Review on Biomedical Techniques for Imaging Electrical Impedance

Electrical impedance of a medium helps to predict the behavior of electrical currents in a medium. Electrical impedance refers indeed to the “difficulty”, for an electrical current, to spread through the medium. While the first impedance measurements were focused on cardiovascular parameters, techniques are now being applied to the whole body, as electrical impedance present important variations through the human body and could then offer a new source of contrast.Combining electrical current, magnetic fields, and acoustics in various ways have led to interesting techniques to image this parameter: Electrical Impedance Tomography, Magnetic Resonance Electrical Impedance Tomography, Acousto-Electric Imaging, Lorentz Force Electrical Impedance Tomography and Magneto-Acoustic Tomography. These techniques are detailed in this review.     

Germline silencing of UASt depends on the piRNA pathway

正The success of the fruit fly Drosophila melanogaster as a model organism is heavily attributed to the expansive range and multitude of genetic and molecular tools available to modify gene expression at will.The Gal4/UAS binary system is one of the most important and widely used genetic tools in Drosophila designed for targeted gene expression(Brand and Perrimon,1993),which allows ectopic expression of any gene(or transgene)in specific tissues,independent of their native regulators.     

Impact of fresh fruit smoothie consumption on apparent health of Asian faces

Skin carotenoid coloration has been proposed as a valid cue to health in humans, reflecting fruit and vegetable intake, and enhancing apparent health. Supplementation with a carotenoid-rich fruit and vegetable smoothie affects skin color, but it is not known if this skin color change enhances healthy appearance. In three experiments, we examine the effects of skin color change induced by supplementation with a carotenoid-rich fruit smoothie (25 mg carotenoids/d) on the apparent health of Malaysian Chinese faces. In experiment 1, observers were asked to identify the healthier looking of pairs of photographs of the same subject taken pre- and post-supplementation (or pre- and post-placebo), choosing the pre-supplementation (or pre-placebo) images. When confounding due to facial expression was eliminated in experiment 2, observers showed no preference for unmodified pre-supplementation photograph or the same image with skin color manipulated to simulate a level of smoothie-induced color change associated with 4 weeks of supplementation. In experiment 3, observers manipulated the skin color of face photographs along the smoothie-induced color change axis to optimize healthy appearance. Observers chose to induce a color change approximately equivalent to one third of the change induced by daily consumption of our carotenoid rich smoothie. This suggests that the skin color change induced by the supplementation enhanced apparent facial health, however the dose and duration of the supplementation overshot the optimal healthy-looking color of Malaysian Chinese skin. This suggests that there is an optimal carotenoid color for healthy appearance, and that this optimal level may be constrained by preferences for averageness, by the association between very yellow skin and ill health, or by negative health impacts of very high doses of carotenoids.     

Effects of charge and hydrophobicity on the oligomerization of peptides derived from IAPP

Changes in pH resulting in modifications of charge can dramatically alter the folding and interaction of proteins. This article probes the effects of charge and hydrophobicity on the oligomerization of macrocyclic β-sheet peptides derived from residues 11–17 of IAPP (RLANFLV). Previous studies have shown that a macrocyclic β-sheet peptide containing this IAPP sequence (peptide 1_Arg) does not form oligomers in aqueous solution at low millimolar concentrations. Replacing arginine with the uncharged isostere citrulline generates a homologue (peptide 1_Cit) that forms a tetramer consisting of a sandwich of hydrogen-bonded dimers. The current study probes the role of charge and hydrophobicity by changing residue 11 to glutamic acid (peptide 1_Glu) and leucine (peptide 1_Leu). Diffusion-ordered spectroscopy (DOSY) studies show that peptides 1_Glu and 1_Leu form tetramers in solution. NOESY studies confirm that both peptides form the same sandwich-like tetramer as peptide 1_Cit. ¹H NMR spectroscopy at various concentrations reveals that peptide 1_Leu has the highest propensity to form tetramers. The effects of pH and charge on oligomerization are further probed by incorporating histidine at position 11 (peptide 1_His). DOSY studies show that peptide 1_His forms a tetramer at high pH. At low pH, peptide 1_His forms a new species that has not been previously observed by our research group—a dimer. These studies demonstrate the importance of charge and hydrophobicity in the oligomerization of IAPP-derived peptides.     

Activation of membrane-bound and soluble Toll-like Receptors 5 in Salmo salar depends on the MyD88 signalling pathway

Background

TLR5M and TLR5S are Toll-like Receptors (TLRs), expressed in teleost fish, that recognize flagellin as a ligand, in the same way as the TLR5 ortholog in mammals. However, it has not been demonstrated whether the signalling pathway induced by these TLRs depends on MyD88 to generate a pro-inflammatory response in Salmo salar.

Structure activity relationships of anthranilic acid-based compounds on cellular and in vivo mitogen activated protein kinase-5 signaling pathways

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The effect of replacing the ester bond with an amide bond and of overall stereochemistry on the activity of daptomycin

Daptomycin, a cyclic lipodepsipeptide antibiotic, has been used clinically since 2003 to treat serious infections caused by Gram-positive bacteria. Although 37?years have passed since daptomycin’s discovery, its mechanism of action is still debated. In this report, the effect of replacing the ester bond with an amide bond, and overall stereochemistry, on daptomycin’s biological activity was examined. Two peptides were prepared in which the threonine4 residue in the active daptomycin analog, Dap-K6-E12-W13, was replaced with (2S,3R)-diaminobutyric acid ((2S,3R)-DABA) or its epimer (2S,3S-DABA) converting the ring-closing ester bond to an amide bond. Both of these peptides were found to be considerably less active than Dap-K6-E12-W13. These results, along with our previous studies on other daptomycin analogs, enabled us to conclude that the ester bond is crucial to daptomycin’s activity. ent-Dap-K6-E12-W13 was found to be at least 133-fold less active than Dap-K6-E12-W13, indicating that a chiral interaction with a chiral target is essential to daptomycin’s activity. Studies examining the binding of Dap-K6-E12-W13 and ent-Dap-K6-E12-W13 to model liposomes consisting of phosphatidylglycerol (PG) and phosphatidylcholine suggest that the stereochemistry of PG plays a crucial role in daptomycin-membrane interactions.     

The study of dental occlusion in ancient skeletal remains from Mallorca (Spain): A new approach based on dental clinical practice

Occlusal characteristics, fundamental to assess the presence of malocclusion, have been often unexplored in bioarchaeological analyses. This is largely due to the fragmented condition of the skeletal remains. By applying a method that considers dental and maxillary features useful to evaluate occlusion in ancient fragmentary material, the purpose of this work is to define the occlusal features and explore the causes of malocclusion in a mediaeval population from Mallorca. The findings of this study suggest that normocclusion was present in ca. 60% of the individuals (N = 31), and that some characteristics, such as molar relationship, were slightly different from those of modern populations. The analysis of the occlusal features revealed for example that open-bite was absent in 85% of the sample, posterior open-bite was completely absent and overbite and overjet were normal in around 90% of the individuals. Statistically significant correlations between canine and molar relationships and between molar relationship and dental wear of the superior and inferior canines and incisors were observed. In addition, wear could affect the curve of Spee. All these findings strengthen the hypothesis that in ancient times malocclusion was not as generalized as in modern times. Although the factors that lead to malocclusion throughout centuries could have several causes, we suggest that in this population dental wear, which is strongly associated with the diet, was the fundamental causing factor.     

Effect of insulin on alpha1-adrenergic actions in hepatocytes from euthyroid and hypothyroid rats. Possible involvement of two pathways in alpha1-adrenergic actions

The effect of insulin on the alpha1-adrenergic stimulation of glycogenolysis and ureogenesis, which is very small or undetectable in hepatocytes from control animals, is marked in hepatocytes from hypothyroid rats; the metabolic actions due to alpha1-adrenergic activation, but not those due to glucagon, were nearly blocked by insulin in cells from hypothyroid rats. The alpha1-adrenergic-mediated stimulation of phosphatidylinositol labelling was not affected by insulin in cells from either control or hypothyroid rats. The data suggest that the alpha1-adrenergic action proceeds through two pathways, one of which is very sensitive to insulin and predominates in cells from hypothyroid rats.     

Scientific Note: First record of the remarkable clearwing moth,Akaisphecia melanopuncta O. Gorbunov & Arita, 1995 (Sesiidae: Sesiinae: Osminiini), from Thailand,with comments on likely Batesian mimicry

The sesiid moth, Akaisphecia melanopuncta O. Gorbunov & Arita, 1995, is recorded from Thailand for the first time, having originally been described from Vietnam and subsequently recorded from Laos. Photographs of a living individual are presented that illustrate that in life it is a very good mimic of red-and-black aposematic Hemiptera (Heteroptera) such as various predatory pyrrhocorids.