Mechanism of Action and Design of Potent Antibacterial Block Copolymer Nanoparticles.

Self-assembled polymer nanoparticles are promising antibacterials, with nonspherical morphologies of particular interest as recent work has demonstrated enhanced antibacterial activity relative to their spherical counterparts. However, the reasons for this enhancement are currently unclear. We have performed a multifaceted analysis of the antibacterial mechanism of action of 1D nanofibers relative to nanospheres by the use of flow cytometry, high-resolution microscopy, and evaluations of the antibacterial activity of pristine and tetracycline-loaded nanoparticles. Low-length dispersity, fluorescent diblock copolymer nanofibers with a crystalline poly(fluorenetrimethylenecarbonate) (PFTMC) core (length = 104 and 472 nm, height = 7 nm, width = 10-13 nm) and a partially protonated poly(dimethylaminoethyl methacrylate) (PDMAEMA) corona (length = 12 nm) were prepared via seeded growth living crystallization-driven self-assembly. Their behavior was compared to that of analogous nanospheres containing an amorphous PFTMC core (diameter of 12 nm). While all nanoparticles were uptaken into Escherichia coli W3110, crystalline-core nanofibers were observed to cause significant bacterial damage. Drug loading studies indicated that while all nanoparticle antibacterial activity was enhanced in combination with tetracycline, the enhancement was especially prominent when small nanoparticles (ca. 15-25 nm) were employed. Therefore, the identified differences in the mechanism of action and the demonstrated consequences for nanoparticle size and morphology control may be exploited for the future design of potent antibacterial agents for overcoming antibacterial resistance. This study also reinforces the requirement of morphological control over polymer nanoparticles for biomedical applications, as differences in activity are observed depending on their size, shape, and core-crystallinity.

Optimization of precision nanofiber micelleplexes for DNA delivery.

As nucleic acid (NA) technologies continue to revolutionize medicine, new delivery vehicles are needed to effectively transport NA cargoes into cells. Uniform and length-tunable nanofiber micelleplexes have recently shown promise as versatile polymeric delivery vehicles for plasmid DNA, however the effects of several key parameters on micelleplex transfection and stability remain unknown. In this work, we compare poly(fluorenetrimethylenecarbonate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PFTMC-b-PDMAEMA) nanofiber micelleplexes to nanosphere micelleplexes and PDMAEMA polyplexes, examining the effects of complexation buffer, the temporal and serum stability of nanofiber micelleplexes, as well as the effects of cell density, cell type, and polymer DPn upon transfection efficiency and cell viability. These studies are vital for understanding the formation and biological activity of micelleplexes in more detail and should inform the future design of more advanced polymeric NA delivery systems.

Length-Controlled Nanofiber Micelleplexes as Efficient Nucleic Acid Delivery Vehicles.

Micelleplexes show great promise as effective polymeric delivery systems for nucleic acids. Although studies have shown that spherical micelleplexes can exhibit superior cellular transfection to polyplexes, to date there has been no report on the effects of micelleplex morphology on cellular transfection. In this work, we prepared precision, length-tunable poly(fluorenetrimethylenecarbonate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PFTMC16-b-PDMAEMA131) nanofiber micelleplexes and compared their properties and transfection activity to those of the equivalent nanosphere micelleplexes and polyplexes. We studied the DNA complexation process in detail via a range of techniques including cryo-transmission electron microscopy, atomic force microscopy, dynamic light scattering, and ζ-potential measurements, thereby examining how nanofiber micelleplexes form, as well the key differences that exist compared to nanosphere micelleplexes and polyplexes in terms of DNA loading and colloidal stability. The effects of particle morphology and nanofiber length on the transfection and cell viability of U-87 MG glioblastoma cells with a luciferase plasmid were explored, revealing that short nanofiber micelleplexes (length < ca. 100 nm) were the most effective delivery vehicle examined, outperforming nanosphere micelleplexes, polyplexes, and longer nanofiber micelleplexes as well as the Lipofectamine 2000 control. This study highlights the potential importance of 1D micelleplex morphologies for achieving optimal transfection activity and provides a fundamental platform for the future development of more effective polymeric nucleic acid delivery vehicles.

Structure-activity relationship studies on divalent naphthalene diimide G quadruplex ligands with anticancer and antiparasitic activity.

Naphthalene diimide (NDI) is a central scaffold that has been commonly used in the design of G-quadruplex (G4) ligands. Previous work revealed notable anticancer activity of a disubstituted N-methylpiperazine propyl NDI G4 ligand. Here, we explored structure-activity relationship studies around ligand bis-N,N-2,7-(3-(4-methylpiperazin-1-yl)propyl)-1,4,5,8-naphthalenetetracarboxylic diimide, maintaining the central NDI core whilst modifying the spacer and the nature of the cationic groups. We prepared new disubstituted NDI derivatives of the original compound and examined their in vitro antiproliferative and antiparasitic activity. Several N-methylpiperazine propyl NDIs showed sub-micromolar activity against Trypanosoma brucei and Leishmania major parasites with up to 30 fold selectivity versus MRC-5 cells. The best compound was a dimorpholino NDI with an IC50 of 0.17 µM against T.brucei and 40 fold selectivity versus MRC-5 cells. However, no clear correlation between G4 binding of the new NDI derivatives and antiproliferative or antiparasitic activity was observed, indicating that other mechanisms of action may be responsible for the observed biological activity.

Gestational weight gain and postpartum weight retention in Tasmanian women: The Baby-bod Study.

Many factors can negatively impact perinatal outcomes, including inappropriate gestational weight gain (GWG). Despite having the greatest potential to influence maternal and infant health, there is a lack of consensus regarding the GWG consistent with a healthy pregnancy. To date, GWG in Northern Tasmania remains understudied. We investigated how maternal pre-pregnancy body mass index (BMI) is related to weight gain during pregnancy and weight retention post-partum, and how maternal pre-pregnancy BMI is related to the mode of delivery. Approximately 300 Tasmanian mothers (n = 291 for mode of delivery and n = 282 for GWG) were included in this study. Analysis of variance and chi square tests were conducted to assess differences in BW of mothers across BMI categories and differences between categorical variables; respectively. Based on pre-pregnancy BMI, mothers were assigned to one of three groups, with healthy weight (<25 kg m-2), with overweight (25-29.9 kg m-2), or with obesity (>30 kg m-2). Pre-pregnancy BMI and body weight (BW) were significantly associated (p<0.001) with post-partum BW at 3 and 6 months. Only 25% of mothers with a normal weight BMI, 34% with overweight and 13% with obesity, achieved the Institute of Medicine (IOM) recommendation for GWG. Interestingly, a number of women in our cohort lost weight during gestation (1.5, 9 and 37% in <25, 25-29.9 and >30 kg m-2 groups, respectively). Further, women with obesity showed the lowest level of BW fluctuation and retained less weight post-partum. The highest number of caesarean sections were observed in mothers who exceeded GWG recommendations. Most mothers either exceeded or failed to achieve IOM recommendations for GWG. To improve the generalisability of these findings, this study should be replicated in a larger representative sample of the Tasmanian maternal population.

Imide Condensation as a Strategy for the Synthesis of Core-Diversified G-Quadruplex Ligands with Anticancer and Antiparasitic Activity*.

A facile imide coupling strategy for the one-step preparation of G-quadruplex ligands with varied core chemistries is described. The G-quadruplex stabilization of a library of nine compounds was examined using FRET melting experiments, and CD, UV-Vis, fluorescence and NMR titrations, identifying several compounds that were capable of stabilizing G-quadruplex DNA with interesting selectivity profiles. The best G4 ligand was identified as compound 3, which was based on a perylene scaffold and exhibited 40-fold selectivity for a telomeric G-quadruplex over duplex DNA. Surprisingly, a tetra-substituted flexible core, compound 11, also exhibited selective stabilization of G4 DNA over duplex DNA. The anticancer and antiparasitic activity of the library was also examined, with the lead compound 3 exhibiting nanomolar inhibition of Trypanosoma brucei with 78-fold selectivity over MRC5 cells. The cellular localization of this compound was also studied via fluorescence microscopy. We found that uptake was time dependant, with localization outside the nucleus and kinetoplast that could be due to strong fluorescence quenching in the presence of small amounts of DNA.

Cellular uptake and targeting of low dispersity, dual emissive, segmented block copolymer nanofibers.

Polymer-based nanoparticles show substantial promise in the treatment and diagnosis of cancer and other diseases. Herein we report an exploration of the cellular uptake of tailored, low dispersity segmented 1D nanoparticles which were prepared from an amphiphilic block copolymer, poly(dihexylfluorene)-b-poly(ethyleneglycol) (PDHF13-b-PEG227), with a crystallizable PDHF core-forming block and a 'stealth' PEG corona-forming block with different end-group functionalities. Segmented C-B-A-B-C pentablock 1D nanofibers with varied spatially-defined coronal chemistries and a selected length (95 nm) were prepared using the living crystallization-driven self-assembly (CDSA) seeded-growth method. As the blue fluorescence of PDHF is often subject to environment-related quenching, a far-red BODIPY (BD) fluorophore was attached to the PEG end-group of the coronal B segments to provide additional tracking capability. Folic acid (FA) was also incorporated as a targeting group in the terminal C segments. These dual-emissive pentablock nanofibers exhibited uptake into >97% of folate receptor positive HeLa cells by flow cytometry. In the absence of FA, no significant uptake was detected and nanofibers with either FA or BD coronal groups showed no significant toxicity. Correlative light and electron microscopy (CLEM) studies revealed receptor-mediated endocytosis as an uptake pathway, with subsequent localization to the perinuclear region. A significant proportion of the nanofibers also appeared to interact with the cell membrane in an end-on fashion, which was coupled with fluorescence quenching of the PDHF core. These results provide new insights into the cellular uptake of polymer-based nanofibers and suggest their potential use in targeted therapies and diagnostics.

Extending the Scope of "Living" Crystallization-Driven Self-Assembly: Well-Defined 1D Micelles and Block Comicelles from Crystallizable Polycarbonate Block Copolymers.

Fiber-like block copolymer (BCP) micelles offer considerable potential for a variety of applications; however, uniform samples of controlled length and with spatially tailored chemistry have not been accessible. Recently, a seeded growth method, termed "living" crystallization-driven self-assembly (CDSA), has been developed to allow the formation of 1D micelles and block comicelles of precisely controlled dimensions from BCPs with a crystallizable segment. An expansion of the range of core-forming blocks that participate in living CDSA is necessary for this technique to be compatible with a broad range of applications. Few examples currently exist of well-defined, water-dispersible BCP micelles prepared using this approach, especially from biocompatible and biodegradable polymers. Herein, we demonstrate that BCPs containing a crystallizable polycarbonate, poly(spiro[fluorene-9,5'-[1,3]-dioxan]-2'-one) (PFTMC), can readily undergo living CDSA processes. PFTMC- b-poly(ethylene glycol) (PEG) BCPs with PFTMC:PEG block ratios of 1:11 and 1:25 were shown to undergo living CDSA to form near monodisperse fiber-like micelles of precisely controlled lengths of up to ∼1.6 µm. Detailed structural characterization of these micelles by TEM, AFM, SAXS, and WAXS revealed that they comprise a crystalline, chain-folded PFTMC core with a rectangular cross-section that is surrounded by a solvent swollen PEG corona. PFTMC- b-PEG fiber-like micelles were shown to be dispersible in water to give colloidally stable solutions. This allowed an assessment of the toxicity of these structures toward WI-38 and HeLa cells. From these experiments, we observed no discernible cytotoxicity from a sample of 119 nm fiber-like micelles to either healthy (WI-38) or cancerous (HeLa) cell types. The living CDSA process was extended to PFTMC- b-poly(2-vinylpyridine) (P2VP), and addition of this BCP to PFTMC- b-PEG seed micelles led to the formation of well-defined segmented fibers with spatially localized coronal chemistries.

Epidemiology and determinants of type 2 diabetes in south Asia.

Type 2 diabetes has rapidly developed into a major public health problem in south Asia (defined here as Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka) in recent decades. During this period, major lifestyle changes associated with economic transition, industrialisation, urbanisation, and globalisation have been key determinants in the increasing burden of non-communicable diseases. A decline in nutrition quality, reduced physical activity, and increased sedentary behaviours are reflected in the increasing prevalence of type 2 diabetes and related risk factors in the region. The International Diabetes Federation 2017 estimates of the prevalence of diabetes in adults in the region range from 4·0% in Nepal to 8·8% in India. The prevalence of overweight ranges from 16·7% in Nepal to 26·1% in Sri Lanka, and the prevalence of obesity ranges from 2·9% in Nepal to 6·8% in Sri Lanka. An increasing proportion of children, adolescents, and women are overweight or obese, leading to a heightened risk of type 2 diabetes. Ethnic south Asians present with greater metabolic risk at lower levels of BMI compared with other ethnic groups (referred to as the south Asian phenotype), with type 2 diabetes often developing at a younger age, and with rapid progression of diabetic complications. Because of the presence of multiple risk factors and a body composition conducive to the development of type 2 diabetes, south Asians should be aggressively targeted for prevention. In this Series paper, we detail trends in the prevalence of diabetes in the region and address major determinants of the disease in the context of nutrition and physical activity transitions and the south Asian phenotype.

Public health and health systems: implications for the prevention and management of type 2 diabetes in south Asia.

Many non-communicable chronic diseases, including type 2 diabetes, are highly prevalent, costly, and largely preventable. The prevention and management of type 2 diabetes in south Asia requires a combination of lifestyle changes and long-term health-care management. However, public health and health-care systems in south Asian countries face serious challenges, including the need to provide services to many people with inadequate resources, and substantial between-population and within-population inequalities. In this Series paper, we explore the importance and particular challenges of public health and health systems in south Asian countries (Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka) with respect to the provision of culturally appropriate lifestyle modification to prevent and manage diabetes, especially in resource-poor settings. Effective primary prevention strategies are urgently needed to counter risk factors and behaviours preconception, in utero, in infancy, and during childhood and adolescence. A concerted focus on education, training, and capacity building at the community level would ensure the more widespread use of non-physician care, including community health workers. Major investment from governments and other sources will be essential to achieve substantial improvements in the prevention and management of type 2 diabetes in the region.

In Situ Synchrotron X-Ray Diffraction Characterization of Corrosion Products of a Ti-Based Metallic Glass for Implant Applications.

Ti-based bulk metallic glasses are under consideration for implants due to their high yield strength and biocompatibility. In this work, in situ synchrotron X-ray diffraction (XRD) is used to investigate the corrosion products formed from corrosion of Ti40 Zr10 Cu34 Pd14 Sn2 bulk metallic glass in artificial corrosion pits in physiological saline (NaCl). It is found that Pd nanoparticles form in the interior of the pits during electrochemical dissolution. At a low pit growth potential, the change in lattice parameter of the Pd nanoparticles is consistent with the formation of palladium hydride. In addition, a salt layer very close to the dissolving interface is found to contain CuCl, PdCl2 , ZrOCl2 ∙8H2 O, Cu, Cu2 O, and several unidentified phases. The formation of Pd nanoparticles (16 ± 10 nm at 0.7 V vs Ag/AgCl) containing small amounts of the other alloying elements is confirmed by transmission electron microscopy. The addition of albumin and/or H2 O2 does not significantly influence the nature of the corrosion products. When considering the biological compatibility of the alloy, the biological reactivity of the corrosion products identified should be explored.

Let Us Talk About Moving: Reframing the Exercise and Physical Activity Discussion.

Noncommunicable and chronic disease are interchangeable terms. According to the World Health Organization, "they are of long duration and generally slow progression. The 4 main types of chronic diseases are cardiovascular diseases (ie, heart attacks and stroke), cancers, chronic respiratory diseases (such as chronic obstructive pulmonary disease and asthma), and diabetes." We have known about the benefits of physical activity (PA) for thousands of years. Perhaps our approach, from public health messaging to the individual clinical encounter, as to how PA and exercise are discussed and prescribed can be improved upon, with the ultimate goal of increasing the likelihood that an individual moves more; ultimately moving more should be the goal. In fact, there is an incongruence between the evidence for the benefits of physical movement and how we message and integrate PA and exercise guidance into health care, if it is discussed at all. Specifically, evidence clearly indicates any migration away from the sedentary phenotype toward a movement phenotype is highly beneficial. As we necessarily move to a proactive, preventive healthcare model, we must reconceptualize how we evaluate and treat conditions that pose the greatest threat, namely chronic disease; there is a robust body of evidence supporting the premise of movement as medicine. The purpose of this perspective paper is to propose an alternate model for promoting, assessing, discussing, and prescribing physical movement.

Is UV-Induced Electron-Driven Proton Transfer Active in a Chemically Modified A·T DNA Base Pair?

Transient electronic and vibrational absorption spectroscopies have been used to investigate whether UV-induced electron-driven proton transfer (EDPT) mechanisms are active in a chemically modified adenine-thymine (A·T) DNA base pair. To enhance the fraction of biologically relevant Watson-Crick (WC) hydrogen-bonding motifs and eliminate undesired Hoogsteen structures, a chemically modified derivative of A was synthesized, 8-(tert-butyl)-9-ethyladenine (8tBA). Equimolar solutions of 8tBA and silyl-protected T nucleosides in chloroform yield a mixture of WC pairs, reverse WC pairs, and residual monomers. Unlike previous transient absorption studies of WC guanine-cytosine (G·C) pairs, no clear spectroscopic or kinetic evidence was identified for the participation of EDPT in the excited-state relaxation dynamics of 8tBA·T pairs, although ultrafast (sub-100 fs) EDPT cannot be discounted. Monomer-like dynamics are proposed to dominate in 8tBA·T.

Divalent Naphthalene Diimide Ligands Display High Selectivity for the Human Telomeric G-quadruplex in K+ Buffer.

Selective G-quadruplex ligands offer great promise for the development of anti-cancer therapies. A novel series of divalent cationic naphthalene diimide ligands that selectively bind to the hybrid form of the human telomeric G-quadruplex in K+ buffer are described herein. We demonstrate that an imidazolium-bearing mannoside-conjugate is the most selective ligand to date for this quadruplex against several other quadruplex and duplex structures. We also show that a similarly selective methylpiperazine-bearing ligand was more toxic to HeLa cancer cells than doxorubicin, whilst exhibiting three times less toxicity towards fetal lung fibroblasts WI-38.

Reassessment of Allied Health Professionals' Level of Self-Efficacy in, Outcome Expectancy in, and Use of Evidence-Based Practice.

AIM: Evidence-based practice (EBP) is fundamental to improving patient outcomes. Factors affecting EBP capabilities are linked with institutional culture and barriers, personal self-belief, and individual ability. To effect change in capabilities, interventions must target barriers and be informed by behaviour change theory. This study measured the effect of training and organisational change on EBP measures amongst allied health professionals. METHODS: All allied health staff (n=196) employed across the Mater Health Services (Brisbane, Queensland) were invited to complete a survey assessing EBP self-efficacy, outcome expectancy and use, as well as EBP training undertaken. Data were compared with those of surveys from 2010 and 2011. RESULTS: Response rate was 70.9% (n=139/196); 32 staff completed all surveys. Significant improvements were observed in staff undertaking training (EBP, p=0.008; research design and analysis, p=0.003) since the first survey. The significant increase in EBP self-efficacy that occurred from T1 to T2 remained at T3 (p=0.008). Fewer between-department differences were observed over time. CONCLUSIONS: This study identified sustained EBP self-efficacy improvements in this cohort and found that between-department differences have virtually disappeared. Ongoing interventions are required to sustain and improve staff's belief in their ability to deliver EBP.

Physical Activity and Health: "What is Old is New Again".

Much recent interest has focused on the relationship between physical activity and health and supported with an abundance of scientific evidence. However, the concept of Exercise is Medicine™ copromoted by the American College of Sports Medicine and American Medical Association and similar august bodies worldwide is far from new--the importance of exercise for health has been reported for centuries. Participation in regular physical activity and exercise provides numerous benefits for health with such benefits typically varying according to the volume completed as reflected by intensity, duration, and frequency. Evidence suggests a dose-response relationship such that being active, even to a modest level, is preferable to being inactive or sedentary. Greatest benefits are commonly associated with the previously sedentary individual assuming a more active lifestyle. There is an apparent linear relationship between physical activity and health status and as a general rule, increases in physical activity and fitness result in additional improvements in health status. This narrative review provides a selective appraisal of the evidence for the importance of physical activity for health, commencing with a baseline historical perspective followed by a summary of key health benefits associated with an active lifestyle.

Atmospheric pitting corrosion of 304L stainless steel: the role of highly concentrated chloride solutions.

The morphology of atmospheric pitting corrosion in 304L stainless steel plate was analysed using MgCl(2) droplets in relation to changes in relative humidity (RH) and chloride deposition density (CDD). It was found that highly reproducible morphologies occur that are distinct at different RH. Pitting at higher concentrations, i.e. lower RH, resulted in satellite pits forming around the perimeter of wide shallow dish regions. At higher RH, these satellite pits did not form and instead spiral attack into the shallow region was observed. Increasing CDD at saturation resulted in a very broad-mouthed pitting attack within the shallow dish region. Large data sets were used to find trends in pit size and morphology in what is essentially a heterogeneous alloy. Electrochemical experiments on 304 stainless steel wires in highly saturated solutions showed that the passive current density increased significantly above 3 M MgCl(2) and the breakdown pitting potential dropped as the concentration increased. It is proposed that the shallow dish regions grow via enhanced dissolution of the passive film, whereas satellite pits and a spiral attack take place with active dissolution of bare metal surfaces.

Overweight and obese adolescent girls: the importance of promoting sensible eating and activity behaviors from the start of the adolescent period.

The adolescent period is associated with changes in eating and activity behaviors in girls. Less reliance on parental provision and choice of food, coupled with a decrease in participation in physical activity and sport, can create an energy imbalance, predisposing to weight gain. Physiological alterations to body composition, reduction in insulin sensitivity, and psychological adjustments may further amplify the risk of becoming overweight and maintaining an unhealthy level of body fat into childbearing years. During pregnancy excess body fat is a risk factor for poor pregnancy outcomes and may predispose an infant to a lifelong heightened risk of being overweight and developing chronic disease. Interventions aimed at preventing the accumulation of body fat in adolescent girls and young women may have far reaching impact and be critically important in reducing intergenerational weight gain. Lifestyle interventions in adolescence have the potential to modify adult obesity risk by switching at-risk individuals from a high to lower obesity risk trajectory. This paper discusses multiple approaches to assist at-risk individuals reduce obesity risk. A key focus is placed on engagement in food preparation and choice, and opportunities for physical activity and sport. Support, education, and opportunity at home and at school, are often associated with the success of lifestyle interventions, and may enable adolescents to make positive choices, and engage in health promoting behaviors during adolescence and childbearing years.

Interaction of erythrocyte eicosapentaenoic acid and physical activity predicts reduced risk of mild cognitive impairment.

OBJECTIVES: To evaluate relationships between self-reported physical activity, proportions of long-chain omega-3 polyunsaturated fatty acids (LCn3) in erythrocyte content (percentage of total fatty acids) and risk of mild cognitive impairment (MCI) in older adults. METHOD: A cross-sectional study was conducted. Community-dwelling male and female (n = 84) participants over the age of 65 years with and without MCI were tested for erythrocyte proportions of the LCn3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Physical activity was measured using a validated questionnaire. RESULTS: The interaction between erythrocyte EPA, but not DHA, and increased physical activity was associated with increased odds of a non-MCI classification. CONCLUSION: An interaction between physical activity and erythrocyte EPA content (percentage of fatty acids) significantly predicted MCI status in older adults. Randomised control trials are needed to examine the potential for supplementation with EPA in combination with increased physical activity to mitigate the risk of MCI in ageing adults.