450 research outputs found

    Spinning, breathing, and flapping: Periodicities in Saturn’s middle magnetosphere

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    In Saturn’s magnetosphere, ubiquitous fluctuations with a period of ~10.7 h have been observed in Saturn kilometric radiation (SKR), auroral emissions, the magnetic field, the electron density, and energetic particle fluxes. Here we characterize previously unstudied periodicities in plasma properties inside of 15 RS near the equatorial plane. Although periodically varying magnetic perturbations rotate relatively smoothly (spinning), plasma properties do not. The phase of the peak value of plasma density or pressure perturbations can change substantially across a few hours of local time or RS. As a means of interpreting observations, we use a magnetohydrodynamic simulation that generates field‐aligned currents centered at 70° invariant latitude in Saturn’s southern ionosphere and rotating at the SKR period. The simulation reproduces many periodic features of the data including not only spinning perturbations but also global‐scale compression and expansion (breathing). Simulated plasma properties are also modulated by periodic large‐scale north‐south motion (flapping) in regions beyond ~15 Saturn radii (RS), which we do not analyze here. Inside of 15 RS, plasma responds to a superposition of spinning and breathing at the spin period, developing perturbations that peak at different phases depending on what is measured and where. Strong compressional effects act impulsively over a limited range of rotation phase. Superposition of local and global‐scale variations produces phase jumps across short distances and can introduce multiple peaks in the variation of plasma properties within one rotation period, accounting for anomalies in the phase dependence of periodic fluctuations identified in the sparse data available.Key PointsEquatorial plasma and field moments in the core region are modulated at the SKR periodThe peak phase of observed plasma properties depends on the location of measurementPeriodic changes in the magnetosphere can be described as spinning, breathing, and flappingPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136320/1/jgra53132-sup-0001-Text_SI-S01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136320/2/jgra53132_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136320/3/jgra53132-sup-0003-Figure_SI-S01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136320/4/jgra53132.pd

    Micro- and nanoparticulates for DNA vaccine delivery

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    DNA vaccination has emerged as a promising alternative to traditional protein-based vaccines for the induction of protective immune responses. DNA vaccines offer several advantages over traditional vaccines, including increased stability, rapid and inexpensive production, and flexibility to produce vaccines for a wide variety of infectious diseases. However, the immunogenicity of DNA vaccines delivered as naked plasmid DNA is often weak due to degradation of the DNA by nucleases and inefficient delivery to immune cells. Therefore, biomaterial-based delivery systems based on micro- and nanoparticles that encapsulate plasmid DNA represent the most promising strategy for DNA vaccine delivery. Microparticulate delivery systems allow for passive targeting to antigen presenting cells through size exclusion and can allow for sustained presentation of DNA to cells through degradation and release of encapsulated vaccines. In contrast, nanoparticle encapsulation leads to increased internalization, overall greater transfection efficiency, and the ability to increase uptake across mucosal surfaces. Moreover, selection of the appropriate biomaterial can lead to increased immune stimulation and activation through triggering innate immune response receptors and target DNA to professional antigen presenting cells. Finally, the selection of materials with the appropriate properties to achieve efficient delivery through administration routes conducive to high patient compliance and capable of generating systemic and local (i.e. mucosal) immunity can lead to more effective humoral and cellular protective immune responses. In this review, we discuss the development of novel biomaterial- based delivery systems to enhance the delivery of DNA vaccines through various routes of administration and their implications for generating immune responses

    Micro- and nanoparticulates for DNA vaccine delivery

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    DNA vaccination has emerged as a promising alternative to traditional protein-based vaccines for the induction of protective immune responses. DNA vaccines offer several advantages over traditional vaccines, including increased stability, rapid and inexpensive production, and flexibility to produce vaccines for a wide variety of infectious diseases. However, the immunogenicity of DNA vaccines delivered as naked plasmid DNA is often weak due to degradation of the DNA by nucleases and inefficient delivery to immune cells. Therefore, biomaterial-based delivery systems based on micro- and nanoparticles that encapsulate plasmid DNA represent the most promising strategy for DNA vaccine delivery. Microparticulate delivery systems allow for passive targeting to antigen presenting cells through size exclusion and can allow for sustained presentation of DNA to cells through degradation and release of encapsulated vaccines. In contrast, nanoparticle encapsulation leads to increased internalization, overall greater transfection efficiency, and the ability to increase uptake across mucosal surfaces. Moreover, selection of the appropriate biomaterial can lead to increased immune stimulation and activation through triggering innate immune response receptors and target DNA to professional antigen presenting cells. Finally, the selection of materials with the appropriate properties to achieve efficient delivery through administration routes conducive to high patient compliance and capable of generating systemic and local (i.e. mucosal) immunity can lead to more effective humoral and cellular protective immune responses. In this review, we discuss the development of novel biomaterial- based delivery systems to enhance the delivery of DNA vaccines through various routes of administration and their implications for generating immune responses

    Amphiphilic Polyanhydride Nanoparticles Stabilize \u3ci\u3eBacillus anthracis\u3c/i\u3e Protective Antigen

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    Advancements towards an improved vaccine against Bacillus anthracis, the causative agent of anthrax, have focused on formulations composed of the protective antigen (PA) adsorbed to aluminum hydroxide. However, due to the labile nature of PA, antigen stability is a primary concern for vaccine development. Thus, there is a need for a delivery system capable of preserving the immunogenicity of PA through all the steps of vaccine fabrication, storage, and administration. In this work, we demonstrate that biodegradable amphiphilic polyanhydride nanoparticles, which have previously been shown to provide controlled antigen delivery, antigen stability, immune modulation, and protection in a single dose against a pathogenic challenge, can stabilize and release functional PA. These nanoparticles demonstrated polymer hydrophobicity-dependent preservation of the biological function of PA upon encapsulation, storage (over extended times and elevated temperatures), and release. Specifically, fabrication of amphiphilic polyanhydride nanoparticles composed of 1,6-bis(p-carboxyphenoxy)hexane and 1,8-bis(p-carboxyphenoxy)-3,6- dioxaoctane best preserved PA functionality. These studies demonstrate the versatility and superiority of amphiphilic nanoparticles as vaccine delivery vehicles suitable for long-term storage

    Diet-microbiome-immune interplay in multiple sclerosis: Understanding the impact of phytoestrogen metabolizing gut bacteria

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    Multiple sclerosis (MS) is a chronic and progressive autoimmune disease of the central nervous system (CNS), with both genetic and environmental factors contributing to the pathobiology of the disease. Although HLA genes have emerged as the strongest genetic factor linked to MS, consensus on the environmental risk factors is lacking. Recently, the gut microbiota has garnered increasing attention as a potential environmental factor in MS, as mounting evidence suggests that individuals with MS exhibit microbial dysbiosis (changes in the gut microbiome). Thus, there has been a strong emphasis on understanding the role of the gut microbiome in the pathobiology of MS, specifically, factors regulating the gut microbiota and the mechanism(s) through which gut microbes may contribute to MS. Among all factors, diet has emerged to have the strongest influence on the composition and function of gut microbiota. As MS patients lack gut bacteria capable of metabolizing dietary phytoestrogen,we will specifically discuss the role of a phytoestrogen diet and phytoestrogen metabolizing gut bacteria in the pathobiology of MS. A better understanding of these mechanisms will help to harness the enormous potential of the gut microbiota as potential therapeutics to treat MS and other autoimmune diseases

    Characterization of DNA Sequences that Confer Complement Resistance in \u3ci\u3eLeishmania chagasi\u3c/i\u3e

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    Serial passage of axenically cultured Leishmania chagasi promastigotes results in a progressive diminution in resistance to complement-mediated lysis (CML), whereas high CML resistance is seen in infectious metacyclic promastigotes from the sandfly vector as well as metacyclic-like promastigotes within low-passage cultures at stationary growth phase. As we previously reported, in a screen seeking to identify novel genes involved in CML resistance: (1) a genomic cosmid library derived from DNA of CML-resistant L. chagasi promastigotes was transfected into highpassage (constitutively CML-sensitive) L. chagasi promastigotes; (2) transformants were screened for acquisition of CML-resistance; (3) multiple cosmid-transfectants exhibited partial CML resistance; and (4) the sequence for one of the cosmids (Cosmid 51) was determined. This report extends the analysis of Cosmid 51, and identifies by deletion analysis a subregion of the cosmid insert that is critical to the CML-resistance phenotype of Cosmid 51 transformants. We also report the sequence determination and initial CML-resistance activity of another cosmid that also confers partial resistance to CML

    Retention of structure, antigenicity, and biological function of pneumococcal surface protein A (PspA) released from polyanhydride nanoparticles

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    Pneumococcal surface protein A (PspA) is a choline-binding protein which is a virulence factor found on the surface of all Streptococcus pneumoniae strains. Vaccination with PspA has been shown to be protective against a lethal challenge with S. pneumoniae, making it a promising immunogen for use in vaccines. Herein, the design of a PspA-based subunit vaccine using polyanhydride nanoparticles as a delivery platform is described. Nanoparticles based on sebacic acid (SA), 1,6-bis-(p-carboxyphenoxy)hexane (CPH) and 1,8-bis-(p-carboxyphenoxy)-3,6- dioxaoctane (CPTEG), specifically 50:50 CPTEG:CPH and 20:80 CPH:SA, were used to encapsulate and release PspA. The protein released from the nanoparticle formulations retained its primary and secondary structure as well as its antigenicity. The released PspA was also biologically functional based on its ability to bind to apolactoferrin and prevent its bactericidal activity towards Escherichia coli. When the PspA nanoparticle formulations were administered subcutaneously to mice, the animals elicited a high titer and high avidity anti-PspA antibody response. Together, these studies provide a framework for the rational design of a vaccine against S. pneumoniae based on polyanhydride nanoparticles

    Childhood neurodevelopment after prescription of maintenance methadone for opioid dependency in pregnancy:a systematic review and meta-analysis

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    Aim: To systematically review and meta‐analyse studies of neurodevelopmental outcome of children born to mothers prescribed methadone in pregnancy. Method: MEDLINE, Embase, and PsycINFO were searched for studies published from 1975 to 2017 reporting neurodevelopmental outcomes in children with prenatal methadone exposure. Results: Forty‐one studies were identified (2283 participants). Eight studies were amenable to meta‐analysis: at 2 years the Mental Development Index weighted mean difference of children with prenatal methadone exposure compared with unexposed infants was −4.3 (95% confidence interval [CI] −7.24 to −1.63), and the Psychomotor Development Index weighted mean difference was −5.42 (95% CI −10.55 to −0.28). Seven studies reported behavioural scores and six found scores to be lower among methadone‐exposed children. Twelve studies reported visual outcomes: nystagmus and strabismus were common; five studies reported visual evoked potentials of which four described abnormalities. Factors that limited the quality of some studies, and introduced risk of bias, included absence of blinding, small sample size, high attrition, uncertainty about polydrug exposure, and lack of comparison group validity. Interpretation: Children born to mothers prescribed methadone in pregnancy are at risk of neurodevelopmental problems but risk of bias limits inference about harm. Research into management of opioid use disorder in pregnancy should include evaluation of childhood neurodevelopmental outcome

    A real-time PCR assay for accurate quantification of the individual members of the Altered Schaedler Flora microbiota in gnotobiotic mice

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    Changes in the gastrointestinal microbial community are frequently associated with chronic diseases such as Inflammatory Bowel Diseases. However, understanding the relationship of any individual taxon within the community to host physiology is made complex due to the diversity and individuality of the gut microbiota. Defined microbial communities such as the Altered Schaedler Flora (ASF) help alleviate the challenges of a diverse microbiota by allowing one to interrogate the relationship between individual bacterial species and host responses. An important aspect of studying these relationships with defined microbial communities is the ability to measure the population abundance and dynamics of each member. Herein, we describe the development of an improved ASF species-specific and sensitive real-time quantitative polymerase chain reaction (qPCR) for use with SYBR Green chemistry to accurately assess individual ASF member abundance. This approach targets hypervariable regions V1 through V3 of the 16S rRNA gene of each ASF taxon to enhance assay specificity. We demonstrate the reproducibility, sensitivity and application of this new method by quantifying each ASF bacterium in two inbred mouse lines. We also used it to assess changes in ASF member abundance before and after acute antibiotic perturbation of the community as well as in mice fed two different diets. Additionally, we describe a nested PCR assay for the detection of lowly abundant ASF members. Altogether, this improved qPCR method will facilitate gnotobiotic research involving the ASF community by allowing for reproducible quantification of its members under various physiological conditions

    Lattice instabilities of PbZrO3/PbTiO3 [1:1] superlattices from first principles

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    Ab initio phonon calculations for the nonpolar reference structures of the (001), (110), and (111) PbZrO_3/PbTiO_3 [1:1] superlattices are presented. The unstable polar modes in the tetragonal (001) and (110) structures are confined in either the Ti- or the Zr-centered layers and display two-mode behavior, while in the cubic (111) case one-mode behavior is observed. Instabilities with pure oxygen character are observed in all three structures. The implications for the ferroelectric behavior and related properties are discussed.Comment: 12 pages, 2 figures, 7 tables, submitted to PR
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