Does α-Amino-β-methylaminopropionic Acid (BMAA) Play a Role in Neurodegeneration?

The association of α-amino-β-methylaminopropionic acid (BMAA) with elevated incidence of amyotrophic lateral sclerosis/Parkinson’s disease complex (ALS/PDC) was first identified on the island of Guam. BMAA has been shown to be produced across the cyanobacterial order and its detection has been reported in a variety of aquatic and terrestrial environments worldwide, suggesting that it is ubiquitous. Various in vivo studies on rats, mice, chicks and monkeys have shown that it can cause neurodegenerative symptoms such as ataxia and convulsions. Zebrafish research has also shown disruption to neural development after BMAA exposure. In vitro studies on mice, rats and leeches have shown that BMAA acts predominantly on motor neurons. Observed increases in the generation of reactive oxygen species (ROS) and Ca2+ influx, coupled with disruption to mitochondrial activity and general neuronal death, indicate that the main mode of activity is via excitotoxic mechanisms. The current review pertaining to the neurotoxicity of BMAA clearly demonstrates its ability to adversely affect neural tissues, and implicates it as a potentially significant compound in the aetiology of neurodegenerative disease. When considering the potential adverse health effects upon exposure to this compound, further research to better understand the modes of toxicity of BMAA and the environmental exposure limits is essential

Effects of high extracellular magnesium on electrophysiological properties of membranes of Retzius neurons in leech Haemopis sanguisuga

Magnesium is a bioessential cation with an important role in the function of excitable cells both in health and disease. Magnesium has therapeutic use as an anticonvulsant, anaesthetic, analgesic and antiarrhythmic agent. The aim of this work was to examine in detail the effects of high extracellular Mg2+ on the nerve cell membrane using classical electrophysiology techniques. The experiments were conducted on Retzius neurons in the isolated segmental ganglia of the leech Haemopis sanguisuga. Intracellular recording of membrane potential and electrical activity, as well as current clamp experiments to examine membrane input resistance and excitability, were performed prior to and during application of 20 mmol dm-3 MgCl2. The paper presents our findings on the effects of high Mg2+ on basic electrophysiological properties and activity of Retzius cells. Depolarization of the membrane potential, a decrease in the frequency of spontaneous activity, an increase in threshold potential, a decrease in cell excitability and an increase in input membrane resistance were found following an application of high Mg2+ solution. The underlying mechanisms of the overall suppressive action of Mg2+ on our cell model are discussed to be multiple Mg2+ effects on different ion channel conductances, with a possibly dominant blockade of Na+ channels and a probable modulation of activity of Ca2+-activated K+ channels by Mg2+

Magnesium effects on nonsynaptic epileptiform activity in leech Retzius neurons

© Institute of Systematics and Evolution of Animals, PAS, Kraków, 2015. The effects of Mg2+ on Ni2+-induced epileptiform bursting activity and input membrane resistance during this activity of leech Retzius neurons were examined using intracellular recordings. To induce epileptiform activity, 3 mmol/l NiCl2 was added into superfusing Ringer (Ri) saline. To test for dose-dependence of the effects of Mg2+ on the induced epileptiformactivity,MgCl2was added in concentrations from1mmol/l to 20mmol/lMg2+ to the Ni2+-containing Ri saline. Input membrane resistance (IMR) was measured in standard Ri, Ni2+ Ri and 20 mmol/lMg2+Ni2+ Ri saline. Superfusion with Ni2+Ri induced epileptiform bursting activity characterized by generation of paroxysmal depolarization shifts (PDSs). Parameters of epileptiform activity including PDS frequency, PDS duration, PDS amplitude and the number of spikes/PDS were measured. Magnesium suppressed Ni2+-induced epileptiform activity, significantly reducing values of all parameters observed in a concentration-dependent manner. The highest concentration applied of 20 mmol/l Mg2+ completely eliminated epileptiform activity. To test for the effect of Mg2+ on membrane conductance during bursting, IMR was measured. Magnesium significantly increased IMR during bursting suppression

Occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in the European survey of carbapenemase-producing Enterobacteriaceae (EuSCAPE): a prospective, multinational study

The members of the European Survey on Carbapenemase-Producing Enterobacteriaceae, (EuSCAPE) Working Group are: Portugal—Manuela Caniça and Vera ManageiroBACKGROUND: Gaps in the diagnostic capacity and heterogeneity of national surveillance and reporting standards in Europe make it difficult to contain carbapenemase-producing Enterobacteriaceae. We report the development of a consistent sampling framework and the results of the first structured survey on the occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in European hospitals. METHODS: National expert laboratories recruited hospitals with diagnostic capacities, who collected the first ten carbapenem non-susceptible clinical isolates of K pneumoniae or E coli and ten susceptible same-species comparator isolates and pertinent patient and hospital information. Isolates and data were relayed back to national expert laboratories, which made laboratory-substantiated information available for central analysis. FINDINGS: Between Nov 1, 2013, and April 30, 2014, 455 sentinel hospitals in 36 countries submitted 2703 clinical isolates (2301 [85%] K pneumoniae and 402 (15%) E coli). 850 (37%) of 2301 K pneumoniae samples and 77 (19%) of 402 E coli samples were carbapenemase (KPC, NDM, OXA-48-like, or VIM) producers. The ratio of K pneumoniae to E coli was 11:1. 1·3 patients per 10 000 hospital admissions had positive clinical specimens. Prevalence differed greatly, with the highest rates in Mediterranean and Balkan countries. Carbapenemase-producing K pneumoniae isolates showed high resistance to last-line antibiotics. INTERPRETATION: This initiative shows an encouraging commitment by all participants, and suggests that challenges in the establishment of a continent-wide enhanced sentinel surveillance for carbapenemase-producing Enterobacteriaeceae can be overcome. Strengthening infection control efforts in hospitals is crucial for controlling spread through local and national health care networks.European Centre for Disease Prevention and Controlinfo:eu-repo/semantics/publishedVersio

Occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in the European survey of carbapenemase-producing Enterobacteriaceae (EuSCAPE): a prospective, multinational study

Background Gaps in the diagnostic capacity and heterogeneity of national surveillance and reporting standards in Europe make it difficult to contain carbapenemase-producing Enterobacteriaceae. We report the development of a consistent sampling framework and the results of the first structured survey on the occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in European hospitals. Methods National expert laboratories recruited hospitals with diagnostic capacities, who collected the first ten carbapenem non-susceptible clinical isolates of K pneumoniae or E coli and ten susceptible same-species comparator isolates and pertinent patient and hospital information. Isolates and data were relayed back to national expert laboratories, which made laboratory-substantiated information available for central analysis. Findings Between Nov 1, 2013, and April 30, 2014, 455 sentinel hospitals in 36 countries submitted 2703 clinical isolates (2301 [85%] Kpneurnoniae and 402 (15%) Ecoli). 850 (37%) of 2301 Kpneumoniae samples and 77 (19%) of 402 Ecoli samples were carbapenemase (KPC, NDM, OXA-48-like, or VIM) producers. The ratio of K pneumoniae to E coli was 11:1.1.3 patients per 10000 hospital admissions had positive clinical specimens. Prevalence differed greatly, with the highest rates in Mediterranean and Balkan countries. Carbapenemase-producing K pneumoniae isolates showed high resistance to last-line antibiotics. Interpretation This initiative shows an encouraging commitment by all participants, and suggests that challenges in the establishment of a continent-wide enhanced sentinel surveillance for carbapenemase-producing Entero-bacteriaeceae can be overcome. Strengthening infection control efforts in hospitals is crucial for controlling spread through local and national health care networks

Occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in the European survey of carbapenemase-producing Enterobacteriaceae (EuSCAPE): a prospective, multinational study

Background Gaps in the diagnostic capacity and heterogeneity of national surveillance and reporting standards in Europe make it difficult to contain carbapenemase-producing Enterobacteriaceae. We report the development of a consistent sampling framework and the results of the first structured survey on the occurrence of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in European hospitals. Methods National expert laboratories recruited hospitals with diagnostic capacities, who collected the first ten carbapenem non-susceptible clinical isolates of K pneumoniae or E coli and ten susceptible same-species comparator isolates and pertinent patient and hospital information. Isolates and data were relayed back to national expert laboratories, which made laboratory-substantiated information available for central analysis. Findings Between Nov 1, 2013, and April 30, 2014, 455 sentinel hospitals in 36 countries submitted 2703 clinical isolates (2301 [85%] Kpneurnoniae and 402 (15%) Ecoli). 850 (37%) of 2301 Kpneumoniae samples and 77 (19%) of 402 Ecoli samples were carbapenemase (KPC, NDM, OXA-48-like, or VIM) producers. The ratio of K pneumoniae to E coli was 11:1.1.3 patients per 10000 hospital admissions had positive clinical specimens. Prevalence differed greatly, with the highest rates in Mediterranean and Balkan countries. Carbapenemase-producing K pneumoniae isolates showed high resistance to last-line antibiotics. Interpretation This initiative shows an encouraging commitment by all participants, and suggests that challenges in the establishment of a continent-wide enhanced sentinel surveillance for carbapenemase-producing Entero-bacteriaeceae can be overcome. Strengthening infection control efforts in hospitals is crucial for controlling spread through local and national health care networks