Ion channel block in rat diaphragm by the venom of the digger wasp Philanthus triangulum

In the rat phrenic nerve-diaphragm preparation the twitch tension and tetanic contractions, already reduced by d-tubocurarine, succinylchloride or neostigmine, are further reduced by the venom of the digger wasp Philanthus triangulum F. The venom reduces the temperature- and voltage-sensitivity of the acetylcholine-receptor-activated ion channels, at the motor end-plate, and shortens the decay time of the miniature end-plate currents, analogous to a block described for the purified toxin, delta-PTX, on insect glutamate-activated channels. Preliminary results show that delta-PTX has an effect similar to that of the total venom on the decay phase of miniature end-plate currents.     

Effects of monocarboxylates and external pH on some parameters of insect muscle fibres

The resting membrane potential and the conductance of flight muscle fibres of the butterfly Pieris brassicae were measured by means of two intracellular electrodes. The intracellular potassium, chloride, and hydrogen ion concentrations were estimated by measuring the concentrations in diluted muscle homogenates. Chloride in the bath was replaced in part by monocarboxylates and the pH was subsequently lowered. Replacement of chloride by propionate caused decrease in the internal chloride concentration, a marked hyperpolarization and a small increase in conductance. Lowering the pH in the propionate saline caused an additional decrease in the internal chloride concentration, an increase in the internal hydrogen ion concentration, a marked depolarization and a concurrent decrease in conductance. This was followed by an irreversible increase in conductance. With glycolate the effects on the membrane parameters were small and with pyruvate no effect was observed.     

Smooth muscle contracting compounds in the venom of Megascolia flavifrons (Hym: Scoliidae) with notes on the stinging behaviour

1. The wasp Megascolia flavifrons stings larvae of the stag beetle Oryctes nasicornis on the ventral side of all segments, except the last three, which do not contain nerve ganglia. 2. Experiments indicate a central rather than a peripheral action of the venom. 3. From pharmacological analysis it is concluded that the venom does not contain cholinergic or serotonergic activity, but contains histamine- and bradykinin-like substances. 4. The presence of histamine was confirmed by a radioenzymatic method.     

Invasive coronary physiology: a Dutch tradition

Invasive coronary physiology has been applied since the early days of percutaneous transluminal coronary angioplasty, and has become a rapidly emerging field of research. Many physiology indices have been developed, tested in clinical studies, and are now applied in daily clinical practice. Recent clinical practice guidelines further support the use of advanced invasive physiology methods to optimise the diagnosis and treatment of patients with acute and chronic coronary syndromes. This article provides a succinct review of the history of invasive coronary physiology, the basic concepts of currently available physiological parameters, and will particularly highlight the Dutch contribution to this field of invasive coronary physiology.

     

Transforming growth factor-beta-mediated mast cell migration depends on mitogen-activated protein kinase activity

Transforming growth factor-beta (TGF-beta) isoforms regulate numerous cellular functions through binding to receptors with intrinsic serine/threonine kinase activity that transduce the intracellular signals via activation of Smad proteins. In this study, we examined the signalling pathways involved in TGF-beta1-mediated growth inhibition and migration in a human mast cell line, HMC-1. TGF-beta1 evoked optimal migration at 40 fM, whereas maximal growth inhibition was obtained at 400 pM. Protein tyrosine kinase inhibitors completely inhibited TGF-beta1-mediated migration, without affecting the antimitogenic response. Smad2 was phosphorylated upon TGF-beta1 treatment, both in the absence and presence of genistein. The mitogen-induced extracellular kinase (MEK) inhibitor, PD98059, blocked the migratory response without affecting growth inhibition. In contrast, the p38 MAP kinase inhibitor, SB203580, had no significant effect on either migration or growth inhibition. These results indicate that different signalling pathways mediate TGF-beta1-induced migration and growth inhibition in HMC-1 cells, where the migration involves MEK activity.     

Effects of the venom of the solitary wasp Philanthus triangulum F. on glutamate uptake in the nerve endings of locust muscles—A high resolution autoradiographic study

Using electron microscope autoradiography it was shown that the glutamate uptake in both glia cells and axon in the synaptic region of locust muscles was reduced to ca. 50% under the influence of the venom of the solitary wasp Philanthus triangulum F. However, the ratio of the glutamate accumulation in the glia and the nerves remained identical. Implications are discussed in relation to known postsynaptic effects of the venom of Philanthus triangulum F.     

Towards a Model of Contemporary Parenting: The Parenting Behaviours and Dimensions Questionnaire

The assessment of parenting has been problematic due to theoretical disagreement, concerns over generalisability, and problems with the psychometric properties of current parenting measures. The aim of this study was to develop a comprehensive, psychometrically sound self-report parenting measure for use with parents of preadolescent children, and to use this empirical scale development process to identify the core dimensions of contemporary parenting behaviour. Following item generation and parent review, 846 parents completed an online survey comprising 116 parenting items. Exploratory and confirmatory factor analyses supported a six factor parenting model, comprising Emotional Warmth, Punitive Discipline, Anxious Intrusiveness, Autonomy Support, Permissive Discipline and Democratic Discipline. This measure will allow for the comprehensive and consistent assessment of parenting in future research and practice.     

Guideline adherence for antithrombotic therapy in acute coronary syndrome: an overview in Dutch hospitals

Objective. To assess current Dutch antithrombotic treatment strategies for acute coronary syndrome (ACS) in light of the current European Society of Cardiology (ESC) guidelines. Methods. For every Dutch hospital with a coronary care unit (CCU) (n = 93) a single cardiologist was interviewed concerning heparin, thienopyridine and GP IIb/IIIa inhibitor (GPI) treatment. In each hospital, we randomly approached one cardiologist assuming equal policy among physicians employed at the same hospital. Results. The response rate was 90%. In 59% of hospitals, treatment of ST-elevation myocardial infarction (STEMI) occurred according to the 2008 ESC STEMI guideline, with unfractionated heparin. In contrast, although not recommended, low-molecular-weight heparin (LMWH) was used in 39% (enoxaparin 19%, dalteparin 12%, nadroparin 8%). In non-STEMI, low-molecular-weight-heparins (LMWHs) were used in 97% of all hospitals. Fondaparinux, agent of choice in a noninvasive strategy for the treatment of non-STEMI, was applied in only 2% of hospitals. Although recommended by the ESC, dose adjustment of LMWH therapy for patients with renal failure is not applied in 71% of hospitals. Likewise, LMWH dose adjustment is not applied for patients aged over 75 years in 92% of hospitals. Conclusion. To a great extent treatment of ACS in the Netherlands occurs according to ESC guidelines. Additional benefit may be achieved by routine dose adjustment of LMWH for patients with renal insufficiency and aged >75 years, since these patients are at high risk of bleeding complications secondary to antithrombotic treatment. Periodical evaluation of real-life practice may improve guideline adherence and potentially improve clinical outcome. (Neth Heart J 2010;18:291-9.)