Search PubMed⌕ Search

Biomedical subjects

B Orser

Publications and source records attributed to B Orser.

18 recordsLinked to original sources
PubMed1997

Magnesium deficiency increases ketamine sensitivity in rats.

PURPOSE: Inhibition of the NMDA receptor likely contributes to ketamine's neurodepressive properties. Magnesium also inhibits the NMDA receptor by binding to a site associated with the ketamine-binding domain. Electrophysiological studies suggest that magnesium prevents ketamine from binding to the NMDA receptor and thereby prevents ketamine inhibition. We undertook an in vivo study to determine if magnesium deficiency was associated with an increased sensitivity to ketamine. METHODS: Weanling rats were maintained on a Mg(2+)-deficient or control diet for 14 days. In Study I, rats were anaesthetized then sacrificed and the Mg2+ concentrations in the brain and plasma were measured. In a second prospective study, experimental animals were rendered hypomagnesaemic and the potency of 125 mg.kg-1 ip ketamine was evaluated. Animals were then were fed a Mg(2+)-containing diet and ketamine sensitivity was re-examined 14 days later. RESULTS: The Mg(2+)-deficient diets rendered the rats hypomagnesaemic as indicated by the brain and plasma concentration of Mg2+. In Study 2, the time to loss of righting reflex was shorter; 1.9 +/- 0.3 min (n = 12) and 2.6 +/- 0.2 min (n = 16, P < 0.05), whereas the latency to toe pinch was prolonged: 25.0 +/- 5.8 min (n = 12) vs 3.1 +/- 2.1 min (n = 16, P < 0.05) in the Mg(2+)-deficient compared with age-matched control animals, respectively. The hypomagnesaemic animals had a higher death rate following ketamine injection. The increased sensitivity to ketamine was no longer apparent when the animals were re-tested following replenishment of Mg2+. CONCLUSION: Hypomagnesaemia is associated with an increased sensitivity to ketamine.

Anesthetics, Dissociative↗
PubMed1994

Propofol and thiopental anesthesia: a comparison of the incidence of dreams and perioperative mood alterations.

The purpose of this study was to investigate perioperative mood profiles and the incidence of dreams in patients receiving anesthesia with either propofol (n = 29) or thiopental (n = 27) in combination with nitrous oxide. The study was a prospective, randomized, and double-blind investigation of female patients undergoing outpatient dilation and curettage. Recall of dreams was assessed 1 h postoperatively and the following day by using a questionnaire designed for surgical patients. Mood profiles were quantified using the Multiple Affect Adjective Check List-Revised (MAACL-R), a self-administered questionnaire which was completed preoperatively and 1 h postoperatively. Our results indicate that postoperatively, all patients were significantly less anxious than preoperatively (P < 0.0001). In the postoperative period, patients receiving propofol exhibited sensation-seeking tendencies (i.e., active, adventurous, aggressive, daring, energetic, enthusiastic, merry) when compared to the thiopental patients (P < 0.02). The incidence of dreams was small and equal in both groups. We conclude that patients anesthetized with propofol and nitrous oxide, as compared to patients anesthetized with thiopental and nitrous oxide, were more likely to demonstrate adventurous tendencies in the postoperative period.

Adult↗
PubMed1991

Influence of gestational age on potential difference across fetal type II alveolar epithelium in alveolar-like structures.

The active transport of ions across fetal pulmonary epithelium results in lung fluid secretion. This study investigated the potential difference (PD) across fetal type II alveolar epithelium, one of the several epithelial cell types in the fetal lung. Aggregates of these cells in alveolar-like structures (ALS) underwent microelectrode impalement to determine the effect of gestational age, and drugs on transcellular PD. In 6 ALS, the intraluminal position of the electrode was confirmed by fluorescent imaging after iontophoretic injection of Lucifer Yellow VS dye. The average PD recorded from the lumens of ALS harvested from 20-day fetal rats was 11.8 +/- (SE) 0.48 mV (lumen-negative; n = 164). Exposure to ouabain 10(-3) M significantly reduced PD from control values of 12.3 +/- (SE) 0.87 to 8.1 +/- (SE) 0.95 mV (p less than 0.01, n = 107) in ALS obtained from 20-day fetal rats. Terbutaline 10(-3) M and furosemide 10(-3) M did not influence PD. Cells obtained from fetuses near term showed a significant reduction in PD. ALS from 18-day (n = 53), 20-day (n = 164) and 22-day (n = 56) fetuses measured 13.5 +/- 0.62, 11.8 +/- 0.48 and 9.3 +/- 0.49 mV, respectively (p less than 0.05 day 18 vs. day 22). These results demonstrate that fetal type II cells grown in organotypic culture maintain a larger transcellular electrical gradient than previously reported. PD decreases with increasing gestational age and can be reduced by the Na-K ATPase inhibitor ouabain.

Animals↗
PubMed1988

Obstetrical epidural anaesthesia in a Canadian outpost hospital.

The number of parturients receiving epidural anaesthesia in university medical centres is increasing. This trend is not paralleled in rural hospitals. Obstetrical epidural anaesthesia as provided in a 40-bed, remote hospital is reviewed for the ten-year period from January 1974 to December 1983. Charts were reviewed retrospectively for 116 patients undergoing epidural blockade. The indications, complication rates, as well as infant outcomes were noted. Seven per cent of all parturients received epidural anaesthetics. Ninety per cent of this group received systemic sedation or narcotics prior to epidural catheter insertion. Nineteen patients (16.3 per cent) experienced a major complication, including four dural punctures (3.4 per cent), ten episodes of significant hypotension (8.6 per cent), blood vessel puncture during catheter insertion in four patients (3.4 per cent), and transient paresthesia in one patient (0.8 per cent). Considerations for the provision of epidural anaesthesia in a remote hospital are discussed.

Anesthesia, Epidural↗
PubMed1988

Blood lead and blood pressure: analysis of cross-sectional and longitudinal data from Canada.

Analysis of data collected during the Canada Health Survey of 1978-1979 indicated a positive relationship between blood lead and blood pressure, but so weak that the range of lead-related variation among members of the general public was estimated to be at most 3.0 mm Hg of diastolic pressure. Even so, a blood lead level in excess of the median value of 10 micrograms/dL entailed a 37% higher risk of having diastolic pressure above 90 mm Hg. In a longitudinal study of lead foundry workers, an association was found between short-term changes in an individual's blood lead level and contemporary changes in diastolic pressure; this remained significant after allowance for age (or time) trends and for effects attributable to changes in body weight. Short-term changes in urinary cadmium levels were similarly predictive of diastolic pressure.

Adult↗
PubMed1983

Hematology quality control and the Coulter S-Plus II.

Establishing thorough maintenance and operational protocols for multichannel hematology instruments is an integral part of any QC program. Implementing appropriate collection techniques and properly informing the technical staff about all protocols are equally important. Selecting standards and/or controls for use on the multichannel instruments frequently presents difficulty. However, fresh WB samples (EDTA, 1 mg/ml) can be used to calibrate the instruments periodically. Additionally, data from the Coulter S-Plus II print-out of WB patient samples can be statistically evaluated using R and/or XB statistics to monitor instrument performance.

Calibration↗