Temporary anions of the dielectric gas C3F7CN and their decay channels.

We probe the transient anion states (resonances) in the dielectric gas C4F7N by the electron energy loss spectroscopy and the dissociative electron attachment spectroscopy. The vibrationally inelastic electron scattering leads to two excitation types. The first is the excitation of specific vibrational modes that are assigned with the help of an infrared spectrum of this molecule and quantum chemistry calculations. In the second type of vibrational excitation, the excess energy is randomized via internal vibrational redistribution in the temporary anion, and the electrons are emitted statistically. The electron attachment proceeds in three different regimes. The first is the formation of the parent C4F7N- anion at energies close to 0 eV. The second is a statistical evaporation of the F-atom, leading to the defluorinated anion C4F6N-. Finally, the third is dissociative electron attachment proceeding via the formation of several resonances and leading to a number of fragments. The present data explain the puzzling recent results of the pulsed-Townsend experiments with this gas.

Dissociative ionization dynamics of dielectric gas C3F7CN.

Fluoronitrile C3F7CN is a promising candidate for the replacement of SF6 dielectric gas in high-voltage insulation. We present a combined experimental and theoretical study on its ionization dynamics probed in the 0-100 eV energy range. We exploited the total ion collection technique to determine the absolute ionization cross section, mass spectrometry to determine the fragment branching ratios and ab initio nonadiabatic molecular dynamics to simulate the ionization process. The latter two approaches showed the dominating presence of the CF3+ cation over the whole electron energy range. The Binary-Encounter-Bethe (BEB) approximation reproduces experimental cross sections very well and reveals that the ionization from a surprisingly large number of orbitals contributes almost equally to the processes. We show that the initially populated cation excited states undergo an ultrafast internal conversion to the ground state where the dissociation into a single decay channel takes place. Implications for the use of C3F7CN as an insulating material are discussed.

VUV action spectroscopy of protonated leucine-enkephalin peptide in the 6-14 eV range.

We have studied the Vacuum Ultraviolet (VUV) photodissociation of gas-phase protonated leucine-enkephalin peptide ion in the 5.7 to 14 eV photon energy range by coupling a linear quadrupole ion trap with a synchrotron radiation source. We report VUV activation tandem mass spectra at 6.7, 8.4, and 12.8 eV photon energies and photodissociation yields for a number of selected fragments. The obtained results provide insight into both near VUV radiation damage and electronic properties of a model peptide. We could distinguish several absorption bands and assign them to particular electronic transitions, according to previous theoretical studies. The photodissociation yields appear to be very different for the various observed fragmentation channels, depending on both the types of fragments and their position along the peptide backbone. The present results are discussed in light of recent gas-phase spectroscopic data on peptides.

Allosteric modulation of metabotropic glutamate receptor 5 affects phosphorylation, internalization, and desensitization of the micro-opioid receptor.

Recent evidence suggests that opioid analgesia and tolerance can be modulated by metabotropic glutamate receptors. Therefore, we studied the functional coupling and desensitization of the micro-opioid receptor (MOR) in human embryonic kidney (HEK) 293 cells which co-express metabotropic glutamate receptor 5 (mGluR5). As demonstrated by the D-Ala2,N-MePhe4,Gl-ol5-enkephalin (DAMGO)-induced inhibition of intracellular cAMP level and by binding studies, the co-expression of mGluR5 had no substantial effect on the agonist binding sites and functional coupling of the MOR. However, in MOR/ mGluR5 co-expressing cells, the non-competitive mGluR5 antagonist MPEP (2-methyl-6-(phenyl-ethynyl)-pyridine) decreases the DAMGO-induced MOR phosphorylation, internalization, and desensitization, whereas non-selective competitive mGluR antagonists or agonists had no effects. These findings indicate that an allosteric modulation of mGluR5 can affect the agonist-induced MOR signalling and regulation. As a mechanistic basis for the observed effects we suggested an interaction/heterodimerization of MOR and mGluR5, which is supported by the DAMGO-induced co-internalization of MOR and mGluR5 and by the increase of MPEP binding sites (Bmax) and a change of the binding affinity (K(D)) of mGluR5 receptors after the co-expression of MOR. In addition, co-immunoprecipitation experiments revealed evidence for an interaction between MOR and mGluR5 which is facilitated by MPEP treatment.

[Total intravenous anesthesia using remifentanil and propofol with midazolam co-induction in laparoscopic surgery of the gallbladder]. / TIVA remifentanilom i propofolom uz koindukciju midazolamom za laparoskopske operacije zucne kese.

We investigated effects of total intravenous anesthesia (TIVA) with propofol and remifentanil (in two parallel continuous infusions), on 28 ASA I-II patients undergoing laparoscopic cholecystectomy. All patients received midazolame (0.05 mg/kg b.w.), and 90 sec thereafter, remifentanil (0.5 g/kg b.w.). Computer controlled intravenous infusion of propofol started at dose of 6 mg/kg/h (by Graseby 3400 Syringe Pump). Muscle relaxation was achieved by rocuronium (0.6 mg/kg b.w.). After endotracheal intubation, rate of propofol was decreased on 3 mg/kg/h and started with another infusion of remifentanil (0.5 ug/kg/min). Before (T0) and after induction (T1), after start of surgery (T2), and at the end of surgery (T3), we evaluated: systolic, diastolic, and medial arterial blood pressure (SAP, DAP, MAP), heart rate (HR), peripheral saturation of O2 (O2Sat), and capnometry (ETCO2), by Datex-Engstrome AS/3 Monitore. It was followed side effects of anaesthesia, early and complete recovery rate, and frequency of nausea and vomiting in postoperative period. Results showed haemodynamic stability of patients after induction in anaesthesia (defined as decreasing of MAP 20%, compared with preinduction values). During investigation (T0-T3), results of 0.2Sat and ETCO2 were excellent (0.60 +/- 2 and 5.1 +/- 2.4 min). There wasonly one case of postoperative nausea and vomiting, and no significant side effects of anaesthesia. TIVA remifentanil-propofol and co-induction with midazolame makes possible haemodynamic stability of patients after induction in anaesthesia, good oxygenation during surgery, fast early and complete recovery, and avoiding of side effects of anaesthesia and postoperative nausea and vomiting. We concluded that it is a good choice of anaesthesia for laparoscopic cholecystectomy.