Vero Cell Cytotoxicity Research Articles

Inhibition of herpes simplex virus 1 (HSV-1) and poliovirus (PV-1) by bacteriocins from lactococcus lactis subsp. lactis and enterococcus durans strains isolated from goat milk

Bacteriocins have unusual inhibitory activity, including antiviral properties, and this can be exploited to give alternative applications. Semi–purified bacteriocins of six lactic acid bacteria (LAB) strains isolated from goat milk (two Lactococcus lactis: GLc03 and GLc05, and four Enterococcus durans: GEn09, GEn12, GEn14 and GEn17) were tested for cytotoxicity in Vero cells (50% Cytotoxicity Concentration: CC50), and for their antiviral activities against herpes simplex virus 1 (HVS-1) and poliovirus (PV-1). Semi-purified bacteriocins presented low cytotoxicity, with CC50 varying from 256.2 µg/mL (GLc05) to 1084.5 µg/mL (GEn14). CC10 was determined for all isolates (GLc03: 36.9 µg/mL; GLc05: 51.2 µg/mL; GEn09: 88.1 µg/mL; GEn12: 99.9 µg/mL; GEn14: 275 µg/mL; and GEn17: 62.2 µg/mL) and considered for antiviral activity assays. Antiviral activity before virus adsorption was recorded against PV-1 for GLc05 (4.9%), GEn09 (3.4%), GEn12 (24.7%) and GEn17 (23.5%), and against HSV-1 for GEn12 (27.9%), GEn14 (58.7%) and GEn17 (39.2%). Antiviral activity after virus adsorption was identified against PV-1 for GLc05 (32.7%), GEn09 (91.0%), GEn12 (93.7%) and GEn17 (57.2%), and against HSV-1 for GEn17 (71.6%). The results obtained indicate the potential of some bacteriocins, particularly those produced by E. durans strains investigated in the present study, in viral inhibition and their application as new antiviral agents.

Enhanced apoptosis, survivin down-regulation and assisted immunochemotherapy by curcumin loaded amphiphilic mixed micelles for subjugating endometrial cancer

Survivin is up-regulated in 83% of endometrial cancer leading to resistance development. As endometrial tumor advances, it also elicits chronic inflammation characterized by increased cytokine secretion and immune cells infiltration. The present study was designed to engineer mixed micellar curcumin loaded formulation for investigating survivin down-regulation, its anti-cancer and cytokine modulatory potential against endometrial cancer Ishikawa cells. Flory–Huggins interaction parameter (χpd) was applied to predict the compatibility between curcumin and surfactant mixture. The developed and characterized formulations were used to comparatively assess hemolysis, cellular uptake, cell-viability, apoptosis, mitochondrial membrane potential loss, rhodamine accumulation and bioavailability. In-vitro cytotoxicity in Vero cells demonstrated no deleterious effects on cell population. We saw better bioavailability, significant rhodamine accumulation, changes in protein expression and modulation in TNF-α, IL-6 and IL-10 levels. In conclusion, developed formulation warrants exploring the therapeutic interventions for overcoming resistance development in endometrial cancer.

Protective Effects of Cell-Free Supernatant and Live Lactic Acid Bacteria Isolated from Thai Pigs Against a Pandemic Strain of Porcine Epidemic Diarrhea Virus.

Porcine epidemic diarrhea virus (PEDV) is a coronavirus which causes severe diarrhea and fatal dehydration in piglets. In general, probiotic supplements could enhance recovery and protect piglets against enteric pathogens. Seven local lactic acid bacteria (LAB), (Ent. faecium 79N and 40N, Lact. plantarum 22F, 25F and 31F, Ped. acidilactici 72N and Ped. pentosaceus 77F) from pig feces were well-characterized as high potential probiotics. Cell-free supernatants (CFS) and live LAB were evaluated for antiviral activities by co-incubation on Vero cells and challenged with a pandemic strain of PEDV isolated from pigs in Thailand. Cell survival and viral inhibition were determined by cytopathic effect (CPE) reduction assay and confirmed by immunofluorescence. At 1:16, CFS dilution (pH 6.3–6.8) showed no cytotoxicity in Vero cells and was therefore used as the dilution for antiviral assays. The diluted CFS of all Lact. plantarum showed the antiviral effect against PEDV; however, the same antiviral effect could not be observed in Ent. faecium and Pediococcus strains. In competitive experiment, only live Lact. plantarum 25F and Ped. pentosaceus 77F showed CPE reduction in the viral infected cells to <50% observed field area. This study concluded that the CFS of all tested lactobacilli, and live Lact. plantarum (22F and 25F) and Pediococcus strains 72N and 77F could reduce infectivity of the pandemic strain of PEDV from pigs in Thailand on the target Vero cells.Electronic supplementary materialThe online version of this article (doi:10.1007/s12602-017-9281-y) contains supplementary material, which is available to authorized users.

Crosslinker Effects on Properties of Hydroxyethylacryl Chitosan/Sodium Alginate Hydrogel Films

SummaryThe aim of this research is to investigate the effects of Ca2+ and Zn2+ ions on the swelling behavior, mechanical property and antibacterial activity of hydroxyethylacryl chitosan (HC)/ sodium alginate (SA) hydrogel films. The hydrogel films composed of HC and SA in different proportions (75:25, 50:50 and 25:75 w/w) were prepared by dipping method using calcium chloride as a single crosslinking agent and both calcium chloride and zinc sulfate as a couple crosslinking agent. The structures of the films were characterized by infrared spectroscopy (FT‐IR). It was found that Ca2+ ions could only crosslink with SA through the formation of ionic bonds while Zn2+ ions could crosslink both HC through the formation of coordinate bonds and SA through the formation of partially ionic or coordinate bonds. The swelling behaviors of the films in phosphate buffered saline (PBS) were investigated. The results showed relatively high stability for the crosslinked films with the couple crosslinking agent. The mechanical properties of the hydrogel films were also tested. It was found that the mechanical properties of the calcium‐zinc crosslinked films were greater than calcium crosslinked films. The values of tensile strength and elongation at break of the calcium‐zinc crosslinked films in the fully hydrated state were up to 12.9 MPa and 67%, respectively. Additionally, the calcium‐zinc crosslinked films evidenced better antibacterial activity to Staphylococcus aureus than calcium crosslinked films. Moreover, all of prepared hydrogel films exhibited no cytotoxicity for Vero cells. The comprehensive results suggest their potential as a wound dressing.

Antiviral activity of the adenosine analogue BCX4430 against West Nile virus and tick-borne flaviviruses

There are currently no approved antiviral therapies against medically important human flaviviruses. The imino-C-nucleoside BCX4430 shows broad-spectrum antiviral activity against a wide range of RNA viruses. Here, we demonstrate that BCX4430 inhibits tick-borne species of the genus Flavivirus; however, the antiviral effect varies against individual species. Micro-molar BCX4430 levels inhibited tick-borne encephalitis virus (TBEV); while, approximately 3–8-fold higher concentrations were needed to inhibit louping ill virus and Kyasanur Forest disease virus. Moreover, the compound strongly inhibited in vitro replication of West Nile virus, a typical mosquito-transmitted flavivirus. Two chemical forms of the compound, i.e. BCX4430 and BCX4430 hydrochloride, were compared and both exerted similar inhibitory profiles in our in vitro antiviral assay systems and no or negligible cytotoxicity in porcine kidney stable and Vero cells. The obtained data indicate that, in addition to mosquito-borne flaviviruses, the compound has strong antiviral activity against members of the TBEV serocomplex.

Antiviral effect of compounds derived from the seeds of Mammea americana and Tabernaemontana cymosa on Dengue and Chikungunya virus infections

BackgroundThe transmission of Dengue virus (DENV) and Chikungunya virus (CHIKV) has increased worldwide, due in part to the lack of a specific antiviral treatment. For this reason, the search for compounds with antiviral potential, either as licensed drugs or in natural products, is a research priority. The objective of this study was to identify some of the compounds that are present in Mammea americana (M. americana) and Tabernaemontana cymosa (T. cymosa) plants and, subsequently, to evaluate their cytotoxicity in VERO cells and their potential antiviral effects on DENV and CHIKV infections in those same cells.MethodsDry ethanolic extracts of M. americana and T. cymosa seeds were subjected to open column chromatographic fractionation, leading to the identification of four compounds: two coumarins, derived from M. americana; and lupeol acetate and voacangine derived from T. cymosa.. The cytotoxicity of each compound was subsequently assessed by the MTT method (at concentrations from 400 to 6.25 μg/mL). Pre- and post-treatment antiviral assays were performed at non-toxic concentrations; the resulting DENV inhibition was evaluated by Real-Time PCR, and the CHIKV inhibition was tested by the plating method. The results were analyzed by means of statistical analysis.ResultsThe compounds showed low toxicity at concentrations ≤ 200 μg/mL. The compounds coumarin A and coumarin B, which are derived from the M. americana plant, significantly inhibited infection with both viruses during the implementation of the two experimental strategies employed here (post-treatment with inhibition percentages greater than 50%, p < 0.01; and pre-treatment with percentages of inhibition greater than 40%, p < 0.01). However, the lupeol acetate and voacangine compounds, which were derived from the T. cymosa plant, only significantly inhibited the DENV infection during the post-treatment strategy (at inhibition percentages greater than 70%, p < 0.01).ConclusionIn vitro, the coumarins are capable of inhibiting infection by DENV and CHIKV (with inhibition percentages above 50% in different experimental strategies), which could indicate that these two compounds are potential antivirals for treating Dengue and Chikungunya fever. Additionally, lupeol acetate and voacangine efficiently inhibit infection with DENV, also turning them into promising antivirals for Dengue fever.

Determination of virulence and antibiotic resistance pattern of biofilm producing Listeria species isolated from retail raw milk.

BackgroundOne of the foodborne pathogens is Listeria monocytogenes, which causes serious invasive illness in elderly and immunocompromised patients, pregnant women, newborns and infants ranking second after salmonellosis because of its high case fatality rate. Listerial cow mastitis marked by abnormal milk, increased cell counts and reduced production has not been reported. Therefore, apparently healthy cows can be reservoirs of L. monocytogenes. A number of 203 udder milk samples from apparently healthy animals (buffalo, n = 100; cow, n = 103) were collected and tested for Listeria. Isolated colonies on the PALCAM agar were Listeria species confirmed according to their biochemical and the Christie–Atkins–Munch-Petersen (CAMP) reactions. The Listeria species pathogenicity of was tested by phosphatidylinositol-specific phospholipase C, DL-alanine-β-naphthylamide HCl, Dalanine-p-nitroanilide tests, chick embryo, mice inoculation tests, Vero cell cytotoxicity and biofilm formation. The virulence-associated genes, hlyA, plcB, actA and iap associated with Listeria were molecularly assayed.ResultsThe 17 isolated Listeria spp. represented a prevalence rate of 8.4 %. Of these 3 (1.4 %), 2 (1 %), 5 (2.5 %), 4 (2 %) and 3 (1.5 %) were confirmed as L. monocytogenes, L. innocua, L. welshimeri, L. seelegeri, respectively. While the L. monocytogenes isolate displayed all the four virulence-associated genes, L. seelegeri carried the hlyA gene only. The L. monocytogenes had a strong in vitro affinity to form a biofilm, in particular serotype 4 which is associated with human infections. L. monocytogenes showed resistance for 9/27 antibiotics.ConclusionsThe biofilm forming capability of the Listeria spps. makes them particularly successful in colonizing surfaces within the host thus being responsible for persistence infections and due to their antimicrobial resistant phenotype that this structure confers. In addition, strains belonging to serotypes associated with human infections and characterized by pathogenic potential (serotype 4) are capable to persist within the processing plants forming biofilm and thus being a medical hazard.

Protective effects of taurine and coenzyme Q10 against perfluorooctanoic acid-induced cytotoxicity in Vero cells: A preliminary study

Among polyphenolic phytoconstituents with anticancer properties, Ellagic acid (EA) is widely reported for its translational potential in vitro but efficient in vivo delivery of EA has been a challenge. We, for the first time, used a tween 80 coated nano delivery of Ellagic acid to evaluate its preclinical efficacy in vitro and in vivo for breast cancer.To overcome the challenges of in vivo delivery, two batches of chitosan-based nanoformulations of EA (with and without tween 80 coating) were prepared by the ionotropic gelation method. The nanoformulations were characterized and further evaluated in vitro against breast cancer cells (MCF7) and in vivo with EAC tumor-bearing mice for establishing their anticancer efficacy compared to Ellagic acid alone. A quantitative simulation study was undertaken to understand if the observed antitumor efficacy is due to the synergistic efficacy of the Chitosan-Ellagic acid combination.Results revealed that nanoformulations consist of good nano-sized encapsulation of EA and showed good drug entrapment-release capacity. Nano-encapsulated EA is biocompatible and exhibited higher cytotoxicity in vitro compared to EA alone. Similarly, significantly higher tumor regression was observed in nano-EA treated mice compared to EA alone, and best efficacy was observed with the nanoformulation with tween 80 coating. Furthermore, nanoformulations showed higher apoptosis in tumor tissues with no significant tissue toxicity in vital organs.We report synergism of Chitosan-Ellagic acid combination in the tween 80 coated nanoparticles of Ellagic acid resulting in enhanced anti-breast tumor efficacy that may be of translational value for other tumor types, too.

The aqueous extract of cinnamon bark ameliorated cisplatin-induced cytotoxicity in vero cells without compromising the anticancer efficiency of cisplatin.

Cis-diammine dichloroplatinum (CDDP) is one of the most important chemotherapeutic agents for cancer treatment. Nonetheless, its notable side effect, nephrotoxicity, undermines its clinical use. The current study was undertaken to evaluate the protective potential of the aqueous extract (AEC) of Cinnamomum cassia (cinnamon) against the cytotoxic effect of CDDP in vitro and to elaborate the molecular mechanism underlying protection. MTT assay was performed to assess viability of the normal kidney Vero cells treated with CDDP and/or AEC. Cells were stained with Coomassie blue, acridine orange and ethidium bromide to highlight morphological features of apoptosis. Caspase-3 activity, DNA fragmentation and reactive oxygen species (ROS) level were monitored to assess biochemical hallmarks of apoptosis. Quantitative RT-PCR and Western blot analyses were performed to elucidate expression of cellular molecules underlying the protective potential of AEC. CDDP-treated Vero cells exhibited hallmarks of apoptosis; these hallmarks were significantly suppressed in the presence of AEC. AEC did not alter activity of CDDP-induced cytotoxicity of breast and liver cancer cells. AEC treatment of Vero cells prevented CDDP-induced increased expression of mitochondrial Bax protein, release of mitochondrial cytochrome c, caspase-3 activation, DNA fragmentation and generation of ROS. AEC up-regulated expression of the cytoprotective gene (heme oxygenase (HO)-1). These findings suggest AEC has protective effects against CDDP-induced toxicity via preventing the activation of various cellular mechanisms mediating apoptotic cell death, without compromising the anticancer efficiency of CDDP. Thus, cinnamon may represent one of the most feasible ways to reduce the risk of CDDP-induced toxicity.

Ligand-Free Synthesis of Tunable Size Ln:BaGdF₅ (Ln = Eu³⁺ and Nd³⁺) Nanoparticles: Luminescence, Magnetic Properties, and Biocompatibility.

Bifunctional and highly uniform Ln:BaGdF5 (Ln = Eu(3+) and Nd(3+)) nanoparticles have been successfully synthesized using a solvothermal method consisting of the aging at 120 °C of a glycerol solution containing the corresponding Lanthanide acetylacetonates and butylmethylimidazolium tetrafluoroborate. The absence of any surfactant in the synthesis process rendered hydrophilic nanospheres (with tunable diameter from 45 nm 85 nm, depending on the cations concentration of the starting solution) which are suitable for bioapplications. The particles are bifunctional because they showed both optical and magnetic properties due to the presence of the optically active lanthanides (Eu(3+) in the visible and Nd(3+) in the NIR regions of the electromagnetic spectrum) and the paramagnetic gadolinium ion, respectively. The luminescence decay curves of the nanospheres doped with different amounts of Eu(3+) and Nd(3+) have been recorded in order to determine the optimum dopant concentration in each case, which turned out to be 5% Eu(3+) and 0.5% Nd(3+). Likewise, proton relaxation times were measured at 1.5 T in water suspensions of the optimum particles found in the luminescence study. The values obtained suggested that both kinds of particles could be used as positive contrast agents for MRI. Finally, it was demonstrated that both the 5% Eu(3+) and 0.5% Nd(3+)-doped BaGdF5 nanospheres showed negligible cytotoxicity for VERO cells for concentrations up to 0.25 mg mL(-1).

Cytotoxicity of Cratoxylum Formosum Subsp. Pruniflorum Gogel Extracts in Oral Cancer Cell Lines.

Oral cancer is a health problem in Thailand. Cratoxylum formosum subsp. pruniflorum Gogel (Teawdang), normally consumed in northeast Thailand, has proven cytotoxic to cervical cancer cell lines including HeLa, SiHa and C-33A. Recently, Asian oral cancer cell lines, ORL-48 and ORL-136, were established. Therefore, we aimed to study cytotoxicity of Teawdang in these. Total phenolic (TPC) and flavonoid content (TFC), and antioxidant activity of Teawdang were also determined. Teawdang was purchased from Khon Kaen market during June-October 2013. Hexane (CHE), ethyl acetate (CEE) and methanol (CME) extracts of its edible part were analyzed for TPC by the folin-ciocalteau method and for TFC by an aluminium colorimetric method. Antioxidant activity and cytotoxicity in normal Vero cells and oral cancer cells were investigated. Cell viability was assessed using 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assays. CME and CEE had higher TPC and TFC and antioxidant activity than CHE. Both CME and CEE, at 200 μg dry wt/mL, were cytotoxic to the studied oral cancer cell lines. However, CME was cytotoxic to Vero cells whereas CEE was not. Compared to Vero cells, CEE significantly inhibited ORL-48 and ORL-136 growth (p=0.03 and p=0.02, respectively). CEE exhibited cytotoxic effects on the studied oral cancer cell lines but not normal Vero cells. The bioactive compounds in CEE should be further purified and elucidated for their mechanisms of action for development as anticancer agents.

Mechanisms of Ricin Toxin Neutralization Revealed through Engineered Homodimeric and Heterodimeric Camelid Antibodies

Novel antibody constructs consisting of two or more different camelid heavy-chain only antibodies (VHHs) joined via peptide linkers have proven to have potent toxin-neutralizing activity in vivo against Shiga, botulinum, Clostridium difficile, anthrax, and ricin toxins. However, the mechanisms by which these so-called bispecific VHH heterodimers promote toxin neutralization remain poorly understood. In the current study we produced a new collection of ricin-specific VHH heterodimers, as well as VHH homodimers, and characterized them for their ability neutralize ricin in vitro and in vivo. We demonstrate that the VHH heterodimers, but not homodimers were able to completely protect mice against ricin challenge, even though the two classes of antibodies (heterodimers and homodimers) had virtually identical affinities for ricin holotoxin and similar IC50 values in a Vero cell cytotoxicity assay. The VHH heterodimers did differ from the homodimers in their ability to promote toxin aggregation in solution, as revealed through analytical ultracentrifugation. Moreover, the VHH heterodimers that were most effective at promoting ricin aggregation in solution were also the most effective at blocking ricin attachment to cell surfaces. Collectively, these data suggest that heterodimeric VHH-based neutralizing agents may function through the formation of antibody-toxin complexes that are impaired in their ability to access host cell receptors.

Development and evaluation of sunscreen creams containing morin-encapsulated nanoparticles for enhanced UV radiation protection and antioxidant activity.

The objective of present work was to develop novel sunscreen creams containing polymeric nanoparticles (NPs) of morin. Polymeric NPs containing morin were prepared and optimized. The creams containing morin NPs were also prepared and evaluated. Optimized NPs exhibited particle size of 90.6 nm and zeta potential of −31 mV. The entrapment efficiency of morin, within the polymeric NPs, was found to be low (12.27%). Fourier transformed infrared spectroscopy and differential scanning calorimetry studies revealed no interaction between morin and excipients. Transmission electron microscopy and atomic force microscopy revealed that the NPs were spherical in shape with approximately 100 nm diameter. Optimized NPs showed excellent in vitro free radical scavenging activity. Skin permeation and deposition of morin from its NPs was higher than its plain form. Different sunscreen creams (SC1–SC8) were formulated by incorporating morin NPs along with nano zinc oxide and nano titanium dioxide. SC5 and SC8 creams showed excellent sun protection factor values (≈40). In vitro and in vivo skin permeation studies of sunscreen creams containing morin NPs indicated excellent deposition of morin within the skin. Morin NPs and optimized cream formulations (SC5 and SC8) did not exhibit cytotoxicity in Vero and HaCaT cells. Optimized sunscreen creams showed excellent dermal safety. SC5 and SC8 creams demonstrated exceptional in vivo antioxidant effect (estimation of catalase, superoxide dismutase, and glutathione) in UV radiation-exposed rats. The optimized sunscreen creams confirmed outstanding UV radiation protection as well as antioxidant properties.

Antiviral Activity of Chrysin Derivatives against Coxsackievirus B3 in vitro and in vivo.

Chrysin is a 5,7-dihydroxyflavone and was recently shown to potently inhibit enterovirus 71 (EV71) by suppressing viral 3C protease (3Cpro) activity. In the current study, we investigated whether chrysin also shows antiviral activity against coxsackievirus B3 (CVB3), which belongs to the same genus (Enterovirus) as EV71, and assessed its ability to prevent the resulting acute pancreatitis and myocarditis. We found that chrysin showed antiviral activity against CVB3 at 10 μM, but exhibited mild cellular cytotoxicity at 50 μM, prompting us to synthesize derivatives of chrysin to increase the antiviral activity and reduce its cytotoxicity. Among four 4-substituted benzyl derivatives derived from C(5) benzyl-protected derivatives 7, 9–11 had significant antiviral activity and showed the most potent activity against CVB3 with low cytotoxicity in Vero cells. Intraperitoneal injection of CVB3 in BALB/c mice with 1×106 TCID50 (50% tissue culture infective dose) of CVB3 induced acute pancreatitis with ablation of acinar cells and increased serum CXCL1 levels, whereas the daily administration of 9 for 5 days significantly alleviated the pancreatic inflammation and reduced the elevation in serum CXCL1 levels. Collectively, we assessed the anti-CVB3 activities of chrysin and its derivatives, and found that among 4-substituted benzyl derivatives, 9 exhibited the highest activity against CVB3 in vivo, and protected mice from CVB3-induced pancreatic damage, simultaneously lowering serum CXCL1 levels.

Recombinant lipoprotein-based vaccine candidates against C. difficile infections.

BackgroundOpportunistically nosocomial infections in hospitalized patients are often related to Clostridium difficile infections (CDI) due to disruption of the intestinal micro-flora by antibiotic therapies during hospitalization. Clostridial exotoxins A and B (TcdA and TcdB) specifically bind to unknown glycoprotein(s) in the host intestine, disrupt the intestinal barrier leading to acute inflammation and diarrhea. The C-terminal receptor binding domain of TcdA (A-rRBD) has been shown to elicit antibody responses that neutralize TcdA toxicity in Vero cell cytotoxicity assays, but not effectively protect hamsters against a lethal dose challenge of C. difficile spores. To develop an effective recombinant subunit vaccine against CDI, A-rRBD was lipidated (rlipoA-RBD) as a rational design to contain an intrinsic adjuvant, a toll-like receptor 2 agonist and expressed in Escherichia coli.ResultsThe purified rlipoA-RBD was characterized immunologically and found to have the following properties: (a) mice, hamsters and rabbits vaccinated with 3 μg of rlipoA-RBD produced strong antibody responses that neutralized TcdA toxicity in Vero cell cytotoxicity assays; furthermore, the neutralization titer was comparable to those obtained from antisera immunized either with 10 μg of TcdA toxoid or 30 μg of A-rRBD; (b) rlipoA-RBD elicited immune responses and protected mice from TcdA challenge, but offered insignificant protection (10 to 20 %) against C. difficile spores challenge in hamster models; (c) only rlipoA-RBD formulated with B-rRBD consistently confers protection (90 to 100 %) in the hamster challenge model; and (d) rlipoA-RBD was found to be 10-fold more potent than A-rRBD as an adjuvant to enhancing immune responses against a poor antigen such as ovalbumin.ConclusionThese results indicate that rlipoA-RBD formulated with B-rRBD could be an excellent vaccine candidate for preclinical studies and future clinical trials.

Uniform Poly(acrylic acid)‐Functionalized Lanthanide‐Doped LaVO4 Nanophosphors with High Colloidal Stability and Biocompatibility

AbstractLn‐doped (Ln = Eu or Nd) LaVO4 nanoparticles functionalized with poly(acrylic acid) (PAA) were prepared from lanthanide and vanadate precursors in the presence of PAA by a simple one‐pot method that consists of a homogeneous precipitation reaction in ethylene glycol/water at a moderate temperature (120 °C). The size of the nanoparticles could be modified in the 40–70 nm range by adjusting the amount of PAA added. The effects of the Eu and Nd contents of these nanomaterials on theirs optical properties (emission intensity and lifetime) were also analyzed to find the optimum nanophosphors. Finally, the nanoparticles showed negligible cytotoxicity for Vero cells at concentrations up to 0.05 mg mL–1 and a high colloidal stability in physiological buffer solutions; therefore, they satisfy the most important requirements for in vitro biotechnological applications.

Role of Proteus mirabilis MR/P fimbriae and flagella in adhesion, cytotoxicity and genotoxicity induction in T24 and Vero cells.

Proteus mirabilis is frequently associated with complicated urinary tract infections (UTI). It is proposed that several virulence factors are associated with P. mirabilis uropathogenicity. The aim of this work was to elucidate genotoxic and cytotoxic effects mediated by MR/P fimbriae and flagella in eukaryotic cells in vitro. Two cell lines (kidney- and bladder-derived) were infected with a clinical wild-type P. mirabilis strain and an MR/P and a flagellar mutant. We evaluated adhesion, genotoxicity and cytotoxicity by microscopy, comet assay and triple staining technique, respectively. Mutant strains displayed lower adhesion rates than the P. mirabilis wild-type strain and were significantly less effective to induce genotoxic and cytotoxic effects compared to the wild type. We report for the first time that P. mirabilis MR/P fimbriae and flagella mediate genotoxic and cytotoxic effects on eukaryotic cells, at least in in vitro conditions. These results could contribute to design new strategies for the control of UTI.

Virulence characterization of non-O157 Shiga toxin-producing Escherichia coli isolates from food, humans and animals

A total of 359 non-O157 STEC isolates from food, humans and animals were examined for serotypes, Shiga toxin subtypes and intimin subtypes. Isolates solely harboring stx2 from the three sources were selected for Vero cell cytotoxicity test. stx subtypes in eae negative isolates were more diverse than in eae positive isolates primarily carrying stx2a. Four eae subtypes (eaeβ,eaeε1,eaeγ1 and eaeγ2/θ) were observed and correlated with serotypes and flagella. Food isolates showed more diverse serotypes, virulence factors and cell cytotoxicities than human isolates. Some isolates from produce belonged to serotypes that have been implicated in human diseases, carried stx2a or/and stx2dact and exhibited high cell cytotoxicity similar to human isolates. This indicates that foods can be contaminated with potentially pathogenic STEC isolates that may cause human diseases. Given the increased produce consumption and growing burden of foodborne outbreaks due to produce, produce safety should be given great importance.

One‐Step Synthesis and Polyacrylic Acid Functionalization of Multifunctional Europium‐Doped NaGdF4 Nanoparticles with Selected Size for Optical and MRI Imaging

AbstractMultifunctional Eu:NaGdF4 nanospheres functionalized with polyacrylic acid (PAA) polymer have been prepared for the first time by a simple one‐pot method that consists of a homogeneous precipitation reaction at 120 °C. The size of the nanospheres, which were polycrystalline and crystallized into a hexagonal structure, could be altered in the 60–95 nm range by adjusting the amount of polyacrylic acid added. The effects of Eu content and particle size of these nanomaterials on their optical properties (emission intensity and lifetime) as well as on their relaxivity (r1 and r2) values were also analyzed to find the optimum system for optical bioimaging and as a positive contrast agent for magnetic resonance imaging (MRI) applications. Finally, such optimum nanoparticles showed negligible cytotoxicity for Vero cells for concentrations up to 0.5 mg mL–1 and a high colloidal stability in 2‐morpholinoethanesulfonic acid solutions, thereby satisfying the most important requirements for their use in biotechnological applications.

Are bigger data sets better for machine learning? Fusing single-point and dual-event dose response data for Mycobacterium tuberculosis.

Tuberculosis is a major, neglected disease for which the quest to find new treatments continues. There is an abundance of data from large phenotypic screens in the public domain against Mycobacterium tuberculosis (Mtb). Since machine learning methods can learn from past data, we were interested in addressing whether more data builds better models. We now describe using Bayesian machine learning to assess whether we can improve our models by combining the large quantities of single-point data with the much smaller (higher quality) dual-event data sets, which use both dose-response data for both whole-cell antitubercular activity and Vero cell cytotoxicity. We have evaluated 12 models ranging from different single-point, dual-event dose-response, single-point and dual-event dose-response as well as combined data sets for three distinct data sets from the same laboratory. We used a fourth data set of active and inactive compounds from the same group as well as a smaller set of 177 active compounds from GlaxoSmithKline as test sets. Our data suggest combining single-point with dual-event dose-response data does not diminish the internal or external predictive ability of the models based on the receiver operator curve (ROC) for these models (internal ROC range 0.83-0.91, external ROC range 0.62-0.83) compared to the orders of magnitude smaller dual-event models (internal ROC range 0.6-0.83 and external ROC 0.54-0.83). In conclusion, models developed with 1200-5000 compounds appear to be as predictive as those generated with 25 000-350 000 molecules. Our results have implications for justifying further high-throughput screening versus focused testing based on model predictions.