Studiereis naar de boekweitvelden (2) : onderzoek en resultaten

Bestuiving boekweit door bijen, onderzoek en resultate

Phospholipase D signaling: orchestration by PIP2 and small GTPases

Hydrolysis of phosphatidylcholine by phospholipase D (PLD) leads to the generation of the versatile lipid second messenger, phosphatidic acid (PA), which is involved in fundamental cellular processes, including membrane trafficking, actin cytoskeleton remodeling, cell proliferation and cell survival. PLD activity can be dramatically stimulated by a large number of cell surface receptors and is elaborately regulated by intracellular factors, including protein kinase C isoforms, small GTPases of the ARF, Rho and Ras families and, particularly, by the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 is well known as substrate for the generation of second messengers by phospholipase C, but is now also understood to recruit and/or activate a variety of actin regulatory proteins, ion channels and other signaling proteins, including PLD, by direct interaction. The synthesis of PIP2 by phosphoinositide 5-kinase (PIP5K) isoforms is tightly regulated by small GTPases and, interestingly, by PA as well, and the concerted formation of PIP2 and PA has been shown to mediate receptor-regulated cellular events. This review highlights the regulation of PLD by membrane receptors, and describes how the close encounter of PLD and PIP5K isoforms with small GTPases permits the execution of specific cellular functions

Rgnef (p190RhoGEF) Knockout Inhibits RhoA Activity, Focal Adhesion Establishment, and Cell Motility Downstream of Integrins

Cell migration is a highly regulated process that involves the formation and turnover of cell-matrix contact sites termed focal adhesions. Rho-family GTPases are molecular switches that regulate actin and focal adhesion dynamics in cells. Guanine nucleotide exchange factors (GEFs) activate Rho-family GTPases. Rgnef (p190RhoGEF) is a ubiquitous 190 kDa GEF implicated in the control of colon carcinoma and fibroblast cell motility.Rgnef exon 24 floxed mice (Rgnef(flox)) were created and crossed with cytomegalovirus (CMV)-driven Cre recombinase transgenic mice to inactivate Rgnef expression in all tissues during early development. Heterozygous Rgnef(WT/flox) (Cre+) crosses yielded normal Mendelian ratios at embryonic day 13.5, but Rgnef(flox/flox) (Cre+) mice numbers at 3 weeks of age were significantly less than expected. Rgnef(flox/flox) (Cre+) (Rgnef-/-) embryos and primary mouse embryo fibroblasts (MEFs) were isolated and verified to lack Rgnef protein expression. When compared to wildtype (WT) littermate MEFs, loss of Rgnef significantly inhibited haptotaxis migration, wound closure motility, focal adhesion number, and RhoA GTPase activation after fibronectin-integrin stimulation. In WT MEFs, Rgnef activation occurs within 60 minutes upon fibronectin plating of cells associated with RhoA activation. Rgnef-/- MEF phenotypes were rescued by epitope-tagged Rgnef re-expression.Rgnef-/- MEF phenotypes were due to Rgnef loss and support an essential role for Rgnef in RhoA regulation downstream of integrins in control of cell migration

Prediction of Common-Mode Currents on Cables Connected to a Multilayer Printed Circuit Board

Common-mode currents through cables connected to printed circuit boards (PCBs) are often the dominant cause interference. Therefore, Bersier proposed in 1983 precompliance tests where a common-mode current is measured or injected though each cable attached to the equipment under test. This relatively simple method has been proven to be accurate and reliable according to many engineers. We model such a test for a PCB and describe the coupling between the signal circuits on a PCB and the circuits formed by the attached cables by means of a transmission-line approach. Demonstration PCBs with linear devices and digital logic showed that for frequencies up to about 700 MHz calculations and measurements on a 20 cm long PCB agreed within 8 dB. Keywords--- Physical Design, Printed Circuit Board (PCB) Design, EMC, Common-mode Currents. I. Introduction All electrical and electronic equipment radiates electromagnetic (EM) waves and is susceptible to external EM waves. With the increasing speed ..

Improving asthma care in children: revealing needs and bottlenecks through in-depth interviews

Abstract Asthma affects 7% of Dutch children and poses an increasing challenge, highlighting the need for effective paediatric asthma care. Achieving optimal asthma control is crucial given the potentially negative long-term effects of bad asthma control on lung development and quality of life in young children. The aim was to understand the challenges and requirements of existing asthma management practices in children. In a qualitative explorative study design, semi-structured, in-depth interviews were held among 37 Dutch stakeholders. A total of 15 patients/parents, 10 general practitioners (GPs), 5 paediatricians/paediatric pulmonologists and 7 nursing specialist/pulmonary nurses participated. Analysis was based on a thematic inductive analysis, using open and axial coding. GPs tended to emphasise the treatment of patients/parents with acute symptoms and underestimate the diagnosis and management of chronic symptoms, leading to possible over- and undertreatment. Asthma care between primary and secondary healthcare is fragmented and worsens these challenges. Moreover, the absence of well-established follow-up structures in primary care contributes to insufficient self-management skills among patients. Shared Decision-Making in children lacks a tailored approach, with variable engagement levels among healthcare providers. Limited focus on preventive strategies leads to little attention to, for example, promoting healthy lifestyles. Moreover, children are often not actively involved in decision-making. The study provides valuable insights to improve the quality and continuity of care for children with asthma and their parents. It underlines the need for a comprehensive and integrated care pathway to minimise the long-term negative effects of uncontrolled asthma