qPET methodology provides semi-automatic quantification for interim FDG-PET response in lymphoma extending ordinal Deauville scoring to a continuous scale. Deauville categories correspond to certain qPET cut values. Thresholds between normal and abnormal response can be derived from the qPET-distribution without need for follow-up data. In our patients, qPET < 1.3 excludes abnormal response with high sensitivity.
Pituitary adenylate cyclase-activating polypeptide (PACAP) is thought to play a hypophysiotropic role, but little is known of the identity of PACAP-stimulated cells in the pituitary, the nature of the PACAP receptors on specific cell types, and the effector systems for these receptors. Here we describe the effects of PACAP in alpha T3-1 cells, a gonadotrope-derived cell line. In these cells, PACAP38 causes concentration-dependent increases in cAMP accumulation (EC50, 3 nM), [3H]inositol phosphate ([3H]IP) production (EC50, 20 nM), and the cytosolic Ca2+ concentration. The Ca2+ response is biphasic and is sustained only in Ca(2+)-containing medium. Intact alpha T3-1 cells possess a single class of [125I]PACAP27-binding sites (Kd, 3.3 nM; binding capacity, 35 fmol/10(6) cells). The rank orders of potencies for stimulation of cAMP and [3H]IP production and for inhibition of [125I] PACAP27 binding by three related peptides are identical (PACAP38 = PACAP27 > > vasoactive intestinal peptide). In addition to stimulation of LH release from primary cultures of rat pituitary cells and [3H] IP accumulation in alpha T3-1 cells, PACAP38 synergizes with low GnRH concentrations in the production of these effects. Moreover, long term exposure to PACAP38 stimulates [3H]thymidine incorporation and increases steady state levels of the gonadotropin alpha-subunit in alpha T3-1 cells. We conclude that alpha T3-1 cells possess type I PACAP receptors which mediate the observed effector system responses, and demonstration of the effects of PACAP on this gonadotrope-derived cell line provides further evidence that gonadotropes are direct targets for PACAP action. The data imply that stimulation of phospholipase-C by PACAP is responsible (at least in part) for the observed increase in cytosolic Ca2+, which, in turn, probably mediates the effects of PACAP on LH release. We suggest, however, that in gonadotropes, the effects of PACAP on cell replication and gonadotropin synthesis may prove more important than the peptide's modest effects on LH release.
The Angiocomb protocol created a noticeable share of long-term survivors and was well tolerated, suggesting that anti-angiogenic therapy for patients with DIPG should be studied more in the future.
Pituitary adenylate cyclase-activating polypeptide (PACAP) acts via type I receptors in the pituitary to stimulate cAMP production. Gonadotropes are likely target cells for PACAP action, and we have recently shown alpha T3-1 cells, a clonal gonadotrope-derived cell line, to be PACAP responsive. Here we have explored the influence of GnRH on PACAP action in alpha T3-1 cells and show that PACAP38-stimulated cAMP production is inhibited by GnRH in both the presence and the absence of a phosphodiesterase inhibitor. This effect appears not to be Ca++ mediated but is mimicked by protein kinase C activation with phorbol 12-myristate 13-acetate. However, GnRH and phorbol 12-myristate 13-acetate do not inhibit binding of [125I]PACAP27 to intact alpha T3-1 cells, nor do they inhibit forskolin- or cholera toxin-stimulated cAMP accumulation, implying that the inhibitory effects are exerted at early stages in the PACAP receptor signaling pathway but distal to receptor occupancy. When cells were preincubated with PACAP38, extensive washing failed to prevent the stimulatory effect of the polypeptide presumably because of the slow rate of receptor-ligand dissociation. However, when the time course of PACAP38-stimulated effects on intracellular cAMP was assessed, the stimulatory effect of PACAP38 could be rapidly reversed by GnRH addition, and the inhibitory effect of GnRH was rapidly be reversed by a GnRH receptor antagonist. The data provide the first demonstration of cross-talk between phospholipase C and adenylate cyclase-activating peptides in gonadotrope-derived cells and establish the potential for hormonal modulation of PACAP action. We suggest that this inhibitory effect of GnRH might enable the releasing hormone to control the kinetics of cAMP signaling in gonadotropes in vivo.
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