An assessment of health hazard/health risk appraisal.

A state-of-the-art review of a widely-used health promotion technique, the health hazard/health risk appraisal (HHA/HRA), was conducted. The review included preparing a 212-item annotated bibliography, compiling an inventory of 217 programs that have used HHA/HRA, holding discussions with HHA/HRA developers and users, conducting formal site visits to 15 HHA/HRA programs, and consultation with experts on epidemiology, biostatistics, and behavioral science as well as developers and users of HHA/HRA. Programs use HHA/HRA primarily as a promotional device, as a tool for structuring education about health-related behaviors, and as a motivational device for stimulating behavioral change. The scientific basis for HHA/HRA risk predictions is problematic, but their arithmetic imprecision is of less concern than insufficiency of the scientific evidence for certain behavioral recommendations, and inaccuracies in client-supplied data. Widely-held beliefs in HHA/HRA's efficacy for motivating behavioral change cannot be substantiated from available evidence, nor can the assumed absence of adverse effects. The importance of this particular health promotion technique appears to have been exaggerated

Microhollow Cathode Discharges

The current–voltage characteristics of hollow cathode discharges and their predischarges in argon under dc and pulsed conditions were found to have a positive slope at pressures up to approximately 50 Torr, and currents up to 20 mA, at a hole diameter of 0.7 mm. In this range of pressure and current, parallel operation of hollow cathode discharges, without ballast, was demonstrated. Scaling to higher pressure is possible by reducing the hole diameter. Pulsed experiments with an array of cathode rings of 75 μm diameter allowed us to obtain parallel operation of more than 50 discharges at a pressure of 350 Torr in air

Are Microbubbles Necessary for the Breakdown of Liquid Water Subjected to a Submicrosecond Pulse?

Electrical breakdown in homogeneous liquid water for an ∼ 100 ns voltage pulse is analyzed. It is shown that electron-impact ionization is not likely to be important and could only be operative for low-density situations or possibly under optical excitation. Simulation results also indicate that field ionization of liquid water can lead to a liquid breakdown provided the ionization energies were very low in the order of 2.3eV. Under such conditions, an electric-field collapse at the anode and plasma propagation toward the cathode, with minimal physical charge transport, is predicted. However, the low, unphysical ionization energies necessary for matching the observed current and experimental breakdown delays of ∼ 70 ns precludes this mechanism. Also, an ionization within the liquid cannot explain the polarity dependence nor the stochastic-dendritic optical emission structures seen experimentally. It is argued here that electron-impact ionization within randomly located microbubbles is most likely to be responsible for the collective liquid breakdown behaviors

Microbubble-Based Model Analysis of Liquid Breakdown Initiation by a Submicrosecond Pulse

An electrical breakdown model for liquids in response to a submicrosecond(∼100ns) voltage pulse is presented, and quantitative evaluations carried out. It is proposed that breakdown is initiated by field emission at the interface of pre-existing microbubbles. Impact ionization within the microbubble gas then contributes to plasma development, with cathode injection having a delayed and secondary role. Continuous field emission at the streamer tip contributes to filament growth and propagation. This model can adequately explain almost all of the experimentally observed features, including dendritic structures and fluctuations in the prebreakdown current. Two-dimensional, time-dependent simulations have been carried out based on a continuum model for water, though the results are quite general. Monte Carlo simulations provide the relevant transport parameters for our model. Our quantitative predictions match the available data quite well, including the breakdown delay times and observed optical emission

Two-dimensional nanosecond electric field mapping based on cell electropermeabilization

Nanosecond, megavolt-per-meter electric pulses cause permeabilization of cells to small molecules, programmed cell death (apoptosis) in tumor cells, and are under evaluation as a treatment for skin cancer. We use nanoelectroporation and fluorescence imaging to construct two-dimensional maps of the electric field associated with delivery of 15 ns, 10 kV pulses to monolayers of the human prostate cancer cell line PC3 from three different electrode configurations: single-needle, five-needle, and flat-cut coaxial cable. Influx of the normally impermeant fluorescent dye YO-PRO-1 serves as a sensitive indicator of membrane permeabilization. The level of fluorescence emission after pulse exposure is proportional to the applied electric field strength. Spatial electric field distributions were compared in a plane normal to the center axis and 15-20 μm from the tip of the center electrode. Measurement results agree well with models for the three electrode arrangements evaluated in this study. This live-cell method for measuring a nanosecond pulsed electric field distribution provides an operationally meaningful calibration of electrode designs for biological applications and permits visualization of the relative sensitivities of different cell types to nanoelectropulse stimulation. PACS Codes: 87.85.M

An Evaluation of HIV Testing Among Inmates in the North Carolina Prison System

We examined the use of voluntary HIV testing among state prisoners in the North Carolina prison system

Associations between county-level voter turnout, county-level felony voter disenfranchisement, and sexually transmitted infections among women in the Southern United States

Purpose: Voting may play a critical role in the allocation of social and structural resources to communities, which in turn shapes neighborhood environments, and ultimately, an individual's sexually transmitted infection (STI) risk. We assessed relationships among county-level voter turnout and felony voter disenfranchisement, and STIs. Methods: This cross-sectional multilevel analysis included 666 women in Alabama, Florida, Georgia, Mississippi, and North Carolina enrolled in the Women's Interagency HIV Study between 2013 and 2015. Having a baseline bacterial STI (chlamydia, gonorrhea, trichomoniasis, or early syphilis) was determined by laboratory testing. We used generalized estimating equations to test relationships between county-level voter turnout in the 2012 general election, county-level percentage of felony disenfranchised voters, and STI prevalence. Results: Eleven percent of participants had an STI. Higher voter turnout corresponded to lower STI prevalence (prevalence ratio = 0.84, 95% confidence interval = 0.73–0.96 per 4 percentage point higher turnout). Greater felony voter disenfranchisement corresponded to higher STI prevalence (prevalence ratio = 1.89, 95% confidence interval = 1.10–3.24 per 4 percentage point higher disenfranchisement). Conclusions: STI prevalence was inversely associated with voter turnout and positively associated with felony voter disenfranchisement. Research should assess causality and mechanisms through which civic engagement shapes sexual health. Expanding political participation, including eliminating discriminatory voting laws, could influence sexual health

Methodological issues in measuring health disparities

OBJECTIVES: This report discusses six issues that affect the measurement of disparities in health between groups in a population: Selecting a reference point from which to measure disparity. Measuring disparity in absolute or in relative terms. Measuring in terms of favorable or adverse events. Measuring in pair-wise or in summary fashion. Choosing whether to weight groups according to group size. Deciding whether to consider any inherent ordering of the groups. These issues represent choices that are made when disparities are measured. METHODS: Examples are used to highlight how these choices affect specific measures of disparity. RESULTS: These choices can affect the size and direction of disparities measured at a point in time and conclusions about the size and direction of changes in disparity over time. Eleven guidelines for measuring disparities are presented. CONCLUSIONS: Choices concerning the measurement of disparity should be made deliberately, recognizing that each choice will affect the results. When results are presented, the choices on which the measurements are based should be described clearly and justified appropriately.By Kenneth Keppel, Elsie Pamuk, John Lynch, Olivia Carter-Pokras, Insun Kim, Vickie Mays, Jeffrey Pearcy, Victor Schoenbach, and Joel S. Weissma

An apoptosis targeted stimulus with nanosecond pulsed electric fields (nsPEFs) in E4 squamous cell carcinoma

Stimuli directed towards activation of apoptosis mechanisms are an attractive approach to eliminate evasion of apoptosis, a ubiquitous cancer hallmark. In these in vitro studies, kinetics and electric field thresholds for several apoptosis characteristics are defined in E4 squamous carcinoma cells (SCC) exposed to ten 300 ns pulses with increasing electric fields. Cell death was >95% at the highest electric field and coincident with phosphatidylserine externalization, caspase and calpain activation in the presence and absence of cytochrome c release, decreases in Bid and mitochondria membrane potential (Δψm) without apparent changes reactive oxygen species levels or in Bcl2 and Bclxl levels. Bid cleavage was caspase-dependent (55–60%) and calcium-dependent (40–45%). Intracellular calcium as an intrinsic mechanism and extracellular calcium as an extrinsic mechanism were responsible for about 30 and 70% of calcium dependence for Bid cleavage, respectively. The results reveal electric field-mediated cell death induction and progression, activating pro-apoptotic-like mechanisms and affecting plasma membrane and intracellular functions, primarily through extrinsic-like pathways with smaller contributions from intrinsic-like pathways. Nanosecond second pulsed electric fields trigger heterogeneous cell death mechanisms in E4 SCC populations to delete them, with caspase-associated cell death as a predominant, but not an unaccompanied event

Nanoelectropulse-driven membrane perturbation and small molecule permeabilization

BACKGROUND: Nanosecond, megavolt-per-meter pulsed electric fields scramble membrane phospholipids, release intracellular calcium, and induce apoptosis. Flow cytometric and fluorescence microscopy evidence has associated phospholipid rearrangement directly with nanoelectropulse exposure and supports the hypothesis that the potential that develops across the lipid bilayer during an electric pulse drives phosphatidylserine (PS) externalization. RESULTS: In this work we extend observations of cells exposed to electric pulses with 30 ns and 7 ns durations to still narrower pulse widths, and we find that even 3 ns pulses are sufficient to produce responses similar to those reported previously. We show here that in contrast to unipolar pulses, which perturb membrane phospholipid order, tracked with FM1-43 fluorescence, only at the anode side of the cell, bipolar pulses redistribute phospholipids at both the anode and cathode poles, consistent with migration of the anionic PS head group in the transmembrane field. In addition, we demonstrate that, as predicted by the membrane charging hypothesis, a train of shorter pulses requires higher fields to produce phospholipid scrambling comparable to that produced by a time-equivalent train of longer pulses (for a given applied field, 30, 4 ns pulses produce a weaker response than 4, 30 ns pulses). Finally, we show that influx of YO-PRO-1, a fluorescent dye used to detect early apoptosis and activation of the purinergic P2X(7 )receptor channels, is observed after exposure of Jurkat T lymphoblasts to sufficiently large numbers of pulses, suggesting that membrane poration occurs even with nanosecond pulses when the electric field is high enough. Propidium iodide entry, a traditional indicator of electroporation, occurs with even higher pulse counts. CONCLUSION: Megavolt-per-meter electric pulses as short as 3 ns alter the structure of the plasma membrane and permeabilize the cell to small molecules. The dose responses of cells to unipolar and bipolar pulses ranging from 3 ns to 30 ns duration support the hypothesis that a field-driven charging of the membrane dielectric causes the formation of pores on a nanosecond time scale, and that the anionic phospholipid PS migrates electrophoretically along the wall of these pores to the external face of the membrane