Cyclin-dependent kinase 5 (Cdk5) is emerging as a neuronal protein kinase involved in multiple aspects of neurotransmission in both post-and presynaptic compartments. Within the reward/motor circuitry of the basal ganglia, Cdk5 regulates dopamine neurotransmission via phosphorylation of the postsynaptic signal transduction pathway integrator, DARPP-32 (dopamine-and cyclic AMPregulated phosphoprotein, M r 32 000). Cdk5 has also been implicated in regulating various steps in the presynaptic vesicle cycle. Here we report that Cdk5 phosphorylates tyrosine hydroxylase (TH), the key enzyme for synthesis of dopamine. Using phosphopeptide mapping, site-directed mutagenesis, and phosphorylation state-specific antibodies, the site was identified as Ser31, a previously defined extracellular signal-regulated kinases 1/2 (ERK1/2) site. The phosphorylation of Ser31 by Cdk5 versus ERK1/2 was investigated in intact mouse striatal tissue using a pharmacological approach. The results indicated that Cdk5 phosphorylates TH directly and also regulates ERK1/2-dependent phosphorylation of TH through the phosphorylation of mitogenactivated protein kinase kinase 1 (MEK1). Finally, phospho-Ser31 TH levels were increased in dopaminergic neurons of rats trained to chronically self-administer cocaine. These results demonstrate direct and indirect regulation of the phosphorylation state of a Cdk5/ERK1/2 site on TH and suggest a role for these pathways in the neuroadaptive changes associated with chronic cocaine exposure. KeywordsCdk5; cocaine; dopamine; MAPK; phosphorylation; tyrosine hydroxylase Tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, was first shown to be regulated by protein phosphorylation 30 years ago (Morgenroth et al. 1975). It is a tetrameric 56 kDa mixed-function monooxygenase that is phosphorylated at four serine NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript residues in the N-terminus (Fig. 1a) (Zigmond et al. 1989;Kumer and Vrana 1996;Fitzpatrick 1999). TH activity is enhanced upon phosphorylation at Ser40 by cAMP-dependent protein kinase (PKA) as well as cGMP-dependent protein kinase (PKG), protein kinase C (PKC) and Ca 2+ -calmodulin-dependent protein kinase II (CaMKII). Phosphorylation of TH at Ser19 by CaMKII (Campbell et al. 1986) has also been associated with increased TH activity (Haycock et al. 1998). Both Ser40 and Ser19 are phosphorylated by mitogen-activated protein kinaseactivated protein (MAPKAP) kinase 2. TH is also phosphorylated by Cdk1 at Ser8 in cultured cells (Hall et al. 1991).Phosphorylation of Ser31 by ERK1/2 has also been suggested to activate TH . Interestingly, phosphorylation of Ser31 in humans may be affected through alternative splicing that results in differences in adjacent amino acid sequences (Sutherland et al. 1993b;Haycock 2002). Phospho-Ser31 TH levels have been shown to be increased by neuronal depolarization, phorbol esters, and nerve growth factor treatment in rat brain slices (Lindgren et al. 2002). Clear evidence...

Health management systems are now standard aspects of complex systems. They monitor the behaviour of components and sub-systems and in the event of unexpected system behaviour diagnose faults that have occurred. Although this process should reduce system downtime it is known that health management systems can generate false faults that do not represent the actual state of the system and cause resources to be wasted. The authors propose a process to address this issue in which Petri nets are used to model complex systems. Faults reported on the system are simulated in the Petri net model to predict the resultant system behaviour. This behaviour is then compared to that from the actual system. Using the standard deviation technique the similarity of the system variables is assessed and the validity of the fault determined. The process has been automated and is tested through application to an experimental rig representing an aircraft fuel system. The success of the process to verify genuine faults and identify false faults in a multi-phase mission is demonstrated. A technique is also presented that is specific to tank leaks where depending on the location and size of the leak, the resulting symptoms will vary.

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Background: Guidelines recommend antithrombotic therapy in patients with nonvalvular atrial fibrillation (NVAF) to reduce the risk of stroke and systemic embolism (SSE) based on an assessment utilizing the CHA2DS2-VASc score. However, a treatment gap exists regarding patients at risk for thromboembolic events. Objectives: The aim of this study was to characterize the use of guideline-directed medical therapy (GDMT) to reduce the risk of SSE in patients with NVAF upon hospital discharge. Methods: This retrospective review evaluated patients admitted to a community hospital with NVAF in 2016. All patients were included except for the following: < 18 years of age, concomitant valvular heart disease, expired during hospitalization, or discharged on hospice care. Descriptive statistics were reported for all parameters. Results: A total of 2739 patients with NVAF were included with 59.9% discharged on GDMT to reduce the risk of SSE. A 1% increase in GDMT at discharge was observed in patients admitted with a history of NVAF (n = 2238; 60.1% vs 61.1%). Patients with first-detected NVAF (n = 501) were discharged on GDMT 54.5% of the time. In patients with a high stroke risk, concomitant heart failure (P = .001) and a lower HAS-BLED score (mean = 2.85 vs 3.18; P < .0001) were associated with receiving GDMT upon discharge. However, patients with increased age (mean = 78.5 vs 76.4; P < .0001), vascular disease (P = .02), prior major bleeding (P < .0001), or first-detected NVAF (P < .0001) were less likely to be discharged on GDMT. Conclusions: Consistent with published registry data, a gap was observed in the use of GDMT to reduce the risk of SSE in patients with NVAF at this institution. Further investigation into methods for improvement is warranted.