Characterization of GABA(B) receptors in the rat peripheral and central nervous system

Recent electrophysiological studies have led to the proposal of subtypes of GABAB receptors. In the rat hippocampus the postsynaptic GABAB receptor is sensitive to the weak GABAB antagonist phaclofen and to pertussis toxin (PTX) whereas the presynaptic receptor is insensitive to both agents. To investigate the presynaptic receptor further the effect of GABAB agonists was studied on the K+-evoked release of endogenous amino acids from rat hippocampal synaptosomes. (-)Baclofen (30-100μM) produced a dose-dependent inhibition of aspartate, glutamate and GABA release evoked by 50mM K+. 3-Aminopropyl-phosphinic acid (3-APA) (30-300μM) failed to inhibit amino acid release. 3-APA is reported to inhibit [3H]-GABA binding to GABAB sites in rat whole brain membranes more potently than the prototypic GABAB ligand (-)baclofen, although in biochemical assays 3-APA is equipotent with (-)baclofen and appears to behave as a partial agonist. Thus 3-APA may distinguish between subtypes of GABAB receptors. For comparison, peripheral GABAB receptors on adrenergic nerve terminals were studied using the electrically stimulated rat anococcygeus muscle preparation. (-)Baclofen, 3-APA and its methyl derivative SKF 97541 produced a dose-dependent inhibition of the electrically-evoked release of preloaded [3H]-noradrenaline (EC50 values of 1.4μM, 0.56μM and 1.25μM respectively). CGP 35348, a selective though relatively weak GABAB antagonist, was compared with two new compounds for their ability to reverse the effect of 30μM (-)baclofen. These compounds were found to antagonize the baclofen response more potently than CGP 35348. Schild analysis of data obtained using the same preparation monitoring antagonism of baclofen-induced inhibition of transmurally-evoked contraction of the muscle indicated the presence of a single receptor type. No evidence was obtained for receptor heterogeneity on adrenergic nerve terminals. Thus, although 3-APA failed to mimic the inhibitory action of (-)baclofen on transmitter release in hippocampal synaptosomes it did produce the same response in the peripheral tissue. Experiments were performed to determine whether 3-APA exhibited a differential selectivity for CNS GABAB receptors in different regions of the rat brain. Since any lack of affinity for hippocampal receptors might go undetected in membrane binding experiments performed in whole brain preparations, studies were performed using receptor autoradiography. 3-APA inhibited [3H]-GABA binding to GABAB sites to the same extent as (-)baclofen in seventeen brain regions including the hippocampus. The lack of difference between 3-APA and (-)baclofen in the hippocampus contrasted with the findings in the release experiments and the possible reasons for this discrepancy are discussed. Following incubation of rat brain slices for 24 hours in PTX specific GABAB binding is reduced throughout the brain with the exception of the corpus striatum. This observation may reflect different post receptor coupling or an inability of the toxin to access striatal neurones. To clarify these observations the effect of PTX on GABAB binding was determined in membranes prepared from the cortices, striata, hippocampi and cerebella of adult and immature rats. Incubation for 30 min in pre-activated PTX reduced specific GABAB binding in all areas except the striatum in the adult animals (10-12 weeks), however in animals of 5-6 weeks or 7-9 weeks old the profile of the PTX effect was quite different. GABAB binding in all brain regions could be reduced by 85% by the inclusion of GTP?S in the incubating medium. Regional and age-related variations in the sensitivity of GABAB binding to PTX may therefore be due to the presence of GABAB receptors linked to different inhibitory G-proteins

Supercritical Carbon dioxide Treatment of the Microalgae Nannochloropsis oculata

The aim of this work was to evaluate the potential of supercritical carbon dioxide (CO2) to extract Fatty Acid Methyl Esters (FAME) from the microalgae Nannochloropsis oculata (N. oculata) at low temperatures (37 and 55 oC) and pressures (5.9 and 7.6 megapascals (MPa)). A qualitative gas chromatography (GC) analysis showed that the individual FAMEs extracted varied depending on the co-solvent (methanol or hexane) used with supercritical CO2. Using hexane, FAME compounds produced were similar to those extracted with soxhlet extraction alone while longer chain FAME were produced when methanol was the co-solvent. The effects of pressure and temperature variations were shown to be of statistical significance. The chromatograms produced in this work demonstrate that altering one of these parameters (co-solvent, temperature, pressure) can produce different compounds owing to the tunability of the technique

First record of biofluorescence in lumpfish (Cyclopterus lumpus), a commercially farmed cleaner fish

This study is the first known observation of biofluorescence in the lumpfish (Cyclopterus lumpus). Individual lumpfish were illuminated with blue excitation lighting for photography with both hyperspectral and filtered multispectral cameras. All photographed juvenile lumpfish (n = 11) exhibited green biofluorescence. Light emissions were characterised with two peaks observed at 545 and 613 nm, with the greatest intensity along the tubercles of the high crest and the three longitudinal ridges. Further research on the dynamics of biofluorescence through the lifecycle of this species is required

A Spiking Neural Network Model of the Medial Superior Olive Using Spike Timing Dependent Plasticity for Sound Localization

Sound localization can be defined as the ability to identify the position of an input sound source and is considered a powerful aspect of mammalian perception. For low frequency sounds, i.e., in the range 270 Hz–1.5 KHz, the mammalian auditory pathway achieves this by extracting the Interaural Time Difference between sound signals being received by the left and right ear. This processing is performed in a region of the brain known as the Medial Superior Olive (MSO). This paper presents a Spiking Neural Network (SNN) based model of the MSO. The network model is trained using the Spike Timing Dependent Plasticity learning rule using experimentally observed Head Related Transfer Function data in an adult domestic cat. The results presented demonstrate how the proposed SNN model is able to perform sound localization with an accuracy of 91.82% when an error tolerance of ±10° is used. For angular resolutions down to 2.5°, it will be demonstrated how software based simulations of the model incur significant computation times. The paper thus also addresses preliminary implementation on a Field Programmable Gate Array based hardware platform to accelerate system performance

Cross-sectional evaluation of a longitudinal consultation skills course at a new UK medical school

Background: Good communication is a crucial element of good clinical care, and it is important to provide appropriate consultation skills teaching in undergraduate medical training to ensure that doctors have the necessary skills to communicate effectively with patients and other key stakeholders. This article aims to provide research evidence of the acceptability of a longitudinal consultation skills strand in an undergraduate medical course, as assessed by a cross-sectional evaluation of students' perceptions of their teaching and learning experiences. Methods: A structured questionnaire was used to collect student views. The questionnaire comprised two parts: 16 closed questions to evaluate content and process of teaching and 5 open-ended questions. Questionnaires were completed at the end of each consultation skills session across all year groups during the 2006-7 academic year (5 sessions in Year 1, 3 in Year 2, 3 in Year 3, 10 in Year 4 and 10 in Year 5). 2519 questionnaires were returned in total. Results: Students rated Tutor Facilitation most favourably, followed by Teaching, then Practice & Feedback, with suitability of the Rooms being most poorly rated. All years listed the following as important aspects they had learnt during the session: • how to structure the consultation • importance of patient-centredness • aspects of professionalism (including recognising own limits, being prepared, generally acting professionally). All years also noted that the sessions had increased their confidence, particularly through practice. Conclusions: Our results suggest that a longitudinal and integrated approach to teaching consultation skills using a well structured model such as Calgary-Cambridge, facilitates and consolidates learning of desired process skills, increases student confidence, encourages integration of process and content, and reinforces appreciation of patient-centredness and professionalism

Applied simulations and integrated modelling for the understanding of toxic and harmful algal blooms (ASIMUTH): Integrated HAB forecast systems for Europe's Atlantic Arc

Reasons for the emergent interest in HABs are abundant, including concerns associated with human health, adverse effects on biological resources, economic losses attributed to recreation, tourism and seafood related industries, and the cost of maintaining public advisory services and monitoring programs for shellfish toxins and water quality. The impact of HABs can potentially be mitigated by early warning of their development. In this regard the project ASIMUTH (Applied Simulations and Integrated Modelling for the Understanding of Toxic and Harmful algal blooms) was borne in order to develop short term HAB alert systems for Atlantic Europe. This was achieved using information on the most current marine conditions (weather, water characteristics, toxicity, harmful algal presence etc.) combined with high resolution local numerical predictions. This integrated, multidisciplinary, trans-boundary approach to the study of HABs developed during ASIMUTH led to a better understanding of the physical, chemical and ecological factors controlling these blooms, as well as their impact on human activities. The outcome was an appropriate alert system for an effective management of areas that are usually associated with HAB events and where these episodes may have a more significant negative impact on human activities. Specifically for the aquaculture industry, the information provided enabled farmers to adapt their working practices in time to prevent mortalities in finfish farms and/or manage their shellfish harvest more effectively. This paper summarises the modelling and alert developments generated by the ASIMUTH project.Versión del editor3,083

Analytical and Biological Characterization of Supercoiled Plasmids Purified by Various Chromatographic Techniques

This is the publisher's version, also available electronically from http://online.liebertpub.com/doi/abs/10.1089/dna.2005.24.819Supercoiled plasmids are an important component of gene-based delivery vehicles. A number of production methods for clinical applications have been developed, each resulting in very high-quality product with low levels of residual contaminants. There is, however, no consensus on the optimal methods to characterize plasmid quality, and further, to determine if these methods are predictive of either product stability or biological activity. We have produced two plasmids using four production purification methodologies based on PolyFlo® and hydrophobic interaction chromatography (HIC), either alone or in tandem processes. In each case, the product was analyzed using standard molecular biological methods. We also performed a number of biophysical analyses such as dynamic light scattering (DLS), circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Minimal differences were detected among the preparations based on the more standard molecular biological methods. Some small differences were detected, however, using biophysical techniques, particularly FTIR and DSC, which may reflect small variations in plasmid tertiary structure and thermal stability. Stability after heat exposure at 60°C, exposure to fetal bovine serum and long-term storage at 4°C varied between plasmids. One plasmid showed no difference in stability depending on the production process, but the other showed significant differences. Evaluation in vivo in models for gene immunization and gene therapy showed significant differences in the response depending on the method of purification. Preparations using a tandem process of PolyFlo used in two separation modes provided higher biological activity compared to a tandem HIC/PolyFlo process or either resin used alone in a single column process. These data indicate that the process by which supercoiled plasmids are made can influence plasmid stability and biological activity and emphasize the need for more rigorous methods to evaluate supercoiled plasmids as gene-delivery vehicles

Bioaccumulation of titanium dioxide nanoparticles in green (Ulva sp.) and red (Palmaria palmata) seaweed

A bioaccumulation study in red (Palmaria palmata) and green (Ulva sp.) seaweed has been carried out after exposure to different concentrations of citrate-coated titanium dioxide nanoparticles (5 and 25 nm) for 28 days. The concentration of total titanium and the number and size of accumulated nanoparticles in the seaweeds has been determined throughout the study by inductively coupled plasma mass spectrometry (ICP-MS) and single particle-ICP-MS (SP-ICP-MS), respectively. Ammonia was used as a reaction gas to minimize the effect of the interferences in the 48Ti determination by ICP-MS. Titanium concentrations measured in Ulva sp. were higher than those found in Palmaria palmata for the same exposure conditions. The maximum concentration of titanium (61.96 ± 15.49 μg g−1) was found in Ulva sp. after 28 days of exposure to 1.0 mg L−1 of 5 nm TiO2NPs. The concentration and sizes of TiO2NPs determined by SP-ICP-MS in alkaline seaweed extracts were similar for both seaweeds exposed to 5 and 25 nm TiO2NPs, which indicates that probably the element is accumulated in Ulva sp. mainly as ionic titanium or nanoparticles smaller than the limit of detection in size (27 nm). The implementation of TiO2NPs in Ulva sp. was confirmed by electron microscopy (TEM/STEM) in combination with energy dispersive X-Ray analysis (EDX)The authors wish to thank the fnancial support of Ministerio de Economía y Competitividad (project INNOVANANO, reference RT2018-099222-B-100), European Union (INTERREG Atlantic Area, project NANOCULTURE, reference EAPA590/2018), and Xunta de Galicia (Grupo de Referencia Competitiva, grant number ED431C 2022/29)S