Search results for "compounds"
showing 10 items of 3372 documents
Validation of a novel automatic deposition of bacteria and yeasts on MALDI target for MALDI-TOF MS-based identification using MALDI Colonyst robot
2017
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) -based identification of bacteria and fungi significantly changed the diagnostic process in clinical microbiology. We describe here a novel technique for bacterial and yeast deposition on MALDI target using an automated workflow resulting in an increase of the microbes' score of MALDI identification. We also provide a comparison of four different sample preparation methods. In the first step of the study, 100 Gram-negative bacteria, 100 Gram-positive bacteria, 20 anaerobic bacteria and 20 yeasts were spotted on the MALDI target using manual deposition, semi-extraction, wet deposition onto 70% formic …
Temperature effect on phase state and reactivity controls atmospheric multiphase chemistry and transport of PAHs
2017
Atmospheric refrigerator increases the global transport and health risks of carcinogenic PAHs.
Invasive Observation by Atomic Force Microscope of a Langmuir-Blodgett Monolayer of Gramicidin
2002
The properties of gramicidin, a linear antibiotic polypeptide of 15 amino acids, have been studied at the air-water interface. Analysis of the pressure-area isotherm is not able to conclude about the conformational behavior of gramicidin in the monolayer. Langmuir-Blodgett deposition of gramicidin layers onto a mica substrate has been developed for atomic force microscopy (AFM) observations. At high pressure of deposition, the gramicidin monolayer is composed of dimers perpendicular to the surface. The possibility of removing the half upper part of this dimer monolayer with the AFM tip is more in favor of a structure of single-stranded helical dimers.
EMG activity of pigeon oesophagus in vivo.
1982
At rest, the pigeon cervical oesophagus, which is entirely smooth muscle, shows electric activity. This activity consists of bursts of spikes with frequency increasing in the oral-aboral direction. The bursts are un-phase locked, and there are no slow waves (E.C.A.). The surgical transection of the oesophageal muscular wall does not affect the electric activity even in a disconnected segment. After asphyxia electric activity persists, whereas the aboral gradient of frequency disappears. Therefore, the electric activity is thought to be myogenic in origin, and the frequency gradient nervous in origin. Atropine and neostigmine administration suggests that the cholinergic system modulates the …
Non-adrenergic non-cholinergic nerve-mediated inhibitory control of pigeon oesophageal muscle.
1996
Pigeon oesophageal smooth muscle in vitro has spontaneous electromechanical activity. In the presence of atropine and guanethidine, electrical field stimulation evokes a transient TTX-sensitive response comprising inhibition of electric bursting activity and muscular relaxation. This NANC inhibitory response was analysed using the K+ channel blockers TEA and apamin, TEA perfusion (0.1-5 mM) induced a concentration-dependent reduction in amplitude of EFS-evoked relaxation. Responses to higher stimulation frequencies were more sensitive to TEA than those to lower ones. The maximum reduction in amplitude (29% of control) was obtained on 30 Hz EFS evoked responses during 5 mM TEA perfusion. In …
Inhibition by oxotremorine of acetylcholine resting release from guinea pig-ileum longitudinal muscle strips
1975
1. Longitudinal muscle strips of the guinea-pig ileum were incubated in Tyrode solution containing either DFP or physostigmine as cholinesterase inhibior. After a 90 min preincubation period the acetylcholine resting release into the medium was determined. Acetylcholine was estimated by gas chromatography. 2. The resting release was 0.39 nmol/g×min irrespective of the cholinesterase inhibitor used. In the presence of hexamethonium, or after omission of external calcium, the resting release fell by 50 and 55%, respectively. 3. Oxotremorine (10−5 and 10−4 M) significantly inhibited the resting release of acetylcholine by 25 and 33%, respectively. The inhibitory effect of oxotremorine was comp…
Modulation by oxotremorine and atropine of acetylcholine release evoked by electrical stimulation of the myenteric plexus of the guinea-pig ileum
1977
1. The effects of oxotremorine and atropine on the release of acetylcholine from longitudinal muscle strips of the guinea-pig ileum stimulated at frequencies between 0.1 and 3 Hz in the presence of eserine were investigated. In control experiments the acetylcholine output per stimulus declined with increasing frequencies of stimulation. 2. Oxotremorine inhibited the release of acetylcholine in a concentration-dependent fashion. At a concentration of 10−6 M oxotremorine, the release evoked by 0.1 Hz was reduced by 54%. With increasing frequencies of stimulation the inhibitory effect of oxotremorine became smaller. 3. Atropine enhanced the output of acetylcholine evoked by electrical stimulat…
Muscarine receptor types mediating autoinhibition of acetylcholine release and sphincter contraction in the guinea-pig iris.
1990
The potencies of several muscarine receptor antagonists in blocking either the autoinhibition of acetylcholine release or the muscarinic contraction of the sphincter muscle upon acetylcholine release were investigated in the guinea-pig iris. The agonist at pre- or postjunctional muscarine receptors was acetylcholine released upon field stimulation (5.5 Hz, 2 min) of the irides preloaded with 14C-choline. The stimulation-evoked 14C-overflow was doubled in the presence of atropine 0.1 mumol/l but unaffected by the agonist (+/-)-methacholine (50 mumol/l). Thus, under the present stimulation conditions, the autoinhibition of acetylcholine release on the guinea-pig iris cholinergic nerves was ne…
Muscarinic inhibition of [3H]-noradrenaline release on rabbit iris in vitro: effects of stimulation conditions on intrinsic activity of methacholine …
1988
1. Rabbit isolated irides were loaded with [3H]-noradrenaline and superfused with Tyrode solution. The inhibition by the muscarinic agonists (+/-)-methacholine and pilocarpine of the [3H]-noradrenaline overflow into the superfusate evoked by field stimulation (pulses of 1 ms duration, 75 mA) was measured as an index of activation of presynaptic muscarinic receptors. 2. The fractional rate of release per pulse during the first stimulation period (S1) was low with 360 pulses at 3 Hz, intermediate with 360 pulses at 10 Hz and high with 1200 pulses at 10 Hz. Upon repetitive stimulation (7 periods at 20 min intervals), the fractional rates of release per pulse during S7 no longer differed, sugge…
Safety and feasibility of atropine added in patients with sub-maximal heart rate during exercise myocardial perfusion SPECT.
2006
Failure to reach 80% of maximal predicted heart rate (HR) during exercise may render a myocardial perfusion single photon emission computed tomography (SPECT) study non-diagnostic for ischemia detection. We sought to investigate the injection of atropine in patients who fail to achieve 80% of age-predicted HR during exercise performed for myocardial perfusion SPECT (MPS), defining its safety and efficacy to raise HR to adequate levels as well as its effect on MPS interpretation.Between January 2002 and December 2004, we studied 3,150 consecutive patients (2,253 men and 897 women, mean age 55 +/- 6 years) who were referred to a single office-based nuclear cardiology laboratory for MPS using …