Pituitary adenylate cyclase-activating polypeptide receptor activation in the hypothalamus recruits unique signaling pathways involved in energy homeostasis.

Pituitary adenylate cyclase activating polypeptide (PACAP) exerts pleiotropic effects on ventromedial nuclei (VMN) of the hypothalamus and its control of feeding and energy expenditure through the type I PAC1 receptor (PAC1R). However, the endogenous role of PAC1Rs in the VMN and the downstream signaling responsible for PACAP's effects on energy balance are unknown. Numerous studies have revealed that PAC1Rs are coupled to both Gαs/adenylyl cyclase/protein kinase A (Gαs/AC/PKA) and Gαq/phospholipase C/protein kinase C (Gαq/PLC/PKC), while also undergoing trafficking following stimulation. To determine the endogenous role of PAC1Rs and downstream signaling that may explain PACAP's pleiotropic effects, we used RNA interference to knockdown VMN PAC1Rs and pharmacologically inhibited PKA, PKC, and PAC1R trafficking. Knocking down PAC1Rs increased meal sizes, reduced total number of meals, and induced body weight gain. Inhibition of either PKA or PKC alone in awake male Sprague-Dawley rats, attenuated PACAP's hypophagic and anorectic effects during the dark phase. However, PKA or PKC inhibition potentiated PACAP's thermogenic effects during the light phase. Analysis of locomotor activity revealed that PKA inhibition augmented PACAP's locomotor effects, whereas PKC inhibition had no effect. Finally, PACAP administration in the VMN induces surface PAC1R trafficking into the cytosol which was blocked by endocytosis inhibitors. Subsequently, inhibition of PAC1R trafficking into the cytosol attenuated PACAP-induced hypophagia. These results revealed that endogenous PAC1Rs uniquely engage PKA, PKC, and receptor trafficking to mediate PACAP's pleiotropic effects in VMN control of feeding and metabolism.NEW & NOTEWORTHY Endogenous PAC1 receptors, integral to VMN management of feeding behavior and body weight regulation, uniquely engage PKA, PKC, and receptor trafficking to mediate the hypothalamic ventromedial nuclei control of feeding and metabolism. PACAP appears to use different signaling mechanisms to regulate feeding behavior from its effects on metabolism.

Embelin Restores Carbapenem Efficacy against NDM-1-Positive Pathogens.

The emergence and spread of carbapenemase in Gram-negative pathogens poses an enormous threat to global public health. New Delhi metallo-ß-lactamase-1 (NDM-1) inactivates nearly every class of ß-lactam antibiotics, including carbapenem; however, there is no clinically useful NDM-1 inhibitor. Embelin, an important ingredient in traditional herbal medicine, has anti-tumor effects. The current study is the first to discover and examine the inhibitory activity of embelin against ß-lactamase NDM-1. The IC50 of embelin was 2.1 ± 0.2 µM when tested against NDM-1 carbapenemase. Most regions of the embelin molecule were buried within NDM-1's active site, and the hydroxyl group of embelin interacted directly with the metal ion Zn2+, as shown by molecular dynamic simulation. Systematic analysis of the antibacterial activities of embelin and antibiotics demonstrated that embelin restored meropenem activity against a panel of NDM-positive pathogens, such as Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii. Based on these results, embelin could be a promising carbapenem adjuvant candidate against NDM-1-producing bacterial strains.

Molecular epidemiology of bla OXA-23 -producing carbapenem-resistant Acinetobacter baumannii in a single institution over a 65-month period in north China.

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii poses a significant threat to hospitalized patients, as few therapeutic options remain. Thus, we investigated the molecular epidemiology and mechanism of resistance of carbapenem-resistant A.baumannii isolates in Beijing, China. METHODS: Carbapenem-resistant A.baumannii isolates (n = 101) obtained between June 2009 and November 2014 were used. Multilocus sequence typing (MLST) and PCR assays for class C and D ß-lactamase were performed on all isolates. S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization were performed to identify the resistance gene location. RESULTS: All 101 A.baumannii isolates were highly resistant to frequently used antimicrobials, and were considered multidrug resistant. A total of 12 sequence types (STs) were identified, including 10 reported STs and 2 novel STs. Eighty-seven isolates were classified to clonal complex 92 (CC92), among which ST191 and ST195 were the most common STs. The bla OXA-23 gene was positive in most (n = 95) of the A.baumannii isolates. Using S1-nuclease digestion PFGE and Southern blot hybridization, 3 patterns of plasmids carrying bla OXA-23 were confirmed. ST191 and ST195 (both harboring bla OXA-23 ) caused outbreaks during the study period, and this is the first report of outbreaks caused by ST191 and ST195 in north China. CONCLUSION: bla OXA-23 -producing A.baumannii ST191 and ST 195 isolates can disseminate in a hospital and are potential nosocomial outbreak strains. Surveillance of imipenem-resistant A.baumannii and antimicrobial stewardship should be strengthened.