Search results for "Methyl Ether"

Probing the low-temperature chemistry of ethanol via the addition of dimethyl ether

2018

Considering the importance of ethanol (EtOH) as an engine fuel and a key component of surrogate fuels, the further understanding of its auto-ignition and oxidation characteristics at engine-relevant conditions (high pressures and low temperatures) is still necessary. However, it remains difficult to measure ignition delay times for ethanol at temperatures below 850 K with currently available facilities including shock tube and rapid compression machine due to its low reactivity. Considering the success of our recent study of toluene oxidation under similar conditions [38], dimethyl ether (DME) has been selected as a radical initiator to explore the low-temperature reactivity of ethanol. In …

ChemInform Abstract: A High-Yielding Modular Access to the Lamellarins: Synthesis of Lamellarin G Trimethyl Ether (Ia), Lamellarin η (II) and Dihydro…

2014

Comparison of the brainstem auditory evoked responses during sevoflurane or alfaxalone anaesthesia in adult cats.

2017

Abstract Objective To compare the effects of general anaesthesia using sevoflurane or alfaxalone on the brainstem auditory evoked response (BAER) test in adult healthy cats. Study design Prospective, clinical, ‘blinded’, crossover study. Animals Ten feral adult healthy cats. Methods Premedication consisted of dexmedetomidine (0.01 mg kg –1 ) intramuscularly (IM). The first general anaesthesia was induced and maintained with sevoflurane (treatment S) for physical examination, BAER test, complete blood tests, thoracic radiographs and abdominal ultrasound. The second general anaesthesia was induced with alfaxalone (treatment A) IM (2 mg kg –1 ) and maintained with alfaxalone (10 mg kg –1 hour …

Does general anesthesia have a clinical impact on intraocular pressure in children?

2016

Summary Background Reliable measurement of intraocular pressure (IOP) is crucial in pediatric patients with suspected glaucoma. General anesthesia (GA) is usually needed in infants to allow a thorough examination. However, anesthesia itself may influence IOP, depending on the type used and the depth of sedation. The purpose of this study was to evaluate the normal distribution of IOP during GA in healthy children and to analyze differences in IOP relative to the anesthetics used and the measurement time point. Methods Approval for this observational study was received from the local institutional review boards and written informed consent was obtained from the children's parents. A total of…

Sevoflurane affects neurogenesis after forebrain ischemia in rats.

2007

BACKGROUND: The effect of sevoflurane on the neuroregenerative potential after neuronal injury is unclear. We investigated the effect of low and high concentrations of sevoflurane on endogenous neurogenesis after cerebral ischemia. METHODS: Anesthetized and ventilated rats were randomized to four different treatment groups. Groups 1 and 2: 1.4% sevoflurane; Groups 3 and 4: 2.8% sevoflurane. In Groups 1 and 3, no cerebral ischemia was induced (sham-operated). In Groups 2 and 4, 10 min of forebrain ischemia was induced by bilateral carotid artery occlusion plus hemorrhagic hypotension. Physiological variables were maintained constant. Bromodeoxyuridine was given as a marker of neurogenesis. A…

Effects of sevoflurane on cognitive deficit, motor function, and histopathology after cerebral ischemia in rats.

2009

Background: The volatile anesthetic sevoflurane exhibits neuroprotective properties when assessed for motor function and histopathology after cerebral ischemia in rats. Damage of hippocampal neurons after ischemia relates to a number of cognitive deficits that are not revealed by testing animals for motor function. Therefore, the present study evaluates cognitive and behavioral function as well as hippocampal damage in rats subjected to cerebral ischemia under sevoflurane compared with fentanyl/nitrous oxide (N 2 O)/O 2 anesthesia. Methods: Thirty-four rats were trained for 10 days using a hole-board test to detect changes in cognitive and behavioral function. Rats were randomly assigned to…

Low-Flow Desflurane and Sevoflurane Anesthesia Minimally Affect Hepatic Integrity and Function in Elderly Patients: Retracted

2000

UNLABELLED Hepatic blood flow is reduced in a dose-related manner by all inhaled anesthetics now in use. We assessed hepatic function in elderly patients anesthetized with desflurane or sevoflurane. We measured the cytosolic liver enzyme alpha glutathione S-transferase (alpha GST), the formation of the lidocaine metabolite monoethylglycinexylidide (MEGX), and gastric mucosal tonometry-derived variables as sensitive markers of hepatic function and splanchnic perfusion. Thirty patients, 70 to 90 yr old, were allocated randomly to receive desflurane or sevoflurane anesthesia. Anesthetic exposure ranged from 2.1-4.5 minimum alveolar concentration hours. No significant changes in standard liver …

Impact of inhalation vs. intravenous anaesthesia on autonomic nerves and internal anal sphincter tone.

2014

Background Pelvic intraoperative neuromonitoring (pIONM) aims to identify and spare the autonomic nerves and maintain patients’ quality of life. The effect of anaesthetic agents on the pIONM signal is unknown; therefore, the aim of the present study was to compare the influences of inhalation anaesthesia (IA) and total intravenous anaesthesia (TIVA). Methods Twenty rectal cancer patients undergoing open nerve-sparing total mesorectal excision (TME) were assigned to pIONM under either IA or TIVA (n = 10 per group). IA was maintained with sevoflurane and TIVA with propofol. During surgery, pelvic autonomic nerves were electrically stimulated under electromyography (EMG) of the internal anal s…

Putative role of nitric oxide synthase isoforms in the changes of nitric oxide concentration in rat brain cortex and cerebellum following sevoflurane…

2005

We have previously observed an increase in nitric oxide (NO) content in rat brain cortex following halothane, sevoflurane or isoflurane anaesthesia. This study was undertaken in order to determine whether isoform-specific nitric oxide synthase (NOS) inhibitors and inducers could modify these increases in NO contents. Rats were subjected to isoflurane and sevoflurane anaesthesia with concomitant administration of neuronal nitric oxide synthase (nNOS) inhibitor 7-Nitro-indazole (7-NI), inducible nitric oxide synthase (iNOS) inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) or lipopolysaccharide. NO concentration in different organs was measured by electron paramagnetic resonance (E…

The Long-Term Effect of Sevoflurane on Neuronal Cell Damage and Expression of Apoptotic Factors After Cerebral Ischemia and Reperfusion in Rats

2006

We investigated the long-term effects of sevoflurane on histopathologic injury and key proteins of apoptosis in a rat hemispheric ischemia/reperfusion model. Sixty-four male Sprague-Dawley rats were randomly assigned to Group 1 (fentanyl and N2O/O2; control) and Group 2 (2.0 vol% sevoflurane and O2/air). Ischemia (45 min) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension (mean arterial blood pressure 40 mm Hg). Animals were killed after 1, 3, 7, and 28 days. In hematoxylin and eosin-stained brain sections eosinophilic hippocampal neurons were counted. Activated caspase-3 and the apoptosis-regulating proteins Bax, Bcl-2, Mdm-2, and p53 were analyzed by i…