Acute gastrointestinal haemorrhage on board a cruise ship in the Antarctic Peninsula.

Antarctic tourism on board cruise ships has expanded since the 1990s, essentially in the Antarctic Peninsula. Due to remoteness, medical cases may evolve into life threatening conditions as emergency medical evacuations are challenging. We discuss the case of a young crew member who suddenly fainted with an epigastric pain and abundant rectal bleeding while on board a cruise ship heading to the Deception Island (62°57.6 South, 60°29.5 West), 44 h away from Ushuaia by sea. A medical evacuation was necessary to save the patient whose haemoglobin level rapidly decreased from 11 g/dL to 8.7 g/dL over an 8 h period due to uncontrolled gastrointestinal bleeding. Following discussions between the French, Chilean and Argentinean Medical Top Side Support and Maritime Rescue Authorities and despite poor weather conditions, an emergency medical evacuation by air to Chile was made possible. The evacuation, which was 2 days shorter compared to an evacuation by sea, allowed the patient to reach a hospital facility in time to save his life whereas he decompensated in haemorrhagic shock. As passengers on cruise ships are typically elderly and often following anticoagulant therapies, the risk of bleeding is most important. Facing a gastric haemorrhage, a transfusion is often required. In remote areas, transfusion of fresh whole blood to stabilize a critical patient until he reaches a hospital must be considered.

Bleeding management in remote environment: the use of fresh whole blood transfusion and lyophilised plasma.

To mitigate medical risks in remote environments, the authors have implemented an innovative integrated medical support solution for bleeding management on board ships since 2013. Fresh whole blood transfusion (FWBT) and lyophilised plasma were put in place to address life threatening haemorrhages in maritime operations in the Arctic and Antarctica. The authors are illustrating the bleeding risks with an actual case occurring in Antarctica prior to the implementation of these procedures. They are presenting the different steps involved in the complex process of FWBT, from blood donors' qualifications to actual transfusions. The pros and cons of blood transfusion in extreme remote environment are discussed, including the training of health care professionals, equipment requirements, legal and ethical issues, decision making in complex blood group matching, medical benefits and risks.

Environmental control and adrenergic regulation of pineal activity in the diurnal tropical rodent, Arvicanthis ansorgei.

Like nocturnal rodents, the diurnal tropical rodent Arvicanthis ansorgei shows a daily rhythm in pineal melatonin content. Seasonal and photoperiodic variations in the biosynthetic activity of the pineal gland: arylalkylamine-N-acetyltransferase (AA-NAT), hydroxyindole-O-methyltransferase (HIOMT) activities and melatonin content were measured in male and female A. ansorgei captured near Samaya, Mali, and kept either under artificial laboratory photoperiods [light-dark (LD) cycles: LD 14:10, LD 12:12 or LD 10:14 or caught in the field in Mali and killed at four different times of the year (January, April, June and November). Under artificial photoperiod, the duration of the nocturnal peak of AA-NAT activity and melatonin content increased with the duration of the dark period while the amplitude did not significantly change. In the field, annual variations in the amplitude of the nocturnal melatonin peak were observed with a maximum in April (highest temperature, low humidity and no grass availability, only seeds) and a minimum in November (high humidity, maximum green grass availability). The variations in the amplitude of the melatonin peak were not correlated with changes in AA-NAT HIOMT activities, suggesting that seasonal variations in the amplitude of the melatonin peak are not driven by these enzymes. Daytime injections of the beta-adrenergic agonist, isoproterenol, stimulated melatonin synthesis in January, April and June, but not in November. The annual differences in the amplitude of the melatonin peak as well as the seasonal differences in the response to an adrenergic stimulation suggest that environmental factors other than photoperiod, such as temperature, humidity and consequent food availability, could be important in the regulation of the annual variations in the pineal biosynthetic activity in this species.

Autosome and sex chromosome diversity among the African pygmy mice, subgenus Nannomys (Murinae; Mus).

The African pygmy mice, subgenus Nannomys, constitute the most speciose lineage of the genus Mus with 19 recognized species. Although morphologically very similar, they exhibit considerable chromosomal diversity which is here confirmed and extended by the G-banding analysis of 65 mice from West and South Africa. On the basis of their karyotype and distribution area, the specimens were assigned to at least five species. Extensive differentiation both within and between species was observed that involved almost exclusively Robertsonian translocations, 23 of which are newly described. Two of the rearrangements were sex chromosome-autosome translocations, associated in some cases with partial deletions of the X or Y chromosomes. Several authors have predicted that the highly deleterious effect of this rearrangement would be reduced if the sex and autosomal segments were insulated by a block of centromeric heterochromatin. The C-banding analyses performed showed that among the species carrying X-autosome translocations, one followed the expected pattern, while the other did not. In this case, functional isolation of the sex and autosome compartments must involve other repetitive sequences or genomic traits that require further molecular characterization. Such studies will provide insight into the causes and consequences of the high diversity of sex chromosome rearrangements in this subgenus.

Temporal organization of the 24-h corticosterone rhythm in the diurnal murid rodent Arvicanthis ansorgei Thomas 1910.

Arvicanthis ansorgei is a diurnal murid rodent from sub-Saharan Africa. The present study reports on the temporal organization of one of the major hormonal rhythms, i.e. the adrenal steroid hormone corticosterone, in an attempt to characterize further the diurnal nature of this species. The data were obtained by means of two different physiological methods: blood sampling and intracerebral microdialysis. The results show a 12-h rhythm of corticosterone release with peak values close to the light-dark (ZT10) and dark-light transition (ZT22-24), which is clearly different from that in a nocturnal animal. Both corticosterone peaks are closely correlated with the occurrence of two major bouts of running wheel activity. As far as we are aware, this is the first demonstration of a hormonal rhythm with a clear crepuscular appearance (peak values around dusk and dawn). In conclusion, these data show that also in a rodent with a diurnal/crepuscular activity pattern, the tight association between the daily corticosterone peak and the onset of activity is maintained. In addition, intracerebral microdialysis is a suitable technique to measure hormonal rhythms when repeated blood sampling is not possible.

Risk propensity in commercial and military pilots.

BACKGROUND: Flight safety is dependent on the quality of the decision-making process, which is closely related to risk taking. The purpose of this descriptive study was to evaluate risk propensity among commercial and military pilots. HYPOTHESIS: Since commercial and military flights are conducted in different environments with different safety policies, our hypothesis was that risk propensity levels observed in these different settings will not be the same. METHODS: We tested 96 French pilots, 63 who were flying commercial aircraft (mean age 43 yr) and 33 serving in military aviation (mean age 33 yr), with the Evaluation of Risk (EVAR) visual analog scale, designed to rate risk proneness, and the Barrat impulsiveness scale. EVAR is composed of 24 items distributed among 5 factors: "self-control," "danger-seeking," "energy," "impulsiveness," and "invincibility." RESULTS: We observed significantly higher scores in all EVAR factors except "impulsiveness" in military pilots compared with commercial pilots. This different risk profile was corroborated by Barrat scores and was not explained by the significant age difference. CONCLUSIONS: The observed difference in risk propensity cannot be explained by this descriptive study. A prospective evaluation of risk proneness beginning with the selection process and continuing through training and military and commercial flying is necessary to assess how a risk proneness profile is determined.

Daily infusion of melatonin entrains circadian activity rhythms in the diurnal rodent Arvicanthis ansorgei.

The effect of exogenous melatonin (MEL) on the circadian system in nocturnal species has been extensively studied, but little is known about its chronobiotic effect in diurnal mammals. The present study investigated the effect of exogenous MEL on the circadian locomotor activity rhythm in the diurnal rodent Arvicanthis ansorgei. Male animals (n=34) were fitted with a subcutaneous catheter for daily infusion of MEL (1 h; 100 microg) and their running wheel activity was recorded. The results showed that administration of MEL to animals free-running in DD entrained their activity rhythm by phase advances at circadian time (CT) 10.62, and by phase delays at CT -0.40 (CT 0, activity onset). The range of entrainment was 17 and 11.5 min for advance and delay stimuli, respectively. Interestingly, in the nocturnal rat and the A. ansorgei, entrainment of the activity rhythm to exogenous MEL by phase advances occurs at exactly the same phase of the circadian cycle. In both nocturnal and diurnal species, the sensitivity window for exogenous MEL is located near the activity/rest transition points. It is concluded that the functional properties of entrainment to exogenous MEL are similar to those of other nonphotic stimuli. Furthermore, A. ansorgei might be an interesting animal model for studies on the chronobiotic effects of exogenous MEL in diurnal mammals including humans.

Pineal arylalkylamine N-acetyltransferase gene expression is highly stimulated at night in the diurnal rodent, Arvicanthis ansorgei.

The different mechanisms underlying the control of diurnal vs. nocturnal activity are still unknown. Regarding the nocturnal synthesis of the pineal hormone, melatonin, experiments performed on diurnal sheep or bovine and on nocturnal rat or hamster revealed important differences in the regulation of the melatonin rate-limiting enzyme, arylalkylamine N-acetyltransferase (AA-NAT). These observations raised the hypothesis that melatonin synthesis may be different in nocturnal vs. diurnal animals. In this study, we cloned the cDNA coding for Aa-nat and analysed the mechanisms of AA-NAT enzyme activation in the pineal gland of the diurnal grass rat, Arvicanthis ansorgei, and compared them to those of the nocturnal Wistar rat, Rattus norvegicus. Aa-nat gene sequences of both species are 86.6% identical. In Arvicanthis, Aa-nat gene expression is markedly increased at the beginning of the night and is followed by a large increase in AA-NAT activity and melatonin content. In contrast, at the end of the night, the decrease in AA-NAT activity and melatonin content precedes that of Aa-nat mRNA. A beta-adrenergic agonist given at daytime reproduces the nocturnal activation of melatonin synthesis, whereas, a beta-adrenergic antagonist given at night-time inhibits AA-NAT activity and melatonin synthesis independently of Aa-nat mRNA. The day-night regulation of melatonin synthesis in the pineal of the diurnal Arvicanthis, involving a transcriptional activation in early night and a post-translational inhibition at late night, is very similar to that of the nocturnal Wistar rat. In conclusion, the fundamental differences underlying melatonin synthesis among species rely upon phylogenetic rather than behavioural differences.

Circadian organization in a diurnal rodent, Arvicanthis ansorgei Thomas 1910: chronotypes, responses to constant lighting conditions, and photoperiodic changes.

Little information is available on circadian organization in diurnal mammals. In the present study, the daily patterns of wheel-running activity were described in a diurnal rodent, Arvicanthis ansorgei Thomas 1910, as assessed by karyological analysis. Among 108 animals born in the colony and studied under a 12:12 light-dark cycle (lights on at 7:00 a.m.), the authors determined the timing of daily activity (i.e., mean onsets and offsets of pattern of locomotor activity) and the level of wheel-running activity performed during daytime versus nighttime. The activity pattern was essentially diurnal in 84% of individuals, 46% being active only during the light period +/- 1 h (activity onsets and offsets at 6:20 a.m. and 7:40 p.m., respectively) and 38% being diurnal with a period of nocturnal activity longer than 1 h (activity onsets and offsets at 5:40 a.m. and 9:30 p.m., respectively). Of the 108 animals, 16% expressed a nocturnal activity with diurnal overlaps no longer than 1 h. In 6 diurnal individuals first exposed to constant light and then to constant dim red light, the endogenous period was shortened from 24.6 +/- 0.1 to 24.0 +/- 0.1 h, respectively. The numbers of wheel revolutions per day and during the active period remained unchanged between the two lighting conditions. In response to different photoperiodic changes from 16:08 to 08:16 light-dark cycles, the phase angle of photic synchronization, estimated by the daily onset of wheel-running activity in 6 diurnal animals, showed marked changes, its timing occurring 2 h before and 0.5 h after the onset of light under short and long photoperiods, respectively. The numbers of wheel revolutions per 24 h and during the active period were modified similarly according to photoperiodic changes. Finally, in 5 diurnal animals exposed to a 12:12 light-dark cycle, the daily pattern of general locomotor activity, determined by telemetry, was not modified by wheel availability. The data indicate that A. ansorgei is an interesting experimental model to understand the regulation of the circadian timing system in day-active species.