The role of serum circulating microbial toxins in severity and cytokine storm of COVID positive patients.

The emergence of Coronavirus disease 2019 (Covid-19) is a global problem nowadays, causing health difficulty with increasing mortality rates, which doesn't have a verified treatment. SARS-CoV-2 infection has various pathological and epidemiological characteristics, one of them is increased amounts of cytokine production, which in order activate an abnormal unrestricted response called "cytokine storm". This event contributes to severe acute respiratory distress syndrome (ARDS), which results in respiratory failure and pneumonia and is the great cause of death associated with Covid-19. Endotoxemia and the release of bacterial lipopolysaccharides (endotoxins) from the lumen into the bloodstream enhance proinflammatory cytokines. SARS-CoV-2 can straightly interplay with endotoxins via its S protein, leading to the extremely elevating release of cytokines and consequently increase the harshness of Covid-19. In this review, we will discuss the possible role of viral-bacterial interaction that occurs through the transfer of bacterial products such as lipopolysaccharide (LPS) from the intestine into the bloodstream, exacerbating the severity of Covid-19 and cytokine storms.

Immune response induced by recombinant pres2/S-protein and a pres2-S-protein fused with a core 18-27 antigen fragment of hepatitis B virus compared to conventional HBV vaccine.

Although comprehensive vaccination is the cornerstone of public health programs to control hepatitis B virus (HBV) infections, 5% of people who receive the existing vaccine do not develop proper immunity against HBV. To overcome this challenge, researchers have tried using various protein fragments encoded by the virus genome to achieve better immunization rates. An important antigenic component of HBsAg called the preS2/S or M protein has also received much attention in this area. The gene sequences of preS2/S and Core18-27 peptide were extracted from the GenBank (NCBI). Final gene synthesis was conducted with pET28. Groups of BALB/c mice were immunized with 10 µg/ml of recombinant proteins and 1 µg/ml CPG7909 adjuvant. Serum levels of IF-γ, TNF-α, IL-2, IL-4, and IL-10 were measured by ELISA assay method on spleen cell cultures on day 45, and IgG1, IgG2a, and total IgG titers obtained from mice serum were quantified on days 14 and 45. Statistical analysis did not show any significant difference between the groups regarding IF-γ level. There were, however, significant differences in terms of IL-2 and IL-4 levels between the groups receiving preS2/S-C18-27 with and without adjuvant and the groups receiving both preS2/S and preS2/S-C18-27 (Plus Recomb-Plus Recomb: the group of mice that received both preS2/S and preS2/S-C18-27 simultaneously). The strongest total antibody production was induced by immunization with both recombinant proteins without CPG adjuvant. The groups that received both preS2/S and preS2/S-C18-27, whether with or without adjuvant, were significantly different from those that received the conventional vaccine considering most abundant interleukins. This difference suggested that higher levels of efficacy can be achieved by the use of multiple virus antigen fragments rather than using a single fragment.

Interaction Between SARS-CoV-2 and Pathogenic Bacteria.

The novel human coronavirus, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which results in the coronavirus disease 2019 (COVID-19), has caused a serious threat to global public health. Therefore, many studies are performed on the causes and prevalence of this disease and the possible co-occurrence of the infection with other viral and bacterial pathogens is investigated. Respiratory infections predispose patients to co-infections and these lead to increased disease severity and mortality. Numerous types of antibiotics have been employed for the prevention and treatment of bacterial co-infection and secondary bacterial infections in patients with a SARS-CoV-2 infection. Although antibiotics do not directly affect SARS-CoV-2, viral respiratory infections often result in bacterial pneumonia. It is possible that some patients die from bacterial co-infection rather than virus itself. Therefore, bacterial co-infection and secondary bacterial infection are considered critical risk factors for the severity and mortality rates of COVID-19. In this review, we will summarize the bacterial co-infection and secondary bacterial infection in some featured respiratory viral infections, especially COVID-19.

Evaluating the Performance of PPE44, HSPX, ESAT-6 and CFP-10 Factors in Tuberculosis Subunit Vaccines.

Mycobacterium tuberculosis (M. tuberculosis) is an intracellular pathogen causing long-term infection in humans that mainly attacks macrophages and can escape from the immune system with the various mechanisms. The only FDA-approved vaccine against M. tuberculosis (MTB) is Mycobacterium bovis bacillus Calmette-Guérin (BCG). The protection of this vaccine typically lasts 10-15 years. Due to the increasing number of people becoming ill with MTB each year worldwide, the need to develop a new effective treatment against the disease has been increased. During the past two decades, the research budget for TB vaccine has quadrupled to over half a billion dollars. Most of these research projects were based on amplifying and stimulating the response of T-cells and developing the subunit vaccines. Additionally, these studies have demonstrated that secretory and immunogenic proteins of MTB play a key role in the pathogenesis of the bacteria. Therefore, these proteins were used to develop the new subunit vaccines. In this review, based on the use of these proteins in the successful new subunit vaccines, the PPE44, HSPX, CFP-10 and ESAT-6 antigens were selected and the role of these antigens in designing and developing new subunit vaccines against TB and for the prevention of TB were investigated.

The impact of the gut microbiome on toxigenic bacteria.

Millions of symbiotic and pathogenic microorganisms known as microbiota colonize the host body. The microbiome plays an important role in human health and colonizes hundreds of different species of multicellular organisms so that they are introduced as the metaorganisms. Changes in the microbial population of the gut microbiome may cause resistance to pathogenic bacteria-induced infection. Understanding the principles of Host-Microbiota Interactions (HMIs) is important because it clarifies our insight towards the mechanisms of infections established in the host. Interactions between the host and the microbiota help answer the question of how a microorganism can contribute to the health or disease of the host. Microbiota can increase host resistance to colonization of pathogenic species. Studying the HMIs network can in several ways delineate the pathogenic mechanisms of pathogens and thereby help to increase useful and novel therapeutic pathways. For example, the potentially unique microbial effects that target the distinct host or interfere with the endogenous host interactions can be identified. In addition, the way mutations in essential proteins in the host and/or in the microbes can influence the interactions between them may be determined. Furthermore, HMIs help in identifying host cell regulatory modules.

Molecular characterization of Shigella species isolated from diarrheal patients in Tehran, Iran: phylogenetic typing and its association with virulence gene profiles and a novel description of Shigella invasion associated locus.

The present study aims to employ a multiplex PCR-based method for phylogenetic typing of Shigella and determine the frequency of several virulence genes among Shigella phylogenetic clades and species. Species identification, phylogenetic typing of 44 previously diagnosed Shigella isolates, and frequency of virulence genes and loci, virA, virB, virF, ipaBCD, ial, sen, and set1A were investigated through performing several PCR assays. Distribution of virulence genes among Shigella phylogenetic clades and species was determined by the statistical analysis. The identities of 40 isolates out of 44 were confirmed as Shigella, and these isolates were classified in four phylogenetic clades, S1 (7.5%), S2 (52.5%), S3 (20%), and S5 (20%) and 4 species, S. sonnei (52.5%), S. flexneri (22.5%), S. dysenteriae (20%), and S. boydii (5%). The prevalence of virA, virB, virF, ipaBCD, ial, sen, and set1A was determined as 67.5%, 72.5%, 72.5%, 65%, 75%, 40%, and 5%, respectively. The presence of sen, uidA, or set1A was found to be statistically correlated with either of Shigella phylogenetic clades or species. A significant statistically association was also determined between set1A and Shigella phylogenetic clades. Furthermore, the nucleotide sequence of invasion-associated locus (ial) was determined and mapped on Shigella genome through in silico analysis. The current study shows the distribution of Shigella isolates and its key virulence genes within the five recently described phylogenetic clades for the first time in the Asia. This is also the first description of ial nucleotide sequence and its exact location on Shigella genome after its initial identification.

Clinical efficacy of convalescent plasma for treatment of COVID-19 infections: Results of a multicenter clinical study.

Since Dec. 2019 the new coronavirus (SARS-CoV-2) has infected millions and claimed life of several hundred thousand worldwide. However, so far no approved vaccine or drug therapy is available for treatment of virus infection. Convalescent plasma has been considered a potential modality for COVID-19 infection. One hundred eighty-nine COVID-19 positive patients including 115 patients in plasma therapy group and 74 patients in control group, registered in the hospitals with confirmed COVID-19 infection, entered this multi-center clinical study. Comparison of outcomes including all-cause mortality, total hospitalization days and patients' need for intubation between the two patient groups shows that total of 98 (98.2 %) of patients who received convalescent plasma were discharged from hospital which is substantially higher compared to 56 (78.7 %) patients in control group. Length of hospitalization days was significantly lower (9.54 days) in convalescent plasma group compared with that of control group (12.88 days). Only 8 patients (7%) in convalescent plasma group required intubation while that was 20 % in control group. This clinical study provides strong evidence to support the efficacy of convalescent plasma therapy in COVID-19 patients and recommends this treatment for management of these patients. Clinical efficacy, immediate availability and potential cost effectiveness could be considered as main advantages of convalescent plasma therapy.

Global estimate of Neisseria meningitidis serogroups proportion in invasive meningococcal disease: A systematic review and meta-analysis.

Using the PRISMA guideline, 102 studies were included in this study. The highest and the lowest proportion of N. meningitidis serogroups in invasive meningococcal disease (IMD) was for NmB with 48.5% (95% CI: 45-52) and NmX with 0.7% (95% CI: 0.3-1.7). Among the WHO regional offices, serogroup NmW with 57.5% (95% CI: 35-77.5) in Eastern Mediterranean, and NmZ with 0.1% (95% CI: 0-0.9) in America had the highest and the lowest proportion of N. meningitidis serogroups in IMD. NmC with 9.7% (95% CI: 5.6-16.2) and NmB with 9.5% (95% CI: 0.2-3.8) had the highest proportion in 1-4 and <1 year age groups, respectively. Our analysis showed that NmB had the highest proportion of N. meningitidis serogroups in IMD worldwide. However, proportion of N. meningitidis serogroups in IMD varied noticeably across countries and age groups. Therefore, establishing appropriate control guidelines depending on the geographical regions and age groups is essential for prevention of IMD.

Evaluation of phytochemical analysis and antimicrobial activities Allium essential oil against the growth of some microbial pathogens.

In this experimental study, the Allium essential oil (AHEO) was extracted through the hydrodistillation method. AHEO components were identified through gas chromatography/mass spectrometry (GC/MS), and its antioxidant properties and total phenolic content were examined through the methods of 2,2-diphenyl-1-picrylhydrazyl (DPPH), ß-carotene/linoleic acid inhibition and Folin-Ciocalteu, respectively. The antimicrobial effect of AHEO was evaluated on Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Streptococcus pyogenes, and Candida albicans through the methods of well diffusion, disk diffusion, minimum inhibitory concentration, and minimum bactericidal/fungicidal concentration. Phytochemical constituents (alkaloids, tannins, saponins, flavone and glycosides) were evaluated. 5-chloroorcylaldehyde with a percentage of 45.6% was the major compound of AHEO. Increasing concentration of AHEO had a significant effect (p ≤ 0.05) on inhibition zone diameter. The MICs of the AHEO varied from 0.25 mg/ml to 2 mg/ml. The MBCs/MFCs of the AHEO varied from 0.25 mg/ml to 4 mg/ml. The results of phytochemical screening of AHEO showed the existence of alkaloids, tannins, saponins, flavone and glycosides. There was also little difference between disk diffusion and well diffusion methods, and the data was well distributed throughout the X and Y components.

Antibacterial activities, phytochemical analysis and chemical composition Makhlaseh extracts against the growth of some pathogenic strain causing poisoning and infection.

The aim of this study was to investigate the antibacterial activities and phytochemical analysis of extracts against the growth of some pathogenic strain causing poisoning and infection (Staphylococcus aureus, Streptococcus pyogenes, Staphylococcus epidermidis, Enterobacter aerogenes, Escherichia coli and Shigella flexneri). Makhlaseh components were identified via gas chromatography/mass spectrometry (GC/MS). Total phenolic content (TPC), alkaloids, tannins and saponins were determined. Antioxidant activity was determined calorimetrically for 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. Antimicrobial effect of extracts was evaluated by five methods, pour plate, well diffusion, disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Camphor was the major compound of Makhlaseh. The TPC of aqueous and ethanolic Makhlaseh extracts was equal to 79.45 ± 1.15 and 115.26 ± 1.23 µg GAE/mg, respectively. The antioxidant activity (IC50) test of aqueous and ethanolic Makhlaseh extracts showed 315.50 ± 1.12 and 118.35 ± 1.08 µg/ml, respectively. MIC of the aqueous extract of Makhlaseh for Enterobacter aerogenes, Escherichia coli, Shigella flexneri, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus pyogenes were 32, 32, 16, 16, 8 and 8 mg/ml, respectively, and the MIC of the ethanolic extract were 16, 16, 16, 8, 4, and 4 mg/ml, respectively. The MBCs of the Makhlaseh extracts varied from 4 mg/ml to 128 mg/ml. Increasing concentration of Makhlaseh extracts had a significant effect (p ≤ 0.05) on inhibition zone diameter. In conclusion, using Makhlaseh extracts as a natural antibacterial composite in vitro have significant antibacterial ability over the studied strains.

Determining the effects of green chemistry synthesized Ag-nisin nanoparticle on macrophage cells.

Bacteriocins are low molecular weight substances produced through post transcriptional changes. These molecules are easily degraded in mammalian gut by proteolytic enzymes especially protease. Nisin is a peptide with 34 aa and its structure contains a pentacyclic lanthionine and 4 beta metyllanthionine residues. Different formulations have been designed for nisin. Since "green synthesis" is a progressive method to prepare anti-microbial and anti-cancer compounds, this study aimed at green synthesis of nisin metal compounds to be used lower concentration still exerting nisin effects. For this purpose, a 1 mg/ml nisin solution was added to a 1 mM silver nitrate solution and incubated to synthesis nano Ag-nisin, then the optical density of new solution was detected using UV spectroscopy. To determine biomolecules in the Ag-nisin solution, the FTIR method was employed. The size and morphology of Ag-nisin was measured by TEM. The toxicity, inflammatory cytokines production, and intracellular ROS quantity was evaluated using MTT, ELISA and flow-cytometry. XRD pattern indicated the silver crystals in Ag-nisin solution. In addition, FTRI findings showed that the carbonyl groups of amino acid are potently able to bind to metal nanoparticles, cover, and prevent them from particle agglomeration. Treating macrophage cells with 10, 25, 50 and 100 µg/ml of Ag-nisin had no significant effect on the cell viability and intracellular ROS quantity compared to the control group. In addition, different concentrations of Ag-nisin had no effect on the IL-10 and TNF-α levels but caused an increased level of IL-12 in comparison with the control group. In the current study, for the first time, green synthesize was used to prepare Ag-nisin particles. The synthesized nanoparticle is able to induce inflammatory activity via increasing IL-12 without any change in the TNF-α level in macrophage cells.

Manufacturing of a novel double-function ssDNA aptamer for sensitive diagnosis and efficient neutralization of SEA.

Staphylococcal enterotoxin A (SEA) is an enterotoxin produced mainly by Staphylococcus aureus. In recent years, it has become the most prevalent compound for staphylococcal food poisoning (SFP) around the world. In this study, we isolate new dual-function single-stranded DNA (ssDNA) aptamers by using some new methods, such as the Taguchi method, by focusing on the detection and neutralization of SEA enterotoxin in food and clinical samples. For the asymmetric polymerase chain reaction (PCR) optimization of each round of systematic evolution of ligands by exponential enrichment (SELEX), we use Taguchi L9 orthogonal arrays, and the aptamer mobility shift assay (AMSA) is used for initial evaluation of the protein-DNA interactions on the last SELEX round. In our investigation the dissociation constant (KD) value and the limit of detection (LOD) of the candidate aptamer were found to be 8.5 ±â€¯0.91 of nM and 5 ng/ml using surface plasmon resonance (SPR). In the current study, the Taguchi and mobility shift assay methods were innovatively harnessed to improve the selection process and evaluate the protein-aptamer interactions. To the best of our knowledge, this is the first report on employing these two methods in aptamer technology especially against bacterial toxin.

Pathogenic potential of Shiga toxin-producing Escherichia coli strains of caprine origin: virulence genes, Shiga toxin subtypes, phylogenetic background and clonal relatedness.

BACKGROUND: All over the world, Shiga toxin-producing Escherichia coli (STEC) are considered as important zoonotic pathogens. Eight serogroups have the greatest role in the outbreaks and diseases caused by STEC which include O26, O45, O103, O111, O113, O121, O145 and O157. Ruminants, especially cattle are the main reservoirs but the role of small ruminants in the epidemiology of human infections has not been thoroughly assessed in many countries. The objective of this research was to investigate the pathogenic potential of the STEC strains isolated from slaughtered goats. In this study, a total of 57 STEC strains were recovered from 450 goats and characterized by subtyping of stx genes, O-serogrouping, phylo-typing and DNA fingerprinting. RESULTS: Amongst 57 STEC strains isolated from goats, the prevalence of stx1 was significantly more than stx2 (98.2% vs. 24.5%; P ≤ 0.05), and 22.8% of strains harbored both stx1 and stx2 genes. Three (5.2%) isolates were characterized as EHEC, which carried both eae and stx genes. A total of five stx-subtypes were recognized namely: stx1c (94.7%), stx1a (53.7%), stx2d (21%), stx2c (17.5%), and stx2a (15.7%). In some parts of the world, these subtypes have been reported in relation with severe human infections. The stx subtypes predominantly occurred in four combinations, including stx1a/stx1c (35%), stx1c (31.5%), stx1c/stx2a/stx2c/stx2d (5.2%) and stx1c/stx2c/stx2d (%5.2%). In serogrouping, the majority of STECs from goats did not belong to the top 8 serogroups but two strains belonged to O113, which has been recognized as an important pathogenic STEC in Australia. Interestingly, none of stx + eae + isolates belonged to the tested serogroups. In phylo-typing the isolates mostly belonged to phylo-group B1 (82.4%), followed by phylo-group A (12.3%). STEC strains showed a substantial diversity in DNA fingerprinting; there were 24 unique ERIC-types (with a ≥95% similarity) among the isolates. CONCLUSIONS: Despite the fact that the top 8 STEC serogroups were uncommon in caprine strains, the presence of highly pathogenic stx subtypes indicates that small ruminants and their products can be considered as an overlooked public health risk for humans, especially in developing countries which consume traditional products.

Bone marrow - mesenchymal stem cells impact on the U937 cells in the presence of staphylococcal enterotoxin B (SEB).

The growing resistance against conventional chemotherapy in acute myeloid leukemia (AML) is a noticeable clinical concern. Therefore, many researchers are looking for novel substances to overcome drug resistance in cancer. Staphylococcal enterotoxin B (SEB) is a superantigen (SAg) and a promising compound which has lethal effects on malignant cells. In this unprecedented study, SEB was used against U937 cells in a co-culture system in the presence of human bone marrow-mesenchymal stem cells (hBM-MSCs). The effects of hBM-MSCs on the proliferation and survival of U937 cell line with SEB was assessed using MTT assay and AnnexinV/PI flowcytometry, respectively. Moreover, the expression of IL-6, IL-10, TGF-ß, and inhibitor of nuclear factor kappa-B kinase (IKKb) was evaluated by real-time PCR technique. The same experiments were also carried out using hBM-MSCs-conditioned medium (hBM-MSCs-CM). The results showed that SEB reduced the proliferation and survival of U937 cell line, but hBM-MSCs or hBM-MSCs-CM suppressed the effects of SEB. Furthermore, real-timePCR demonstrated that SEB could decrease the expression of IL-6, IL-10, and TGF-ß in hBM-MSCs (P < .05), while the production of IKKb was increased in comparison with the control group. These findings help us to have a broader understanding ofthe usage of SEB in the treatment of haematological malignancies, especially if it is targeted against hBM-MSCs to disrupt their supportive effects on malignant cells.

Virulence genes, Shiga toxin subtypes, major O-serogroups, and phylogenetic background of Shiga toxin-producing Escherichia coli strains isolated from cattle in Iran.

The aim of this study was to investigate the virulence potential of the isolated bovine STEC for humans in Iran. In this study a collection of STEC strains (n = 50) had been provided via four stages, including sampling from feces of cattle, E. coli isolation, molecular screening of Shiga toxin (stx) genes, and saving the STEC strains from various geographical areas in Iran. The STEC isolates were subjected to stx-subtyping, O-serogrouping, and phylo-grouping by conventional polymerase chain reaction (PCR). Occurrence of stx1 (52%) and stx2 (64%) was not significantly different (p = 0.1), and 16% of isolates carried both stx1 and stx2, simultaneously. In addition, 36% and 80% of the isolates were positive for eae and ehxA, respectively. Molecular subtyping showed that stx1a (52%), stx2a (44%), stx2c (44%), and stx2d (30%) were the most prevalent subtypes; two combinations stx2a/stx2c and stx2c/stx2d coexisted in 18% and 10% of STEC strains, respectively. Three important non-O157 serogroups, including O113 (20%), O26 (12%), and O111 (10%), were predominant, and none of the isolates belonged to O157. Importantly, one O26 isolate carried stx1, stx2, eae and ehxA and revealed highly virulent stx subtypes. Moreover, all the 21 serogrouped strains belonged to the B1 phylo-type. Our study highlights the significance of non-O157 STEC strains carrying highly pathogenic virulence genes in cattle population as the source of this pathogen in Iran. Since non-O157 STEC strains are not routinely tried in most diagnostic laboratories, majority of the STEC-associated human infections appear to be overlooked in the clinical settings.

The inhibitory impacts of Lactobacillus rhamnosus GG-derived extracellular vesicles on the growth of hepatic cancer cells.

Bacterial extracellular vesicles (EVs) have come forth into notice as possible important agent to mediate host-pathogen interactions. In this scientific research, the authors have tried to find out the effect of EVs derived from Lactobacillus rhamnosus GG (LDEVs) on the apoptosis induction in HepG2 cell line. The EVs were purified from the conditioned medium of Lactobacillus rhamnosus GG using ultrafiltration and confirmed by transmission electron microscopy (TEM). The HepG2 cells were treated with different concentrations of purified LDEVs and the cytotoxicity and their effects on the expression of bcl-2 and bax genes were assessed by the MTT assay and semi-quantitative RT-PCR, respectively. The MTT assay showed that only 100 µg/ml of LDEVs had a significant cytotoxic effect on cancer cells (p < 0.05). The apoptotic index (bax/bcl2 expression ratio) was significantly increased after treating with 50 and 100 µg/ml LDEVs (p < 0.05). Increased bax/bcl-2 ratio was led to cancer cell death.

Cellular and molecular mechanisms of acute exposure to sulfur mustard: a systematic review.

CONTEXT: Mustard gas (e.g. sulfur mustard (SM)) has been used as a chemical agent in several battles and is still a potential worldwide menace. Besides local absorption, particularly in the skin, eyes and lungs, systemic spread of the agent also has detrimental effects on gonads, bone marrow and nervous system. Moreover, chronic exposure of SM to respiratory system causes death. Inducing oxidative stress, and disturbing DNA and tissue repair systems, inflammation and cell death signaling pathways have been introduced as molecular mechanisms of the injury. METHODS: In this systematic review, more than 1200 (2000-2014) articles focusing on gross or molecular pathological reports in the acute phase of the respiratory injury after SM exposure were reviewed, followed by two different layers of gross and molecular pathological data (clinic and laboratory) integrated together in a spatio-temporal order. Role of epithelial, neutrophil and macrophage cells and three signaling pathways of inflammation, oxidative stress and cell death are covered in details. RESULTS AND CONCLUSION: Our results propose a critical role of interleukin-17 producing cells in acute and chronic inflammatory responses.

Isolation of a new ssDNA aptamer against staphylococcal enterotoxin B based on CNBr-activated sepharose-4B affinity chromatography.

Staphylococcus aureus are potent human pathogens possessing arsenal of virulence factors. Staphylococcal food poisoning (SFP) and respiratory infections mediated by staphylococcal enterotoxin B (SEB) are common clinical manifestations. Many diagnostic techniques are based on serological detection and quantification of SEB in different food and clinical samples. Aptamers are known as new therapeutic and detection tools which are available in different ssDNA, dsDNA and protein structures. In this study, we used a new set of ssDNA aptamers against SEB. The methods used included preparation of a dsDNA library using standard SEB protein as the target analyte, affinity chromatography matrix in microfuge tubes, SELEX procedures to isolate specific ssDNA-aptamer as an affinity ligand, aptamer purification using ethanol precipitation method, affinity binding assay using ELISA, aptamer cloning and specificity test. Among 12 readable sequences, three of them were selected as the most appropriate aptamer because of their affinity and specificity to SEB. This study presents a new set of ssDNA aptamer with favorable selectivity to SEB through 12 rounds of SELEX. Selected aptamers were used to detect SEB in infected serum samples. Results showed that SEB c1 aptamer (2 µg SEB/100 nM aptamer) had favorable specificity to SEB (kd = 2.3 × 10(-11) ). In conclusion, aptamers can be considered as useful tools for detecting and evaluating SEB. The results showed that affinity chromatography was an affordable assay with acceptable accuracy to isolate sensitive and selective novel aptamers. Copyright © 2016 John Wiley & Sons, Ltd.

High prevalence of extensively drug-resistant and metallo beta-lactamase-producing clinical Acinetobacter baumannii in Iran.

Acinetobacter species particularly Acinetobacter baumannii (A. baumannii) have been widely reported as broad-spectrum antibiotic resistant pathogens. Expression of various types of metallo beta-lactamases (MBL), classified as Ambler class B, has been associated with carbapenem resistance. Here, we attempted to assess the frequency of extensively drug-resistant (XDR) and MBL-producing A. baumannii among clinical isolates. 86 clinical A. baumannii strains were collected from 2014 to 2015 and their susceptibility to meropenem (10 µg), imipenem (10 µg), azteronem (30 µg), pipracillin (100 µg) tazobactam (110 µg), tobramycin (10 µg), fosfomycin (200 µg), rifampicin (5 µg), colistin (10 µg), tigecycline (15 µg), sulbactam/ampicillin (10 µg + 10 µg) and polymixin B (300 U) was evaluated using disk diffusion method. The MBL-producing isolates were screened using combined disc diffusion method. Furthermore, the presence of blaVIM, blaIMP, blaSPM, blaGIM, blaSIM and blaNDM was detected by PCR. 34.9% of isolates were recovered from bronchoalveolar lavage (BAL). 81 (94.2%) and 62 (71.2%) isolates were multidrug resistance (MDR) and XDR, respectively. 44 (51.2%) and 65 (75.6%) isolates were MBL-producing strains with resistance to imipenem and meropenem, respectively. 2 (2.3%), 13 (15.1%), 2 (2.3%), 4 (4.7%) and 2 (2.3%) isolates carried blaVIM, blaIMP, blaSPM, blaGIM and blaSIM genes, respectively. Our data showed that the rate of XDR and MBL A. baumannii is on the rise.

Expression of neutrophil gelatinase-associated lipocalin (NGAL) in peripheral nerve repair.

INTRODUCTION: Trauma is one of the causes of peripheral nerve injuries. Free radicals increase after tissue damage. Free radicals are usually scavenged and detoxified by antioxidants. In this study, we assessed the antioxidative role of the NGAL molecule in sciatic nerve repair in rats. MATERIALS AND METHODS: The sciatic nerves of 40 rats were crushed and the total mRNA of samples from day 1 and 3 and week 1, 3, 5 post injury was extracted. The expression of the NGAL gene was confirmed by RT-PCR. For immunohistochemistry analysis, the samples were fixed in paraformaldehyde and cut in 20 micrometer slices by cryostat. RESULTS: The expression of NGAL significantly upregulated in day 1, 3 and week 1 following the crushing of sciatic nerves in comparison with the intact nerves. Immunohistochemistry results also confirmed the protein expression of this gene. DISCUSSION: The NGAL molecule showed upregulation in the degeneration process after nerve injury, so it may play an important role in nerve repair.