No abstract

Background:The acute stress secretagogue PACAP leads to catecholamine release, but the source of calcium necessary for secretion is unknown. Results: PACAP stimulation increases LVA Ca v 3.2 influx in a PKC-dependent process. Conclusion: PACAP-mediated acute sympathetic stress functionally recruits a pool of latent Ca v 3.2 channels to supply calcium for secretion. Significance: Native sympathoadrenal stimulation elicits catecholamine release through a non-canonical mechanism.

Purpose Establishing reliable methods for interpreting elevated cerebral amyloid-β plaque on PET scans is increasingly important for radiologists, as availability of PET imaging in clinical practice increases. We examined a three-step method to detect plaque in cognitively normal older adults, focusing on the additive value of quantitative information during the PET scan interpretation process. Methods Fifty-five F-18 florbetapir PET scans were evaluated by three experienced raters. Scans were first visually interpreted as having “elevated” or “non-elevated” plaque burden (“Visual Read”). Images were then processed using a standardized quantitative analysis software (MIMneuro) to generate whole brain and region of interest (ROI) standard uptake value ratios (SUVRs). This “Quantitative Read” was considered elevated if at least two of six ROIs had an SUVR >1.1. The final interpretation combined both visual and quantitative data together (“VisQ Read”). Cohen’s kappa values were assessed as a measure of interpretation agreement. Results Plaque was elevated in 25.5–29.1% of the 165 total Visual Reads. Inter-rater agreement was strong (Kappa=0.73–0.82) and consistent with reported values. Quantitative Reads were elevated in 45.5% of participants. Final VisQ Reads changed from initial Visual Reads in 16 (9.7%) interpretations, with most changing from “non-elevated” Visual Reads to “elevated.” These changed interpretations demonstrated lower plaque quantification than those initially read as “elevated” that remained unchanged. Inter-rater variability improved for VisQ Reads with the addition of quantitative information (Kappa=0.88–0.96). Conclusion Inclusion of quantitative information increases consistency of PET scan interpretations for early detection of cerebral amyloid-β plaque accumulation.

DBT and FFDM mammograms more frequently include posterior or lateral tissue, the inframammary fold on MLO views, the pectoralis muscle on CC views, and skin folds than FS mammograms. Inclusion of more breast tissue with newer technologies suggests traditional positioning standards, in conjunction with updated standardized positioning training, are still applicable at the expense of including more skin folds.

Na(18)F PET/CT is the most comprehensive imaging modality for the evaluation of osseous metastatic disease. Although further data acquisition is necessary to expand cost-benefit analyses of this imaging agent, emerging data reinforce its diagnostic advantage, suggest methods to mitigate impediments to broader utilization of Na(18)F PET/CT, and introduce a potentially viable technique for single-session combined Na(18)F and FDG PET/CT staging of soft-tissue and osseous disease.

Patient breast density notification and radiologists' recommendations for supplemental screening with breast ultrasound increase patient utilization of automated screening breast ultrasound examinations.

Hill J, Lee SK, Samasilp P, Smith C. Pituitary adenylate cyclaseactivating peptide enhances electrical coupling in the mouse adrenal medulla. Am J Physiol Cell Physiol 303: C257-C266, 2012. First published May 16, 2012; doi:10.1152/ajpcell.00119.2012.-Neuroendocrine adrenal medullary chromaffin cells receive synaptic excitation through the sympathetic splanchnic nerve to elicit catecholamine release into the circulation. Under basal sympathetic tone, splanchnicreleased acetylcholine evokes chromaffin cells to fire action potentials, leading to synchronous phasic catecholamine release. Under elevated splanchnic firing, experienced under the sympathoadrenal stress response, chromaffin cells undergo desensitization to cholinergic excitation. Yet, stress evokes a persistent and elevated adrenal catecholamine release. This sustained stress-evoked release has been shown to depend on splanchnic release of a peptide transmitter, pituitary adenylate cyclase-activating peptide (PACAP). PACAP stimulates catecholamine release through a PKC-dependent pathway that is mechanistically independent of cholinergic excitation. Moreover, it has also been reported that shorter term phospho-regulation of existing gap junction channels acts to increase junctional conductance. In this study, we test if PACAP-mediated excitation upregulates cell-cell electrical coupling to enhance chromaffin cell excitability. We utilize electrophysiological recordings conducted in adrenal tissue slices to measure the effects of PACAP stimulation on cell coupling. We report that PACAP excitation increases electrical coupling and the spread of electrical excitation between adrenal chromaffin cells. Thus PACAP acts not only as a secretagogue but also evokes an electrical remodeling of the medulla, presumably to adapt to the organism's needs during acute sympathetic stress. acute stress; catecholamine; connexin-43; connexin-36; gap junction ADRENAL MEDULLARY CHROMAFFIN cells are neural crest-derived neurosecretory cells that release catecholamine into the bloodstream (2). Chromaffin cells are innervated by the bifurcating sympathetic splanchnic nerve. Under sympathetic tone, corresponding to the "rest and digest" metabolic state, the splanchnic nerve fires at a modest rate to maintain catecholamine homeostasis. Splanchnic-released acetylcholine binds to nicotinic ionotropic receptors on the chromaffin cell membrane, leading to action potential firing and controlled, phasic catecholamine release (1,7,13,18). Under the acute sympathetic stress response, the splanchnic nerve fires at a heightened rate, leading to rapid and robust cholinergic-evoked catecholamine secretion (25). Yet, the cholinergic pathway rapidly desensitizes (4, 5, 29) while elevated catecholamine secretion persists (44). Pituitary adenylate cyclase-activating peptide (PACAP) is a noncholinergic splanchnic-derived peptide transmitter released selectively during elevated splanchnic firing. PACAP has been identified as the peptide transmitter driving tonic catecholamine secretion after desensi...

PurposeThe aim of this study was to identify which patient characteristics are associated with the highest likelihood of positive findings on 11C-acetate PET/computed tomography attenuation correction (CTAC) (PET/CTAC) scan when imaging for recurrent prostate cancer.MethodsFrom 2007 to 2011, 250 11C-acetate PET/CTAC scans were performed at a single institution on patients with prostate cancer recurrence after surgery, brachytherapy, or external beam radiation. Of these patients, 120 met our inclusion criteria. Logistic regression analysis was used to examine the relationship between predictability of positive findings and patients’ characteristics, such as prostate-specific antigen (PSA) level at the time of scan, PSA kinetics, Gleason score, staging, and type of treatment before scan.ResultsIn total, 68.3% of the 120 11C-acetate PET/CTAC scans were positive. The percentage of positive scans and PSA at the time of scanning and PSA velocity (PSAV) had positive correlations. The putative sensitivity and specificity were 86.6% and 65.8%, respectively, when a PSA level greater than 1.24 ng/mL was used as the threshold for scanning. The putative sensitivity and specificity were 74% and 75%, respectively, when a PSAV level greater than 1.32 ng/mL/y was used as the threshold. No significant associations were found between scan positivity and age, PSA doubling time, Gleason score, staging, or type of treatment before scanning.ConclusionsThis retrospective study suggests that threshold models of PSA greater than 1.24 ng/mL or PSAV greater than 1.32 ng/mL per year are independent predictors of positive findings in 11C-acetate PET/CTAC imaging of recurrent prostate cancer.