TRAAK is a mammalian neuronal mechano-gated K+ channel

The novel structural class of mammalian channels with four transmembrane segments and two pore regions comprise background K+ channels (TWIK-1, TREK-1, TRAAK, TASK, and TASK-2) with unique physiological functions (1-6). Unlike its counterparts, TRAAK is only expressed in neuronal tissues, including brain, spinal cord, and retina (1). This report shows that TRAAK, which was known to be activated by arachidonic acid (3), is also opened by membrane stretch. Mechanical activation of TRAAK is induced by a convex curvature of the plasma membrane and can be mimicked by the amphipathic membrane crenator trinitrophenol. Cytoskeletal elements are negative tonic regulators of TRAAK. Membrane depolarization and membrane crenation synergize with stretch-induced channel opening. Finally, TRAAK is reversibly blocked by micromolar concentrations of gadolinium, a well known blocker of stretch-activated channels. Mechanical activation of TRAAK in the central nervous system may play an important role during growth cone motility and neurite elongation.     

Identification of the receptor subtype involved in the analgesic effect of neurotensin

The neuropeptide neurotensin (NT) elicits hypothermic and naloxone-insensitive analgesic responses after brain injection. Recent pharmacological evidence obtained with NT agonists and antagonists suggests that these effects are mediated by a receptor distinct from the initially cloned high-affinity NT receptor (NTR1). The recent cloning of a second NT receptor (NTR2) prompted us to evaluate its role in NT-induced analgesia. Intracerebroventricular injections in mice of two different antisense oligodeoxynucleotides from the NTR2 markedly decreased NTR2 mRNA and protein and reduced NT-induced analgesia. This effect was specific, because NTR1 levels were unaffected, and sense or scramble oligodeoxynucleotides had no effect. Structure-activity studies revealed a close correlation between the analgesic potency of NT analogs and their affinity for the NTR2 and disclosed potent and selective agonists of this receptor. These data confirm that NTR1 is involved in the NT-elicited turning behavior and demonstrate that the NTR2 mediates NT-induced analgesia.     

Early transvaginal ultrasound following an accurately dated pregnancy: the importance of finding a yolk sac or fetal heart motion

Our goals were to determine the prognostic value of a yolk sac or fetal heart motion seen during an early accurately dated transvaginal ultrasound (TVU). We reviewed 225 consecutive pregnancies for fetal heart motion data. Furthermore, 63 pregnancies following in-vitro fertilization were reviewed for yolk sac information. The TVU was performed between 5 and 6 weeks following presumed conception (heart motion data) and between 22 and 32 days following in-vitro fertilization (yolk sac data). Pregnancies were followed until an ongoing pregnancy or spontaneous abortion was documented. The presence of a yolk sac between 22 and 32 days from fertilization was associated with the development of fetal heart motion in 94% of cases. The absence of the yolk sac by 32 days after fertilization was always associated with a poor outcome. In women < 36 years of age, the presence of fetal heart motion was associated with a spontaneous abortion in only 4.5% of the cases. However, the incidence of spontaneous abortion following fetal heart motion increased to 10% in women 36-39 years and 29% in women > or = 40 years of age. The presence of heart motion should not be considered a reassuring sign in the older woman. These data have implications regarding early embryology and the counselling of infertility patients.     

The tetramethylammonium chloride method for screening of cDNA libraries using highly degenerate oligonucleotides obtained by backtranslation of amino-acid sequences

We describe a method for screening of cDNA libraries with highly degenerate oligonucleotides using tetramethylammonium chloride (TMAC). This method is a convenient alternative to using probes generated by the polymerase chain reaction (PCR), especially when these cannot easily be made. Nylon filters were prehybridized in buffered sodium chloride and hybridized with labelled oligonucleotide in buffer containing 3 M TMAC. In TMAC the melting temperature of the oligonucleotide is independent of the G + C content, thus only depending on the length. This was confirmed by the cloning of 13 specific cDNAs with G + C contents between 27% and 61% using 15- to 20-mer oligonucleotides with a degeneracy up to 512. The method was further improved for highly degenerate oligonucleotides by testing hybridization of four 18-mer oligonucleotides, each containing one deoxyinosine (I) instead of A, G, C or T, respectively. Oligonucleotides containing I pairing with A, G or T may have slightly lower melting temperatures than those pairing with C. At practical circumstances all oligonucleotides hybridize about equally well at hybridization temperatures 10 degrees C below the irreversible melting temperature. This was further confirmed by the cloning of four cDNAs with oligonucleotides containing deoxyinosines at 3 or 4 ambiguous positions.     

Hybrid vortex simulations of wind turbines using a three‐dimensional viscous–inviscid panel method

A hybrid filament‐mesh vortex method is proposed and validated to predict the aerodynamic performance of wind turbine rotors and to simulate the resulting wake. Its novelty consists of using a hybrid method to accurately simulate the wake downstream of the wind turbine while reducing the computational time used by the method. The proposed method uses a hybrid approach, where the near wake is resolved by using vortex filaments, which carry the vorticity shed by the trailing edge of the blades. The interaction of the vortex filaments in the near vicinity of the wind turbine is evaluated using a direct calculation, whereas the contribution from the large downstream wake is calculated using a mesh‐based method. The hybrid method is first validated in detail against the well‐known MEXICO experiment, using the direct filament method as a comparison. The second part of the validation includes a study of the influence of the time‐integration scheme used for evolving the wake in time, aeroelastic simulations of the National Renewable Energy Laboratory 5 MW wind turbine and an analysis of the central processing unit time showing the gains of using the hybrid filament‐mesh method. Copyright © 2017 John Wiley & Sons, Ltd.     

Review of When I grow up . . . Career expectations and aspirations of Canadian school children/Quand je serai adulte, je . . . Les attentes et les aspirations des écoliers Canadiens à l'égard de leur carrière.

Reviews the book, When I grow up . . . Career expectations and aspirations of Canadian school children/Quand je serai adulte, je . . . Les attentes et les aspirations des écoliers Canadiens à l'égard de leur carrière by Dormer Ellis and Lyz Sayer (1986). The focus of this 77-page bilingual book is to compare the differences between male and female school children's career aspirations (ideal choices) and career expectations (realistic choices). While school children may aspire to certain occupations of their dreams, their realistic choices may be tempered by what society may view as appropriate. The book, funded by the Women's Bureau, is divided into six chapters that describe the study and some conclusions of the study's implication. Although this is the first study of its kind in Canada and it is a needed addition to the literature, this book could have been presented as an article rather than in its present form, saving a good deal of space and money. (PsycINFO Database Record (c) 2010 APA, all rights reserved)