Genetic variation in haemoglobin is associated with evolved changes in breathing in high-altitude deer mice

Physiological systems often have emergent properties but the effects of genetic variation on physiology are often unknown, which presents a major challenge to understanding the mechanisms of phenotypic evolution. We investigated whether genetic variants in haemoglobin (Hb) that contribute to high-altitude adaptation in deer mice (Peromyscus maniculatus) are associated with evolved changes in control of breathing. We created F2 inter-population hybrids of highland and lowland deer mice to test for phenotypic associations of α- and β-globin variants on a mixed genetic background. Hb genotype had expected effects on Hb-O2 affinity that were associated with differences in arterial O2 saturation in hypoxia. However, high-altitude genotypes were also associated with breathing phenotypes that should contribute to enhancing O2 uptake in hypoxia. Mice with highland α-globin exhibited a more effective breathing pattern, with highland homozygotes breathing deeper but less frequently across a range of inspired O2, and this difference was comparable to the evolved changes in breathing pattern in deer mouse populations native to high altitude. The ventilatory response to hypoxia was augmented in mice that were homozygous for highland β-globin. The association of globin variants with variation in breathing phenotypes could not be recapitulated by acute manipulations of Hb-O2 affinity, because treatment with efaproxiral (a synthetic drug that acutely reduces Hb-O2 affinity) had no effect on breathing in normoxia or hypoxia. Therefore, adaptive variation in haemoglobin may have unexpected effects on physiology in addition to the canonical function of this protein in circulatory O2 transport.

Protective Face Masks: Effect on the Oxygenation and Heart Rate Status of Oral Surgeons during Surgery

Background: Safety in medical work requires eye protection, such as glasses, and protective facial masks (PFM) during clinical practice to prevent viral respiratory infections. The use of facial masks and other full personal protective equipment increases air flow resistance, facial skin temperature and physical discomfort. The aim of the present study was to measure surgeons’ oxygenation status and discomfort before and after their daily routine activities of oral interventions. Methods: 10 male voluntary dentists, specializing in oral surgery, and 10 male voluntary doctors in dentistry, participating in master’s courses in oral surgery in the Department of Oral Surgery of the University of Chieti, with mean age 29 ± 6 (27–35), were enrolled. This study was undertaken to investigate the effects of wearing a PFM on oxygenation status while the oral surgeons were actively working. Disposable sterile one-way surgical paper masks (Surgical Face Mask, Euronda, Italy) and FFP2 (Surgical Face Mask, Euronda, Italy) were used and the mask position covering the nose did not vary during the procedures. The FFP2 was covered by a surgical mask during surgical treatment. A pulse oximeter was used to measure the blood oximetry saturation during the study. Results: In all 20 surgeons wearing FFP2 covered by surgical masks, a reduction in arterial O2 saturation from around 97.5% before surgery to 94% after surgery was recorded with increase of heart rates. A shortness of breath and light-headedness/headaches were also noted. Conclusions: In conclusion, wearing an FFP2 covered by a surgical mask induces a reduction in circulating O2 concentrations without clinical relevance, while an increase of heart frequency and a sensation of shortness of breath, light-headedness/headaches were recorded.

Comparisons of tramadol with pethidine for prevention of post anaesthetic shivering in elective abdominal surgery

Background: Postoperative shivering is a common event of unknown etiology. Objectives: To compare the efficiency of tramadol with that of pethidine in controlling post anaesthetic shivering. Methods: This double . blind randomized clinical trial was performed on 120 consecutive patients who received general anaesthesia for elective abdominal surgery. Intravenous tramadol (1mg.kg-1) or pethidine (0.5mg.kg-1) was administered to alternate subjects who developed post anaestheic shivering. They were monitored in the recovery room for 1 hour and the cessation time of shivering, recurrence of the events, duration of recovery, respiratory depression, arterial O2 saturation, nausea and vomiting were recorded. Results: Forty-eight patients (40%) had post anaesthetic shivering. In the tramadol group, shivering terminated within 5 minutes after injection. They had no recurrence of shivering, respiratory depression, reduction in SPO2, nausea and vomiting during the period of recovery. In the pethidine group, shivering terminated within 8 minutes after injection, but in 7 patients it recurred after 30 minutes. Similarly, 6 patients had respiratory depression, reduction in SPO2 and 10 patients had nausea, vomiting but none of them needed further medication. Conclusion: Tramadol is superior to pethidine as it induces a faster termination of post anaesthetic shivering and does not entail adverse effects on the respiratory system. DOI: http://dx.doi.org/10.3126/hren.v10i3.7139 Health Renaissance; September-December 2012; Vol 10 (No.3);220-223