Differential actions of AMP kinase on ATP‐sensitive K+ currents in ventral tegmental area and substantia nigra zona compacta neurons

ATP‐sensitive K⁺ (K‐ATP) channels play significant roles in regulating the excitability of dopamine neurons in the substantia nigra zona compacta (SNC). We showed previously that K‐ATP channel function is up‐regulated by AMP‐activated protein kinase (AMPK). This study extended these studies to the neurons adjacent to the SNC in the ventral tegmental area (VTA). Using patch pipettes to record whole‐cell currents in slices of rat midbrain, we found that the AMPK activator A769662 increased the amplitude of currents evoked by the K‐ATP channel opener diazoxide in presumed dopamine‐containing VTA neurons. However, current evoked by diazoxide with A769662 was significantly smaller in VTA neurons compared to SNC neurons. Moreover, a significantly lower proportion of VTA neurons responded to diazoxide with outward current. However, A769662 was able to increase the incidence of diazoxide‐responsive neurons in the VTA. In contrast, A769662 did not potentiate diazoxide‐evoked currents in presumed non‐dopamine VTA neurons. These results show that AMPK activation augments K‐ATP currents in presumed dopamine neurons in the VTA and SNC, although diazoxide‐evoked currents remain less robust in the VTA. We conclude that K‐ATP channels may play important physiological roles in VTA and SNC dopamine neurons.     

Brain network dynamics in the human articulatory loop

Objective

The articulatory loop is a fundamental component of language function, involved in the short-term buffer of auditory information followed by its vocal reproduction. We characterized the network dynamics of the human articulatory loop, using invasive recording and stimulation.

Role of the BrafV637E mutation in hepatocarcinogenesis induced by treatment with diethylnitrosamine in neonatal B6C3F1 mice

The BrafV637E mutation is frequently reported in mouse hepatic tumors, depending on the mouse strain, and corresponds to the human BrafV600E mutation. In this study, we detected the BrafV637E mutation by whole‐exome analysis in 4/4 hepatic tumors induced by neonatal treatment with diethylnitrosamine (DEN) in male B6C3F1 mice. We also detected the BrafV637E mutation in 54/63 (85.7%) hepatic lesions, including microscopic foci and grossly visible tumors, by PCR‐direct sequencing. Although the mutation was detected in 5/7 (71.4%) hepatic tumors induced by neonatal DEN treatment followed by repeated CCl₄ administration, it was not detected in 24 tumors induced by CCl₄ treatment without DEN or in eight spontaneous lesions in B6C3F1 mice, suggesting that the mutation is induced by the genotoxic action of DEN. The DEN‐induced tumors exhibited hyperphosphorylation of ERK1 and Akt, suggesting that the BrafV637E mutation might activate the MAPK and Akt pathways. Moreover, the DEN‐induced tumors overexpressed mRNAs for the oncogene‐induced senescence (OIS) markers such as p15^Ink4b and p19^Arf as well as pro‐survival/pro‐proliferative cytokines/chemokines such as complement C5/C5a, ICAM‐1, IL‐1 receptor antagonist and CXCL9, suggesting that the BrafV637E mutation influences the expression of genes involved in either OIS or cellular growth/survival. Liver‐specific expression of mutated Braf under control of the albumin enhancer/promoter resulted in an enlarged liver that consisted entirely of small basophilic hepatocytes resembling DEN‐induced preneoplastic hepatocytes with ERK1/Akt hyperphosphorylation and C5/C5a overexpression. These results indicate that the BrafV637E mutation induces hepatocytic changes in DEN‐induced hepatic tumors. © 2016 The Authors. Molecular Carcinogenesis published by Wiley Periodicals, Inc.     

Hippocampal ischemia causes deficits in local field potential and synaptic plasticity

The long-term enhancement in glutamate receptor mediated excitatory responses has been observed in stroke model. This pathological form of plasticity, termed post-ischemic long-term potentiation (i-LTP), points to functional reorganization after stroke. Little is known, however, about whether and how this i-LTP would affect subsequent induction of synaptic plasticity. Here, we first directly confirmed that i-LTP was induced in the endothelin-1-induced ischemia model as in other in vitro models. We also demonstrated increased expression of NR2B, CaMKII and p-CaMKII, which are reminiscent of i-LTP. We further induced LTP of field excitatory postsynaptic potentials (fEPSPs) on CA1 hippocampal neurons in peri-infarct regions of the endothelin-1-induced mini-stroke model. We found that LTP of fEPSPs, induced by high-frequency stimulation, displayed a progressive impairment at 12 and 24 hours after ischemia. Moreover, using in vivo multi-channel recording, we found that the local field potential, which represents electrical property of cell ensembles in more restricted regions, was also dampened at these two time points. These results suggest that i-LTP elevates the induction threshold of subsequent synaptic plasticity. Our data helps to deepen the knowledge of meta-synaptic regulation of plasticity after focal ischemia.     

Effects of Aloe-emodin and Emodin on Proliferation of the MKN45 Human Gastric Cancer Cell Line

Aloe-emodin (1, 8-dihydroxy-3-hydroxyl-methylanthraquinone; AE) and emodin (1,3,8-trihydroxy-6-methylanthraquinone; EM) are anthraquinone derivatives that have been detected in some medical plants andshare similar anthraquinone structures. AE and EM have been shown to exhibit anticancer activities in variouscancer cell lines; however, the inhibitory effects of these derivatives on the growth of cancer cells were previouslyreported to be different. Gastric cancer is the second most common cause of cancer cell death worldwide. In thepresent study, we examined the inhibitory effects of 0.05 mM AE and 0.05 mM EM on the proliferation of theMKN45 human gastric cancer cell line. The proliferation of MKN45 cells was significantly inhibited in AE- andEM-treated groups 24 h and 48 h after treatment. Furthermore, the inhibitory effects of EM were stronger thanthose of AE. The cell cycle of MKN45 cells were arrested in G0/G1 phase or G0/G1 and G2/M phases by AE andEM, respectively. However, an analysis of intracellular polyamine levels and DNA fragmentation revealed thatthe mechanisms underlying cell death following cell arrest induced by AE and EM differed.     

Naturally appearing N-feruloylserotonin isomers suppress oxidative burst of human neutrophils at the protein kinase C level

N-feruloylserotonin (N-f-5HT) isomers, isolated from seeds of Leuzea carthamoides (Wild) DC, inhibited dose-dependent oxidative burst in human whole blood and isolated neutrophils in vitro, which were measured by luminol- and/or isoluminol-enhanced chemiluminescence in the following rank order of stimuli: PMA > OpZ > calcium ionophore A23187. In isolated neutrophils that were stimulated with PMA, N-f-5HT isomers were effective against extracellular and intracellular reactive oxygen species. Liberation of ATP, analysis of apoptosis, and recombinant caspase-3 activity revealed that N-f-5HT isomers, used in concentrations up to 100 μM, did not alter the viability and integrity of isolated neutrophils. Western blot analysis documented that in concentrations of 10 and 100 μM, N-f-5HT isomers significantly decreased PMA-induced phosphorylation of PKC α/β II. The results suggest that N-f-5HT isomers are an effective, naturally occurring substance with a potent pharmacological effect on the oxidative burst of human neutrophils. It should be further investigated for its pharmacological activity against oxidative stress in ischemia-reperfusion, inflammation and other pathological conditions.     

CaIPF14030 negatively modulates intracellular ATP levels during the development of azole resistance in Candida albicans

Aim:

Widespread and repeated use of azoles, particularly fluconazole, has led to the rapid development of azole resistance in Candida albicans. We investigated the role of CaIPF14030 during the development of azole resistance in C albicans.

Methods:

The expression of CaIPF14030 was measured by quantitative RT-PCR, and CaIPF14030 was disrupted by the hisG-URA3-hisG (URA-blaster) method. The sensitivity of C albicans to azoles was examined using a spot assay, and the intracellular ATP concentrations were measured by a luminometer.

Results:

CaIPF14030 expression in C albicans was up-regulated by Ca²⁺ in a calcineurin-dependent manner, and the protein was overexpressed during the stepwise acquisition of azole resistance. However, disruption or ectopic overexpression of CaIPF14030 did not affect the sensitivity of C albicans to azoles. Finally, we demonstrated that disruption of CaIPF14030 significantly increased intracellular ATP levels, and overexpression significantly decreased intracellular ATP levels in C albicans.

Conclusion:

CaIPF14030 may negatively modulate intracellular ATP levels during the development of azole resistance in C albicans.     

Disulfide‐Containing Hyperbranched Polyethylenimine Derivatives via Click Chemistry for Nonviral Gene Delivery

Reducible disulfide‐containing hyperbranched PEI‐SS‐HP was synthesized via click chemistry and evaluated as nonviral gene carrier. The structure of the polymers was confirmed by ¹H NMR and FTIR. It was shown that the PEI‐SS‐HP was able to bind plasmid DNA to positively charged nanoparticles. The reduction sensitivity of the PEI‐SS‐HP was confirmed by gel retardation assay in the presence of DTT mimicking an intracellular reductive environment. In vitro experiments revealed that the reducible PEI‐SS‐HP not only had much lower cytotoxicity, but also posed superior transfection activity as compared to non‐degradable 25‐kDa PEI. The results indicate that a reducibly degradable PEI‐SS‐HP can be a promising gene vector.

     

The repositioning of the anti-fungal agent ciclopirox olamine as a novel therapeutic agent for the treatment of haematologic malignancy

What is known and Objective: 6‐Cyclohexyl‐1‐hydroxy‐4‐methyl‐2(1H)‐pyridone (ciclopirox) and specifically its olamine salt 6‐cyclohexyl‐1‐hydroxy‐4‐methyl‐2(1H)‐pyridone 2‐aminoethanol salt (ciclopirox olamine) are anti‐fungal agents currently used for the treatment of mild to moderate cutaneous fungal infection. Our objective is to comment on the opportunity to rapidly reposition ciclopirox and its olamine for the treatment of haematologic malignancy by leveraging its prior published toxicology and pharmacology data. Comment: Ciclopirox olamine chelates intracellular iron and displays preclinical efficacy in the treatment of haematologic malignancy. Currently, an ongoing study is evaluating topical ciclopirox olamine for the treatment of cervical cancer. Doses of ciclopirox olaine required for a systemic anti‐cancer effect appear pharmacologically achievable. However, caution is required as at the highest doses tested in animal toxicology studies, irreversible cardiac degeneration was observed. What is new and Conclusion: The existing pharmacology and toxicology data suggest that systemic ciclopirox olamine could be repositioned as a new investigational anti‐cancer agent. The available pharmacology and toxicology data should aid in the design of phase I clinical trials of this agent in patients with refractory haematologic malignancies.     

Mobile phone in the chain of survival

Each day, approximately 750 Europeans suffer from an out-of-hospital cardiac arrest, which presents a large public health problem. In such circumstances, rapid activation of the Chain of Survival with effective and continuous realisation of its four links can have a large impact on survival. Mobile phones, which have become the most ubiquitous piece of modern technology, possess a strong potential to strengthen each link of the chain. Initially, they can be used to educate rescuers about appropriate actions performed in each step of the resuscitation process. However, mobile phones can also assume a more active role of helping the rescuer in a real medical emergency. They have a potential to allow for a faster and superior emergency medical services contact, assure a higher quality of cardiopulmonary resuscitation (CPR) and quicker retrieval of an automated external defibrillator and facilitate a finer post-resuscitation care through telemedical and clinical decision support systems. Smartphones, mobile phones with advanced computing abilities and connectivity, should be considered as medical devices, and their use, among lay rescuers and medical professionals in cardiovascular emergencies, further investigated and strongly encouraged.