. Furthermore, we focused on interactions between trauma severity and trait neuroticism in predicting PTSD symptoms following an accidental explosion; these results may provide a better understanding of the origins of adolescent mental health and illness.In conclusion, our results suggest that both trauma severity and trait neuroticism influence subsequent PTSD symptoms after trauma exposure, and that trait neuroticism seems to moderate the association between trauma severity and PTSD symptoms. Therefore, findings of the current research may have important clinical implications for preventing and treating stress-related disorders in adolescents in the aftermath of traumatic accidents. Mental health professionals should offer support to reduce the development of PTSD among adolescents after accidental explosions, especially for those who witnessed injury or death, or lost family members, houses, or property during the incident. Education and interventions could also be employed to help adolescent survivors cope with PTSD.S1 Dataset(XLS)Click here for additional data file.