The application of synthetic antibacterial minerals to combat topical infections: exploring a mouse model of MRSA infection.

The development of new antibiotics has stalled, and novel strategies are needed as we enter the age of antibiotic resistance. Certain naturally occurring clays have been shown to be effective in killing antibiotic resistant bacteria. However, these natural clays are too variable to be used in clinical settings.

Wavefront shaping with a Hadamard basis for scattering soil imaging.

Soil is a scattering medium that inhibits imaging of plant-microbial-mineral interactions that are essential to plant health and soil carbon sequestration. However, optical imaging in the complex medium of soil has been stymied by the seemingly intractable problems of scattering and contrast. Here, we develop a wavefront shaping method based on adaptive stochastic parallel gradient descent optimization with a Hadamard basis to focus light through soil mineral samples.

Synthetic antibacterial minerals: harnessing a natural geochemical reaction to combat antibiotic resistance.

The overuse of antibiotics in clinical and livestock settings is accelerating the selection of multidrug resistant bacterial pathogens. Antibiotic resistant bacteria result in increased mortality and financial strain on the health care and livestock industry. The development of new antibiotics has stalled, and novel strategies are needed as we enter the age of antibiotic resistance.

Label-Free Multiphoton Imaging of Microbes in Root, Mineral, and Soil Matrices with Time-Gated Coherent Raman and Fluorescence Lifetime Imaging.

Imaging biogeochemical interactions in complex microbial systems─such as those at the soil-root interface─is crucial to studies of climate, agriculture, and environmental health but complicated by the three-dimensional (3D) juxtaposition of materials with a wide range of optical properties. We developed a label-free multiphoton nonlinear imaging approach to provide contrast and chemical information for soil microorganisms in roots and minerals with epi-illumination by simultaneously imaging two-photon excitation fluorescence (TPEF), coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and sum-frequency mixing (SFM). We used fluorescence lifetime imaging (FLIM) and time gating to correct CARS for the autofluorescence background native to soil particles and fungal hyphae (TG-CARS) using time-correlated single-photon counting (TCSPC).

Influence of Uranium Concentration and pH on U-Phosphate Biomineralization by OR37.

Uranium contamination of soils and groundwater in the United States represents a significant health risk and will require multiple remediation approaches. Microbial phosphatase activity coupled to the addition of an organic P source has recently been studied as a remediation strategy that provides an extended release of inorganic P (Pi) into U-contaminated sites, resulting in the precipitation of -autunite minerals. Previous laboratory- and field-based biomineralization studies have investigated environments with relatively high U concentrations (>20 μM).

Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH.

Natural organic matter is known to influence the mobility of plutonium (Pu) in the environment via complexation and reduction mechanisms. Hydroxamate siderophores have been specifically implicated due to their strong association with Pu. Hydroxamate siderophores can also break down into di and monohydroxamates and may influence the Pu oxidation state, and thereby its mobility.

Unearthing the Antibacterial Mechanism of Medicinal Clay: A Geochemical Approach to Combating Antibiotic Resistance.

Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe(2+) and Al(3+) that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply.

Reversal of the Drug Binding Pocket Defects of the AcrB Multidrug Efflux Pump Protein of Escherichia coli.

Unlabelled: The AcrB protein of Escherichia coli, together with TolC and AcrA, forms a contiguous envelope conduit for the capture and extrusion of diverse antibiotics and cellular metabolites. In this study, we sought to expand our knowledge of AcrB by conducting genetic and functional analyses. We began with an AcrB mutant bearing an F610A substitution in the drug binding pocket and obtained second-site substitutions that overcame the antibiotic hypersusceptibility phenotype conferred by the F610A mutation.

Importance of Real-Time Assays To Distinguish Multidrug Efflux Pump-Inhibiting and Outer Membrane-Destabilizing Activities in Escherichia coli.

Unlabelled: The constitutively expressed AcrAB multidrug efflux system of Escherichia coli shows a high degree of homology with the normally silent AcrEF system. Exposure of a strain with acrAB deleted to antibiotic selection pressure frequently leads to the insertion sequence-mediated activation of the homologous AcrEF system. In this study, we used strains constitutively expressing either AcrAB or AcrEF from their normal chromosomal locations to resolve a controversy about whether phenylalanylarginine β-naphthylamide (PAβN) inhibits the activities of AcrAB and AcrEF and/or acts synergistically with antibiotics by destabilizing the outer membrane permeability barrier.

Mineralogical variables that control the antibacterial effectiveness of a natural clay deposit.

As antibiotic-resistant bacterial strains emerge and pose increased global health risks, new antibacterial agents are needed as alternatives to conventional antimicrobials. Naturally occurring antibacterial clays have been identified which are effective in killing antibiotic-resistant bacteria. This study examines a hydrothermally formed antibacterial clay deposit near Crater Lake, OR (USA).

Comparing and contrasting methods for tenodesis of the ruptured distal biceps tendon.

The evidence is clear that anatomic reinsertion is the best treatment for an active, compliant patient with an acute distal biceps rupture or a subacute rupture without significant proximal retraction of the tendon. Patients with partial tears and chronic ruptures require surgical attention when persistently symptomatic. Biceps tenodesis through dual incisions or a single anterior incision is a safe, highly reliable, and effective operation.