Glucocorticoids rapidly inhibit oxytocin-stimulated adrenocorticotropin release from rat anterior pituitary cells, without modifying intracellular calcium transients

Glucocorticoid hormones suppress the secretion of ACTH evoked by secretagogues such as CRF and arginine vasopressin. In this study, we investigated the effects of glucocorticoids on ACTH release induced by oxytocin (OT) and on intracellular free calcium ion levels in corticotropes prepared from the adenohypophyses of female Wistar rats. Pulsatile additions of physiological concentration of OT (10 nM) to superfused anterior pituitary cells caused pulsatile ACTH release about 4-fold above basal secretion with similar peak amounts of ACTH during subsequent OT pulses. Exposure of the cells to corticosterone (100 nM) or to a selective glucocorticoid receptor agonist RU 28362 (100 nM) for 30 min suppressed OT-stimulated but not basal ACTH release by approximately 60%. Inhibition gradually disappeared during subsequent pulses of OT in the absence of corticosterone. Pretreatment with the selective antagonist RU 38486 (1 microM) completely blocked the inhibitory effect of corticosterone on OT-induced ACTH secretion. Changes in free cytosolic calcium levels in single cultured pituitary cells were measured using the calcium indicator Fura-2. OT caused calcium transients in corticotropes, which were identified by immunocytochemistry. They responded in a similar manner to a second OT stimulus when preincubated for 30 min with corticosterone (1 microM) or with RU 28362 (1 microM). Our data indicate that glucocorticoids, via glucocorticoid receptors, rapidly inhibit OT-stimulated ACTH secretion by corticotropes without affecting intracellular calcium transients due to OT. Therefore, we conclude that rapid inhibition of ACTH release by glucocorticoids interferes with cellular signal transduction beyond the step of calcium mobilization

Residual Stresses in Layered Manufacturing

Layered Manufacturing processes accumulate residual stresses during materialbuildup. These stresses may cause part warping and layer delamination. This paper presents work done on investigating residual stress accumulation andp(i,rt distortion of Layered Manufactured artifacts. A simple analyticaLmodel was developed and used to determine how the number of layers and the layer thickness influences part warping. Resllits show that thin layers produce lower part deflection as compared with depositing fewer and thicker layers. In addition to the analytical work, a finite element model wasdeveloped and used to illvestigate the deposition pattern's influence on. the part deflection. Finite element model and corresponding experimental analysis showed that the geometry of the deposition pattern significantly affects the resulting part distortion. This finite element model was also used to investigate an inter-layer surface defect,. known as the Christmas Thee Step, that is associated with Shape Deposition Manufacturing. Results indicate that the features of this defect are influenced only by the material deposited close. to the part·surface and the particular material deposited. The step is not affected by the deposition pattern.Mechanical Engineerin

Oxytocin at physiological concentrations evokes adrenocorticotropin (ACTH) release from corticotrophs by increasing intracellular free calcium mobilized mainly from intracellular stores. Oxytocin displays synergistic or additive effects on ACTH-releasing factor or arginine vasopressin-induced ACTH secretion, respectively

The potency of oxytocin (OT) in evoking ACTH secretion by isolated, superfused rat adenohypophyseal corticotrophs and its enhancement by CRF and arginine vasopressin (AVP) were analyzed. Each secretagogue effectively released ACTH from adenohypophyseal cells when added separately in pulsatile fashion in physiological concentrations based on hypophyseal portal blood (OT, 10 nM; AVP, 0.5 nM; CRF, 0.1 nM). OT released ACTH at concentrations as low as 1 nM. Moreover, a dose- response relationship up to 10 microM was revealed. Combinations of a constant amount of CRF (0.1 nM) with increasing concentrations of OT exerted a synergistic effect on ACTH release. In contrast, OT given in various concentrations in combination with AVP (0.5 nM) produced an additive effect on ACTH release. To study the mechanism of action of OT on ACTH secretion, cytosolic free calcium levels in single pituitary cells exposed to OT or AVP were measured using the calcium-sensitive fluorescent indicator Fura-2. Corticotrophs among mixed adenohypophyseal cell types in the primary cultures were identified by immunocytochemistry. More than 500 cells were individually stimulated with OT or AVP. Basal cytosolic free calcium levels ranged between 80- 130 nM free calcium. The addition of 100 nM OT or 1 microM AVP increased the cytosolic free calcium concentration within 3 sec to values ranging from 500-800 nM. An increase in intracellular calcium ranging from 200-500 nM due to OT could still be observed after extracellular calcium depletion. Taken together, our data demonstrate that physiological concentrations of OT stimulate ACTH secretion, independent of the other ACTH secretagogues, by mobilizing calcium mainly from intracellular stores

Neutral Current π0\pi^0 Production in MiniBooNE

This paper describes the analysis used to determine the neutral current $\pi^0$ production in MiniBooNE in bins of momentum. Additionally, a measurement of the relative coherent production of $\pi^0$s is discussed. The coherent production rate is found to be (19.5 $\pm$1.1 (stat) $\pm$2.5 (sys))% of the total exclusive neutral current $\pi^0$ production rate.Comment: Prepared for the Proceedings of Neutrino Interactions 200

Interpreting experimental bounds on D^0 - \bar{D^0} mixing in the presence of CP violation

We analyse the most recent experimental data regarding D^0 - \bar{D^0} mixing, allowing for CP violation. We focus on the dispersive part of the mixing amplitude, M^D_{12}, which is sensitive to new physics contributions. We obtain a constraint on the mixing amplitude: |M^D_{12}| < 6.2\times 10^{-11} MeV at 95% C.L. . This constraint is weaker by a factor of about three than the one which is obtained when no CP violation is assumed.Comment: 9 pages, revtex4; One reference updated, one reference added, footnote 3 correcte

Providing assistance to incarcerated fathers who have child support obligations can help their post-release community reintegration

Among the growing discussions about race, justice, inequality and incarceration there has been a greater concern over the financial obligations placed on those who are convicted of crimes. In new research, Caterina G. Roman and Nathan W. Link examine the effects of ongoing child support payments on incarcerated fathers after their release, finding that less than a third had their payments changed whilst in prison, and that over 90 percent had payments in arrears after release. They argue that the multiple social services involved with incarcerated fathers both pre and post imprisonment need to provide more coordinated support so that child support orders do not become unwieldy, burdensome arrears

Regulation of hematopoietic stem cell activity by inflammation

Hematopoietic stem cells (HSCs) are quiescent cells with self-renewal capacity and the ability to generate all mature blood cells. HSCs normally reside in specialized niches in the bone marrow that help maintain their quiescence and long-term repopulating activity. There is emerging evidence that certain cytokines induced during inflammation have significant effects on HSCs in the bone marrow. Type I and II interferons, tumor necrosis factor, and LPS directly stimulate HSC proliferation and differentiation, thereby increasing the short-term output of mature effector leukocytes. However, chronic inflammatory cytokine signaling can lead to HSC exhaustion and may contribute the development of hematopoietic malignancies. Pro-inflammatory cytokines such as G-CSF can also indirectly affect HSCs by altering the bone marrow microenvironment, disrupting the stem cell niche and leading to HSC mobilization into the blood. Herein, we review our current understanding of the effects of inflammatory mediators on HSCs, and we discuss the potential clinical implications of these findings with respect to bone marrow failure and leukemogenesis

Are We Seeing Magnetic Axis Reorientation in the Crab and Vela Pulsars?

Variation in the angle $\alpha$ between a pulsar's rotational and magnetic axes would change the torque and spin-down rate. We show that sudden increases in $\alpha$, coincident with glitches, could be responsible for the persistent increases in spin-down rate that follow glitches in the Crab pulsar. Moreover, changes in $\alpha$ at a rate similar to that inferred for the Crab pulsar account naturally for the very low braking index of the Vela pulsar. If $\alpha$ increases with time, all pulsar ages obtained from the conventional braking model are underestimates. Decoupling of the neutron star liquid interior from the external torque cannot account for Vela's low braking index. Variations in the Crab's pulse profile due to changes in $\alpha$ might be measurable.Comment: 14 pages and one figure, Latex, uses aasms4.sty. Accepted to ApJ Letter