Functional differences of iodinated obestatin peptides: in vitro metabolic stability profile

Peptides are small polymers of 50 amino acids, situated between organic molecules and proteins. Most peptides perform a biochemical-physical function and are therefore considered as potential drugs. In vivo studies, such as blood-brain barrier transport and medical imaging require sensitive analytical techniques, achieved by using radiolabeled tracers. These peptide tracers are synthesised from the reaction with radioactive sodium iodide, incorporating the iodine in the tyrosine or histidine amino acid residue[1]. However, next to enzymatic degradation, it is reported that deiodination occurs in vitro as well as in vivo [2, 3]. This phenomenon should be taken into account since the deiodinated metabolite(s) can cause the biologic activity. Therefore, the in vitro stability of different iodinated mouse obestatin derivatives is characterised in the main metabolic compartments: plasma, liver and kidney. Using LC-UV for quantification, significant differences in the degradation kinetics of the iodinated peptides, arising from both enzymatic proteolysis and deiodination, were found when compared to the native, unmodified peptide. LC-MS/MS analysis demonstrated that the cleavage sites were dependent upon the biological matrix and the location of the amino acid residue incorporating the iodine atom(s). The degrading enzymes were found to target peptide bonds further away from the iodine incorporation, while proteolytic cleavages of nearby peptide bonds were inhibited. Di-iodinated amino acid residue containing peptides were found to be more susceptible to deiodination than the mono-iodinated derivative. References [1] J. Nemeth, G. Oroszi, B. Jakab, M. Magyarlaki, Z. Szilvassy, E. Roth, B. Farkas, Journal of Radioanalytical and Nuclear Chemistry 2002, 251, 129. [2] J. C. Solis-S, P. Villalobos, A. Orozco, C. Valverde-R, Journal of Endocrinology 2004, 181, 385. [3] E. R. Goldberg, L. A. Cohen, Bioorganic Chemistry 1993, 21, 41

Surface enhanced Raman spectroscopy on single mode nanophotonic-plasmonic waveguides

We analyze the generation of Surface Enhanced Raman Spectroscopy signals from integrated bowtie antennas, excited and collected by a single mode silicon nitride waveguide, and discuss strategies to enhance the Signal-to-Noise Ratio

Surface enhanced Raman spectroscopy using a single mode nanophotonic-plasmonic platform

Surface Enhanced Raman Spectroscopy (SERS) is a well-established technique for enhancing Raman signals. Recently photonic integrated circuits have been used, as an alternative to microscopy based excitation and collection, to probe SERS signals from external metallic nanoparticles. However, in order to develop quantitative on-chip SERS sensors, integration of dedicated nanoplasmonic antennas and waveguides is desirable. Here we bridge this gap by demonstrating for the first time the generation of SERS signals from integrated bowtie nanoantennas, excited and collected by a single mode waveguide, and rigorously quantify the enhancement process. The guided Raman power generated by a 4-Nitrothiophenol coated bowtie antenna shows an 8 x 10^6 enhancement compared to the free-space Raman scattering. An excellent correspondence is obtained between the theoretically predicted and observed absolute Raman power. This work paves the way towards fully integrated lab-on-a-chip systems where the single mode SERS-probe can be combined with other photonic, fluidic or biological functionalities.Comment: Submitted to Nature Photonic

Endovenous laser ablation: the role of intraluminal blood

AbstractObjectiveIn this histological study, the role of the intraluminal blood during endovenous laser ablation was assessed.MethodsIn 12 goats, 24 lateral saphenous veins were treated with a 1500-nm diode laser. Four goats were treated in an anti-Trendelenburg position (group 1). The next four goats were treated in a Trendelenburg position (group 2) and the remaining four goats in the Trendelenburg position with additional injection of tumescent liquid (group 3). Postoperatively, the veins were removed after 1 week and sent for histological examination. We measured the number of perforations. Vein wall necrosis and the perivenous tissue destruction were quantified using a graded scale.ResultsThe ‘calculated total vein wall destruction’ was significantly higher in the third group (81.83%), as compared with groups one (61.25%) (p < 0.001) and two (65.92%) (p < 0.001). All three groups showed a significant difference in the perivenous tissue destruction scale (p < 0.001) with the lowest score occurring in the third group. Vein wall perforations were significantly more frequent in groups one and two as compared with the third group (T-test respectively p < 0.001, p = 0.02).ConclusionA higher intraluminal blood volume results in reduced total vein wall destruction. Injection of tumescent liquid prevents the perivenous tissue destruction and minimises the number of perforations

On-chip enhanced raman spectroscopy using metal slot waveguide

info:eu-repo/semantics/publishe

Self-assembled hexagonal double fishnets as negative index materials

We show experimentally the successful use of colloidal lithography for the fabrication of negative index metamaterials in the near-infrared wavelength range. In particular, we investigated a specific implementation of the widely studied double fishnet metamaterials, consisting of a gold-silica-gold layer stack perforated by a hexagonal array of round holes. Tuning of the hole diameter allows us to tailor these self-assembled metamaterials both as single- ({\epsilon} < 0) and double ({\epsilon} < 0 and {\mu} < 0) negative metamaterials

Foci of segmentally contracted sarcomeres in trapezius muscle biopsy specimens in myalgic and nonmyalgic human subjects : preliminary results

Objective The myofascial trigger point hypothesis postulates that there are small foci of contracted sarcomeres in resting skeletal muscle. Only one example, in canine muscle, has been published previously. This study evaluated human muscle biopsies for foci of contracted sarcomeres. Setting The Departments of Rehabilitation Sciences and Physiotherapy at Ghent University, Ghent, Belgium. Subjects Biopsies from 28 women with or without trapezius myalgia were evaluated, 14 in each group. Methods Muscle biopsies were obtained from regions of taut bands in the trapezius muscle and processed for light and electron microscopy and for histochemical analysis. Examination of the biopsies was blinded as to group. Results A small number of foci of segmentally contracted sarcomeres were identified. One fusiform segmental locus involved the entire muscle fiber in tissue from a myalgic subject. Several transition zones from normal to contracted sarcomeres were found in both myalgic and nonmyalgic subjects. The distance between Z-lines in contracted sarcomeres was about 25–45% of the same distance in normal sarcomeres. Z-lines were disrupted and smeared in the contracted sarcomeres. Conclusions A small number of foci of segmentally contracted sarcomeres were found in relaxed trapezius muscle in human subjects, a confirmation of the only other example of spontaneous segmental contraction of sarcomeres (in a canine muscle specimen), consistent with the hypothesis of trigger point formation and with the presence of trigger point end plate noise