Depolymerisation and rearrangement of actin filaments during exocytosis in rat peritoneal mast cells: involvement of ryanodine-sensitive calcium stores

Cytoskeletal F-actin associated with synaptic vesicles and granules plays an important role during Ca²⁺-mediated exocytosis. In the present work, we have used amperometry and confocal fluorescence to study the role of internal Ca²⁺ in the rearrangement of F-actin (visualised with phalloidin-Alexa 546) during exocytosis in rat mast cells. The F-actin-depolymerising drug, latrunculin A, and the ryanodine receptor agonists ryanodine and caffeine that, per se did not induce exocytosis, enhanced the exocytotic responses elicited by compound 48/80 (C48/80). They also induced cortical actin depolymerisation in the presence or absence of external Ca²⁺. Degranulation induced by C48/80 was accompanied by the formation of a cytoplasmic F-actin network. Depletion of internal Ca²⁺ with cyclopiazonic acid inhibited latrunculin potentiation of C48/80-stimulated exocytosis and completely blocked the formation of the cytoplasmic F-actin network. This indicates that the mobilisation of Ca²⁺ from ryanodine-sensitive intracellular stores plays an important role in the depolymerisation of the cortical F-actin barrier and possibly in the formation of the internal F-actin network during exocytotic activation of peritoneal mast cells.     

No One-Size-Fits-All: Sexual Health Education Preferences in Patients with Breast Cancer

Annals of Surgical Oncology - Using explanatory mixed methods, we characterize the education that patients with breast cancer received about potential sexual health effects of treatment and explore...     

Associations Between Sexual Trauma and Sexual Relationship Power Among Latina Immigrant Farmworkers: The Moderating Role of Gender Norms

Sexual trauma is a national public health concern due to the alarming rates at which it occurs and decades of research supporting its long-term deleterious effects on health outcomes. We assessed the impact of gender norms and sexual trauma on power within sexual relationships among Latina immigrant farmworkers. At baseline, participants (N  = 175) completed a survey examining demographic information, sexual trauma history, and gender norms; a follow-up was administered 6 months later. Past sexual trauma was associated with less power in sexual relationships, r  = −.25, p < .001, as was endorsement of traditional Latina gender norms (i.e., marianismo): sexual relationship control, r  = −.38, p < .001; sexual decision-making dominance, r  = −.21, p  = .005. In contrast, egalitarian gender norm endorsement was associated with higher levels of sexual relationship control, r  = .37, p < .001, and sexual decision-making dominance, r  = .17, p  = .023. Gender norms moderated the association between sexual trauma and sexual relationship power. Specifically, women who subscribed more to marianismo and reported sexual trauma had less decision-making dominance in sexual relationships, whereas those with lower ratings of marianismo reported higher levels of decision-making dominance despite sexual trauma, R²  = .03, p  = .022. Sexual trauma history coupled with higher ratings of egalitarian gender norms was associated with higher levels of sexual relationship control, DR²  = .02, p  = .023. These results highlight the importance of culturally informed research to increase the sexual and overall health of vulnerable populations (e.g., Latina immigrant farmworkers).     

Dermal toxicity,eye and dermal irritation and skin sensitization evaluation of a new formulation of Bacillus thuringiensis var israelensis SH-14

Bacillus thuringiensis (Bt) is the best known and most widely used of all pesticidal microbes. The aim of this study was to assess the toxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14 in rats through acute dermal toxicity, dermal and eye irritation experiments. The acute dermal toxicity and dermal and eye irritation studies were performed using rabbits according to the United States Environmental Protection Agency guidelines 885.3100, 870.2500 and 870.2500, respectively. The skin sensitization study was carried out in accordance to the EPA OPPTS 870.2600 using guinea pigs. There was no mortality and no evidence of treatment-related toxicity in acute dermal toxicity test. No dermal responses, including erythema/eschar or edema, were found in rabbits treated with the new formulation of Bti SH-14. Minimum response was observed after eye application of test substance. No skin sensitization reactions were observed after the challenge with the new formulation of Bti SH-14 in the Bti SH-14-treated guinea pigs. In summary, the present study demonstrated that the new formulation of Bti SH-14 is not acutely toxic via dermal route, has low eye irritation and would not cause dermal irritation or hypersensitivity to tested animals.     

Potassium conductance of the squid giant axon is modulated by ATP.

This communication reports a modulating effect of intracellular ATP on the steady-state and kinetic properties of the delayed rectifier of the giant axon of the squid. When internally dialyzed or perfused giant axons from Loligo plei or Loligo pealei are voltage clamped at -60 mV and washed free of ATP, the potassium current at 0 mV is decreased, and the time course of the potassium current is faster. Upon readmitting ATP, the potassium current for pulses to potentials more positive than -30 mV is increased by a factor of up to 2.5, while for pulses to potentials more negative than -30 mV, it is decreased. In the presence of ATP the turn-on of the time course of the potassium current is slower, but the turn-off of the time course is faster. The effect of ATP is only observed when magnesium ions are present in the internal medium; ADP or the nonhydrolyzable ATP analogue adenosine 5'-[beta, gamma-methylene]-triphosphate has no effect. When the holding potential is -70 mV, the conductance-voltage curve is shifted to more positive potentials by ATP, but the maximum conductance is only slightly increased. Most of the effects of ATP may be explained by a phosphorylation step that alters the voltage sensor of the activation and inactivation gates of the potassium channels shifting the voltage dependence of both processes to more depolarized potentials.