The low-oxygen regions of the world’s oceans have been shown to be major sources of nitrous oxide, a trace gas in the atmosphere that contributes to both greenhouse warming and the destruction of stratospheric ozone. Nitrous oxide can be produced as a by-product of nitrification or an intermediate of denitrification; low oxygen conditions enhance the yield of nitrous oxide from both pathways. W...

The nos (nitrous oxide reductase) operon of Paracoccus denitrificans contains a nosX gene homologous to those found in the nos operons of other denitrifiers. NosX is also homologous to NirX, which is so far unique to P. denitrificans. Single mutations of these genes did not result in any apparent phenotype, but a double nosX nirX mutant was unable to reduce nitrous oxide. Promoter-lacZ assays a...

We have studied the effect of nitrous oxide on bispectral index (BIS), calculated from a bipolar encephalogram. Inhalation of 70% nitrous oxide resulted in loss of consciousness in all healthy volunteers (n = 10) but no change in BIS. Brief inhalation up to 1.2% sevoflurane also resulted in loss of consciousness in volunteers (n = 5), but with sevoflurane, BIS decreased. BIS and the haemodynami...

We have examined the role of benzodiazepine receptors in nitrous oxide-induced neuronal depression in rats. The changes in neuronal excitability induced by nitrous oxide and the benzodiazepine inverse agonist, Ro15-4513, were monitored by measurement of visual evoked potentials (VEP). Administration of Ro15-4513 10 mg kg-1 i.p., in rats breathing air, did not affect the amplitude or latency of ...

Nitrous oxide pollution is common in paediatric anaesthetic practice. A questionnaire was sent to all UK members of the Association of Paediatric Anaesthetists requesting details of three areas of their paediatric practice relating to nitrous oxide: attitudes to its use; current usage; and availability of alternatives. Replies were received from 296 (68%) consultants. Of these, 169 (57%) stated...

OBJECTIVES Switching from maintenance of general anesthesia with an ether anesthetic to maintenance with high-dose (concentration >50% and total gas flow rate >4 liters per minute) nitrous oxide is a common practice used to facilitate emergence from general anesthesia. The transition from the ether anesthetic to nitrous oxide is associated with a switch in the putative mechanisms and sites of a...

BACKGROUND Nitrous oxide, in a concentration of 50% or more, is a known cerebral vasodilator. This study investigated whether a lower dose (30%) of nitrous oxide would also increase cerebral blood flow. In addition, the authors wished to study whether the increase in cerebral blood flow was accompanied by an increase in cerebral metabolism. METHODS Multimodal Magnetic Resonance Imaging at 3T ...

BACKGROUND The mechanisms by which general anesthetics, including xenon and nitrous oxide, act are only beginning to be discovered. However, structural approaches revealed weak but specific protein-gas interactions. METHODS To improve knowledge, we performed x-ray crystallography studies under xenon and nitrous oxide pressure in a series of 10 binding sites within four proteins. RESULTS Wha...

We analysed the nitrous oxide composition of the intraocular gas bubble following vitrectomy and fluid-air exchange in 12 patients. Samples were taken under standardised conditions at 20 minutes after completion of the fluid-air exchange. Analysis was conducted by a Medishield MS2 mass spectrometer. The percentage composition of nitrous oxide in the samples varied between 4 and 21% (mean 9%). T...

1258 June 2013 NITROUS oxide has long been known to be an impotent and unpredictable human anesthetic.1 In this issue of the journal, Chen et al.2 report that nitrous oxide in clinical use is a potent and predictable human genotoxin. The authors observe that maintenance of anesthesia with 70% nitrous oxide and sevoflurane in patients undergoing colorectal surgery doubles the incidence of DNA da...