Glycine induces a novel form of long-term potentiation in the superficial layers of the superior colliculus

1. The mammalian superior colliculus (SC) is a midbrain nucleus containing space maps of different sensory modalities which show various forms of age- and activity-dependent plasticity in vivo and in vitro. In the present study, we aimed to characterize the role of glycine (Gly) receptors in the SC, and we observed that application of glycine (Gly; 500 μM and 3 mM) for 7 min to SC slices of adult guinea-pigs caused a novel form of long-term potentiation (termed LTP_gly) of evoked excitatory postsynaptic potentials recorded in the superficial layers.
2. The strength of potentiation was found to be concentration-dependent and partially independent from synaptic stimulation.
3. LTP_gly did not involve NMDA receptor activation as proven by the lack of inhibition by 100 μM D,L-2-amino-5-phosphonovaleric acid (APV) and 10 μM MK-801.
4. LTP_gly could only be masked but not prevented by strychnine (100 μM) and remained undisturbed in the presence of picrotoxin (100 μM).
5. Inhibition of carbonic anhydrase by acetazolamide (20 μM) had no effect on LTP_gly suggesting that the excitatory action of Gly is not due to a differential breakdown of the Cl⁻/HCO₃⁻ gradients.
6. As indicated by the inhibition of LTP_gly of the fEPSP slope by the L-type calcium channel blocker nifedipine (20 μM), voltage-dependent calcium channels are the source for Ca²⁺ elevation as the intracellular trigger.
7. Our data provide the first evidence for a role of Gly in SC synaptic transmission. They illustrate a so far unknown action of Gly which can lead to long-lasting changes of synaptic efficacy and which is not mediated via NMDA-related or strychnine-sensitive binding sites.

     

The mGlu2 but not the mGlu3 receptor mediates the actions of the mGluR2/3 agonist, LY379268, in mouse models predictive of antipsychotic activity

Rationale Group II metabotropic glutamate receptors (mGluRs) comprise the mGluR2 and mGluR3 subtypes, the activation and modulation of which has been suggested to be beneficial for treating schizophrenia. Genetic association studies suggest limited association between mGluR2 and schizophrenia but some association between mGluR3 and schizophrenia. Conversely, pre-clinical studies suggest that mGluR2 may be responsible for mediating the antipsychotic activity of mGluR2/3 agonists, although to date, the role of mGluR3 has not been specifically assessed. Objectives The aim of this study is to use recently generated mGluR3 and mGluR2 knockout mice to investigate which of the group II mGluRs mediates the actions of the mGluR2/3 agonist, LY379268, in two mouse models predictive of antipsychotic activity. Materials and methods LY379268 (0.3–10 mg/kg SC), phencyclidine (PCP; 1–5 mg/kg IP), and amphetamine 1–10 mg/kg IP) were assessed on locomotor activity and behaviour in C57Bl/6J and transgenic mice. LY379268 was then assessed on PCP (5 mg/kg IP)- and amphetamine (2.5 mg/kg IP)-induced hyperactivity and behaviour in C57Bl/6J and transgenic mice. Results PCP (5 mg/kg)-evoked hyperactivity and behavioural alterations, i.e. circling, falling, stereotypy and ataxia, as well as amphetamine (2.5 mg/kg)-evoked hyperactivity, were dose-dependently attenuated by LY379268 (0.3–3 mg/kg) in C57Bl/6J mice. One milligram per kilogram of LY379268 reversed PCP-evoked hyperactivity and behavioural alterations in wild-type (WT) and mGluR3 knockout mice but not in mice lacking mGluR2. Similarly, 3 mg/kg LY379268 reversed amphetamine-evoked hyperactivity in WT and mGluR3 knockout mice but not in mice lacking mGluR2. Conclusion The mGlu2 but not the mGlu3 receptor subtype mediates the actions of the mGluR2/3 agonist, LY379268, in mouse models predictive of antipsychotic activity.     

Strain variation in tumor necrosis factor induction by parasites from children with acute falciparum malaria.

A small proportion of individuals infected with Plasmodium falciparum develop cerebral malaria. Why it affects some infected individuals but not others is poorly understood. Since tumor necrosis factor (TNF) has been implicated strongly in the pathogenesis of cerebral malaria, here we have compared different parasite isolates for their ability to induce TNF production by human mononuclear cells in vitro. Wild isolates were collected from 34 Gambian children with cerebral malaria and 66 children with uncomplicated malaria fever. Cerebral malaria isolates tended to stimulate more TNF production than mild malaria isolates, but there was considerable overlap between the two groups, and the present data provide only limited support for the hypothesis that cerebral malaria is caused by strains of P. falciparum inducing high levels of TNF. However, it is notable that the amounts of TNF induced by different wild isolates from a single locality differed by over 100-fold. The biological significance of this polymorphism deserves further scrutiny in view of the central role that TNF is believed to play in host defense and in the clinical symptomatology of human malaria.     

In vitro activities of penciclovir and acyclovir against herpes simplex virus types 1 and 2.

Penciclovir (PCV) and acyclovir are acyclic guanine analogs which inhibit herpes simplex virus (HSV) DNA polymerase. Their 50% infective doses were 0.5 to 0.8 microgram/ml for clinical isolates of HSV-1 and 1.3 to 2.2 micrograms/ml for HSV-2. Furthermore, HSV-infected cultures receiving 2-h pulses of PCV had 2- to 50-fold less HSV than acyclovir-treated cultures, consistent with the prolonged intracellular half-life of PCV triphosphate.     

Contemporary (2009-2014) clinical outcomes after femoropopliteal bypass surgery for chronic limb threatening ischemia are inferior to those reported in the UK Bypass versus Angioplasty for Severe Ischaemia of the Leg (BASIL) trial (1999-2004)

BackgroundBypass surgery (BS) remains the gold standard revascularization strategy in patients with chronic limb-threatening ischemia (CLTI) owing to infrainguinal disease. The Bypass versus Angioplasty for Severe Ischaemia of the Leg (BASIL)-1 trial showed that, in patients with CLTI who survived for 2 years or more, BS resulted in better clinical outcomes. Despite this finding, there has been an increasing trend toward an endovascular-first approach to infrainguinal CLTI. Our aim was to investigate whether changes in practice have impacted the clinical outcomes of BS in our unit 10 years after BASIL-1.MethodsData for patients who underwent femoropopliteal (FP) BS in BASIL-1 (1999-2004) were retrieved from trial case record forms. The comparator contemporary series (CS) comprised all patients undergoing FP BS for CLTI in our unit between 2009 and 2014. Demographic and clinical outcome data on patients in the CS were collected from the prospectively collected hospital electronic notes. Anatomic patterns of disease in the BASIL-1 and CS cohorts were scored using the Bollinger and GLASS criteria. Statistical analysis was performed in SAS v9.4.ResultsThere were 128 patients from BASIL-1 and 50 patients in the CS. Baseline age, gender, affected limb, and diabetes prevalence were similar, as were days spent in hospital out to 12 months and length of follow-up. BASIL-1 patients were more likely to be current smokers (P = .000) and had a higher creatinine (P = .04). The 30-day morbidity and mortality were higher in BASIL-1 (45.3% vs 22%; P = .004). There was no significant difference between BASIL-1 and CS with regard to run-off Bollinger (37.7 vs 32.1; P = .167) and IP GLASS (0 vs 0; P = .390) scores, with both groups having a median of two runoff vessels. Amputation-free survival (62% vs 28%; hazard ratio [HR], 1.86; 95% confidence interval [CI], 1.18-2.93; P = .007), limb salvage (85% vs 69%; HR, 2.31; 95% CI, 1.14-4.68; P = .02), overall survival (69% vs 35%; HR, 1.66; 95% CI, 1.00-2.74; P = .05) and major adverse limb events (67% vs 47%; HR, 1.93; 95% CI, 1.15-3.22; P = .01) were all significantly better in BASIL-1.ConclusionsAlthough 30-day mortality and morbidity were significantly lower, all of the examined longer term clinical outcomes after FP BS were significantly worse in the CS group a decade on from BASIL-1. Further research in the form of prospective cohort studies and randomized controlled trials is urgently required to determine if the CS data reported herein are generalizable to current vascular surgical practice and, if so, to determine the reasons for these unexpected outcomes.     

Ethanol protects cultured neurons against amyloid-β and α-synuclein-induced synapse damage

The loss of synapses and a corresponding reduction in synaptic proteins are histopathological features of Alzheimer’s disease that correlate strongly with dementia. Here we report that stable Aβ oligomers secreted by 7PA2 cells reduced the amount of synaptophysin, a protein used as an indicator of synapse density, in cultured cortical and hippocampal neurons. Pre-treatment with physiologically relevant concentrations of ethanol (0.02–0.08%) protected neurons against Aβ-induced synapse damage. Ethanol also protected neurons against synapse damage induced by α-synuclein (αSN), pre-synaptic aggregates of which are characteristic of Parkinson’s disease and dementia with Lewy bodies. Exposure of neurons to ethanol did not affect the accumulation of Aβ at synapses, rather it reduced the Aβ and αSN-induced activation of cytoplasmic phospholipase A₂ (cPLA₂) within synapses. Ethanol did not affect synapse damage caused by platelet-activating factor or prostaglandin E₂, bioactive lipids that are formed following the activation of cPLA₂. These results may help explain epidemiological reports that moderate alcohol consumption protects against the development of dementia in Alzheimer’s and Parkinson’s diseases.