A model for estimating costs and benefits of new vaccine technologies from the perspective of both buyers and sellers.

Although vaccination is widely considered one of the most cost-effective health interventions available, global coverage rates for many vaccines remain lower than necessary for disease elimination and eradication. New vaccine technologies can play an important role in addressing barriers to vaccination and increasing coverage rates. To identify and prioritize vaccine technology investments, decision makers must be able to compare the overall costs and benefits of each investment option. While these data points may exist, they are often confined to silos. Decision makers would benefit from a model that synthesizes this broad range of data and provides clear and actionable information. To facilitate vaccine investment, purchasing and deployment decisions, we developed a systematic and transparent cost-benefit model that estimates the value and risk of a given investment scenario from the perspective of both "buyers" (e.g., global donors, country governments) and "sellers" (e.g., developers, manufacturers) of vaccines. This model, which can be used to evaluate scenarios related to a single vaccine presentation or a portfolio of vaccine presentations, leverages our published approach for estimating the impact of improved vaccine technologies on vaccination coverage rates. This article presents a description of the model and provides an illustrative example application to a portfolio of measles-rubella vaccine technologies currently under development. Although the model is generally applicable to organizations involved in vaccine investment, manufacturing or purchasing, we believe it may be particularly useful to those engaged in vaccine markets that rely strongly on funding from institutional donors.

Exposure to psychotropic medications and COVID-19 course after hospital admission: Results from a prospective cohort study.

OBJECTIVE: There is evidence of a bidirectional association between COVID-19 disease and psychiatric disorders. We aimed to assess whether exposure to psychotropic medications prior to hospitalization was associated with mortality or discharge within 30 days after hospital admission. METHODS: In this prospective study, we included all individuals with a laboratory-confirmed COVID-19 infection who were admitted to the Bologna University Hospital between 1st March 2020 and 31st January 2021. We collected data about pre-existing psychiatric disorders and the use of psychotropic medications at the admission. As univariate analyses, we estimated cumulative incidence functions for 30-day mortality and discharge stratifying by exposure to each of the psychotropic medication classes. Finally, we fitted Cox regression models to estimate cause-specific Hazard Ratios (HR) of 30-day mortality and discharge. Results were adjusted for sociodemographic (age, sex), clinically relevant variables (comorbidity, c-reactive protein levels, severity of disease at presentation, history of smoking, study period), and psychiatric variables (psychiatric disorder diagnosis, number of psychotropic medications). RESULTS: Out of a total of 1238 hospitalized patients, 316 were prescribed psychotropic medications at the time of admission. Among these, 45 (3.6%) were taking a first-generation antipsychotics (FGA) and 66 (5.3%) a second generation antipsychotic (SGA). Exposure to SGA was associated with increased rates of 30-day mortality (HR = 2.01, 95%CI = 1.02-3.97) and exposure to FGA was associated with decreased rates of 30-day discharge (HR = 0.55, 95%CI = 0.33-0.90). CONCLUSION: Patients with COVID-19 infection exposed to FGA and SGA may have worse COVID-19 infection outcomes.

Public views of community pharmacy services during the COVID-19 pandemic: a national survey.

OBJECTIVE: To assess public opinion about community pharmacy services in Lebanon during the COVID-19 pandemic. METHOD: A cross-sectional study using an online questionnaire was conducted between April and August of 2021. A link was shared randomly among the Lebanese population using WhatsApp and Facebook. Public perceptions were explored within 3 different indicators: general services (B) dispensing (C), and storage (D). Chi-square, Student's test and ANOVA tests were used. p < 0.05 was considered statistically significant. RESULTS: Out of 491 responses, only 9.6% scored above the 75th percentile (19.3% for the general services, 2.4% for dispensing indicator and 12.6% for storage indicator). The main concerns focused on lack of medication and reduced opening hours; however, 67.1% of respondents preferred consulting the community pharmacist instead of visiting primary health care centers, doctor's private clinic and hospitals. Higher mean values of indicators B, C and in the overall indicator were significantly found in the presence of a pharmacist compared to the support pharmacy workforce. CONCLUSION: The overall public perception was inadequate. Significant difference in terms of quality of services was detected in the presence and absence of a community pharmacist during the crisis. It is recommended that the Order of Pharmacist of Lebanon (OPL) and the Ministry of Public Health (MOPH) undergo further steps mainly to enforce the laws concerning dispensing and storage indicators, improve the services in terms of extending the opening hours, ensure the availability of medicines and increase public awareness.

The current trends and challenges towards good community pharmacy practice and the way forward.

Background: The practice of pharmacy continues to evolve. Comprehensive research to monitor and assess the development of the practice is needed. Good Pharmacy Practices (GPP) have been adopted by many countries to enhance the quality of services. Little information is available concerning how pharmacy practices are being implemented in developing countries. Lebanon being a developing country is a good example where community pharmacy practice doesn't follow clear guidelines and no evidence of good clinical practice. Objectives: This study aims to highlight GPP implementation, to identify obstacles impeding implementation, and to suggest how its application could be facilitated in Lebanon. Methods: The review included studies published in English during the last five years covering aspects of pharmacy practice in relation to GPP standards. The search excluded research related to hospital pharmacy practice and primary health care centers since they have their own quality standards. Results: The research identified 20 recent studies that covered aspects of community pharmacy practice in Lebanon in relation to GPP standards. Eight of the studies related to research and professional development,5 related to the provision of medicines,4 related to interaction and communication,1 related to trainees,1 related to pharmacotherapy monitoring, and 1 related to documentation systems. An additional 6 studies provided insight into factors that affect the pharmacy practice in general. It is apparent that the pharmacy practice would benefit if pharmacists were better supported with financial incentives and a readjustment of their working conditions as this would have a positive impact on their productivity, job satisfaction, and overall well-being. The review indicated that the standard of research and professional development was the most studied topic and it was recommended that pharmacists develop their research capabilities. It was observed that there is a tendency towards implementing Continuous Education for pharmacists and obstacles primarily included work and family commitments, lack of interest, lack of time, difficulties in commuting, and lack of competence in the use of technology. This standard is aligned with the FIP's developmental goal of continuing professional development strategies. The search also identified only one pilot study to assess GGP compliance among community pharmacies in Lebanon. This pilot study was limited and showed low adherence of community pharmacies in Lebanon to GPP standards.Barriers to implementation are lack of enforcing laws,inadequate dissemination of the standards among the community pharmacists, poor public perception, and the financial and soscioeconomically crisis facing Lebanon. Conclusion: Collaborated efforts are needed to implement GPP standards in Lebanon.It is recommended to undergo training and awareness sessions to community pharmacists thus enhancing their commitment and motivation. It is also recommended to establish key performance indicators to monitor the implementation. Indicators should include structure indicators for regulating the storage of medications, process indicators for regulating the dispensing, and outcome indicators for reporting patient safety incidents, measuring public satisfaction and the provision and use of medicines.These recommendations can be used by Health authorities and Pharmacy educational institutions in Lebanon and in all similar low-income countries.

A method for estimating the impact of new vaccine technologies on vaccination coverage rates.

Vaccines are one of the most cost-effective tools for improving human health and well-being. The impact of a vaccine on population health is partly determined by its coverage rate, the proportion of eligible individuals vaccinated. Coverage rate is a function of the vaccine presentation and the population in which that presentation is deployed. This population includes not only the individuals vaccinated, but also the logistics and healthcare systems responsible for vaccine delivery. Because vaccine coverage rates remain below targets in many settings, vaccine manufacturers and purchasers have a shared interest in better understanding the relationship between vaccine presentation, population characteristics, and coverage rate. While there have been some efforts to describe this relationship, existing research and tools are limited in their ability to quantify coverage rate changes across a broad set of antigens, vaccine presentations, and geographies. In this article, we present a method for estimating the impact of improved vaccine technologies on vaccination coverage rates. It is designed for use with low- and middle-income country vaccination programs. This method uses publicly available data and simple calculations based on probability theory to generate coverage rate values. We first present the conceptual framework and mathematical approach. Using a Microsoft Excel-based implementation, we then apply the method to a vaccine technology in early-stage development: micro-array patch for a measles-rubella vaccine (MR-MAP). Example outputs indicate that a complete switch from the current subcutaneous presentation to MR-MAP in the 73 countries ever eligible for Gavi support would increase overall vaccination coverage by 3.0-4.9 percentage points depending on the final characteristics of the MR-MAP. This change equates to an additional 2.6-4.2 million children vaccinated per year. Our method can be readily extended to other antigens and vaccine technologies to provide quick, low-cost estimates of coverage impact. As vaccine manufacturers and purchasers face increasingly complex decisions, such estimates could facilitate objective comparisons between options and help these decision makers obtain the most value for money.

A Rapid Cost Modeling Tool for Evaluating and Improving Public Health Supply Chain Designs.

Effective and efficient health supply chains play a vital role in achieving health outcomes by ensuring supplies are available for people to access quality health services. However, supplying health commodities to service delivery points is complex and costly in many low- and middle-income countries. Thus, governments and partner organizations are often interested in understanding how to design their health supply chains more cost efficiently.Several modeling tools exist in the public and private market that can help assess supply chain efficiency and identify supply chain design improvements. These tools are generally capable of providing users with very precise cost estimates, but they often use proprietary software and require detailed data inputs. This can result in a somewhat lengthy and expensive analysis process, which may be prohibitive for many decision makers, especially in the early stages of a supply chain design process. For many use cases, such as advocacy, informing workshop and technical meetings, and narrowing down initial design options, decision makers may often be willing to trade some detail and accuracy in exchange for quicker and lower-cost analysis results. To our knowledge, there are no publicly available tools focused on generating quick, high-level estimates of the cost and efficiency of different supply chain designs.To address this gap, we designed and tested an Excel-based Rapid Supply Chain Modeling (RSCM) Tool. Our assessment indicated that, despite requiring significantly less data, the RSCM Tool can generate cost estimates that are similar to other common analysis and modeling methods. Furthermore, to better understand how the RSCM Tool aligns with real-world processes and decision-making timelines, we used it to inform an ongoing immunization supply chain redesign in Angola. For the use cases described above we believe that the RSCM Tool addresses an important need for quicker and less expensive ways to identify more cost-efficient supply chain designs.

Follow-up blood cultures are associated with improved outcome of patients with gram-negative bloodstream infections: retrospective observational cohort study.

OBJECTIVES: We examined factors associated with follow-up blood cultures (FUBCs) in patients with monomicrobial Gram-negative (GN) bloodstream infection (BSI) and investigated the impact of FUBCs on therapeutic management and patient outcome. METHODS: A retrospective cohort analysis was conducted of adult patients diagnosed with GN-BSI at a tertiary-care university hospital during 2013-2016. FUBCs performed between 24 hours and 7 days after index BCs was the exposure variable. Risk factors for 30-day mortality were analysed by multivariate Cox analysis on the overall cohort, including FUBCs as a time-varying covariate and on 1:1 matched patients according to Sequential Organ Failure Assessment (SOFA) score and time to FUBC. RESULTS: In 278 (17.6%) of 1576 patients, FUBCs were performed within a median of 3 and 2 days after index BCs and active antibiotic therapy initiation. Persistent BSI was found in 107 (38.5%) of 278 patients. FUBCs were performed in more severely ill patients, with nonurinary sources, difficult-to-treat pathogens and receipt of initial inappropriate therapy. Source control and infectious disease consultation rates were higher among patients with preceding FUBCs and was associated with longer treatment duration. Thirty-day mortality was 10.4%. Independent risk factors for mortality were Charlson comorbidity index (hazard ratio (HR) 1.12) SOFA (HR 1.11), septic shock (HR 2.64), urinary source (HR 0.60), central venous catheter source (HR 2.30), complicated BSI (HR 2.10), carbapenem resistance (HR 2.34), active empiric therapy (HR 0.68), source control (HR 0.34) and FUBCs (HR 0.48). Association between FUBCs and lower mortality was confirmed in the 274 matched pairs. CONCLUSIONS: FUBCs were performed in more severe GN-BSIs, yielding a high rate of persistent BSI. In this context, FUBCs were associated with lower mortality.

The impact of carbapenemase-producing Enterobacteriaceae colonization on infection risk after liver transplantation: a prospective observational cohort study.

OBJECTIVE: To investigate the impact of colonization with carbapenemase-producing Enterobacteriaceae (CPE) on the CPE infection risk after liver transplantation (LT). METHODS: Prospective cohort study of all adult patients undergoing LT at our centre over an 8-year period (2010-2017). Individuals were screened for CPE colonization by rectal swabs at inclusion onto the waiting list, immediately before LT and weekly after LT until hospital discharge. Asymptomatic carriers did not receive decolonization, anti-CPE prophylaxis or pre-emptive antibiotic therapy. Participants were followed up for 1 year after LT. RESULTS: We analysed 553 individuals who underwent a first LT, 38 were colonized with CPE at LT and 104 acquired colonization after LT. CPE colonization rates at LT and acquired after LT increased significantly over the study period: incidence rate ratios (IRR) 1.21 (95% CI 1.05-1.39) and 1.17 (95% CI 1.07-1.27), respectively. Overall, 57 patients developed CPE infection within a median of 31 (interquartile range 11-115) days after LT, with an incidence of 3.05 cases per 10 000 LT-recipient-days and a non-significant increase over the study period (IRR 1.11, 95% CI 0.98-1.26). In multivariable analysis, CPE colonization at LT (hazard ratio (HR) 18.50, 95% CI 6.76-50.54) and CPE colonization acquired after LT (HR 16.89, 95% CI 6.95-41.00) were the strongest risk factors for CPE infection, along with combined transplant (HR 2.60, 95% CI 1.20-5.59), higher Model for End-Stage Liver Disease at the time of LT (HR 1.03, 95% CI 1.00-1.07), prolonged mechanical ventilation (HR 2.63, 95% CI 1.48-4.67), re-intervention (HR 2.16, 95% CI 1.21-3.84) and rejection (HR 2.81, 95% CI 1.52-5.21). CONCLUSIONS: CPE colonization at LT or acquired after LT were the strongest predictors of CPE infection. Prevention strategies focused on LT candidates and recipients colonized with CPE should be investigated.

Adherence to international guidelines for the treatment of meningitis infections in Lebanon.

OBJECTIVES: To assess meningitis treatment in Lebanon's compatibility with the Infectious Diseases Society of America (IDSA) guidelines and the effect of non-compliance on mortality. Methods: This is a retrospective study, conducted in 5 Lebanese hospitals, and enrolling all patients diagnosed with meningitis who presented to the involved hospitals from January 2008 to December 2016.  Results: A total of 252 participants were enrolled in the study. Of these patients, 205 (82.7%) were diagnosed with viral meningitis and 47 (17.3%) with bacterial meningitis, which was confirmed using laboratory tests. For patients with viral meningitis, 128 (62.4%) remained on the initial prescribed antibiotics despite the negative cerebrospinal fluid (CSF) and blood culture results. For bacterial meningitis patients, 30.8% received treatment regimen incompatible with the IDSA guidelines. The most common reason for the treatment incompatibility was the definitive drug choice after the culture results (49.1%) and the least common reason was inappropriate hospital stay days (25.9%). The mortality rate was 13.5%. Having low proteins values in the CSF (odds ratio=0.095) was associated with lower mortality compared to patients with normal protein values. Conclusion: This study shows a high percentage of inappropriate treatment in Lebanese hospitals despite these hospitals having adopted international treatment guidelines. This inappropriate management was associated with an increasing rate of mortality and neurological complications.

CO2 and N2O from water resource recovery facilities: Evaluation of emissions from biological treatment, settling, disinfection, and receiving water body.

Water resource recovery facilities (WRRFs) contribute to climate change and air pollution, as they are anthropogenic potential sources of direct and indirect emission of greenhouse gases (GHGs). Studies concerning the monitoring and accounting for GHG emissions from WRRFs are of increasing interest. In this study, the floating hood technique for gas collection was coupled with the off-gas method to monitor and apportion nitrous oxide (N2O) and carbon dioxide (CO2) emissions from both aerated and non-aerated tanks in a municipal water resource recovery facility, in order to investigate its carbon footprint (CFP). To our knowledge, this is the first time that the chamber technique was applied to evaluate gas fluxes from the settler, where an emission factor (EF) of 4.71 ∗ 10-5 kgCO2,eq kgbCOD-1 was found. Interesting results were found in the disinfection unit, which was the major contributor to direct N2O emissions (with a specific emission factor of 0.008 kgCO2,eq kgbCOD-1), due to the chemical interaction between hydroxylamine and the disinfectant agent (hypochlorite). The specific emission factor of the biological aerated tank was 0.00112 kgCO2,eq kgbCOD-1. The average direct CO2 emission was equal to 0.068 kgCO2 kgbCOD-1 from the activated sludge tank and to 0.00017 kgCO2 kgbCOD-1 from the secondary clarifier. Therefore, taking into account the contribution of both direct N2O and CO2 emissions, values of 0.069 kgCO2,eq kgbCOD-1, 0.008 kgCO2,eq kgbCOD-1 and 0.00022 kgCO2,eq kgbCOD-1, were found for the net CFP of the aerated compartment, the disinfection unit and the clarifier, respectively. The plant energy Footprint (eFP) was also evaluated, confirming that the aeration system is the major contributor to energy consumption, as well as to indirect CO2 emission, with a specific eFP of 1.49 kWh kgbCOD-1.

Treatment duration for Escherichia coli bloodstream infection and outcomes: retrospective single-centre study.

OBJECTIVES: To investigate the impact of treatment duration on mortality and on relapse in patients with Escherichia coli bloodstream infection (BSI). METHODS: Retrospective single-centre study of patients diagnosed with E. coli BSI at our centre over a 4-year period. EXCLUSION CRITERIA: age <18 years, clinical data not available, polymicrobial BSI, failure to receive in vitro active therapy, and death while receiving antibiotic therapy. Exposure variable was treatment duration dichotomized into short (≤10 days) and long (>10 days) therapy. Primary end point was all-cause mortality within 90 days after index BSI. Secondary end point was relapse, defined as repeat isolation of E. coli from blood cultures within 90 days after index BSI, in patients with documented clinical cure and completion of therapy for the initial episode. RESULTS: Of the 856 analysed patients: 426 received short and 430 received long therapy. All-cause mortality at day 90 occurred in 47 patients; on multivariate analysis, short therapy was not associated with a higher risk of mortality, also after adjusting the model for the propensity score of receiving short therapy. Relapse occurred in 42 patients. Independent risk factors for relapse using death as competing risk were immunosuppression (subhazard ratio 4.67, p < 0.001), and end-stage liver disease (subhazard ratio 2.58, p 0.013). The propensity-weighted estimation of the average treatment effect for relapse reduction with long therapy (>10 days) was -1.6% (p 0.26) in the total population, and -7.1% (p 0.18) in immunocompromised patients. CONCLUSIONS: We could not identify shorter treatment duration as a risk factor for mortality and for relapse in patients with E. coli BSI.

Self-medication misuse in the Middle East: a systematic literature review.

Regulations usually distinguish between prescription-only (POM) and over-the-counter (OTC) medicines. The former requires medical prescription; the latter are available for SM of common minor or easily treated ailments. However, in the Eastern Mediterranean countries, theoretical prescription medicines can easily be purchased without a prescription, as self-medication (SM) resulting in potential misuse and unnecessary risk for patients. The magnitude of this activity is uncertain. The aim of this article, therefore, is to undertake a comprehensive review to identify the different types of medicines that can easily be purchased as SM in Middle East and recognized as misused. An extensive review of the published literature (1990-2015) was conducted using Pubmed, web of science, Cochrane, and Google Scholar databases, for OTC medicine misuse in the Middle East. A total of 72 papers were identified. Medicines involved in misuse included: codeine containing products, topical anesthetics, topical corticosteroids, antimalarial, and antibiotics. Self-medication misuse of medicines seemed widespread. Individual treatment patterns were not clearly identified. Studies were not standardized, limiting the comparability between studies and the estimation of the scale of misuse. Pharmacists, friends, or parents were found to be the main sources of SMs. Knowledge and attitudes are an important contributing factor in the misuse of these medications. Strategies and interventions to limit misuse were rarely identified in literature. In conclusion, a massive problem involving a range of medicines was found in Middle East. Standardization of studies is a prerequisite to the understanding and prevention of misuse of self-medication.

Ligand Characteristics Important to Avidity Interactions of Multivalent Nanoparticles.

Multivalent interactions involve the engagement of multiple ligand-receptor pairs and are important in synthetic biology as design paradigms for targeted nanoparticles (NPs). However, little is known about the specific ligand parameters important to multivalent interactions. We employed a series of oligonucleotides as ligands conjugated to dendrimers as nanoparticles, and used complementary oligonucleotides on a functionalized SPR surface to measure binding. We compared the effect of ligand affinity to ligand number on the avidity characteristics of functionalized NPs. Changing the ligand affinity, either by changing the temperature of the system or by substitution noncomplementary base pairs into the oligonucleotides, had little effect on multivalent interaction; the overall avidity, number of ligands required for avidity per particle, and the number of particles showing avidity did not significantly change. We then made NP conjugates with the same oligonucleotide using an efficient copper-free click chemistry that resulted in essentially all of the NPs in the population exceeding the threshold ligand value. The particles exceeding the threshold ligand number again demonstrated high avidity interactions. This work validates the concept of a threshold ligand valence and suggests that the number of ligands per nanoparticle is the defining factor in achieving high avidity interactions.

Jagged 1 is a major Notch ligand along cholangiocarcinoma development in mice and humans.

Intrahepatic cholangiocarcinoma (ICC) is a rare yet deadly malignancy with limited treatment options. Activation of the Notch signalling cascade has been implicated in cholangiocarcinogenesis. However, while several studies focused on the Notch receptors required for ICC development, little is known about the upstream inducers responsible for their activation. Here, we show that the Jagged 1 (Jag1) ligand is almost ubiquitously upregulated in human ICC samples when compared with corresponding non-tumorous counterparts. Furthermore, we found that while overexpression of Jag1 alone does not lead to liver tumour development, overexpression of Jag1 synergizes with activated AKT signalling to promote liver carcinogenesis in AKT/Jag1 mice. Histologically, tumours consisted exclusively of ICC, with hepatocellular tumours not occurring in AKT/Jag1 mice. Furthermore, tumours from AKT/Jag1 mice exhibited extensive desmoplastic reaction, an important feature of human ICC. At the molecular level, we found that both AKT/mTOR and Notch cascades are activated in AKT/Jag1 ICC tissues, and that the Notch signalling is necessary for ICC development in AKT/Jag1 mice. In human ICC cell lines, silencing of Jag1 via specific small interfering RNA reduces proliferation and increases apoptosis. Finally, combined inhibition of AKT and Notch pathways is highly detrimental for the in vitro growth of ICC cell lines. In summary, our study demonstrates that Jag1 is an important upstream inducer of the Notch signalling in human and mouse ICC. Targeting Jag1 might represent a novel therapeutic strategy for the treatment of this deadly disease.

Repeated dose (28-day) administration of silver nanoparticles of varied size and coating does not significantly alter the indigenous murine gut microbiome.

Silver nanoparticles (AgNPs) have been used as antimicrobials in a number of applications, including topical wound dressings and coatings for consumer products and biomedical devices. Ingestion is a relevant route of exposure for AgNPs, whether occurring unintentionally via Ag dissolution from consumer products, or intentionally from dietary supplements. AgNP have also been proposed as substitutes for antibiotics in animal feeds. While oral antibiotics are known to have significant effects on gut bacteria, the antimicrobial effects of ingested AgNPs on the indigenous microbiome or on gut pathogens are unknown. In addition, AgNP size and coating have been postulated as significantly influential towards their biochemical properties and the influence of these properties on antimicrobial efficacy is unknown. We evaluated murine gut microbial communities using culture-independent sequencing of 16S rRNA gene fragments following 28 days of repeated oral dosing of well-characterized AgNPs of two different sizes (20 and 110 nm) and coatings (PVP and Citrate). Irrespective of size or coating, oral administration of AgNPs at 10 mg/kg body weight/day did not alter the membership, structure or diversity of the murine gut microbiome. Thus, in contrast to effects of broad-spectrum antibiotics, repeat dosing of AgNP, at doses equivalent to 2000 times the oral reference dose and 100-400 times the effective in vitro anti-microbial concentration, does not affect the indigenous murine gut microbiome.

Effects of particle size and coating on toxicologic parameters, fecal elimination kinetics and tissue distribution of acutely ingested silver nanoparticles in a mouse model.

Consumer exposure to silver nanoparticles (AgNP) via ingestion can occur due to incorporation of AgNP into products such as food containers and dietary supplements. AgNP variations in size and coating may affect toxicity, elimination kinetics or tissue distribution. Here, we directly compared acute administration of AgNP of two differing coatings and sizes to mice, using doses of 0.1, 1 and 10 mg/kg body weight/day administered by oral gavage for 3 days. The maximal dose is equivalent to 2000× the EPA oral reference dose. Silver acetate at the same doses was used as ionic silver control. We found no toxicity and no significant tissue accumulation. Additionally, no toxicity was seen when AgNP were dosed concurrently with a broad-spectrum antibiotic. Between 70.5% and 98.6% of the administered silver dose was recovered in feces and particle size and coating differences did not significantly influence fecal silver. Peak fecal silver was detected between 6- and 9-h post-administration and <0.5% of the administered dose was cumulatively detected in liver, spleen, intestines or urine at 48 h. Although particle size and coating did not affect tissue accumulation, silver was detected in liver, spleen and kidney of mice administered ionic silver at marginally higher levels than those administered AgNP, suggesting that silver ion may be more bioavailable. Our results suggest that, irrespective of particle size and coating, acute oral exposure to AgNP at doses relevant to potential human exposure is associated with predominantly fecal elimination and is not associated with accumulation in tissue or toxicity.

Characterization of Folic Acid and Poly(amidoamine) Dendrimer Interactions with Folate Binding Protein: A Force-Pulling Study.

Atomic force microscopy force-pulling experiments have been used to measure the binding forces between folic acid (FA) conjugated poly(amidoamine) (PAMAM) dendrimers and folate binding protein (FBP). The generation 5 (G5) PAMAM conjugates contained an average of 2.7, 4.7, and 7.2 FA per dendrimer. The most probable rupture force was measured to be 83, 201, and 189 pN for G5-FA2.7, G5-FA4.7, and G5-FA7.2, respectively. Folic acid blocking experiments for G5-FA7.2 reduced the frequency of successful binding events and increased the magnitude of the average rupture force to 274 pN. The force data are interpreted as arising from a network of van der Waals and electrostatic interactions that form between FBP and G5 PAMAM dendrimer, resulting in a binding strength far greater than that expected for an interaction between FA and FBP alone.

Formulation, high throughput in vitro screening and in vivo functional characterization of nanoemulsion-based intranasal vaccine adjuvants.

Vaccine adjuvants have been reported to induce both mucosal and systemic immunity when applied to mucosal surfaces and this dual response appears important for protection against certain pathogens. Despite the potential advantages, however, no mucosal adjuvants are currently approved for human use. Evaluating compounds as mucosal adjuvants is a slow and costly process due to the need for lengthy animal immunogenicity studies. We have constructed a library of 112 intranasal adjuvant candidate formulations consisting of oil-in-water nanoemulsions that contain various cationic and nonionic surfactants. To facilitate adjuvant development we first evaluated this library in a series of high-throughput, in vitro assays for activities associated with innate and adaptive immune activation in vivo. These in vitro assays screened for the ability of the adjuvant to bind to mucin, induce cytotoxicity, facilitate antigen uptake in epithelial and dendritic cells, and activate cellular pathways. We then sought to determine how these parameters related to adjuvant activity in vivo. While the in vitro assays alone were not enough to predict the in vivo adjuvant activity completely, several interesting relationships were found with immune responses in mice. Furthermore, by varying the physicochemical properties of the surfactant components (charge, surfactant polar head size and hydrophobicity) and the surfactant blend ratio of the formulations, the strength and type of the immune response generated (TH1, TH2, TH17) could be modulated. These findings suggest the possibility of using high-throughput screens to aid in the design of custom adjuvants with unique immunological profiles to match specific mucosal vaccine applications.

Evaluating binding avidities of populations of heterogeneous multivalent ligand-functionalized nanoparticles.

Ligand-functionalized, multivalent nanoparticles have been extensively studied as targeted carriers in biomedical applications for drug delivery and imaging. The chemical synthesis method used, however, generates nanoparticles that are heterogeneous with respect to the number of ligands on each nanoparticle. This article examines the role this heterogeneity in ligand number plays in multivalent interactions between nanoparticle ligands and targeted receptors. We designed and synthesized a model heterogeneous multivalent nanoparticle system and developed a unique kinetic analysis to quantify the avidity interactions. This system used mono-dispersed poly(amidoamine) (PAMAM) dendrimers that were then chemically functionalized with ssDNA oligonucleotides as to yield the heterogeneous nanoparticle platform (ligand valencies n = 1.7, 3.1, 6), and employed complementary oligonucleotides as targeted receptors on a surface plasmon resonance (SPR) biosensor to evaluate the multivalent binding of the nanoparticle population. Kinetic analysis of both parallel initial rate and dual-Langmuir analyses of SPR binding curves was performed to assess avidity distributions. We found that batches of multivalent nanoparticles contain both fast- and slow-dissociation subpopulations, which can be characterized as having "weak" and "strong" surface interactions ("binding"), respectively. Furthermore, we found that the proportion of "strong" binders increased as a function of the mean oligonucleotide valence of the nanoparticle population. These analyses allowed an assessment of how avidity distributions are modulated by the number of functionalized ligands and suggested that there are threshold valences that differentiated fast- and slow-dissociation nanoparticles.