Impact of orthophosphate on the solubility and properties of lead orthophosphate nanoparticles.

Orthophosphate (PO) is a commonly used corrosion control treatment to reduce lead (Pb) concentrations in drinking water. PO reduces Pb concentrations by forming relatively insoluble lead phosphate (Pb-PO) minerals. In some cases, however, Pb-PO minerals have been observed to form nanoparticles, and if suspended in water, these nanoparticles can be mobile and reach consumer taps.

A holistic approach to lead pipe scale analysis: Importance, methodology, and limitations.

With lead service lines (LSLs) remaining for decades to come, scale analyses are critical to helping limit lead exposure from drinking water. This laboratory has used an integrated suite of analytical techniques to characterize the elemental composition, mineral identification, and physical features of scales, helping the water industry to evaluate, predict, and reduce lead corrosion. The methods used in this laboratory to prepare and analyze the LSL scale, and guidance to achieving reliable and meaningful results, are described.

Quantifying Molecular Dynamics within Complex Cellular Morphologies using LLSM-FRAP.

Quantifying molecular dynamics within the context of complex cellular morphologies is essential toward understanding the inner workings and function of cells. Fluorescence recovery after photobleaching (FRAP) is one of the most broadly applied techniques to measure the reaction diffusion dynamics of molecules in living cells. FRAP measurements typically restrict themselves to single-plane image acquisition within a subcellular-sized region of interest due to the limited temporal resolution and undesirable photobleaching induced by 3D fluorescence confocal or widefield microscopy.

When light meets biology - how the specimen affects quantitative microscopy.

Fluorescence microscopy images should not be treated as perfect representations of biology. Many factors within the biospecimen itself can drastically affect quantitative microscopy data. Whereas some sample-specific considerations, such as photobleaching and autofluorescence, are more commonly discussed, a holistic discussion of sample-related issues (which includes less-routine topics such as quenching, scattering and biological anisotropy) is required to appropriately guide life scientists through the subtleties inherent to bioimaging.

Hexameric rings of the scaffolding protein CheW enhance response sensitivity and cooperativity in chemoreceptor arrays.

The chemoreceptor array is a supramolecular assembly that enables cells to respond to extracellular cues dynamically and with great precision and sensitivity. In the array, transmembrane receptors organized as trimers of dimers are connected at their cytoplasmic tips by hexameric rings of alternating subunits of the kinase CheA and the scaffolding protein CheW (CheA-CheW rings). Interactions of CheW molecules with the members of receptor trimers not directly bound to CheA-CheW rings may lead to the formation of hexameric CheW rings in the chemoreceptor array.

The LRRK2 G2019S mutation alters astrocyte-to-neuron communication via extracellular vesicles and induces neuron atrophy in a human iPSC-derived model of Parkinson's disease.

Astrocytes are essential cells of the central nervous system, characterized by dynamic relationships with neurons that range from functional metabolic interactions and regulation of neuronal firing activities, to the release of neurotrophic and neuroprotective factors. In Parkinson's disease (PD), dopaminergic neurons are progressively lost during the course of the disease, but the effects of PD on astrocytes and astrocyte-to-neuron communication remain largely unknown. This study focuses on the effects of the PD-related mutation LRRK2 G2019S in astrocytes generated from patient-derived induced pluripotent stem cells.

Variability and sampling of lead (Pb) in drinking water: Assessing potential human exposure depends on the sampling protocol.

Lead (Pb) in drinking water has re-emerged as a modern public health threat which can vary widely in space and in time (i.e., between homes, within homes and even at the same tap over time).

Orthophosphate Interactions with Destabilized PbO Scales.

This research presents two case studies in which a change in the disinfectant from free chlorine to chloramine caused an increase in lead corrosion. In both systems, the predominantly tetravalent lead (PbO) scales destabilized as a result of disinfectant change. Orthophosphate corrosion control was used in both systems, and the effect of this treatment chemical on the destabilized PbO scales was examined.

Lead Particle Size Fractionation and Identification in Newark, New Jersey's Drinking Water.

Following a pH reduction in their drinking water over a span of more than 20 years, the City of Newark, New Jersey, has struggled with elevated lead (Pb) release from Pb service lines and domestic plumbing in the zone fed by the Pequannock Water Treatment Plant. In response, Newark initiated orthophosphate addition and provided faucet-mounted point-of-use (POU) filters and pitcher filters certified for Pb and particulate reduction under NSF/ANSI Standards 53 and 42 to residential homes in that zone. Water chemistry analysis and size fractionation sampling were performed at four of these houses.

Probability of Immobilization on Host Cell Surface Regulates Viral Infectivity.

The efficiency of a virus to establish its infection in host cells varies broadly among viruses. It remains unclear if there is a key step in this process that controls viral infectivity. To address this question, we use single-particle tracking and Brownian dynamics simulation to examine human immunodeficiency virus type 1 (HIV-1) infection in cell culture.

Practical Considerations in Particle and Object Tracking and Analysis.

The rapid advancement of live-cell imaging technologies has enabled biologists to generate high-dimensional data to follow biological movement at the microscopic level. Yet, the "perceived" ease of use of modern microscopes has led to challenges whereby sub-optimal data are commonly generated that cannot support quantitative tracking and analysis as a result of various ill-advised decisions made during image acquisition. Even optimally acquired images often require further optimization through digital processing before they can be analyzed.

Water quality-pipe deposit relationships in Midwestern lead pipes.

The conventional wisdom of lead-scale solubility has been built over the years by geochemical solubility models, experimental studies, and field sampling utilizing multiple protocols. Rarely, have the mineral phases from scales formed in real-world drinking water lead service lines (LSLs) been compared to theoretical predictions. In this study, model predictions are compared to LSL scales from 22 drinking water distribution systems.

A bacterial immunomodulatory protein with lipocalin-like domains facilitates host-bacteria mutualism in larval zebrafish.

Stable mutualism between a host and its resident bacteria requires a moderated immune response to control bacterial population size without eliciting excessive inflammation that could harm both partners. Little is known about the specific molecular mechanisms utilized by bacterial mutualists to temper their hosts' responses and protect themselves from aggressive immune attack. Using a gnotobiotic larval zebrafish model, we identified an secreted immunomodulatory protein, AimA.

Noncritical Signaling Role of a Kinase-Receptor Interaction Surface in the Escherichia coli Chemosensory Core Complex.

In Escherichia coli chemosensory arrays, transmembrane receptors, a histidine autokinase CheA, and a scaffolding protein CheW interact to form an extended hexagonal lattice of signaling complexes. One interaction, previously assigned a crucial signaling role, occurs between chemoreceptors and the CheW-binding P5 domain of CheA. Structural studies showed a receptor helix fitting into a hydrophobic cleft at the boundary between P5 subdomains.

Mineralogical Evidence of Galvanic Corrosion in Drinking Water Lead Pipe Joints.

Galvanic corrosion as a mechanism of toxic lead release into drinking water has been under scientific debate in the U.S. for over 30 years.

Dynasore inhibition on productive infection of HIV-1 in commonly used cell lines is independent of transferrin endocytosis.

The route of HIV-1 entry for productive infection in CD host cells is a fundamental question for the molecular understanding of HIV-1 infection and transmission. Although direct fusion has long been thought to be the mode of entry, recent studies have suggested that productive entry of HIV-1 may actually occur through dynamin-dependent endocytosis. In several of these studies, dynasore, a noncompetitive inhibitor of the GTPase activity of dynamin, has been used to support this conclusion.

Scale Formation Under Blended Phosphate Treatment for a Utility With Lead Pipes.

US corrosion control practice often assumes that the orthophosphate component of blended phosphate corrosion inhibitors causes the formation of low-solubility lead-orthophosphate solids that control lead release into drinking water. This study identified the solids that formed on the interior surface of a lead service line and a galvanized steel pipe excavated from a system using a proprietary blended phosphate chemical. The scale was analyzed by X-ray diffraction, X-ray fluorescence, and scanning electron microscopy/energy dispersive spectroscopy.

Multibuilding Block Janus Synthesized by Seed-Mediated Self-Assembly for Enhanced Photothermal Effects and Colored Brownian Motion in an Optical Trap.

The asymmetrical features and unique properties of multibuilding block Janus nanostructures (JNSs) provide superior functions for biomedical applications. However, their production process is very challenging. This problem has hampered the progress of JNS research and the exploration of their applications.

Optical manipulation of a single human virus for study of viral-cell interactions.

Although Ashkin and Dziedzic first demonstrated optical trapping of individual tobacco mosaic viruses in suspension as early as 1987, this pioneering work has not been followed up only until recently. Using human immunodeficiency virus type 1 (HIV-1) as a model virus, we have recently demonstrated that a single HIV-1 virion can be stabled trapped, manipulated and measured in physiological media with high precision. The capability to optically trap a single virion in suspension not only allows us to determine, for the first time, the refractive index of a single virus with high precision, but also quantitate the heterogeneity among individual virions with single-molecule resolution, the results of which shed light on the molecular mechanisms of virion infectivity.

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry.

The envelope glycoprotein (Env) gp120/gp41 is required for HIV-1 infection of host cells. Although in general it has been perceived that more Env gives rise to higher infectivity, the precise quantitative dependence of HIV-1 virion infectivity on Env density has remained unknown. Here we have developed a method to examine this dependence.

Label-free detection and manipulation of single biological nanoparticles.

In the past several years, there have been significant advances in the field of nanoparticle detection for various biological applications. Of considerable interest are synthetic nanoparticles being designed as potential drug delivery systems as well as naturally occurring or biological nanoparticles, including viruses and extracellular vesicles. Many infectious diseases and several human cancers are attributed to individual virions.

Low contribution of PbO2-coated lead service lines to water lead contamination at the tap.

To determine if residential water sampling corroborates the expectation that formation of stable PbO2 coatings on lead service lines (LSLs) provides an effective lead release control strategy, lead profile sampling was evaluated for eight home kitchen taps in three U.S. cities with observed PbO2-coated LSLs (Newport, Rhode Island; Cincinnati and Oakwood, Ohio).

Single-image diffusion coefficient measurements of proteins in free solution.

Diffusion coefficient measurements are important for many biological and material investigations, such as studies of particle dynamics and kinetics, and size determinations. Among current measurement methods, single particle tracking (SPT) offers the unique ability to simultaneously obtain location and diffusion information about a molecule while using only femtomoles of sample. However, the temporal resolution of SPT is limited to seconds for single-color-labeled samples.