The price of sex: condom use and the determinants of the price of sex among female sex workers in eastern zimbabwe.

Background. Higher prices for unprotected sex threaten the high levels of condom use that contributed to the decline in Zimbabwe's human immunodeficiency virus (HIV) epidemic. To improve understanding of financial pressures competing against safer sex, we explore factors associated with the price of commercial sex in rural eastern Zimbabwe. Methods. We collected and analyzed cross-sectional data on 311 women, recruited during October–December 2010, who reported that they received payment for their most-recent or second-most-recent sex acts in the past year. Zero-inflated negative binomial models with robust standard errors clustered on female sex worker (FSW) were used to explore social and behavioral determinants of price. Results. The median price of sex was $10 (interquartile range [IQR],$5–$20) per night and$10 (IQR, $5–$15) per act. Amounts paid in cash and commodities did not differ significantly. At the most-recent sex act, more-educated FSWs received 30%–74% higher payments. Client requests for condom use significantly predicted protected sex (P < .01), but clients paid on average 42.9% more for unprotected sex. Conclusions. Within a work environment where clients' preferences determine condom use, FSWs effectively use their individual capital to negotiate the terms of condom use. Strengthening FSWs' preferences for protected sex could help maintain high levels of condom use

Effects of vertical confinement on gelation and sedimentation of colloids

We consider the sedimentation of a colloidal gel under confinement in the direction of gravity. The confinement allows us to compare directly experiments and computer simulations, for the same system size in the vertical direction. The confinement also leads to qualitatively different behaviour compared to bulk systems: in large systems gelation suppresses sedimentation, but for small systems sedimentation is enhanced relative to non-gelling suspensions, although the rate of sedimentation is reduced when the strength of the attraction between the colloids is strong. We map interaction parameters between a model experimental system (observed in real space) and computer simulations. Remarkably, we find that when simulating the system using Brownian dynamics in which hydrodynamic interactions between the particles are neglected, we find that sedimentation occurs on the same timescale as the experiments, however the thickness of the "arms" of the gel is rather larger in the experiments, compared with the simulations. An analysis of local structure in the simulations showed similar behaviour to gelation in the absence of gravity

Rho GTPases show differential sensitivity to nucleotide triphosphate depletion in a model of ischemic cell injury

Rho GTPases are critical for actin cytoskeletal regulation, and alterations in their activity may contribute to altered cytoskeletal organization that characterizes many pathological conditions, including ischemia. G protein activity is a function of the ratio of GTP-bound (active) to GDP-bound (inactive) protein, but the effect of altered energy metabolism on Rho protein activity has not been determined. We used antimycin A and substrate depletion to induce depletion of intracellular ATP and GTP in the kidney proximal tubule cell line LLC-PK10 and measured the activity of RhoA, Rac1, and Cdc42 with GTPase effector binding domains fused to glutathione S-transferase. RhoA activity decreased in parallel with the concentration of ATP and GTP during depletion, so that by 60 min there was no detectable RhoA-GTP, and recovered rapidly when cells were returned to normal culture conditions. Dissociation of the membrane-actin linker ezrin, a target of RhoA signaling, from the cytoskeletal fraction paralleled the decrease in RhoA activity and was augmented by treatment with the Rho kinase inhibitor Y27632. The activity of Cdc42 did not decrease significantly during depletion or recovery. Rac1 activity decreased moderately to a minimum at 30 min of depletion but then increased from 30 to 90 min of depletion, even as ATP and GTP levels continued to fall. Our data are consistent with a principal role for RhoA in cytoskeletal reorganization during ischemia and demonstrate that the activity of Rho GTPases can be maintained even at low GTP concentrations

The ErbB2ΔEx16 splice variant is a major oncogenic driver in breast cancer that promotes a pro-metastatic tumor microenvironment.

Amplification and overexpression of erbB2/neu proto-oncogene is observed in 20-30% human breast cancer and is inversely correlated with the survival of the patient. Despite this, somatic activating mutations within erbB2 in human breast cancers are rare. However, we have previously reported that a splice isoform of erbB2, containing an in-frame deletion of exon 16 (herein referred to as ErbB2ΔEx16), results in oncogenic activation of erbB2 because of constitutive dimerization of the ErbB2 receptor. Here, we demonstrate that the ErbB2ΔEx16 is a major oncogenic driver in breast cancer that constitutively signals from the cell surface. We further show that inducible expression of the ErbB2ΔEx16 variant in mammary gland of transgenic mice results in the rapid development of metastatic multifocal mammary tumors. Genetic and biochemical characterization of the ErbB2ΔEx16-derived mammary tumors exhibit several unique features that distinguish this model from the conventional ErbB2 ones expressing the erbB2 proto-oncogene in mammary epithelium. Unlike the wild-type ErbB2-derived tumors that express luminal keratins, ErbB2ΔEx16-derived tumors exhibit high degree of intratumoral heterogeneity co-expressing both basal and luminal keratins. Consistent with these distinct pathological features, the ErbB2ΔEx16 tumors exhibit distinct signaling and gene expression profiles that correlate with activation of number of key transcription factors implicated in breast cancer metastasis and cancer stem cell renewal

Stoichiometry of cationic nutrients in Phaeozems derived from skarn and Acrisols from other parent materials in lowland forests of Thailand

Some soils under tropical forests in western Thailand are derived from skarn complexes of hydrothermally metamorphosed granitic, calcareous and ultramafic rocks. We used data from six large, long-term forest ecological research plots to compare the soils derived from skarn with forest soils derived from granites and sedimentary parent materials elsewhere Thailand. The soils derived from skarn are Vermic Phaeozems and have deep, dark, worm-worked topsoils and bimodal particle size distributions of coarse sand and grit in clay or fine loam matrices. They are eutrophic with respect to both labile and non-labile forms of the mineral nutrients. The soils derived from other parent materials are mostly Acrisols. Analyses of variance for the cationic nutrients taken independently clearly distinguished the Phaeozems from the Acrisols. The two groups are also stoichiometrically distinct with respect to the main cationic nutrients, as depicted graphically by nutrient roses and as quantified as M+:TEB ratios. The cationic stoichiometric proportions also differentiated between the Acrisols on different plots and parent materials; and between the Phaeozems in our study and eutrophic soils in lowland forests elsewhere in the lowland tropics, with the Phaeozems having lower exchangeable Ca and Mg contents but higher exchangeable K. Subsoil cationic stoichiometric profiles appear to derive from parent materials, but those of the topsoil may be modified by selective biotic recycling. Nonetheless, inherited lithogenic stoichiometric ratios are still apparent in our topsoils. The forests on skarn in West Thailand are varied and overlap with those on Acrisols and other soils. This confirms earlier findings that climate and disturbance history have more influence than soils on the regional distribution of forest types in Thailand, although soils can be important at more local scales

Interactive effects of low molecular weight carbon compounds on N2O emissions

Low molecular weight carbon (C) compounds in hotspots such as the rhizosphere can greatly affect nitrate reduction processes. Towards a better prediction of N2O emission from denitrification, we are still lacking understanding of responses to the supply of complex C compound mixtures such as rhizodeposits versus the often examined response to individually amended C compounds. In a laboratory study, we applied three C compounds, glucose, citric acid and glutamic acid, individually or as a three-compound mixture to 14NH415NO3 amended soil at 80% water-filled pore space. For the individual C compound treatments, the substrateswere enriched in 13C-C. The mixture was enriched in 13C-C either in all constituent compounds or in one of the compounds only, resulting in four different treatments. This set-up enabled quantification of the utilization of each compound for heterotrophic respiration when applied individually and in combination, and for this to be related to the dynamics of 15N-NO3- reduction to 15N-N2O. The total 15N-N2O emission from the compound mixture over 10 days was similar to the total emission predicted from the average of the individual compound treatments This could suggest potential predictability of denitrification responses to complex mixtures of C based on knowledge of its constituents. However, immediate and simultaneous peaks of 15N-N2O and 13C-CO2 fluxes from the compound mixture contrasted with observed delays in 15N-N2O and 13C-CO2 fluxes when the compounds had been applied individually. Moreover, relative contributions of the C compounds to 13C-CO2 respiration from the compound mixture were different from the predicted contributions based on their individual application. While contributions of glutamic acid-C and citric acid-C to respiration in mixture during peak 15N-N2O emission were increased, glucose utilization in the mixture treatment was significantly lower. These findings give a glimpse of the challenges we are facing when trying to predict nitrate reduction occurring in the rhizosphere where interactions between C compounds and the soil matrix, as well as within the wider heterotrophic community, determine process rates. Given that most of our understanding of the role of C in regulating nitrate reduction, is informed from single compound studies, we require more evidence on the effects and innate interactions of compound mixtures to be able to predict responses to C sources

The price of sex: condom use and the determinants of the price of sex among female sex workers in eastern zimbabwe.

BACKGROUND: Higher prices for unprotected sex threaten the high levels of condom use that contributed to the decline in Zimbabwe's human immunodeficiency virus (HIV) epidemic. To improve understanding of financial pressures competing against safer sex, we explore factors associated with the price of commercial sex in rural eastern Zimbabwe. METHODS: We collected and analyzed cross-sectional data on 311 women, recruited during October-December 2010, who reported that they received payment for their most-recent or second-most-recent sex acts in the past year. Zero-inflated negative binomial models with robust standard errors clustered on female sex worker (FSW) were used to explore social and behavioral determinants of price. RESULTS: The median price of sex was $10 (interquartile range [IQR],$5-$20) per night and$10 (IQR, $5-$15) per act. Amounts paid in cash and commodities did not differ significantly. At the most-recent sex act, more-educated FSWs received 30%-74% higher payments. Client requests for condom use significantly predicted protected sex (P < .01), but clients paid on average 42.9% more for unprotected sex. CONCLUSIONS: Within a work environment where clients' preferences determine condom use, FSWs effectively use their individual capital to negotiate the terms of condom use. Strengthening FSWs' preferences for protected sex could help maintain high levels of condom use

Preparation of films of a highly aligned lipid cubic phase

We demonstrate a method by which we can produce an oriented film of an inverse bicontinuous cubic phase (QII D) formed by the lipid monoolein (MO). By starting with the lipid as a disordered precursor (the L3 phase) in the presence of butanediol, we can obtain a film of the QII D phase showing a high degree of in-plane orientation by controlled dilution of the sample under shear within a linear flow cell. We demonstrate that the direction of orientation of the film is different from that found in the oriented bulk material that we have reported previously; therefore, we can now reproducibly form QII D samples oriented with either the [110] or the [100] axis aligned in the flow direction depending on the method of preparation. The deposition of MO as a film, via a moving fluid− air interface that leaves a coating of MO in the L3 phase on the capillary wall, leads to a sample in the [110] orientation. This contrasts with the bulk material that we have previously demonstrated to be oriented in the [100] direction, arising from flow producing an oriented bulk slug of material within the capillary tube. The bulk sample contains significant amounts of residual butanediol, which can be estimated from the lattice parameter of the QII D phase obtained. The sample orientation and lattice parameters are determined from synchrotron small-angle X-ray scattering patterns and confirmed by simulations. This has potential applications in the production of template materials and the growth of protein crystals for crystallography as well as deepening our understanding of the mechanisms underlying the behavior of lyotropic liquid-crystal phases