Biology of the sauropod dinosaurs: the evolution of gigantism

The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism. We review the biology of sauropod dinosaurs in detail and posit that sauropod gigantism was made possible by a specific combination of plesiomorphic characters (phylogenetic heritage) and evolutionary innovations at different levels which triggered a remarkable evolutionary cascade. Of these key innovations, the most important probably was the very long neck, the most conspicuous feature of the sauropod bauplan. Compared to other herbivores, the long neck allowed more efficient food uptake than in other large herbivores by covering a much larger feeding envelope and making food accessible that was out of the reach of other herbivores. Sauropods thus must have been able to take up more energy from their environment than other herbivores. The long neck, in turn, could only evolve because of the small head and the extensive pneumatization of the sauropod axial skeleton, lightening the neck. The small head was possible because food was ingested without mastication. Both mastication and a gastric mill would have limited food uptake rate. Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates. The extensive pneumatization of the axial skeleton resulted from the evolution of an avian-style respiratory system, presumably at the base of Saurischia. An avian-style respiratory system would also have lowered the cost of breathing, reduced specific gravity, and may have been important in removing excess body heat. Another crucial innovation inherited from basal dinosaurs was a high BMR. This is required for fueling the high growth rate necessary for a multi-tonne animal to survive to reproductive maturity. The retention of the plesiomorphic oviparous mode of reproduction appears to have been critical as well, allowing much faster population recovery than in megaherbivore mammals. Sauropods produced numerous but small offspring each season while land mammals show a negative correlation of reproductive output to body size. This permitted lower population densities in sauropods than in megaherbivore mammals but larger individuals. Our work on sauropod dinosaurs thus informs us about evolutionary limits to body size in other groups of herbivorous terrestrial tetrapods. Ectothermic reptiles are strongly limited by their low BMR, remaining small. Mammals are limited by their extensive mastication and their vivipary, while ornithsichian dinosaurs were only limited by their extensive mastication, having greater average body sizes than mammals.

Allometry of visceral organs in living amniotes and its implications for sauropod dinosaurs

Allometric equations are often used to extrapolate traits in animals for which only body mass estimates are known, such as dinosaurs. One important decision can be whether these equations should be based on mammal, bird or reptile data. To address whether this choice will have a relevant influence on reconstructions, we compared allometric equations for birds and mammals from the literature to those for reptiles derived from both published and hitherto unpublished data. Organs studied included the heart, kidneys, liver and gut, as well as gut contents. While the available data indicate that gut content mass does not differ between the clades, the organ masses for reptiles are generally lower than those for mammals and birds. In particular, gut tissue mass is significantly lower in reptiles. When applying the results in the reconstruction of a sauropod dinosaur, the estimated volume of the coelomic cavity greatly exceeds the estimated volume of the combined organ masses, irrespective of the allometric equation used. Therefore, substantial deviation of sauropod organ allometry from that of the extant vertebrates can be allowed conceptually. Extrapolations of retention times from estimated gut contents mass and food intake do not suggest digestive constraints on sauropod dinosaur body size.

Traveller's thrombosis: international consensus statement

In 2001, consensus meetings on traveller's thrombosis were held in Vienna and Berlin. The results of these conferences were subsequently published in VASA 2002. In 2006 a follow-up conference was organized in Hall, Tirol, Austria, in order to review new and emerging data and to update the conclusions and recommendations of the 2001 meetings. Prior to the conference key papers from peer-reviewed journals were pre-circulated to all participants. The consensus group discussed the data and drafted an updated statement. Thereafter, the writing group summarised the results including the pre-circulated material and additional papers identified by a formal literature search up to December 2007. In this article current knowledge on the incidence, pathophysiology and prevention of traveller's thrombosis is summarised. The assessment of individual risk is described and recommendations for prevention of traveller's thrombosis are given, based upon the conclusions of the Hall Conference.

Physical inactivity and cognitive functioning: results from bed rest studies

In addition to multiple health benefits, participation in physical activity can enhance cognitive functioning. Less clear is how reducing physical activity levels affects cognition, an issue potentially addressed by bed rest studies having included cognitive tests. Detailed and reviewed here are 17 such studies, featuring 251 subjects, bed rest for 7-70 days, and tests of cognition ranging from reaction time to executive functions. The reported effects of bed rest on cognitive performance vary considerably, from a generally expected worsening to an improvement. Practice effects could be implicated in the performance improvements, and reports of worsening are often of limited interpretability or the results were not replicated. Any cognitive effects of bed rest thus remain to be established. Detrimental effects could influence the in-progress plans for human spaceflights to Mars (simulated by bed rest), and have implications for medical conditions promoting inactivity and lifestyles that are largely sedentary.

Cardiac markers (BNP, NT-pro-BNP, Troponin I, Troponin T, in female amateur runners before and up until three days after a marathon

PURPOSE

Transient cardiac ventricular dysfunction or sudden cardiac deaths have been reported for male athletes participating in marathon racing. Less is known about the myocardial response in females. We examined natriuretic peptides and cardiac troponins in female athletes after a marathon.

METHODS

At the 31st real,- Berlin Marathon plasma levels of NT-pro-BNP, BNP, cTnI and cTnT were measured in 15 women (age 35+/-6 years; finishing times between 3:22 h and 5:21 h) at four different time points (before, immediately after, day one and day three).

RESULTS

An increase in [NT-pro-BNP] was observed immediately after the marathon (median [NT-pro-BNP] before: 39.6 pg ml(-1), after: 138.6 pg ml(-1), p=0.003) with a further increase on day one. [BNP] did not increase immediately after the marathon but increased on day one (median [BNP] before: 15 pg ml(-1), day one: 27.35 pg ml(-1), p=0.006). On day three, [NT-pro-BNP] and [BNP] returned to initial values. [cTnI] was under the detection limit prior to the marathon in all runners. [cTnT] was under the detection limit before the marathon except in one runner who presented a concentration of 0.03 ng ml(-1). Cardiac troponins (median [cTnl] after: 0.098 ng ml(-1), p=0.028; median [cTnT] after: 0.032 ng ml(-1), p=0.012) increased immediately after the marathon and returned to initial values on day one [cTnT] and three [cTnI].

DISCUSSION

Parameters representing cardiac stress increased in females after a marathon. Different kinetics of natriuretic peptides BNP and NT-pro-BNP post-marathon could be due to their different half-lives and dependence on renal function. The increase of cTnI and cTnT may result from minor myocardial lesions.

Changes in the haemostatic system after thermoneutral and hyperthermic water immersion

Warm water bathing is a popular recreational activity and is frequently used in rehabilitation medicine. Although well tolerated in most cases, there are reports indicating an increased risk of thrombotic events after hot tub bathing. The effects of a 45 min thermoneutral bath followed by a 50 min bath with increasing water temperature (maximum 41 degrees C) until reaching a body core temperature of 39 degrees C on factors of blood coagulation and fibrinolysis were studied in eight healthy male volunteers. Blood was obtained after a 45-min resting period as control and after the thermoneutral and hyperthermic bath as well as after another 45 min recovery period at the end of the study. Hyperthermic immersion (HI) lead to a shortening of activated partial thromboplastin time (aPTT) (P < 0.05). Fibrinogen concentration decreased immediately after HI (P < 0.05) but increased during recovery (P < 0.05). Plasminogen activator inhibitor (PAI) activity decreased during HI (P < 0.05), D-dimer concentration was not found to change. Thrombocyte count increased (P < 0.05) during HI. The increases in tissue-type plasminogen activator concentration as well as leucocyte count during HI were due to haemoconcentration. Prothrombin time, PAI-activity and granulocyte count decreased during thermoneutral immersion (P < 0.05). Warm water bathing leads to haemoconcentration and minimal activation of coagulation. The PAI-1 activity is decreased. A marked risk for thrombotic or bleeding complications during warm water bathing in healthy males could not be ascertained.

Body mass estimations for Plateosaurus engelhardti using laser scanning and 3D reconstruction methods

Both body mass and surface area are factors determining the essence of any living organism. This should also hold true for an extinct organism such as a dinosaur. The present report discusses the use of a new 3D laser scanner method to establish body masses and surface areas of an Asian elephant (Zoological Museum of Copenhagen, Denmark) and of Plateosaurus engelhardti, a prosauropod from the Upper Triassic, exhibited at the Paleontological Museum in Tübingen (Germany). This method was used to study the effect that slight changes in body shape had on body mass for P. engelhardti. It was established that body volumes varied between 0.79 m(3) (slim version) and 1.14 m(3) (robust version), resulting in a presumable body mass of 630 and 912 kg, respectively. The total body surface areas ranged between 8.8 and 10.2 m(2), of which, in both reconstructions of P. engelhardti, approximately 33% account for the thorax area alone. The main difference between the two models is in the tail and hind limb reconstruction. The tail of the slim version has a surface area of 1.98 m(2), whereas that of the robust version has a surface area of 2.73 m(2). The body volumes calculated for the slim version were as follows: head 0.006 m(3), neck 0.016 m(3), fore limbs 0.020 m(3), hind limbs 0.08 m(3), thoracic cavity 0.533 m(3), and tail 0.136 m(3). For the robust model, the following volumes were established: 0.01 m(3) head, neck 0.026 m(3), fore limbs 0.025 m(3), hind limbs 0.18 m(3), thoracic cavity 0.616 m(3), and finally, tail 0.28 m(3). Based on these body volumes, scaling equations were used to assess the size that the organs of this extinct dinosaur have.

Leg edema formation and venous blood flow velocity during a simulated long-haul flight

INTRODUCTION

Long-distance traveling in a sitting position may be associated with an increased incidence for venous thromboembolism. As major contributing factors immobility and compression of leg veins are discussed. At present no studies have been performed measuring the time course of lower limb blood flow, leg volume and leg tissue thickness during a long-haul flight.

MATERIALS AND METHODS

We measured limb volumes (plethysmographic method), lower leg tissue thickness and lower limb venous hemodynamics before, during and after 10 h sitting in modern aircraft chairs under normobaric hypoxia in healthy volunteers (n=12).

RESULTS

Lower leg volume was already significantly increased after 4 h sitting (+109 ml) reaching its maximum after 10 h (+145 ml). These changes were accompanied by an increased body weight, total body water, extracellular water and tissue thickness of the tibia. No significant changes were measured for leg vessel cross-section diameters and maximal flow velocities in superficial femoral veins. After 10 h sitting core temperature, overall surface temperature and skin temperatures in front of the tibia were significantly increased. All parameters returned to baseline one day after sitting.

CONCLUSIONS

Prolonged sitting in modern aircraft seats is associated with a remarkable fluid accumulation in the lower legs which mainly occurred during the first hours. These fluid shifts were independent of lower limb venous hemodynamics and vessel cross-sectional diameters.

Changes in blood coagulation of arm and leg veins during a simulated long-haul flight

INTRODUCTION

Long-haul flights are associated with an increased incidence for venous thromboembolic events. At present, markers of coagulation and fibrinolysis were only analyzed from arm veins after long distance travel. Respective data from leg veins are missing.

MATERIALS AND METHODS

Here, we measured these parameters in healthy volunteers (n=12) before and after 10 h sitting in modern aircraft chairs under normobaric hypoxia (corresponding to 2400 m altitude). Blood was collected from arm and leg veins before, immediately after and 1 day after sitting in the hypoxic chamber.

RESULTS

We did not find any evidence for a significant intravasal thrombin and fibrin formation and a changed fibrinolytic activity, neither in arm nor in leg vein blood. TAT, PAP, and PAI-1 remained unchanged, and the increases of F1+2 in arm veins and of d-dimer in leg veins were within the upper reference limits. Moreover, there was no evidence of activation of coagulation as measured by thrombelastography (ROTEM(R)) and the new Thrombin Dynamic Test at both locations. There was no evidence of arm or leg hemoconcentration.

CONCLUSIONS

In healthy volunteers, prolonged sitting in ergonomically superior aircraft seats does not induce significant changes in blood coagulation and fibrinolysis in venous blood of arm or leg. Since this study was performed under moderate hypoxia, reduction in oxygen pressure seems not to be a crucial factor for venous thrombosis at long-haul flights.

Water immersion is associated with an increase in aquaporin-2 excretion in healthy volunteers

Here, we report the alterations in renal water handling in healthy volunteers during a 6 h thermoneutral water immersion at 34 to 36 degrees C. We found that water immersion is associated with a reversible increase in total urinary AQP2 excretion.

Improvement of metabolic syndrome markers through altitude specific hiking vacations

To study the influence of a 3-week hiking vacation at moderate (1700 m) and low altitude (LA) (200 m) on key-markers of the metabolic syndrome, 71 male volunteers (age 36-66 yr old) with the metabolic syndrome [according to the National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) - or World Health Organization (WHO) - definition] participated in the study and were randomly assigned into a moderate altitude (MA) group (1700 m, no. 36) and a low altitude (LA) group (200 m, no. 35). The 3-week vacation program included 12 moderate- intensity guided hiking tours [4 times/week, 55-65% heart rate maximum (HRmax)] with a total exercise time of 29 h plus moderate recreational activities. Both study groups had a comparable and balanced nutrition with no specific dietary restrictions. Anthropometric, metabolic and cardiovascular parameters were measured 10-14 days before vacation, several times during the 3-week vacation, 7-10 days and 6-8 weeks after return. All participants tolerated the vacation without any adverse effects. Body weight, body fat, waist-circumference, fasting glucose, total cholesterol, LDL-cholesterol (LDL-C), plasma fibrinogen, resting systolic and diastolic blood pressure were significantly decreased over time in both study groups. In the LA group, fasting insulin and homeostasis model assessment (HOMA)-index were significantly decreased one week after return. Relative cycle ergometry performance was significantly increased after return compared to baseline. In both study groups, waist-to-hip ratio (WHR), 2-h oral glucose tolerance test (OGTT), HDL-cholesterol (HDL-C), and triglycerides remained unchanged. The 3-week vacation intervention at moderate and LA had a positive influence on all key-markers of the metabolic syndrome. No clinically relevant differences could be detected between the study groups. A hiking vacation at moderate and LA can be recommended for people with stable, controlled metabolic and cardiovascular risk factors.

Anemia and erythropoietin in space flights

Since the very early manned missions in space, a state of anemia associated with reduced erythropoietin levels and reduced plasma volume was disclosed. The reduction in red blood cell mass is driven by a process of selective hemolysis, which has been named neocytolysis. This phenomenon also occurs in people living at a high altitude who descend rapidly to sea level. The origin of the signal leading to destruction of newly produced red blood cells probably is located in central circulation, but the operating mechanism is unknown. The importance of plasma cell volume reduction in the genesis of a lower red cell mass also is supported by the inverse correlation seen at moderate altitude. People arriving at moderate altitude have increased erythropoietin concentration that decreases after a few days and is in inverse correlation with central venous pressure. Studies under simulated microgravity conditions in human beings (bed rest, head-down tilt at -6 degrees , water immersion) and in rats provide further insight in unraveling the mechanism of astronauts' anemia, a problem difficult to study in space because of the limited availability of spaceflights.

Observation of serum erythropoietin concentrations in female athletes for up to eight days after a marathon run

Erythropoietin (EPO) was studied in 13 female marathon runners before and up to 8 days after a competition marathon run. The median baseline control value was 13.7 U/l. No change in EPO concentration was found immediately (15 min.) and one day after the run. However, a median increase in EPO concentration (18.1 U/l) was found on day three post-exercise (p< 0.05). On day 8 no change was found compared to pre-exercise values. This late increase in EPO concentration would seem to be responsible for the well known increase of red blood cell mass in long distance runners.

Erythropoietin as a Volume-Regulating Hormone: An Integrated View

The intravascular volume consists of 40% to 45% red cells. Their production is controlled predominantly by erythropoietin (EPO), a hormone that is secreted particularly when tissue hypoxia is present. Because of this high percentage of the total intravascular volume the question comes to mind that, in addition to hypoxia, can volume-regulation mechanisms, known to be responsible for the maintenance of plasma volume, modulate EPO secretion when the total vascular volume changes? Indeed, there is evidence that in situations in which the intravascular volume or specifically the intrathoracic volume is altered, EPO secretion is affected. EPO secretion increases when the intrathoracic volume decreases 24 hours after water immersion or after endurance exercise when a negative water balance prevails. A head-down tilt on the other side induces central engorgement leading to a decrease of EPO concentrations. Under these experimental conditions no hypoxia was seen, supporting the idea that a volume stimulus outgoing from intrathoracic parts of the circulation modulated EPO secretion. Further observations from the clinical side are needed to support these ideas and the consequences need to be implemented into clinical practice.

Austrian Moderate Altitude Study (AMAS 2000): Erythropoietic Activity and Hb–O2 Affinity During a 3-Week Hiking Holiday at Moderate Altitude in Persons with Metabolic Syndrome

Moderate altitude hypoxia (1500 to 2500 m) is known to stimulate erythropoiesis and to improve oxygen transport to tissue by a reduction of Hb-O(2) affinity. Whether this adaptation also occurs in tourists with metabolic syndrome has not yet been investigated sufficiently. Thus, we performed a prospective field study to measure erythropoietic parameters and oxygen transport properties in 24 male volunteers with metabolic syndrome during a 3- week holiday program at 1700 m consisting of four guided, individually adapted hiking tours per week. The following examinations were performed: baseline investigations at 500 m (T1); examinations at moderate altitude on day 1 (T2), day 4 (T3), day 9 (T4), and day 19 (T5); and postaltitude tests (T6) 7 to 10 days after return. On day 1 and day 19, a walk on a standardized hiking test route with oxygen saturation (SpO(2)) measure points was performed. Hemoglobin, packed cell volume, and red cell count showed changes over time, with higher values at T5 as compared to baseline. Reticulocyte count and erythropoietin (EPO) were increased at T2 and increased further until T5. EPO declined toward prealtitude values. P50-value (blood PO(2) at 50% hemoglobin oxygen saturation at actual pH) increased during the altitude sojourn (maximum increase at T5 by +0.40 kPa). At T5 all volunteers had a higher SpO(2) before, during, and at the end of the test route compared to T1. During adaptation to moderate altitude, persons with metabolic syndrome exhibit an increase in EPO and a rightward shift of the oxygen dissociation curve that is similar to healthy subjects.

Interaction of hypoxia and haemostasis

For an extended period of time various research projects have been conducted on the relationship of hypoxia and haemostasis. The enclosed article contains the conclusion to which extent lack of oxygen can activate the coagulation system and induce a prothrombotic state. The majority of studies proved a shortening of coagulation times during acute exposure to hypoxia, whereas activated parameters of coagulation and fibrinolysis like prothrombin fragment F1+2 as well as thrombin-antithrombin III complexes and D-dimer remained mostly unmodified. It is suggested that a prolonged sojourn at high altitudes could lead to activation of the coagulation system through an increase of haematocrit and blood viscosity. Recently it was proven that people living at high altitudes show an enhanced risk of stroke incidents. The significance of the change in haemostasis on that outcome has not yet been part of the research. However, it has been proven that the activity of the coagulation system does not play a pathophysiological part in the development of acute mountain sickness and high altitude pulmonary edema. Recent studies also demonstrated that moderate hypoxia during long haul flights may not be the main trigger in inducing deep vein thrombosis in passengers.

Formation of edema and fluid shifts during a long-haul flight

BACKGROUND

More than 1.5 billion passengers travel by aircraft every year. Leg edema, as a sign of venous stasis, is a well-known problem among passengers during and after long-haul flights. Until now, no studies have been done on the development of leg edema and fluid shifts under real flight conditions. The aim of our study was to evaluate edema formation in the leg and to investigate possible fluid shifts to the interstitial space under real flight conditions.

METHODS

Twenty participants, 10 without risk and 10 with moderate risk for venous thrombosis, were selected. They flew from Vienna to Washington, flight time 9 h, and returned 2 days later. Investigations were done 48 h before the flight, between the fifth and eighth flight hour on board to Washington and back to Vienna, immediately after arrival in Vienna, and 1 and 3 days after arrival. Plethysmographic measurements were carried out using an optoelectronic scanner system (Perometer). Thickness of the skin was measured at the forehead and in front of the tibia.

RESULTS

There were no differences in all measurements between both groups. The volume of the leg increased from 8242 +/- 1420 mL to 8496 +/- 1474 mL after the flight (p <.001). Volume accumulation was distributed to the lower leg as well as to the thigh. Skin thickness in front of the tibia increased significantly during the flight (p <.05), and remained elevated 1 day after arrival.

CONCLUSION

We have demonstrated that long-haul flights induce significant fluid accumulation in the lower extremity, involving the lower leg and thigh. This increase in tissue thickness was maintained for some days after the flights.

Austrian Moderate Altitude Study (AMAS 2000) - fluid shifts, erythropoiesis, and angiogenesis in patients with metabolic syndrome at moderate altitude (congruent with 1700 m)

It was hypothesized that subjects with metabolic syndrome (hypertension, obesity, hyperlipidemia, diabetes mellitus): (1) develop measurable peripheral edema at moderate altitude and (2) might show differences on erythropoiesis, iron status and vascular endothelial growth factor (VEGF) in comparison to healthy subjects during and after a long-term stay (3-week exposure) at moderate altitude (congruent with 1700 m). Twenty-two male subjects with metabolic syndrome were selected. Baseline investigations (t1) were performed in Innsbruck (500 m). All participants were transferred by bus to 1700 m (Alps) and remained there for 3 weeks with examinations on day 1 (after the first night at altitude, t2), day 4 (t3), day 9 (t4) and day 19 (t5). After returning to Innsbruck, post-altitude examinations were conducted after 7-10 days (t6) and 6-7 weeks (t7), respectively. Body mass was decreased from t1 to t7 (P<0.01). Total body water was decreased at t2 (P<0.01), returned to control level (t3, t4), and was found elevated at t7 (P<0.01). Lean body mass did not change, but body fat decreased during the study (P<0.01). Tissue thickness at the forehead decreased during and after altitude exposure (P<0.01), whereas tissue thickness at the tibia did not alter. Erythropoietin (EPO) was elevated as early as t2 and remained increased until t5. Reticulocyte count was increased at t3 and remained above pre-altitude values. VEGF levels were unchanged. After a 3-week exposure to moderate altitude, patients with metabolic syndrome had reduced their body mass, mainly because of a reduction in body fat. The moderate altitude was found to stimulate erythropoiesis in these patients but this was not sufficient to increase serum VEGF concentration.

Austrian Moderate Altitude Study 2000 (AMAS 2000). The effects of moderate altitude (1,700 m) on cardiovascular and metabolic variables in patients with metabolic syndrome

We investigated the changes in the cardiovascular system [resting blood pressure (BP) and heart rate (HR), measured by means of a 24-h ambulatory BP and a holter-electrocardiogram (ECG)], glycemic parameters, and lipid metabolism of subjects suffering from metabolic syndrome during a 3-week sojourn at 1,700 m in the Austrian Alps. A total of 22 male subjects with metabolic syndrome were selected. Baseline investigations were performed at Innsbruck (500 m above sea level). During the 3-week altitude stay the participants simulated a holiday with moderate sports activities. Examinations were performed on days 1, 4, 9, and 19. After returning to Innsbruck, post-altitude examinations were conducted after 7-10 days and 6-7 weeks, respectively. The 24-h ambulatory BP and holter ECG revealed a decrease in average HR, BP, and rate pressure product (RPP: systolic blood pressure x HR) after 3 weeks of altitude exposure. In some patients, an increase in premature ventricular beats was observed at the end compared to the beginning of the exposure to moderate altitude. The ECG revealed no ischemic ST-segment changes. Maximal physical capacity as measured by symptom-limited maximal cycle ergometry tests remained unchanged during the study. Six weeks after the altitude exposure the blood pressure increased again and returned to pretest levels. The Homeostasis Model Assessment index, which is a measure of insulin resistance, decreased significantly and glucose concentrations obtained after an oral glucose tolerance test were significantly lower after the stay at altitude compared to the basal values. We conclude that after a 3-week exposure to moderate altitude, patients with metabolic syndrome (1) tolerated their sojourn without any physical problems, (2) exhibited short-term favorable effects on the cardiovascular system, and (3) had significant improvements in glycemic parameters that were paralleled by a significant increase in high-density-lipoprotein-cholesterol.

Influence of endurance exercise (triathlon) on circulating transferrin receptors and other indicators of iron status in female athletes

Numerous reports have described a poor iron status in female endurance athletes. However, the traditionally applied indicators of iron status (hemoglobin, ferritin, transferrin) may not truly reflect the iron status. Therefore we studied the newly developed soluble transferrin receptor and other indicators of iron status in twelve female endurance athletes before and after a triathlon race. Resting values showed a poor iron status in the participants of the race. Serum TfR concentration increased slightly after the race. However, if the values are corrected for hemoconcentration no change could be found. Hemoglobin, serum ferritin and transferrin values were increased after the race.

Voice monitoring to measure emotional load during short-term stress

It is well known that there is a relationship between the voice the human emotional status. Previous studies have demonstrated that changes of fundamental frequency ( f(0)), in particular, have a significant relationship with emotional load. The aim of the present study was to investigate how f(0) changes in response to an unknown emotionally stressful task under real-life conditions. A further question was whether repetitions of this task lead to an adaptation of f(0), indicating a lower emotional load. The participants of this study included 26 healthy males. f(0) and heart rate ( f(c)) were recorded for baseline testing (BLT) under relaxed laboratory conditions. Then the participants were asked to negotiate a natural obstacle by way of sliding down a rope hanging from a handlebar without any safety provisions, thus being exposed to the danger of a fall from a height of up to 12 m into shallow water (guerrilla slide I, GSI). The task was repeated after 30 min (GSII) and after 3 days of physical strain (GSIII). Immediately before starting the task the participants were asked to give a standardised speech sample, during which f(c) was recorded. The mode value of f(0) ( f(0,mode)) of the speech samples was used for further analysis. The mean (SD) value of f(0,mode) at BLT was 114.9 (14.8) Hz; this increased to 138.8 (19.6) Hz at GSI ( P<0.000), decreased to 135.9 (19.6) Hz at GSII and to 130.0 (21.5) Hz at GSIII ( P=0.012). The increase in f(c) was significantly different from BLT to GSI ( P<0.000). The repetitions of the task did not produce significant changes in f(c). It was shown that f(0,mode) is a sensitive parameter to describe changes in emotional load, at least in response to short-term psychoemotional stress, and seems to throw light upon the amount of adaptation caused by increased experience.

[Traveler's thrombosis: incidence, etiology, prevention]

The number of persons traveling by airplane, railway or bus is on the increase. Recently, there has been a growing number of reports on travel-related disorders after long journeys, especially long-haul flights (i.e. deep venous thrombosis (DVT) and pulmonary thromboembolism (VTE), also known as "economy class syndrome" or "traveler's thrombosis"). The exact incidence of travel related thrombosis is not known. Contributing factors for DVT and VTE are sitting in a cramped position for hours, low humidity and lowered oxygen pressure in the aircraft cabin, reduced fluid intake and dehydration, as well as individual risk factors. In this review article definitions for risk groups (low, moderate and high risk for DVT and VTE) and recommendations for prevention (leg exercise, fluid intake, compression stockings and application of low molecular weight heparins) of travel related thrombosis, based on the outcome of a recent expert meeting, are presented.