Spider neurotoxins targeting voltage-gated sodium channels

The voltage-gated sodium (Nav) channel is a target for a number of drugs, insecticides, and neurotoxins. These bind to at least seven identified neurotoxin binding sites and either block conductance or modulate sodium channel gating and/or kinetics. A number of polypeptide toxins from the venoms of araneomorph and mygalomorph spiders have been isolated and characterized that interact with several of these sites. Certain huwentoxins and hainantoxins appear to target site 1 to block Nav channel conductance. The δ-atracotoxins and Magi 4 slow Nav-channel inactivation via an interaction with neurotoxin site 3. The δ-palutoxins, and most likely μ-agatoxins and curtatoxins, target site 4. However, their action is complex with the μ-agatoxins causing a hyperpolarizing shift in the voltage-dependence of activation, an action analogous to scorpion β-toxins, but with both δ-palutoxins and μ-agatoxins slowing Nav channel inactivation, a site 3-like action. Many spider toxins target undefined sites, while others are likely to cross-react with other ion channels due to conserved structures within domains of voltage-gated ion channels. It is already clear, however, that many spider toxins represent highly potent and specific molecular tools to define novel links between sites modulating channel activation and inactivation. Other spider toxins show phyla specificity and are being considered as lead compounds for the development of biopesticides. Others display tissue specificity via interactions with specific Nav channel subtypes and should provide useful tools to delineate the molecular determinants to target ligands to these channel subtypes. These studies are being greatly assisted by the determination of the pharmacophore of these toxins, but without precise identification of their binding site and mode of action their potential in the mentioned areas remains underdeveloped. Copyright © 2005 Taylor & Francis Inc

Educational drama in the teaching of education for sustainability

In this paper, I describe part of my research project that examines the use of Educational Drama in Education for Sustainability in the upper stages of the primary school (10- and 11-year-olds). Central to the research is a small-scale qualitative research study. Here, I describe the educational focus of the study and outline the methodology. Central to the study was a series of drama lessons (taught by me) based on environmental themes. The lessons link with some of the key aims in Education for Sustainability - to help young people to develop awareness, knowledge and concepts, to encourage positive attitudes and personal lifestyle decisions and to help them to acquire action skills in and for the environment. The locus is within the Scottish education system. A number of key data were generated during the teaching and evaluation of the lessons. These take the form of field notes, children's evaluations of their work and learning, observation schedules, taped interviews with participants and observers and videotapes of the lessons. The analysis of the data is ongoing, but already there is substantial evidence to suggest that the drama was instrumental in helping the children to achieve the learning outcomes set for the lessons. Some of that evidence is presented here. I suggest that the active, participative learning central to drama is particularly useful for allowing children to develop skills in communication, collaboration and expressing ideas and opinions. Also, the immersion in the imagined context and narrative, integral to the 'stories' in the drama, allows the children to feel sympathy for and empathy with people who are affected by environmental issues and problems. In giving the children a context for research and in helping them to plan solutions and to suggest alternatives, the drama allows the participants opportunities to rehearse active citizenship and facilitates learning in Education for Sustainability

Biology of childhood germ cell tumours, focussing on the significance of microRNAs.

Genomic and protein-coding transcriptomic data have suggested that germ cell tumours (GCTs) of childhood are biologically distinct from those of adulthood. Global messenger RNA profiles segregate malignant GCTs primarily by histology, but then also by age, with numerous transcripts showing age-related differential expression. Such differences are likely to account for the heterogeneous clinico-pathological behaviour of paediatric and adult malignant GCTs. In contrast, as global microRNA signatures of human tumours reflect their developmental lineage, we hypothesized that microRNA profiles would identify common biological abnormalities in all malignant GCTs owing to their presumed shared origin from primordial germ cells. MicroRNAs are short, non-protein-coding RNAs that regulate gene expression via translational repression and/or mRNA degradation. We showed that all malignant GCTs over-express the miR-371-373 and miR-302/367 clusters, regardless of patient age, histological subtype or anatomical tumour site. Furthermore, bioinformatic approaches and subsequent Gene Ontology analysis revealed that these two over-expressed microRNAs clusters co-ordinately down-regulated genes involved in biologically significant pathways in malignant GCTs. The translational potential of this finding has been demonstrated with the detection of elevated serum levels of miR-371-373 and miR-302/367 microRNAs at the time of malignant GCT diagnosis, with levels falling after treatment. The tumour-suppressor let-7 microRNA family has also been shown to be universally down-regulated in malignant GCTs, because of abundant expression of the regulatory gene LIN28. Low let-7 levels resulted in up-regulation of oncogenes including MYCN, AURKB and LIN28 itself, the latter through a direct feedback mechanism. Targeting LIN28, or restoring let-7 levels, both led to effective inhibition of this pathway. In summary, paediatric malignant GCTs show biological differences from their adult counterparts at a genomic and protein-coding transcriptome level, whereas they both display very similar microRNA expression profiles. These similarities and differences may be exploited for diagnostic and/or therapeutic purposes.This is the final version. It was first published by Wiley in Andrology at http://onlinelibrary.wiley.com/doi/10.1111/andr.277/full

Structure and function of δ-atracotoxins: Lethal neurotoxins targeting the voltage-gated sodium channel

δ-Atracotoxins (δ-ACTX), isolated from the venom of Australian funnel-web spiders, are responsible for the potentially lethal envenomation syndrome seen following funnel-web spider envenomation. They are 42-residue polypeptides with four disulfides and an 'inhibitor cystine-knot' motif with structural but not sequence homology to a variety of other spider and marine snail toxins. δ-Atracotoxins induce spontaneous repetitive firing and prolongation of action potentials resulting in neurotransmitter release from somatic and autonomic nerve endings. This results from a slowing of voltage-gated sodium channel inactivation and a hyperpolarizing shift of the voltage-dependence of activation. This action is due to voltage-dependent binding to neurotoxin receptor site-3 in a similar, but not identical, fashion to scorpion α-toxins and sea anemone toxins. Unlike other site-3 neurotoxins, however, δ-ACTX bind with high affinity to both cockroach and mammalian sodium channels but low affinity to locust sodium channels. At present the pharmacophore of δ-ACTX is unknown but is believed to involve a number of basic residues distributed in a topologically similar manner to scorpion α-toxins and sea anemone toxins despite distinctly different protein scaffolds. As such, δ-ACTX provide us with specific tools with which to study sodium channel structure and function and determinants for phyla- and tissue-specific actions of neurotoxins interacting with site-3. © 2004 Elsevier Ltd. All rights reserved

Mothers’ work–family conflict and enrichment:associations with parenting quality and couple relationship

Background Employment participation of mothers of young children has steadily increased in developed nations. Combining work and family roles can create conflicts with family life, but can also bring enrichment.Work–family conflict and enrichment experienced by mothers may also impact children’s home environments via parenting behaviour and the couple relationship, particularly in the early years of parenting when the care demands for young children is high. Methods In order to examine these associations, while adjusting for a wide range of known covariates of parenting and relationship quality, regression models using survey data from 2151 working mothers of 4- to 5-year-old children are reported. Results/Conclusion Results provided partial support for the predicted independent relationships between work–family conflict, enrichment and indicators of the quality of parenting and the couple relationship

Rapid and Accurate Assessment of GPCR-Ligand Interactions Using the Fragment Molecular Orbital-Based Density-Functional Tight-Binding Method

The reliable and precise evaluation of receptor–ligand interactions and pair-interaction energy is an essential element of rational drug design. While quantum mechanical (QM) methods have been a promising means by which to achieve this, traditional QM is not applicable for large biological systems due to its high computational cost. Here, the fragment molecular orbital (FMO) method has been used to accelerate QM calculations, and by combining FMO with the density-functional tight-binding (DFTB) method we are able to decrease computational cost 1000 times, achieving results in seconds, instead of hours. We have applied FMO-DFTB to three different GPCR–ligand systems. Our results correlate well with site directed mutagenesis data and findings presented in the published literature, demonstrating that FMO-DFTB is a rapid and accurate means of GPCR–ligand interactions

Treatment and outcomes of UK and German patients with relapsed intracranial germ cell tumors following uniform first-line therapy

We aimed to retrospectively assess treatments/outcomes, including the value of high-dose-chemotherapy and autologous-stem-cell-rescue (HDC + AuSCR) and re-irradiation, in a large, European patient-cohort with relapsed intracranial germ-cell-tumors (GCTs) receiving uniform first-line therapy, including radiotherapy as standard-of-care. Fifty-eight UK/German patients (48 male/10 female) with relapsed intracranial-GCTs [13 germinoma/45 non-germinomatous GCT (NGGCT)] treated 1996-2010 as per the SIOP-CNS-GCT-96 protocol were evaluated. For germinoma, six patients relapsed with germinoma and five with NGGCT (one palliative, one teratoma patient excluded). Five-year overall-survival (OS) for the whole-group (n = 11) was 55%. Four of six germinoma relapses and two of five relapsing with NGGCT were salvaged; patients were salvaged with either standard-dose-chemotherapy (SDC) and re-irradiation or HDC + AuSCR with/without re-irradiation. Of 45 relapsed NGGCT patients, 13 were excluded (three non-protocol adherence, five teratoma, five palliation). Five-year OS for the remaining 32 relapsed malignant NGGCT patients treated with curative intent was 9% (95%CI: 2-26%). By treatment received, 5-year OS for the 10 patients receiving SDC and 22 patients treated with intention for HDC + AuSCR was 0% (0-0%) and 14% (3-36%), respectively. The three relapsed NGGCT survivors had raised HCG markers alone; two received additional irradiation. Patients with relapsed germinoma had better 5-year OS than those with relapsed NGGCT (55 vs. 9%; p = 0.007). Patients with relapsed germinoma were salvaged both with SDC and re-irradiation or HDC + AuSCR with/without re-irradiation; both represent valid treatment options. Outcomes for malignant relapse following initial diagnosis of NGGCT were exceptionally poor; the few survivors received thiotepa-based HDC + AuSCR, which is a treatment option at first malignant relapse for such patients, with further surgery/irradiation where feasible

Metabonomics and Intensive Care

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901

Characterising Inter-helical Interactions of G Protein-Coupled Receptors with the Fragment Molecular Orbital Method

G-protein coupled receptors (GPCRs) are the largest superfamily of membrane proteins, regulating almost every aspect of cellular activity and serving as key targets for drug discovery. We have identified an accurate and reliable computational method to characterise the strength and chemical nature of the inter-helical interactions between the residues of transmembrane (TM) domains during different receptor activation states, something that cannot be characterised solely by visual inspection of structural information. Using the fragment molecular orbital (FMO) quantum mechanics method to analyse 35 crystal structures representing different branches of the class A GPCR family, we have identified 69 topologically-equivalent TM residues that form a consensus network of 51 inter-TM interactions, providing novel results that are consistent with and help to rationalise experimental data. This discovery establishes a comprehensive picture of how defined molecular forces govern specific inter-helical interactions which, in turn, support the structural stability, ligand binding and activation of GPCRs

A pipeline to quantify serum and cerebrospinal fluid microRNAs for diagnosis and detection of relapse in paediatric malignant germ-cell tumours

Background:The current biomarkers alpha-fetoprotein and human chorionic gonadotropin have limited sensitivity and specificity for diagnosing malignant germ-cell tumours (GCTs). MicroRNAs (miRNAs) from the miR-371-373 and miR-302/367 clusters are overexpressed in all malignant GCTs, and some of these miRNAs show elevated serum levels at diagnosis. Here, we developed a robust technical pipeline to quantify these miRNAs in the serum and cerebrospinal fluid (CSF). The pipeline was used in samples from a cohort of exclusively paediatric patients with gonadal and extragonadal malignant GCTs, compared with appropriate tumour and non-tumour control groups.Methods:We developed a method for miRNA quantification that enabled sample adequacy assessment and reliable data normalisation. We performed qRT-PCR profiling for miR-371-373 and miR-302/367 cluster miRNAs in a total of 45 serum and CSF samples, obtained from 25 paediatric patients.Results:The exogenous non-human spike-in cel-miR-39-3p and the endogenous housekeeper miR-30b-5p were optimal for obtaining robust serum and CSF qRT-PCR quantification. A four-serum miRNA panel (miR-371a-3p, miR-372-3p, miR-373-3p and miR-367-3p): (i) showed high sensitivity/specificity for diagnosing paediatric extracranial malignant GCT; (ii) allowed early detection of relapse of a testicular mixed malignant GCT; and (iii) distinguished intracranial malignant GCT from intracranial non-GCT tumours at diagnosis, using CSF and serum samples.Conclusions:The pipeline we have developed is robust, scalable and transferable. It potentially promises to improve clinical management of paediatric (and adult) malignant GCTs