A Cation-Dependent Dual Activation Motif for Anionic Ring-Opening Polymerization of Cyclic Esters.

A new organocatalyst for the ring-opening polymerization of lactones has been identified. Under the tested conditions, the anions of 2,2'-bisindole promote fast, living polymerizations (as short as 10 ms) which are selective for chain elongation over transesterification (D ≤ 1.1). While structurally related to (thio)urea anion catalysts, anions of 2,2'-bisindole activate the monomer via the counterion rather than through hydrogen bonding. This new activation motif enables modulation of the polymerization rate by 2 orders of magnitude by changing the counterion.

Ultrasound as a Learning Tool in Bachelor-Level Anatomy Education.

Point of care ultrasound (POCUS) has become an increasingly common diagnostic tool in the clinical environment. As a result, it is being used earlier for medical students in Undergraduate Medical Education (UME) as a learning tool for the basic sciences including gross anatomy. There is little literature, however, to support its utility for basic science education in students currently seeking a bachelor's degree. This study consisted of fourteen currently enrolled bachelor students with previous instruction in human anatomy and physiology. Students participated in an ultrasound didactic and an interactive ultrasound experience with volunteers. Before and after this session, students were asked to complete an assessment measuring their spatial understanding of the human anatomy and their ability to locate structures using ultrasound. Wilcoxon's signed-rank tests comparing assessment scores showed significant improvement on both portions of the assessment. Based on this improvement, we suggest that ultrasound is a valid educational tool which can be used at the bachelor-level to effectively enhance students' learning of anatomy and provide hands on experience with modern technology. Further research with larger samples will be necessary to determine whether it would supplement or replace more traditional teaching modalities.

The unexpected role of bioaerosols in the Oxidative Potential of PM.

Bioaerosols represent up to 15-25% of PM by mass, but there is currently no assessment of their impact on Oxidative Potential (OP), or capacity of particulate matter (PM) to produce damaging oxidative reactions in the human lungs. Here, the OP of selected bioaerosols (bacteria cells vs fungal spores) was assessed through the cell-free DTT assay. Results show that bioaerosols induce Reactive Oxygen Species (ROS) production, varying along the microorganism type, species, and concentration. Fungal spores show up to 10 times more ROS generation than bacterial cells. At the highest concentrations, fungal spores present as much oxidative reactivity as the most redox-active airborne chemicals (Copper, Naphtoquinone). Moreover, bioaerosols substantially influence OP of ambient PM and that of its chemical constituents: in presence of A. fumigatus spores, the OP of Cu/NQ is increased by a factor of 2 to 5, whereas, 104 and 105 S. epidermidis bacterial cells.mL-1 halves the OP of Cu/NQ. Finally, viable and gamma-rays-killed model bioaerosols present similar oxidative reactivity, suggesting a metabolism-independent cellular mechanism. These results reveal the importance of bioaerosols for PM reactivity. PM toxicity can be modified due to bioaerosols contribution or by their ability to modulate the OP of toxic chemicals present in PM.

Antibiotic pollution in the Katari subcatchment of the Titicaca Lake: Major transformation products and occurrence of resistance genes.

An increasing number of studies pointed out the ubiquitous presence of medical residues in surface and ground water as well as in soil compartments. Not only antibiotics can be found in the environment but also their transformation products about which little information is generally available. The development of bacterial resistance to antibiotics is particularly worrying as it can lead to sanitary and health problems. Studies about the dissemination of antibiotics and associated resistances in the Bolivian Altiplano are scarce. We provide baseline information on the occurrence of Sulfamethoxazole (SMX) and Trimethoprim (TMP) antibiotics as well as on the most common human SMX transformation products (TP) and on the occurrence of sulfonamide resistance genes. The studied water and soil compartments presented high levels of antibiotic pollution. This situation was shown to be mainly linked with uncontrolled discharges of treated and untreated wastewaters, resulting on the presence of antibiotics in the Titicaca Lake. SMX TPs were detected in surface waters and on soil sampled next to the wastewater treatment plant (WWTP). SMX resistance genes sulI and sulII were widely detected in the basin hydrological network, even in areas unpolluted with antibiotics. Mechanisms of co-selection of antibiotic- and metal- resistance may be involved in the prevalence of ARG's in pristine areas with no anthropogenic activity and free of antibiotic pollution.

Application of synchrotron X-ray microtomography for visualizing bacterial biofilms 3D microstructure in porous media.

The development of reliable models to accurately predict biofilm growth in porous media relies on a good knowledge of the temporal evolution of biofilms structure within the porous network. Since little is known on the true 3D structure of biofilms developed in porous media, this work aimed at developing a new experimental protocol to visualize the 3D microstructure of bacterial biofilms in porous media. The main originality of the proposed procedure lies on the combination of the more recent advances in synchrotron microtomography (Paganin mode) and of a new contrast agent (1-chloronaphtalene) that has never been applied to biofilm visualization. It is shown that the proposed methodology takes advantage of the contrasting properties of 1-chloronaphtalene to prevent some limitations observed with more classical contrast agents. A quantitative analysis of the microstructural properties (volume fractions and specific surface area) of bacterial biofilms developed in columns of clay beads is also proposed on the basis of the obtained 3D images.

Dental fluorosis linked to degassing of Ambrym volcano, Vanuatu: a novel exposure pathway.

Ambrym in Vanuatu is a persistently degassing island volcano whose inhabitants harvest rainwater for their potable water needs. The findings from this study indicate that dental fluorosis is prevalent in the population due to fluoride contamination of rainwater by the volcanic plume. A dental survey was undertaken of 835 children aged 6-18 years using the Dean's Index of Fluorosis. Prevalence of dental fluorosis was found to be 96% in the target area of West Ambrym, 71% in North Ambrym, and 61% in Southeast Ambrym. This spatial distribution appears to reflect the prevailing winds and rainfall patterns on the island. Severe cases were predominantly in West Ambrym, the most arid part of the island, and the most commonly affected by the volcanic plume. Over 50 km downwind, on a portion of Malakula Island, the dental fluorosis prevalence was 85%, with 36% prevalence on Tongoa Island, an area rarely affected by volcanic emissions. Drinking water samples from West Ambrym contained fluoride levels from 0.7 to 9.5 ppm F (average 4.2 ppm F, n = 158) with 99% exceeding the recommended concentration of 1.0 ppm F. The pathway of fluoride-enriched rainwater impacting upon human health as identified in this study has not previously been recognised in the aetiology of fluorosis. This is an important consideration for populations in the vicinity of degassing volcanoes, particularly where rainwater comprises the primary potable water supply for humans or animals.

Charitable giving expenditures and the faith factor.

Using a permanent income hypothesis approach and an income-giving status interaction effect, a double hurdle model provides evidence of significant differences from the impact of household income and various household characteristics on both a household's likelihood of giving and its level of giving to religion, charity, education, others outside the household, and politics. An analysis of resulting income elasticity estimates revealed that households consider religious giving a necessity good at all levels of income, while other categories of giving are generally found to be luxury goods. Further, those who gave to religion were found to give more to education and charity then those not giving to religion, and higher education households were more likely to give to religion than households with less education. This analysis suggests that there may be more to religious giving behavior than has been assumed in prior studies and underscores the need for further research into the motivation for religious giving. Specifically, these findings point to an enduring, internal motivation for giving rather than an external, "What do I get for what I give," motive.

Gravity replacement during running in simulated microgravity.

INTRODUCTION: During treadmill exercise on the International Space Station (ISS), a restoring load from a subject load device (SLD) is applied through a shoulder-and-waist harness to pull the exercising crewmember toward the treadmill surface. The capacity of this arrangement to provide 1-g-like reaction forces may be critical for effective use of the treadmill as a countermeasure to musculoskeletal changes during prolonged spaceflight. This study in simulated microgravity evaluated the comfort and function during running of the ISS harness used with a new SLD in a system that allows more even distribution of the load between the waist and shoulders. METHODS: Using a zero-gravity locomotion simulator, 12 subjects completed three 5-min running trials at a constant speed (3.35 m x s(-1)) using three SLD loads [50%, 75%, and 100% of bodyweight (BW)] presented at random and a shoulder-to-waist loading ratio of 50:50. Subjective ratings of discomfort, ground reaction forces (GRFs), and SLD loads were collected. RESULTS: A load of 100% BW resulted in similar GRF profiles (peak and rate of change of force) to those reported for 1-g running over ground and were also comfortably tolerated (mean Borg scale rating 3.9/10). DISCUSSION: With an appropriate harness and SLD system, 1-g-like GRF profiles can be generated at the feet during simulated microgravity running. Such forces can be achieved with a level of discomfort rated better than "somewhat uncomfortable," suggesting that running with 1-g loads could be an effective component of musculoskeletal countermeasures during long-duration spaceflight.

Effect of left ventricular function on long-term left ventricular pacing and sensing threshold.

BACKGROUND: The effect of left ventricular (LV) systolic function on the long-term left ventricular pacing and sensing threshold is unclear. METHODS AND RESULTS: We studied the effect of LV ejection fraction (LVEF) on the LV pacing and sensing threshold in 56 patients (mean age: 70.2 +/- 10.5 years) underwent permanent LV pacing using a self-retaining coronary sinus lead (Model 1055 K, St Jude Medical, USA). In 49 patients, the LV lead was implanted for conventional pacemaker indication (sick sinus syndrome = 14, heart block = 26 or slow atrial fibrillation = 9). The remaining 7 patients were implanted for congestive heart failure. The LV pacing and sensing threshold, and lead impedance were compared between patients with LVEF <40% (Group 1, n = 28) and LVEF >40% (Group 2, n = 28) during implant and at 3-month follow up. The LV pacing lead was successfully implanted in all patients without any lead dislodgement on follow-up. At implant, Group 1 patients had a significant lower R wave amplitude, but similar LV pacing threshold and lead impedance as compared to Group 2. However, at 3-month follow-up, Group 1 patients had a significantly higher LV pacing threshold compared to Group 2 patients. There were no significant differences in the sensing threshold and lead impedance between the two groups. Furthermore, there was also a significant interval increase in LV pacing threshold in Group 1 patients (0.94 +/- 0.12 V) after 3 months, but not in Group 2 patients (0.16 +/- 0.08 V, p < 0.01). CONCLUSIONS: The results of this study suggest that the LV systolic function has a significant impact on the long-term LV pacing threshold. The long-term left ventricular pacing threshold in patients with left ventricular systolic dysfunction increased after implant and was higher than patients with normal left ventricular systolic function.

Do clinical and angiographic parameters predict failure of medical therapy in patients suitable for coronary angioplasty?

AIMS: Recent studies have suggested that patients with coronary disease suitable for angioplasty have an equally good outcome with medical therapy if clinically stable. Complex lesion morphology may predict acute events without intervention and stenosis severity influences the degree of collateralisation. This study was designed to assess the influence of these factors on clinical outcome. METHODS AND RESULTS: A retrospective review of patients suitable for angioplasty who were randomised to initial medical therapy as part of a multicentre study. Angiograms were reviewed for lesion characteristics, TIMI flow grade, and degree of collateralisation. Angiograms were available on 79 patients (13 female, 66 male). Mean age was 54.8 years (range 43-68) in the group crossing-over to revascularisation, and 58.4 (range 37-78) in the group who did not (P=ns). Seventeen patients crossed-over (two to CABG, 15 to PTCA) at 5.4 months (range 0-10) after initial angiography. Disease progression had occurred in 10/17 patients (58.8%), three of whom developed a new occlusion. Collateralisation was more likely in smokers, independent of lesion severity (P<0.05). Time to cross-over was not influenced by progression of disease. Crossing-over was not affected by age, diabetic status, cholesterol level, vessel involved, lesion severity, TIMI flow, lesion morphology, collateralisation, or the number of vessels diseased, but was more likely in females (P<0.05). CONCLUSION: This group of patients generally does well with medical therapy. Whilst the numbers are relatively small, there does not appear to be any reliable prospective marker, including the presence of spontaneous collateral channels on diagnostic angiography, to indicate which patients will fail medical therapy and require revascularisation.

Heart rate dependency of pulse pressure amplification and arterial stiffness.

BACKGROUND: Pulse pressure and aortic pulse wave velocity, measures of arterial stiffness, are both important determinants of cardiovascular risk. However, assessment of peripheral pulse pressure does not always provide a reliable measure of changes in central pulse pressure or arterial stiffness. The aim of the present study was to assess the effect of acute changes in heart rate on arterial stiffness and on peripheral and central pulse pressure in healthy subjects. METHODS: Twenty subjects (age range, 20 to 72 years) were studied at cardiac catheterization. Pulse wave analysis was used to determine central pressure, augmentation index (AIx), a measure of systemic arterial stiffness, and aortic pulse wave velocity (PWV) during right atrial pacing (80 to 120 beats/min). RESULTS: Pulse pressure amplification increased during pacing due to a reduction in central pressure augmentation. AIx was significantly and inversely related to heart rate (r = -0.70, P < .001) due to an alteration in the relative timing of the reflected pressure wave, rather than a reduction in arterial stiffness, as PWV did not change. CONCLUSIONS: These data suggest that peripheral pulse pressure does not provide an accurate assessment of changes in central hemodynamics in relation to changes in heart rate, and that aortic stiffness is not affected by acute changes in heart rate.