Ag Dose Research Articles

Antibacterial efficacy of low-dosage silver nanoparticle-sodium alginate-chitosan nanocomposite films against pure and clinical acne strains.

The silver nanoparticles-sodium alginate-chitosan (AgNPs-Alg-Chi) nanocomposite film is a compelling material with demonstrated antibacterial efficacy against various pure bacterial strains. However, its potential cytotoxicity at elevated Ag doses warrants investigation. There is a notable dearth of studies assessing its antibacterial effectiveness against clinically relevant bacterial strains, notably Cutibacterium acnes. This study aims to assess the antibacterial efficacy of the low-dose AgNPs-Alg-Chi nanocomposite films on both pure bacterial strains and strains isolated from clinical samples obtained from 65 acne patients. The films were synthesized using green methods, incorporating kumquat (Citrus japonica) extract as a silver ion-reducing agent. The material characterization methods include UV-Vis and FTIR spectroscopies, SEM-EDS, XPS, cell culture, and MTT assay. We successfully fabricated the AgNPs-Alg-Chi nanocomposite films with a low-loading dose of Ag NPs (≤11 μg mL-1, and 37.8 ± 11.5 nm in size). The AgNPs-Alg-Chi nanocomposite film demonstrated comparable antibacterial efficacy to the AgNPs-Chi solution, with MIC values ranging from 3.67 to 5.50 μg mL-1 (p > 0.05) across all strains. Importantly, the AgNPs-Alg-Chi films demonstrated excellent biocompatibility with human keratinocytes (HaCaT cells), maintaining cell viability above 70%. The present AgNPs-Alg-Chi nanocomposite films synthesized by a green approach demonstrated potent antibacterial activity, making them promising for further development into suitable products for human use.

The results of a survey of Russian doctors in order to identify the compliance of the management of children with chronic urticaria with clinical recommendations

Introduction. Primary observation of children with (CU) in Russia is performed by pediatricians, dermatologists, and algologists. It is unclear how clinical guidelines are used in a heterogeneous group of specialists.Materials and methods. Online survey of pediatricians, allergists, and dermatologists (n = 304) in the Russian Federation using a questionnaire, from 5 blocks of questions related to etiology, diagnosis, and therapy. 316 physicians with a median experience of 10 [5; 20] years were included in the questionnaire.Results. 83.3 % of respondents observed no more than 2 children with CU per month. Self-education to expand knowledge (video lectures, special literature) was indicated by 72.6 % of participants. The clinical guidelines used by physicians were documents of pediatric and allergy associations of Russia (77.3 and 55.9 %, respectively), international guides were used by 27 % of respondents.The most frequent deviations from the recommended algorithm were the prescription of biochemical blood tests (64.9 %), ultrasound examination of organs (56.9 %), consultations of specialists without indications: gastroenterologist (48.2 %), infectious disease specialist (31.8 %), rheumatologist (27.1 %). The autologous serum test in children is not used by 87.2 % of physicians for various reasons.During allergy testing, respondents recommend: the concentration of total IgE in serum (63.9 %), the number of eosinophils in the blood (61.2 %). The importance of determining specific IgE was indicated by no more than one third of the respondents. Skin tests during remission period were supported by 59.1 % of all physicians, who considered allergologic examination to be necessary. Diet: 18.6 % of respondents do not recommend a special diet for children; 27.7 % exclude from the diet foods to which sensitization is detected, the rest recommend an nonspecific elimination diet.Antihistamines of 2nd generation (AG II) are the most used in clinical practice (86.5 %). Physicians named cetirizine (25.7 %) and levocetirizine (19.7 %) as the drugs of choice up to 12 years of age. The need to double the dose of AG II in the absence of response to the standard dose was supported by 59.5 % of physicians. The other physicians preferred a change of AG II molecule in the standard dose. Experience with the use of omalizumab was reported by 20 % of specialists, with 76.3 % understanding the significance and willingness to use biologic therapy. If omalizumab is ineffective, 44.1 % of physicians consider glucocorticosteroids to be the drug of choice; 38.8 % — cyclosporine A. About one third of physicians use alternative therapies not considered in the clinical guidelines.Conclusion. A significant number of physicians do not use recommendations based on evidence-based studies in real practice. AG II are the basis of CU therapy in children in all age groups.

Engineering Dumbbell-Shaped Au Nanobipyramid/Ag-CeO2 Plasmonic Bimetal-Semiconductor Heterostructures for Nitroaromatic Reduction

Precisely engineering the morphology of plasmonic metal–semiconductor heterostructures (PMSHs) is essential for fully utilizing the localized surface plasmon resonance (LSPR) function. However, most of the PMSHs mainly depend on the LSPR contribution of a single plasmonic metal, while the bimetal semiconductor heterostructures have been rarely reported. Herein, a series of dumbbell-shaped bimetal semiconductor heterostructures, based on Au nanobipyramids (AuNBPs, average length of 96 ± 3 nm, waist diameter of 29 ± 3 nm), lateral surfaces covered with rice-shaped Ag layers (thickness less than 5 nm), and a tip loaded with cap-shaped CeO2 (average size of 44 nm), were engineered. By simply tuning the dose of Ag+ and CTAC, we can precisely engineer the morphology of PMSHs from dumbbell-shaped monometal semiconductors (AuNBP–CeO2) to a core/shell/shell structure (AuNBP@Ag@CeO2) and to the dumbbell-shaped bimetal semiconductor AuNBP/Ag–CeO2. Notably, the AuNBP/Ag–CeO2 nanostructure exhibits higher activity in photocatalytic nitroreduction of 4-NP than AuNBP–CeO2. Mechanism analysis demonstrated that the bimetal semiconductor dumbbell-shaped AuNBP/Ag–CeO2 shows stronger electromagnetic field enhancement than the monometal semiconductor dumbbell-shaped AuNBP–CeO2, which promotes the generation of hot electrons more efficiently. This work offers an insight into precisely engineering plasmonic bimetallic semiconductor heterostructures for photocatalytic applications.

A randomized double-blind controlled proof-of-concept study of alanyl-glutamine for reduction of post-myomectomy adhesions

Study ObjectiveTo test the hypothesis that intraperitoneal instillation of a single bolus dose of l-alanyl-l-glutamine (AG) will reduce the incidence, extent and/or severity of adhesions following myomectomy and establish preliminary safety and tolerability of AG in humans. DesignPhase 1,2 Randomized, double-blind, placebo-controlled study (DBRCT). SettingTertiary care gynecology surgical centre. PatientsThirty-eight women who underwent myomectomies by laparoscopy (N = 38; AG-19 vs Placebo-19) or laparotomy (N = 10; AG-5 vs Placebo-5) with a scheduled second-look laparoscopy (SLL) 6–8 weeks later. Thirty-two patients in the laparoscopy arm completed SLL. InterventionsBolus dose of AG or normal saline solution control (0.9% NaCl) administered intraperitoneally immediately prior to suture closure of the laparoscopic ports. The average dose was 170 mL of AG or control based on a dosing scheme of 1 g/kg bodyweight. MeasurementsDigital recordings obtained for all procedures. The primary endpoint was reduction in the incidence, severity and extent of post-operative adhesions analyzed by intention-to-treat (ITT) approach. Three independent, blinded reviewers evaluated all operative video recordings to assess presence of adhesions. Post-hoc analysis assessed presence or absence of adhesions in the peritoneal cavity. Secondary endpoints assessed safety and tolerability of AG. Main resultsAdministration of AG reduced the incidence, severity and/or extent of post-operative adhesions (p = 0.046). The presence of adhesions in the AG group was lower than in the Control group (p = 0.041). Adhesion improvement was achieved in 15 of 15 (100%) in the AG group versus 5 of 17 (29.6%) in the placebo group. No serious adverse events were reported. No differences in safety parameters were observed. ConclusionsIntraperitoneal l-alanyl-l-glutamine reduced adhesion formation in all patients following laparoscopic myomectomy. Complete absence of adhesions was achieved at all abdominal sites in 93% of patients. Results confirm AG’s known effects on cellular mechanisms of adhesiogenesis and lay the foundation for new adhesion prophylaxis research and treatment.

Multistep IgE Mast Cell Desensitization Is a Dose- and Time-Dependent Process Partially Regulated by SHIP-1

Multistep mast cell desensitization blocks the release of mediators following IgE crosslinking with increasing doses of Ag. Although its invivo application has led to the safe reintroduction of drugs and foods in IgE-sensitized patients at risk for anaphylaxis, the mechanisms of the inhibitory process have remained elusive. We sought to investigate the kinetics, membrane, and cytoskeletal changes and to identify molecular targets. IgE-sensitized wild-type murine (WT) and FcεRIα humanized (h) bone marrow mast cells were activated and desensitized with DNP, nitrophenyl, dust mites, and peanut Ags. The movements of membrane receptors, FcεRI/IgE/Ag, actin, and tubulin and the phosphorylation of Syk, Lyn, P38-MAPK, and SHIP-1 were assessed. Silencing SHIP-1 protein was used to dissect the SHIP-1 role. Multistep IgE desensitization of WT and transgenic human bone marrow mast cells blocked the release of β-hexosaminidase in an Ag-specific fashion and prevented actin and tubulin movements. Desensitization was regulated by the initial Ag dose, number of doses, and time between doses. FcεRI, IgE, Ags, and surface receptors were not internalized during desensitization. Phosphorylation of Syk, Lyn, p38 MAPK, and SHIP-1 increased in a dose-response manner during activation; in contrast, only SHIP-1 phosphorylation increased in early desensitization. SHIP-1 phosphatase function had no impact on desensitization, but silencing SHIP-1 increased β-hexoxaminidase release, preventing desensitization. Multistep IgE mast cell desensitization is a dose- and time-regulated process that blocks β-hexosaminidase, impacting membrane and cytoskeletal movements. Signal transduction is uncoupled, favoring early phosphorylation of SHIP-1. Silencing SHIP-1 impairs desensitization without implicating its phosphatase function.

Nanoparticle dose and antigen loading attenuate antigen-specific T-cell responses.

Immune-mediated hypersensitivities such as autoimmunity, allergy, and allogeneic graft rejection are treated with therapeutics that suppress the immune system, and the lack of specificity is associated with significant side effects. The delivery of disease-relevant antigens (Ags) by carrier systems such as poly(lactide-co-glycolide) nanoparticles (PLG-Ag) and carbodiimide (ECDI)-fixed splenocytes (SP-Ag) has demonstrated Ag-specific tolerance induction in model systems of these diseases. Despite therapeutic outcomes by both platforms, tolerance is conferred with different efficacy. This investigation evaluated Ag loading and total particle dose of PLG-Ag on Ag presentation in a coculture system of dendritic cells (DCs) and Ag-restricted T cells, with SP-Ag employed as a control. CD25 expression was observed in nearly all T cells even at low concentrations of PLG-Ag, indicating efficient presentation of Ag by dendritic cells. However, the secretion of IL-2, Th1, and Th2 cytokines (IFNγ and IL-4, respectively) varied depending on PLG-Ag concentration and Ag loading. Concentration escalation of soluble Ag resulted in an increase in IL-2 and IFNγ and a decrease in IL-4. Treatment with PLG-Ag followed a similar trend but with lower levels of IL-2 and IFNγ secreted. Transcriptional Activity CEll ARrays (TRACER) were employed to measure the real-time transcription factor (TF) activity in Ag-presenting DCs. The kinetics and magnitude of TF activity was dependent on the Ag delivery method, concentration, and Ag loading. Ag positively regulated IRF1 activity and, as carriers, NPs and ECDI-treated SP negatively regulated this signaling. The effect of Ag loading and dose on tolerance induction were corroborated in vivo using the delayed-type hypersensitivity (DTH) and experimental autoimmune encephalomyelitis (EAE) mouse models where a threshold of 8 μg/mg Ag loading and 0.5 mg PLG-Ag dose were required for tolerance. Together, the effect of Ag loading and dosing on in vitro and in vivo immune regulation provide useful insights for translating Ag-carrier systems for the clinical treatment of immune disorders.

Phytofabrication of bimetallic silver-copper/biochar nanocomposite for environmental and medical applications

In the current study, a novel, green, low-cost, and sustainable path for the phyto-fabrication of Ag–Cu biochar nanocomposite (Ag–Cu/biochar) by Atriplex halimus biomass and aqueous extract is described. Surface plasmon resonance peaks were detected at 450 nm and 580 nm signifying the formation of both silver and copper nanoparticles, respectively on the biochar surface. XRD analysis confirmed the crystal structure of the phytosynthesized Ag–Cu/biochar whereas FT-IR, SEM, EDX, and XPS analyses confirmed the successful phytofabrication of the composite. Ag and Cu nanoparticles loaded on the biochar surface were almost spherically-shaped with a particle size ranging from 25 nm to 45 nm. Zeta potential of −25.5 mV showed the stability of Ag–Cu/biochar. The potential of this novel nanocomposite in the removal of doxycycline (DOX) was evident under different conditions as it reached nearly 100% under the optimum reaction conditions (DOX concentration; 50 ppm, pH; 9, a dose of Ag–Cu/biochar; 0.01 g, temperature; 25 °C, and H2O2 concentration; 100 mM). The promising regeneration of Ag–Cu/biochar was evident as the removal efficiency was 81% after 6 consecutive cycles. Ag–Cu/biochar was also shown an excellent antimicrobial activity against gram-negative bacteria as well a promising antioxidant activity.

Synthesis of silver nanoparticles using Plantago lanceolata extract and assessing their antibacterial and antioxidant activities

Silver nanoparticles (Ag. NPs) have shown a biological activity range, synthesized under different environment-friendly approaches. Ag. NPs were synthesized using aqueous crude extract (ACE) isolated from Plantago lanceolata. The ACE and Ag. NPs were characterized and assessed their biological and antioxidant activities. The existence of nanoparticles (NPs) was confirmed by color shift, atomic force microscopy (AFM), and UV–Vis’s spectroscopy. The FT-IR analysis indicated the association of biomolecules (phenolic acid and flavonoids) to reduce silver (Ag+) ions. The SEM study demonstrated a sphere-shaped and mean size in the range of 30 ± 4 nm. The EDX spectrum revealed that the Ag. NPs were composed of 54.87% Ag with 20 nm size as identified by SEM and TEM. AFM has ended up being exceptionally useful in deciding morphological elements and the distance across of Ag. NPs in the scope of 23–30 nm. The TEM image showed aggregations of NPs and physical interaction. Ag. NPs formation also confirmed by XPS, DRS and BET studies. Ag. NPs showed efficient activity as compared to ACE, and finally, the bacterial growth was impaired by biogenic NPs. The lethal dose (LD50) of Ag. NPs against Agrobacterium tumefaciens, Proteus vulgaris, Staphylococcus aureus, and Escherichia coli were 45.66%, 139.71%, 332.87%, and 45.54%, with IC50 (08.02 ± 0.68), (55.78 ± 1.01), (12.34 ± 1.35) and (11.68 ± 1.42) respectively, suppressing the growth as compared to ACE. The antioxidant capacity, i.e., 2,2-diphenyl-1-picrylhydrazyl (DPPH) of Ag. NPs were assayed. ACE and Ag. NPs achieved a peak antioxidant capacity of 62.43 ± 2.4 and 16.85 ± 0.4 μg mL−1, compared to standard (69.60 ± 1.1 at 100 μg mL−1) with IC50 (369.5 ± 13.42 and 159.5 ± 10.52 respectively). Finally, the Ag. NPs synthesized by P. lanceolata extract have an excellent source of bioactive natural products (NP). Outstanding antioxidant, antibacterial activities have been shown by NPs and can be used in various biological techniques in future research.

B cells promote CD8 Tcell primary and memory responses to subunit vaccines.

SUMMARYThe relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells while the so-called “helper” cells provide signals to B cells, influencing their class switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells exhibit an accelerated contraction after certain infections in B-cell-deficient mice. Here, we find that B cells significantly enhance primary CD8 T cell responses after vaccination. Moreover, memory CD8 numbers and function are impaired in B-cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also show that interleukin-27 production by B cells contributes to their impact on primary, but not memory, CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies.

The Effect of Antigen Dose and Antigen Presenting Process on T Cell Stimulation: A Method for Enrichment of TB10.4 Antigen-specific T-cell Clones.

T-lymphocytes have critical functions in the immune responses against viral and intracellular bacterial infections as well as cancers. Antigen (Ag)-specific T-lymphocyte clones enriched and expanded in vitro are valuable tools in the study of immune responses in animal models and adoptive T-cell therapy of patients with cancer or infection. We described a method for inducing, enriching, and replicating Ag-specific poly-clonal T-cells from BALB/c mice infected with live Bacillus Calmette Guérin (BCG) bacterium. During a 7-8 days procedure, T-lymphocytes were purified from immune cells of lymph nodes stimulated with immunodominant Ag of BCG, TB10.4, and expanded by interleukin -2 cytokine. We evaluated the effect of Ag doses (1, 10, and 100 μg/mL) and exposure method of Ag presenting cells (APCs) to T-cells, on T-cells' proliferation, viability, and Interferon-gamma (IFN-γ) secretion at 2, 5, and 7 days after Ag stimulation. Increasing Ag concentration increased the average cell division, but at the highest dose of Ag (100 μg/mL), T-cell viability is decreased. Only clones induced by 10 μg/mL Ag produced a desirable amount of IFN-γ. Incubation of Ag and APCs, 24 h before T-lymphocytes addition, increased the proliferation and viability of cells. T cells are in a more favorable condition around day 5 of Ag stimulation in terms of proliferation and survival, and it is the desired time for T cell restimulation. For optimal preparation of specific T-cells for adoptive cell transfer, optimization of Ag dose, the order of APCs and T-cells exposure with Ag, and the duration of initial Ag stimulation, as well as the time for restimulation, is essential.

PH-Responsive "Smart" Hydrogel for Controlled Delivery of Silver Nanoparticles to Infected Wounds.

Persistent wound infections have been a therapeutic challenge for a long time. Current treatment approaches are mostly based on the delivery of antibiotics, but these are not effective for all infections. Here, we report the development of a sensitive pH-responsive hydrogel that can provide controlled, pH-triggered release of silver nanoparticles (AgNPs). This delivery system was designed to sense the environmental pH and trigger the release of AgNPs when the pH changes from acidic to alkaline, as occurs due to the presence of pathogenic bacteria in the wound. Our results show that the prepared hydrogel restricts the release of AgNPs at acidic pH (pH = 4) but substantially amplifies it at alkaline pH (pH = 7.4 and pH = 10). This indicates the potential use of the hydrogel for the on-demand release of Ag+ depending on the environmental pH. In vitro antibacterial studies demonstrated effective elimination of both Gram-negative and positive bacteria. Additionally, the effective antibacterial dose of Ag+ showed no toxicity towards mammalian skin cells. Collectively, this pH-responsive hydrogel presents potential as a promising new material for the treatment of infected wounds.

Human CD8+ T Cells Exhibit a Shared Antigen Threshold for Different Effector Responses.

T cells recognizing cognate pMHC Ags become activated to elicit a myriad of cellular responses, such as target cell killing and the secretion of different cytokines, that collectively contribute to adaptive immunity. These effector responses have been hypothesized to exhibit different Ag dose and affinity thresholds, suggesting that pathogen-specific information may be encoded within the nature of the Ag. In this study, using systematic experiments in a reductionist system, in which primary human CD8+ T cell blasts are stimulated by recombinant peptides presented on MHC Ag alone, we show that different inflammatory cytokines have comparable Ag dose thresholds across a 25,000-fold variation in affinity. Although costimulation by CD28, CD2, and CD27 increased cytokine production in this system, the Ag threshold remained comparable across different cytokines. When using primary human memory CD8+ T cells responding to autologous APCs, equivalent thresholds were also observed for different cytokines and killing. These findings imply a simple phenotypic model of TCR signaling in which multiple T cell responses share a common rate-limiting threshold and a conceptually simple model of CD8+ T cell Ag recognition, in which Ag dose and affinity do not provide any additional response-specific information.

Size, concentration, coating, and exposure time effects of silver nanoparticles on the activities of selected soil enzymes

Silver nanoparticles (AgNPs) have a wide variety of applications in consumer products and can directly or indirectly leak into environmental compartments such as soil. The environmental risks associated with AgNPs must be assessed to assist in the development of regulatory guidelines. Because they are linked to numerous soil ecosystem functions, soil enzyme activities are very sensitive to any changes in soil management caused by environmental or human factors. Therefore, changes in soil enzymatic activities upon exposure to AgNPs can serve as early indicators of any adverse effect that these particles might have on soil quality. The objective of this study was to investigate the effect of the concentration of AgNPs (1, 10, and 100 mg kg−1 soil), size of particles (30, 80, and 200 nm), nanoparticle coatings (citrate, lipoic acid, and polyvinylpyrrolidone), and contact time between nanoparticles and soil (3 h, 3 d, and 30 d) on two soil enzymes, phenol oxidase and arylamidase, in a silt loam soil. Soil samples were treated with silver ions with similar treatments, and enzyme assays were performed to understand how the enzyme activities differed under the influence of ionic silver and nano-silver. The results revealed that the effect of AgNPs and silver ions on the soil enzymatic activities depended on the Ag dose and length of exposure more than on the particle size and coating. Soil arylamidase and phenol oxidase activities were generally inhibited in the presence of a high concentration of AgNPs and AgNO3 (100 mg kg−1 soil), though in low Ag concentrations, there was no significant inhibition. The levels of inhibition varied notably in relation to the enzyme type, wherein the arylamidase activity was affected severely compared to phenol oxidase. The effect of silver ions dissolved from AgNPs was not significant, indicating that the adverse effects on enzyme functioning was caused by the AgNPs themselves.

Study on the osteogenesis of rat mesenchymal stem cells and the long-term antibacterial activity of Staphylococcus epidermidis on the surface of silver-rich TiN/Ag modified titanium alloy.

The main causes of failure of orthopedic implants are infection and poor bone ingrowth. Surface modification of the implants to allow for long-term antibacterial and osteogenic functions is an effective solution to prevent failure of the implants. We developed silver-rich TiN/Ag nano-multilayers on the surface of titanium alloy with different doses of Ag+ . The antibacterial stability and osteogenesis of the silver-rich surface were determined by evaluating the adhesion and proliferation of Staphylococcus epidermidis, and the adhesion, proliferation, alkaline phosphatase activity, extracellular matrix mineralization, and the expression level of genes involved in osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). The results demonstrated that the antibacterial rates (Ra) of 5 × 1016 -Ag, 1 × 1017 -Ag, 5 × 1017 -Ag, and 1 × 1018 -Ag were respectively 46.21%, 85.66%, 94.99%, 98.48%, and 99.99%. After subcutaneous implantation in rats or immersion in phosphate buffered saline for up to 12 weeks, the silver-rich surface of the titanium alloy showed long-term stable inhibition of Staphylococcus epidermidis. Furthermore, in vitro and in vivo studies indicated that the Ag-implanted titanium did not show apparent cytotoxicity and that lower Ag+ implanted groups (5 × 1016 -Ag, 1 × 1017 -Ag) had better viability and biological safety when compared with higher Ag+ implanted groups. In addition, when compared with the Ti6Al4V-group, all Ag-implanted groups exhibited enhanced osteogenic indicators in rat BMSCs. Regarding osteogenic indicators, the surfaces of the 5 × 1017 -Ag group had better osteogenic effects than those of other groups. Therefore, the proper dose of Ag+ implanted TiN/Ag nano-multilayers may be one of the options for the hard tissue replacement materials with antibacterial activity and osteogenic functions.

Smartphone controlled interactive portable device for theranostics in vitro

In this work, a smartphone controlled interactive theranostic device has been developed to perform in vitro photodynamic therapy (PDT) and diagnostic assays for treatment assessment on a single platform. Further, silver nanorod (Ag NR) was identified as a photosensitizer and its effect was studied in three different cell lines. PDT was achieved with Ag NRs using low irradiation (1.4 mW/cm2 at 632 nm) from light emitting diodes (LEDs) in the device. Specifically, PDT in conjugation with widely used chemotherapeutic drug doxorubicin (Dox) proved effective in killing of HeLa cancer cells and multicellular tumor spheroids at a minimum dose of Ag (2.5 μg/mL). The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and LDH (lactate dehydrogenase) assays performed with the device indicated the therapeutic success of the delivered PDT. The device is portable and can be adapted for different wavelength irradiations and radiation doses. Additionally, wireless operation using a custom designed smartphone application makes it convenient to use in complex environments without much of human intervention.

Speciation Analysis of the Uptake and Biodistribution of Nanoparticulate and Ionic Silver in Escherichia coli.

A new method was developed to determine the nanoparticulate and ionic silver (Ag) species in bacteria (Escherichia coli, E. coli). By removal of the cell wall with lysozyme, the cell surface-adsorbed Ag species were separated from the intracellular Ag species, which were extracted by tetramethylammonium hydroxide and determined by size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICP-MS). The detection limit is 3 ng/107 CFU/mL (where CFU is colony-forming unit) for both silver nanoparticles (AgNPs) and ionic Ag(I) species. The cell wall-adsorbed Ag was calculated by subtracting the contents of the intra- and extracellular Ag from the total exposure dose of Ag, and therefore the biodistribution of Ag species was profiled. We then applied this strategy to quantitatively analyze extra- and intracellular Ag species in E. coli after respective exposure to Ag+ and 10 and 30 nm AgNPs at different effective concentrations (EC10, EC50, and EC90). Results showed that the intracellular and cell wall-bound Ag account for 5.98-15.21% and 25.13-64.43% of the exposed dose, respectively, and AgNPs could transform into complexed or free Ag+. Our method opens new avenues for the quantitative analysis of the uptake and biodistribution of nanoparticles and their transformation species in bacteria.

Nitrate reduction via micro-electrolysis on Zn-Ag bimetal combined with photo-assistance

A selective and efficient chemical reduction of nitrate to nitrogen gas using micro-electrolysis on ZnAg combined with a photo-assisted reduction in the presence of formic acid was investigated. The 99.58% removal of nitrate, 0.073 min−1 of rate constant and 94.3% nitrogen selectivity were achieved in Zn-Ag/hv/HCOOH system under the initial pH 2.5, 13.8 mmol/L of formic acid and 60 g/L of Zn-0.06%Ag dose at 60 min. The Zn-Ag/hv/HCOOH system had the highest removal rate and nitrogen selectivity for nitrate reduction compared with the alone or two combinations of ZnAg bimetals, formic acid, and UV-A. Furthermore, the co-existence anions of HCO3− and CO32− showed a negative effect on nitrate reduction while SO42− had slightly promoted the reduction process. During the nitrate reduction by Zn-Ag/hv/HCOOH process, rapid reduction of NO3− to NO2− was primarily caused by ZnAg bimetal. Subsequently, the conversion of NO2− to N2 was mainly owing to the produced CO2− by the reaction of formic acid and UV-A. The results suggested a novel strategy of chemical reduction combined with photoreduction for denitrification with high reaction kinetic as well as high nitrogen gas selectivity.

Understanding how AKT phosphorylation of hnRNPA1 modulates T cell fate and function

Abstract T regulatory cells (Treg) play a significant role in maintaining self-tolerance and preventing autoimmune diseases. We and others have shown that low dose favors Treg and T helper (Th) 2 cell differentiation, while high Ag dose stimulation activates the PI3K/Akt/mTOR pathway, favoring inflammatory Th1 and Th17 cell differentiation (Tconv). Differences in PI3K/Akt/mTOR signaling not only affects T cell fate but our research shows that Akt phosphorylation of the RNA-binding protein, (RBP) heterogeneous nuclear ribonucleoprotein (hnRNP) A1, is dependent on TCR signal strength. RBPs such as hnRNPA1 are emerging as regulators of RNA processing and stability in immune cells, and the effect of RBP on T cell differentiation is a growing subject of interest. We have shown hnRNPA1 is required for optimal Treg differentiation by performing knockdown experiments, and our present research is focused on identifying a role for Akt phosphorylation in hnRNPA1 function. HnRNPA1 is known to have a single Akt phosphorylation site at S199 and our lab has generated a new mutant mouse model, hnRNPA1-S199A (mA1). This mutation affects the ability of Akt to phosphorylate hnRNPA1 in all immune cells. Using Cytek’s Aurora flow cytometer we characterized the immune cell populations of mA1 at steady state. Preliminary data do not indicate any major changes in innate immune and B cells populations at steady state. We observed modest changes in CD4 T cell population frequencies at steady state. Current work using In vitro skewing suggests that Akt phosphorylation of hnRNPA1 influences Treg fate. This project suggests a novel mechanism by which Akt modulates T cell fate.

1417. Evaluating the Dissonance Between Cmax and AUC with Clinically Utilized Aminoglycoside (AG) Dosing Regimens: Use of Tobramycin (TOB) Against Pseudomonas aeruginosa (PA) as a Case Study

BackgroundCurrent dogma suggests optimizing AG doses based on peak concentration (Cmax), without consideration of daily drug exposure (AUC24). The correlation between attainment of the TOB pharmacokinetic-pharmacodynamic (PK-PD) targets, Cmax:MIC and AUC24:MIC ratio was explored using a TOB population PK (PPK) model, Monte Carlo simulation, and PA nonclinical PK-PD data.MethodsSimulated TOB plasma concentration-time profiles for traditional (TD) and extended interval (EID) dosing regimens were generated using a published PPK model [Aarons. Br J Clin Pharmacol 1989;28:305–14]. Simulations were performed by bootstrapping from a database of >1,400 infected patients enrolled in clinical trials to achieve n = 1,000 per renal function group defined by varying creatinine clearance ranges. Variability in average TOB AUC24 and Cmin over 48 hours was assessed to determine dosing regimens that produced, for each renal group, (1) ≤50% difference in median AUC24 compared with that of normal renal function (90–120 mL/minute); (2) ≤25% of simulated AUC24 values beyond the fifth and 95th percentiles of the AUC24 distribution for normal renal function; and (3) ≤20% of Cmin values >2 mg/L. Once these requirements were met across renal groups, the percentages of simulated patients achieving the Cmax:MIC target ≥10 and AUC24:MIC target for 1-log10CFU reduction (≥83.9) at MIC values of 0.5–2 mg/L were assessed.ResultsDistributions of simulated TOB AUC24 and Cmin values by renal group are shown in Figure 1. Figures 2 and 3 depict the discordance between Cmax:MIC and AUC24:MIC target attainment for TD and EID, respectively. Of 6,000 simulated patients receiving TD, 20.0% achieved the AUC24:MIC target at an MIC = 1 mg/L without producing a Cmax:MIC ≥10, whereas 55.1% of 5,000 simulated patients receiving EID failed to achieve the AUC24:MIC target despite producing a Cmax:MIC ≥10.ConclusionAt clinically relevant MICs, AG TD regimens optimized based on Cmax may result in patients receiving higher than necessary doses, while EID regimens may lead to underdosing. Given the transient nature of a peak concentration compared with overall drug exposure, the adequacy of AG dosing should consider variability in drug clearance (AUC24) over variability in distributional volume (Cmax). Disclosures All authors: No reported disclosures.

The Effect of Pulsed Laser Radiation on a Si Layer with a High Dose of Implanted Ag+ Ions

With the purpose of creating a thin composite layer of Ag:Si containing Ag nanoparticles (NPs), the effect of a nanosecond pulse produced by ruby laser (λ = 0.694 µm) on single-crystal c-Si implanted with a high dose of Ag+ ions is studied. The pulsed laser annealing (PLA) is carried out with an energy density exceeding the melting threshold of amorphous а-Si (W ≥ 1.2 J/cm2). During the PLA, temporal dynamics of reflectivity R(t) of probing laser radiation (λ = 1.064 µm) from the Ag:Si layer is explored and compared to data on the melt existence time obtained by the computer simulation. The morphology of the surface, crystallinity, and spectral optical reflection R(λ) of Ag:Si layers subject to PLA are studied. PLA is found to cause melting and subsequent crystallization of the implanted а-Si with ion-synthesized Ag NPs. In addition, a decrease of the surface roughness from 9 to 3–4 nm and redistribution of Ag NP sizes into two fractions—fine (5–15 nm) and larger (40–60 nm)—are observed. The weakening of plasmon intensity Ag NPs in Si (λmax = 835 nm) is observed in R(λ) spectra of an Ag:Si layer after PLA as compared with the initial implanted surface. This weakening may be caused by a decrease in concentration of Ag atoms in the immediate proximity to the surface as a result of Ag impurity partial diffusion within the melted layer, as well as Ag partial evaporation during the PLA.