Characterization of L-type calcium channel activity in atrioventricular nodal myocytes from rats with streptozotocin-induced Diabetes mellitus

© 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society. Cardiovascular complications are common in patients with Diabetes mellitus (DM). In addition to changes in cardiac muscle inotropy, electrical abnormalities are also commonly observed in these patients. We have previously shown that spontaneous cellular electrical activity is altered in atrioventricular nodal (AVN) myocytes, isolated from the streptozotocin (STZ) rat model of type-1 DM. In this study, utilizing the same model, we have characterized the changes in L-type calcium channel activity in single AVN myocytes. Ionic currents were recorded from AVN myocytes isolated from the hearts of control rats and from those with STZ-induced diabetes. Patch-clamp recordings were used to assess the changes in cellular electrical activity in individual myocytes. Type-1 DM significantly altered the cellular characteristics of L-type calcium current. A reduction in peak ICaL density was observed, with no corresponding changes in the activation parameters of the current. L-type calcium channel current also exhibited faster time-dependent inactivation in AVN myocytes from diabetic rats. A negative shift in the voltage dependence of inactivation was also evident, and a slowing of restitution parameters. These findings demonstrate that experimentally induced type-1 DM significantly alters AVN L-type calcium channel cellular electrophysiology. These changes in ion channel activity may contribute to the abnormalities in cardiac electrical function that are associated with high mortality levels in patients with DM

Characterization of L-type calcium channel activity in atrioventricular nodal myocytes from rats with streptozotocin-induced Diabetes mellitus

© 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society. Cardiovascular complications are common in patients with Diabetes mellitus (DM). In addition to changes in cardiac muscle inotropy, electrical abnormalities are also commonly observed in these patients. We have previously shown that spontaneous cellular electrical activity is altered in atrioventricular nodal (AVN) myocytes, isolated from the streptozotocin (STZ) rat model of type-1 DM. In this study, utilizing the same model, we have characterized the changes in L-type calcium channel activity in single AVN myocytes. Ionic currents were recorded from AVN myocytes isolated from the hearts of control rats and from those with STZ-induced diabetes. Patch-clamp recordings were used to assess the changes in cellular electrical activity in individual myocytes. Type-1 DM significantly altered the cellular characteristics of L-type calcium current. A reduction in peak ICaL density was observed, with no corresponding changes in the activation parameters of the current. L-type calcium channel current also exhibited faster time-dependent inactivation in AVN myocytes from diabetic rats. A negative shift in the voltage dependence of inactivation was also evident, and a slowing of restitution parameters. These findings demonstrate that experimentally induced type-1 DM significantly alters AVN L-type calcium channel cellular electrophysiology. These changes in ion channel activity may contribute to the abnormalities in cardiac electrical function that are associated with high mortality levels in patients with DM

Background synaptic activity in rat entorhinal cortex shows a progressively greater dominance of inhibition over excitation from deep to superficial layers

The entorhinal cortex (EC) controls hippocampal input and output, playing major roles in memory and spatial navigation. Different layers of the EC subserve different functions and a number of studies have compared properties of neurones across layers. We have studied synaptic inhibition and excitation in EC neurones, and we have previously compared spontaneous synaptic release of glutamate and GABA using patch clamp recordings of synaptic currents in principal neurones of layers II (L2) and V (L5). Here, we add comparative studies in layer III (L3). Such studies essentially look at neuronal activity from a presynaptic viewpoint. To correlate this with the postsynaptic consequences of spontaneous transmitter release, we have determined global postsynaptic conductances mediated by the two transmitters, using a method to estimate conductances from membrane potential fluctuations. We have previously presented some of this data for L3 and now extend to L2 and L5. Inhibition dominates excitation in all layers but the ratio follows a clear rank order (highest to lowest) of L2>L3>L5. The variance of the background conductances was markedly higher for excitation and inhibition in L2 compared to L3 or L5. We also show that induction of synchronized network epileptiform activity by blockade of GABA inhibition reveals a relative reluctance of L2 to participate in such activity. This was associated with maintenance of a dominant background inhibition in L2, whereas in L3 and L5 the absolute level of inhibition fell below that of excitation, coincident with the appearance of synchronized discharges. Further experiments identified potential roles for competition for bicuculline by ambient GABA at the GABAA receptor, and strychnine-sensitive glycine receptors in residual inhibition in L2. We discuss our results in terms of control of excitability in neuronal subpopulations of EC neurones and what these may suggest for their functional roles. © 2014 Greenhill et al

Mechanisms for collaboration: a design and evaluation framework for multi-user interfaces

Multi-user interfaces are said to provide “natural” interaction in supporting collaboration, compared to individual and noncolocated technologies. We identify three mechanisms accounting for the success of such interfaces: high awareness of others' actions and intentions, high control over the interface, and high availability of background information. We challenge the idea that interaction over such interfaces is necessarily “natural” and argue that everyday interaction involves constraints on awareness, control, and availability. These constraints help people interact more smoothly. We draw from social developmental psychology to characterize the design of multi-user interfaces in terms of how constraints on these mechanisms can be best used to promote collaboration. We use this framework of mechanisms and constraints to explain the successes and failures of existing designs, then apply it to three case studies of design, and finally derive from them a set of questions to consider when designing and analysing multi-user interfaces for collaboration

A pre-post study of behavioural determinants and practice change in Ugandan Clinical Officers

The data for this research was collected as part of a training course delivered by the Greater Manchester Critical Care Skills Institute in Gulu, Uganda. Travel, accommodation and associated costs were funded by Greater Manchester Critical Care Skills Institute. Members of the training team collected data and their time both in delivering the course and collecting data was unfunded i.e., voluntary (MJJ, RmC, HS, AS, SC, SW). Data collection was supported by other self-funded volunteers (HP, SR). Research design, data analysis and write up was conducted by unfunded volunteers (all authors). There was no formal role for the funding body in the study design, data collection, analysis or write up. However, authors of the paper are active members of the Greater Manchester Critical Care Skills Institute (AS, MJJ, RMc, HS, SC, SW).Peer reviewedPublisher PD

Children’s Moral Emotion Attribution in the Happy Victimizer Task: The Role of Response Format

Previous research in the happy victimizer tradition indicated that preschool and early elementary-school children attribute positive emotions to the violator of a moral norm, whereas older children attribute negative moral emotions. Cognitive and motivational processes have been suggested as underlying this developmental shift. The current research investigated whether making the happy victimizer task less cognitively demanding, by providing children with alternative response formats, would increase children’s attribution of moral emotions and moral motivation. In Study 1, 93 4- to 7-year-old British children responded to the happy victimizer questions either in a normal condition (where they spontaneously pointed with a finger), a wait condition (where they had to wait before giving their answers), or an arrow condition (where they had to point with a paper arrow). In Study 2, 40 Spanish 4-year-old children responded in the happy victimizer task either in a normal or a wait condition. In both studies, participants’ attribution of moral emotions and moral motivation was significantly higher in the conditions with alternative response formats (wait, arrow) than in the normal condition. The role of cognitive abilities for emotion attribution in the happy victimizer task is discussed

Contesting the Dominant Discourse of Child Sexual Abuse: Sexual Subjects, Agency, and Ethics

Responding to previous scholars’ call to explore the complexities of child sexual abuse (CSA), this article presents narratives of CSA and scrutinizes a binary construction underpinning this discourse of CSA, namely, the positioning of children as powerless and adults as powerful. The narratives belong to three Indonesian young people who have had sexual interactions with adults when they were children. The findings demonstrate how this binary positioning has been both drawn upon and resisted in the ways participants understand their sexual experiences. This article contributes to the existing literature by providing analyses of some vignettes of everyday experiences of how children might be constituted as sexual subjects, including their capability to exercise agency, perform resistance, and negotiate ethics. The implications of the findings are discussed in relation to how the recognition of children as sexual subjects and their sexual agency might be beneficial for parents, educators, and counselors

Working memory, reading ability and the effects of distance and typicality on anaphor resolution in children

We investigated the time course of anaphor resolution in children and whether this is modulated by individual differences in working memory and reading skill. The eye movements of 30 children (10?11 years) were monitored as they read short paragraphs in which (1) the semantic typicality of an antecedent and (2) its distance in relation to an anaphor were orthogonally manipulated. Children showed effects of distance and typicality on the anaphor itself and also on the word to the right of the anaphor, suggesting that anaphoric processing begins immediately but continues after the eyes have left the anaphor. Furthermore, children showed no evidence of resolving anaphors in the most difficult condition (distant atypical antecedent), suggesting that anaphoric processing that is demanding may not occur online in children of this age. Finally, working memory capacity and reading comprehension skill affect the magnitude and time course of typicality and distance effects during anaphoric processing

Gating of a pH-Sensitive K2P Potassium Channel by an Electrostatic Effect of Basic Sensor Residues on the Selectivity Filter

K+ channels share common selectivity characteristics but exhibit a wide diversity in how they are gated open. Leak K2P K+ channels TASK-2, TALK-1 and TALK-2 are gated open by extracellular alkalinization. The mechanism for this alkalinization-dependent gating has been proposed to be the neutralization of the side chain of a single arginine (lysine in TALK-2) residue near the pore of TASK-2, which occurs with the unusual pKa of 8.0. We now corroborate this hypothesis by transplanting the TASK-2 extracellular pH (pHo) sensor in the background of a pHo-insensitive TASK-3 channel, which leads to the restitution of pHo-gating. Using a concatenated channel approach, we also demonstrate that for TASK-2 to open, pHo sensors must be neutralized in each of the two subunits forming these dimeric channels with no apparent cross-talk between the sensors. These results are consistent with adaptive biasing force analysis of K+ permeation using a model selectivity filter in wild-type and mutated channels. The underlying free-energy profiles confirm that either a doubly or a singly charged pHo sensor is sufficient to abolish ion flow. Atomic detail of the associated mechanism reveals that, rather than a collapse of the pore, as proposed for other K2P channels gated at the selectivity filter, an increased height of the energetic barriers for ion translocation accounts for channel blockade at acid pHo. Our data, therefore, strongly suggest that a cycle of protonation/deprotonation of pHo-sensing arginine 224 side chain gates the TASK-2 channel by electrostatically tuning the conformational stability of its selectivity filter

Talaromyces atroroseus, a new species efficiently producing industrially relevant red pigments

Some species of Talaromyces secrete large amounts of red pigments. Literature has linked this character to species such as Talaromyces purpurogenus, T. albobiverticillius, T. marneffei, and T. minioluteus often under earlier Penicillium names. Isolates identified as T. purpurogenus have been reported to be interesting industrially and they can produce extracellular enzymes and red pigments, but they can also produce mycotoxins such as rubratoxin A and B and luteoskyrin. Production of mycotoxins limits the use of isolates of a particular species in biotechnology. Talaromyces atroroseus sp. nov., described in this study, produces the azaphilone biosynthetic families mitorubrins and Monascus pigments without any production of mycotoxins. Within the red pigment producing clade, T. atroroseus resolved in a distinct clade separate from all the other species in multigene phylogenies (ITS, β-tubulin and RPB1), which confirm its unique nature. Talaromyces atroroseus resembles T. purpurogenus and T. albobiverticillius in producing red diffusible pigments, but differs from the latter two species by the production of glauconic acid, purpuride and ZG-1494α and by the dull to dark green, thick walled ellipsoidal conidia produced. The type strain of Talaromyces atroroseus is CBS 133442