Novel Topical Microbicides Through Combinatorial Strategies

Purpose Developing microbicides for topical epithelial applications is extremely challenging, as evidenced by the scarcity of approved products even after decades of research. Chemical enhancers, including surfactants, are known to be effective antimicrobial agents but are typically toxic towards epithelial cells. Here, we report on the discovery of unique surfactant formulations with improved safety and efficacy profile for epithelial applications, via a combination of high throughput screening techniques. Methods Over three-hundred formulations derived from nine surfactants were screened for antibacterial properties against E. coli in vitro. A subset of these formulations showed high antibacterial activity and was screened for cytotoxicity in vitro. Formulations showing high antibacterial activity and reduced cytotoxicity compared to their individual components were tested for efficacy against B. thailendensis, a model for melioidosis-causing B. pseudomallei. Results Lead formulations showed lower toxicity towards epidermal keratinocytes, with LC50 values up to 3.5-fold higher than their component surfactants, while maintaining antibacterial efficacy against B. thailendensis. Conclusions Our results demonstrate that such a combinatorial screening approach can be used for designing safe and potent microbicides for epithelial applications

Difficulties when Assessing Birdsong Learning Programmes under Field Conditions: A Re-Evaluation of Song Repertoire Flexibility in the Great Tit

There is a remarkable diversity of song-learning strategies in songbirds. Establishing whether a species is closed- or open-ended is important to be able to interpret functional and evolutionary consequences of variation in repertoire size. Most of our knowledge regarding the timing of vocal learning is based on laboratory studies, despite the fact that these may not always replicate the complex ecological and social interactions experienced by birds in the wild. Given that field studies cannot provide the experimental control of laboratory studies, it may not be surprising that species such as the great tit that were initially assumed to be closed-ended learners have later been suggested to be open-ended learners. By using an established colour-ringed population, by following a standardized recording protocol, and by taking into account the species' song ecology (using only recordings obtained during peak of singing at dawn), we replicated two previous studies to assess song repertoire learning and flexibility in adult wild great tits elicited by social interactions. First, we performed a playback experiment to test repertoire plasticity elicited by novel versus own songs. Additionally, in a longitudinal study, we followed 30 males in two consecutive years and analysed whether new neighbours influenced any change in the repertoire. Contrary to the previous studies, song repertoire size and composition were found to be highly repeatable both between years and after confrontation with a novel song. Our results suggest that great tits are closed-ended learners and that their song repertoire probably does not change during adulthood. Methodological differences that may have led to an underestimation of the repertoires or population differences may explain the discrepancy in results with previous studies. We argue that a rigorous and standardized assessment of the repertoire is essential when studying age- or playback-induced changes in repertoire size and composition under field conditions

Effect of stress relieving heat treatment on surface topography and dimensional accuracy of incrementally formed grade 1 titanium sheet parts

The forming of parts with an optimized surface roughness and high dimensional accuracy is important in many applications of incremental sheet forming (ISF). To realize this, the effect of stress relieving heat treatment of grade-1 Ti parts performed before and after forming on the surface finish and dimensional accuracy was studied. It was found that heat treatment at a temperature of 540 °C for 2 h improves the surface finish of formed parts resulting in a surface with little or no visible tool marks. Additionally, it improves the dimensional accuracy of parts after unclamping from the rig used for forming, in particular, that of parts with shallow wall angles (typically <25°). It was also noted that post-forming heat treatment improves the surface finish of parts. The surface topography of formed parts was studied using interferometry to yield areal surface roughness parameters and subsequently using secondary electron imaging. Back-scatter electron microscopy imaging results coupled with energy-dispersive X-ray (EDX) analysis showed that heat treatment prior to forming leads to tool wear as indicated by the presence of Fe in samples. Furthermore, post-forming heat treatment prevents curling up of formed parts due to compressive stresses if the formed part is trimmed

Analysis of visitors’ mobility patterns through random walk in the Louvre Museum

This paper proposes a random walk model to analyze visitors' mobility patterns in a large museum. Visitors' available time makes their visiting styles different, resulting in dissimilarity in the order and number of visited places and in path sequence length. We analyze all this by comparing a simulation model and observed data, which provide us the strength of the visitors' mobility patterns. The obtained results indicate that shorter stay-type visitors exhibit stronger patterns than those with the longer stay-type, confirming that the former are more selective than the latter in terms of their visitation type.Comment: 16 pages, 5 figures, 4 table

An approach to identify a minimum and rational proportion of caesarean sections in resource-poor settings: a global network study

BACKGROUND: Caesarean section prevalence is increasing in Asia and Latin America while remaining low in most African regions. Caesarean section delivery is effective for saving maternal and infant lives when they are provided for medically-indicated reasons. On the basis of ecological studies, caesarean delivery prevalence between 9% and 19% has been associated with better maternal and perinatal outcomes, such as reduced maternal land fetal mortality. However, the specific prevalence of obstetric and medical complications that require caesarean section have not been established, especially in low-income and middle-income countries (LMICs). We sought to provide information to inform the approach to the provision of caesarean section in low-resource settings. METHODS: We did a literature review to establish the prevalence of obstetric and medical conditions for six potentially life-saving indications for which caesarean section could reduce mortality in LMICs. We then analysed a large, prospective population-based dataset from six LMICs (Argentina, Guatemala, Kenya, India, Pakistan, and Zambia) to determine the prevalence of caesarean section by indication for each site. We considered that an acceptable number of events would be between the 25th and 75th percentile of those found in the literature. FINDINGS: Between Jan 1, 2010, and Dec 31, 2013, we enrolled a total of 271 855 deliveries in six LMICs (seven research sites). Caesarean section prevalence ranged from 35% (3467 of 9813 deliveries in Argentina) to 1% (303 of 16 764 deliveries in Zambia). Argentina's and Guatemala's sites all met the minimum 25th percentile for five of six indications, whereas sites in Zambia and Kenya did not reach the minimum prevalence for caesarean section for any of the indications. Across all sites, a minimum overall caesarean section of 9% was needed to meet the prevalence of the six indications in the population studied. INTERPRETATION: In the site with high caesarean section prevalence, more than half of the procedures were not done for life-saving conditions, whereas the sites with low proportions of caesarean section (below 9%) had an insufficient number of caesarean procedures to cover those life-threatening causes. Attempts to establish a minimum caesarean prevalence should go together with focusing on the life-threatening causes for the mother and child. Simple methods should be developed to allow timely detection of life-threatening conditions, to explore actions that can remedy those conditions, and the timely transfer of women with those conditions to health centres that could provide adequate care for those conditions. FUNDING: Eunice Kennedy Shriver National Institute of Child Health and Human Development

In Vitro Surfactant Structure-Toxicity Relationships: Implications for Surfactant Use in Sexually Transmitted Infection Prophylaxis and Contraception

Background The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs) makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. Methodology/Principal Findings We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants – nonionic (Triton X-100 and monolaurin), zwitterionic (DDPS), anionic (SDS), and cationic (CnTAB (n = 10 to 16), C12PB, and C12BZK) – were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC) suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C12PB and C12BZK, does not justify their use as contraceptive agents. C12PB and C12BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations. Conclusions/Significance Our results contribute to understanding the mechanisms involved in surfactant toxicity, have a predictive value with regard to their safety, and may be used to design more effective and less harmful surfactants for use in topical applications for STI prophylaxis.Foundation for Science and Technology of the Portuguese Ministry of Science and Higher Educatio

Crossing borders to bind proteins—a new concept in protein recognition based on the conjugation of small organic molecules or short peptides to polypeptides from a designed set

A new concept for protein recognition and binding is highlighted. The conjugation of small organic molecules or short peptides to polypeptides from a designed set provides binder molecules that bind proteins with high affinities, and with selectivities that are equal to those of antibodies. The small organic molecules or peptides need to bind the protein targets but only with modest affinities and selectivities, because conjugation to the polypeptides results in molecules with dramatically improved binder performance. The polypeptides are selected from a set of only sixteen sequences designed to bind, in principle, any protein. The small number of polypeptides used to prepare high-affinity binders contrasts sharply with the huge libraries used in binder technologies based on selection or immunization. Also, unlike antibodies and engineered proteins, the polypeptides have unordered three-dimensional structures and adapt to the proteins to which they bind. Binder molecules for the C-reactive protein, human carbonic anhydrase II, acetylcholine esterase, thymidine kinase 1, phosphorylated proteins, the D-dimer, and a number of antibodies are used as examples to demonstrate that affinities are achieved that are higher than those of the small molecules or peptides by as much as four orders of magnitude. Evaluation by pull-down experiments and ELISA-based tests in human serum show selectivities to be equal to those of antibodies. Small organic molecules and peptides are readily available from pools of endogenous ligands, enzyme substrates, inhibitors or products, from screened small molecule libraries, from phage display, and from mRNA display. The technology is an alternative to established binder concepts for applications in drug development, diagnostics, medical imaging, and protein separation