Activation of Fyn tyrosine kinase upon secretagogue stimulation of bovine chromaffin cells

Adrenal medullary chromaffin cells derive from the neural crest during embryogenesis and differentiate into dedicated secretory cells that release catecholamines in response to acetylcholine in vivo or nicotinic agonists in vitro. Previous studies have indicated that tyrosine kinases participate in early secretagogue-induced events in these cells and are required for exocytosis. Abundant levels of the cytoplasmic tyrosine kinases, c-Src and c-Yes, have been detected in chromaffin cells, thereby implicating them as kinases relevant to these events. However, c-Src has been found to undergo a decrease in activity following secretagogue-stimulation, and c-Yes appears to exist in a constitutively low activity state, suggesting that other tyrosine kinases are involved. Furthermore, other members of the Src family of tyrosine kinases have been implicated as playing roles in secretion in a variety of cell types. Therefore, we sought to determine if other Src family members were present in chromaffin cells, and if so, to examine them for subcellular localization and changes in activity following treatment with nicotinic agonists. To this end, antibodies for Fyn, Lck, Lyn, and Fgr were assembled and used in immunoprecipitation, in vitro autokinase, and Western immunoblotting assays. Of these four kinases, only Fyn was found to be expressed at detectable levels. Differential centrifugation studies revealed that Fyn resides predominantly (>95%) in the crude plasma membrane fraction and undergoes nicotinic- and carbachol-induced activation. This activation is reduced by the nicotinic antagonist, mecamylamine, is not elicited by muscarine, and is dependent upon the presence of extracellular Ca²⁺. These results suggest that Fyn is involved in signalling through the nicotinic receptor and may be one of the relevant kinases responsible for at least some of the tyrosine phosphorylations detected after stimulation. © 1996 Wiley-Liss, Inc.     

Intercostal nerve blockade with liposomal bupivacaine reduces length of stay after video assisted thoracic surgery (VATS) lobectomy

BackgroundIntercostal nerve blockade (INB) for thoracic surgery analgesia has gained popularity in practice, but evidence demonstrating its efficacy remains sparse and inconsistent. We investigated the effect of INB with standard bupivacaine (SB) with epinephrine versus liposomal bupivacaine (LB) versus a mixed solution of the two on postoperative pain control and outcomes in video assisted thoracoscopic lobectomy patients.MethodsSince 2014, our practice has shifted from using INBs with SB with epinephrine, to LB, to a mix of the two as the central component of multimodal analgesia after video assisted thoracoscopic surgery. The blocks are performed in a standardized fashion under thoracoscopic visualization consecutively from two rib spaces above to two below the outermost incisions. We retrospectively compared all minimally invasive lobectomies performed at our institution between January 2014 and July 2018 by type of local anesthetic used for INB. We examined median length of stay (LOS), opioid utilization, and subjective pain scores [0–10].ResultsOut of 302 minimally invasive lobectomy patients, 34 received SB with epinephrine, 222 received LB alone, and 46 received the mixed solution. LOS was almost a full day shorter in the LB group than in the SB group (34.8 vs. 56.5 hours, P=0.01). There was nearly 25% lower median total morphine equivalent utilization in the mixed solution cohort compared to the LB cohort (−7.1 mg, P=0.02). Additionally, IV morphine equivalent utilization was over 50% lower in the mixed solution group than in the SB with epinephrine group (−10.0 mg, P=0.03).ConclusionsOur study is by far the largest (N=302) to compare types of local anesthetic used for INB within a uniform case population. The reductions in LOS and opiate utilization observed in our study among patients receiving LB-based formulations were both statistically and clinically significant.     

Increased activation of the fear neurocircuitry in children exposed to violence

Most studies investigating the effect of childhood trauma on the brain are retrospective and mainly focus on maltreatment, whereas different types of trauma exposure such as growing up in a violent neighborhood, as well as developmental stage, could have differential effects on brain structure and function. The current magnetic resonance imaging study assessed the effect of trauma exposure broadly and violence exposure more specifically, as well as developmental stage on the fear neurocircuitry in 8‐ to 14‐year‐old children and adolescents (N = 69). We observed reduced hippocampal and increased amygdala volume with increasing levels of trauma exposure. Second, higher levels of violence exposure were associated with increased activation in the amygdala, hippocampus, and ventromedial prefrontal cortex during emotional response inhibition. This association was specifically observed in children younger than 10 years. Finally, increased functional connectivity between the amygdala and brainstem was associated with higher levels of violence exposure. Based on the current findings, it could be hypothesized that trauma exposure during childhood results in structural changes that are associated with later risk for psychiatric disorders. At the same time, it could be postulated that growing up in an unsafe environment leads the brain to functionally adapt to this situation in a way that promotes survival, where the long‐term costs or consequences of these adaptations are largely unknown and an area for future investigations.     

18F-labeled FECNT: a selective radioligand for PET imaging of brain dopamine transporters

Fluorine-18 labeled 2beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(2-fluoroethyl)nort ropane (FECNT) was synthesized in the development of a dopamine transporter (DAT) imaging ligand for positron emission tomography (PET). The methods of radiolabeling and ligand synthesis of FECNT, and the results of the in vitro characterization and in vivo tissue distribution in rats and in vivo PET imaging in rhesus monkeys of [18F]FECNT are described. Fluorine-18 was introduced into 2beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(2-fluoroethyl)nort ropane (4) by preparation of 1-[18F]fluoro-2-tosyloxyethane (2) followed by alkylation of 2beta-carbomethoxy-3beta-(4-chlorophenyl)nortropane (3) in 21% radiochemical yield (decay corrected to end of bombardment [EOB]). Competition binding in cells stably expressing the transfected human DAT serotonin transporter (SERT) and norepinephrine transporter (NET) labeled by [3H]WIN 35428, [3H]citalopram, and [3H]nisoxetine, respectively, indicated the following order of DAT affinity: GBR 12909 > CIT > 2beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(3-fluoropropyl) nortropane (FPCT) > FECNT. The affinity of FECNT for SERT and NET was 25- and 156-fold lower, respectively, than for DAT. Blocking studies were performed in rats with a series of transporter-specific agents and demonstrated that the brain uptake of [18F]FECNT was selective and specific for DAT-rich regions. PET brain imaging studies in monkeys demonstrated high [18F]FECNT uptake in the caudate and putamen that resulted in caudate-to-cerebellum and putamen-to-cerebellum ratios of 10.5 at 60 min. [18F]FECNT uptake in the caudate/putamen peaked in less than 75 min and exhibited higher caudate- and putamen-to-cerebellum ratios at transient equilibrium than reported for 11C-WIN 35,428, [11C]CIT/RTI-55, or [18F]beta-CIT-FP. Analysis of monkey arterial plasma samples using high performance liquid chromatography determined that there was no detectable formation of lipophilic radiolabeled metabolites capable of entering the brain. In equilibrium displacement experiments with CIT in rhesus monkeys, radioactivity in the putamen was displaced with an average half-time of 10.2 min. These results indicate that [18F]FECNT is a radioligand that is superior to 11C-WIN 35,428, [11C]CIT/RTI-55, [18F]beta-CIT-FP, and [18F]FPCT for mapping brain DAT in humans using PET.