Bacterial pathogens resistant to antibiotics have become a serious health threat. Those species which have developed resistance against multiple drugs such as the carbapenems, are more lethal as ...these are last line therapy antibiotics. Current diagnostic tests for these resistance traits are based on singleplex target amplification techniques which can be time consuming and prone to errors. Here, we demonstrate a chip based optofluidic system with single molecule sensitivity for amplification-free, multiplexed detection of plasmids with genes corresponding to antibiotic resistance, within one hour. Rotating disks and microfluidic chips with functionalized polymer monoliths provided the upstream sample preparation steps to selectively extract these plasmids from blood spiked with E. coli DH5α cells. Waveguide-based spatial multiplexing using a multi-mode interference waveguide on an optofluidic chip was used for parallel detection of three different carbapenem resistance genes. These results point the way towards rapid, amplification-free, multiplex analysis of antibiotic-resistant pathogens.
Glycaemic control is an inadequate surrogate marker of cardiovascular event reduction in patients with type 2 diabetes. Clinical trials to date have been unsuccessful in identifying a therapeutic ...approach that addresses the underlying problem in diabetes (glycaemic control) and reduces cardiovascular risk. The potential for some agents to increase the risk of cardiovascular events has led to substantial changes in regulatory requirements for new anti-diabetic therapies. These requirements, while key to ensuring the cardiovascular safety of new agents, fail to emphasize the need to show clinical benefits, such as less visual impairment, less need for dialysis, or fewer cardiovascular events and deaths. Changes in test results such as glycaemic control, serum creatinine, micro-albuminuria, or retinopathy are inadequate surrogates. Regulators should consider the potential advantages of offering extended patent protection in order to encourage companies to conduct long-term trials in diabetes and many other chronic medical conditions. Cooperative efforts among physicians, clinical trialists, regulators, and sponsors are needed to address unresolved issues including re-defining therapeutic targets that are meaningful to patients with diabetes, determining the appropriate length of follow-up for future trials, and considering the ethical and operational challenges of non-inferiority designs.
Students in many jurisdictions can study Mathematics at different levels in their final 2 years of secondary education. The levels of Mathematics range from standard (not involving calculus), through ...basic calculus, to more advanced treatments of calculus and algebra. In this context, some students can elect to study Mathematics at a level below their ability. We consider the situation in New South Wales (NSW), Australia, where most Year 12 students who apply to university are awarded a percentile ranking, namely the Australian Tertiary Admission Rank (ATAR). The ATAR reflects students' results in the final 2 years of secondary education and frequently determines what they can study at university. As the study of Mathematics is often segregated by gender, it is of interest to explore how boys' and girls' choices about level of Mathematics study affect their ATAR. We analyze administrative data for 46,000 senior secondary students in NSW who completed their Year 12 in 2011 and the Longitudinal Survey of Australian Youth (LSAY) for the same cohort. Using two-level regressions that control for relevant student and school characteristics, we find that, for a given level of performance in Mathematics in Year 10, girls see greater improvement than boys in Year 12 for all levels of Mathematics except the most advanced course. Girls who study basic Mathematics achieve ATAR increments as high as girls in some advanced courses. We discuss how awareness of these results may influence students' decisions on what level of Mathematics to study in Years 11 and 12. Author abstract
Ultrasound was employed to increase the growth rate of bacterial cells attached to surfaces. Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli cells adhered to and grew on a ...polyethylene surface in the presence of ultrasound. It was found that low‐frequency ultrasound (70 kHz) of low acoustic intensity (<2 W/cm2) increased the growth rate of the cells compared to growth without ultrasound. However, at high intensity levels, cells were partially removed from the surface. Ultrasound also enhanced planktonic growth of S. epidermidis and other planktonic bacteria. It is hypothesized that ultrasound increases the rate of transport of oxygen and nutrients to the cells and increases the rate of transport of waste products away from the cells, thus enhancing their growth.
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► Perfluorocarbon emulsions were formed by sonication and stabilized with DPPC. ► Emulsion size could be reduced to 50nm or 100nm by extrusion through a filter. ► Emulsion droplets ...were encapsulated in liposomes by the refolding of lipid sheets. ► The size of the resulting eLiposomes could also be controlled by extrusion.
This paper discusses the formation of eLiposomes, defined as a liposome with internal emulsion droplets. Liposomes have been investigated as passively targeted drug carriers due to their ability to deliver drugs to a cancerous tumor via the enhanced permeability and retention (EPR) effect. The enclosed emulsion droplets in an eLiposome add the ability to further control the location and time of release from the liposome with ultrasound. Emulsion droplets were formed from perfluorohexane (PFC6) by sonication at 20kHz and stabilized with dipalmitoyl phosphatidyl choline (DPPC). The size of the resulting droplets was reduced to approximately 100nm or 50nm by extrusion through polycarbonate filters of the same size at 50°C. Small unilamellar vesicles (SUVs) were prepared from DPPC by thin film hydration and extrusion through a 50nm filter. Interdigitated DPPC sheets were prepared from the SUVs by the addition of ethanol to a concentration of 3M. Excess ethanol was removed by centrifugation washing. The sheets were mixed with emulsion and the solution was heated to 50°C, resulting in the refolding of the DPPC sheets into closed vesicles. Emulsion droplets were encapsulated inside of the newly formed eLiposomes. The size of the eLiposomes was reduced by extrusion. Cryogenic transmission electron microscopy (cryoTEM) and negative-staining TEM were used to image the emulsion droplets and the eLiposomes. Encapsulation of emulsion droplets was verified by rotating the microscope stage of cryoTEM samples.
There is widespread concern about the reduction in the number of students in Australia studying calculus-based mathematics courses in the final year of secondary education. Over the last 20 years in ...New South Wales, we have seen a dramatic increase in the number of students studying general mathematics in place of calculus courses. The concern arises because students graduating from high school with no calculus are often not well equipped for many aspects of university-level study. This paper explores one potential reason for this in New South Wales, namely the scaling algorithm used to derive the Australian Tertiary Admission Rank. At a time when we are encouraging students to study higher mathematics, this paper contributes to the discussion by illustrating some empirical evidence, based on an analysis of published output from the application of the scaling algorithm used to derive Australian Tertiary Admission Ranks, as to why students may be opting for lower level mathematics at the Year 12 level in great numbers. Author abstract
A new drug delivery modality was developed based on drug encapsulation in polymeric micelles followed by a controlled release at the tumor site triggered by ultrasound focused on the tumor. ...Ultrasound not only released drug from micelles but also enhanced the local uptake of both free and encapsulated drug by tumor cells, thus providing effective drug targeting. The significant success of in vitro studies of this new drug delivery technique warranted extending studies to animal experiments. Here the results of the in vitro studies of the above technique are summarized and the first in vivo experiments using colon cancer model in rats are reported. The in vivo results showed that application of low-frequency ultrasound (20 and 70 kHz) significantly reduced the tumor size when compared with non-insonated controls; this result indicated in vivo drug targeting to tumors by ultrasound.
The authors examined the efficacy of
Bacillus anthracis protective antigen (PA) combined with adjuvants as vaccines against an aerosol challenge of virulent anthrax spores in rhesus macaques. ...Adjuvants tested included i) aluminum hydroxide (Alhydrogel), ii) saponin QS-21 and iii) monophosphoryl lipid A (MPL) in squalene/ lecithin/Tween 80 emulsion (SLT). Animals were immunized once with either 50 μg of recombinant PA plus adjuvant, or with Anthrax Vaccine Adsorbed (AVA), the licensed human anthrax vaccine. The serological response to PA was measured by enzymelinked immunosorbent assay. Lymphocyte proliferation and serum neutralization of
in vitro lethal toxin cytotoxicity were also assayed. In all vaccine groups, anti-PA IgM and IgG titers peaked at 2 weeks and 4–5 weeks postimmunization, respectively. Five weeks postimmunization, animals in all vaccine groups demonstrated PA-specific lymphocyte proliferation and sera that neutralized in vitro cytotoxicity. Six weeks after immunization, the animals were challenged by aerosol with approximately 93 LD
50 of virulent anthrax spores. Animals were bled daily for 1 week to monitor bacteremia, and deaths were recorded. Anti-PA ELISA titers in all groups of immunized animals were substantially increased 2 weeks after challenge. One dose of each vaccine provided significant protection ( > 90%) against inhalation anthrax in the rhesus macaques.
A custom ultrasonic exposure chamber with real-time fluorescence detection was used to measure acoustically-triggered drug release from Pluronic P-105 micelles under continuous wave (CW) or pulsed ...ultrasound in the frequency range of 20 to 90 kHz. The measurements were based on the decrease in fluorescence intensity when drug was transferred from the micelle core to the aqueous environment. Two fluorescent drugs were used: doxorubicin (DOX) and its paramagnetic analogue, ruboxyl (Rb). Pluronic P-105 at various concentrations in aqueous solutions was used as a micelle-forming polymer. Drug release was most efficient at 20-kHz ultrasound and dropped with increasing ultrasonic frequency despite much higher power densities. These data suggest an important role of transient cavitation in drug release. The release of DOX was higher than that of Rb due to stronger interaction and deeper insertion of Rb into the core of the micelles. Drug release was higher at lower Pluronic concentrations, which presumably resulted from higher local drug concentrations in the core of Pluronic micelles when the number of micelles was low. At constant frequency, drug release increased with increasing power density. At constant power density and for pulse duration longer than 0.1 s, peak release under pulsed ultrasound was the same as stationary release under CW ultrasound. Released drug was quickly re-encapsulated between the pulses of ultrasound, which suggests that upon leaving the sonicated volume, the non-extravasated and non-internalized drug would circulate in the encapsulated form, thus preventing unwanted drug interactions with normal tissues.
Aims: The aim of this study is to investigate whether pulsed ultrasound (US) in combination with gentamicin yields a decreased viability of bacteria in biofilms on bone cements in vivo.
Methods and ...Results: Bacterial survival on bone cement in the presence and absence of ultrasound was compared in a rabbit model. Two bone cement samples with an Escherichia coli ATCC 10798 biofilm were implanted in a total of nine rabbits. In two groups bone cement discs loaded with gentamicin, freshly prepared and aged were used, and in one group unloaded bone cement discs in combination with systemically administered gentamicin. Pulsed ultrasound with a frequency of 28·48 kHz and a maximum acoustic intensity of 500 mW cm−2 was applied continuously from 24 h till 72 h postsurgery on one of the two implanted discs. After euthanization and removal of the bacteria from the discs, the number of viable bacteria were quantified and skin samples were analysed for histopathological examination. Application of ultrasound, combined with gentamicin, reduced the viability of the biofilms in all three groups varying between 58 and 69% compared with the negative control. Histopathological examinations showed no skin lesions.
Conclusions: Ultrasound resulted in a tendency of improved efficacy of gentamicin, either applied locally or systemically. Usage of ultrasound in this model proved to be safe.
Significance and Impact of the Study: This study implies that ultrasound could improve the prevention of infection immediately after surgery, especially because the biomaterials, gentamicin and ultrasound used in this model are all in clinical usage, but not yet combined in clinical practice.
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