Hematological changes and athletic performance in horses in response to high altitude (3,800 m)

This study had two goals: 1) measure hematologic changes with high-altitude acclimatization in horses; and 2) assess the effect of 9 days at high altitude on subsequent athletic performance at low altitude. Six horses performed standardized exercise tests on a dirt track (before and during time at altitude) and treadmill (pre- and postaltitude exposure). Resting and immediate postexercise blood samples were measured for blood volume, lactate, red cell number, packed cell volume, and 2,3-diphosphoglycerate (DPG) concentrations at 225 m, over a 9-day period at 3,800 m, and shortly after returning to 225 m. Acclimatization produced increases in total red cell volume (38.2 +/- 2.4 to 48.1 +/- 2.9 ml/kg, P = 0.004) and DPG/hemoglobin concentrations (19.4 +/- 1.7 increased to 29.4 +/- 0. 4 micromol/g, P = 0.004). Two performance variables, heart rate recovery postexercise and lactate recovery, were faster after acclimatization.     

珙桐(Davidia involucrata Baill.)苞片功能性状及性状间关系对海拔的响应

珙桐(Davidia involucrata Baill.)的苞片被认为是对传粉者和非生物因素等驱动力的适应,往往受到环境因子的影响。为揭示其功能性状及其性状间关系对海拔的响应,本研究采用独立样本t检验和标准化主轴分析方法对比了四川龙苍沟1400和1800 m不同海拔珙桐种群中花苞片的功能性状和性状间关系。结果显示:1)低海拔(1400 m)珙桐种群大、小苞片的长、宽和面积,以及单花苞片总面积均显著大于高海拔(1800 m)种群(P<0.05),且高、低海拔种群的大、小苞片面积及重量呈等比例生长; 2)低海拔珙桐种群大、小苞片干重及单花苞片总干重均显著高于高海拔种群(P<0.05); 3)高、低海拔种群的花序轴长与干重均无显著差异(P=0.446; P=0.791),高海拔花序轴干重与长间呈异速生长关系,而低海拔呈等速生长关系; 4)珙桐大、小苞片的长宽间、面积间以及重量间关系在高、低海拔上均表现出等速生长,单花苞片的总面积和总干重分别与花序轴干重在高、低海拔上均表现出等速生长关系,而与花序轴长表现出异速生长关系。上述结果表明,珙桐苞片的功能性状及其性状间关系在不同海拔存在...     

Physical and Chemical Limnology of 34 Lentic Waterbodies along a Tropical‐to‐Alpine Altitudinal Gradient in Nepal

Physical and chemical factors were studied in 34 lentic waterbodies distributed along a steep altitudinal gradient ranging from tropical (77 m) to high alpine (up to 4,980 m) environments in Nepal. Bicarbonate and calcium were dominant among anions and cations, respectively, reflecting a strong influence of carbonate weathering and watershed area, rather than altitudinal climate. The relative patterns of dominant ions were similar among lakes in all altitudinal regions, although total concentrations increased with decreasing altitude. Total suspended solids were relatively high in the study lakes, as is also typical of rivers in the Ganges watershed. Suspended solids had a greater influence on water transparency than did algal biomass in the study lakes. In general, high‐altitude waterbodies were oligotrophic, while those at low altitude were eutrophic. The productivity of high‐altitude study lakes appeared to be limited by both available phosphorus and nitrogen, while lowland ones were nitrogen‐limited. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparison of the reproductive performance of rats at high altitude (3,800m) and at sea level

Estrous cycles and reproductive performance were compared among rats born at high altitude, rats of Berkeley stock transported to 3,800 m, and sea level controls. Disturbances of reproductive function observed in experimental groups were not due to reduced food intake. Estrous cycles of Berkeley stock at 3,800 m were normal, whereas cycles of high altitude native rats were irregular and fertility was impaired. Litter size was reduced in both groups at high altitude with fewer implantation sites than numbers of corpora lutea observed in the Berkeley stock rats at 3,800 m. In the high altitude native animals, numbers of corpora lutea correlated with implantation sites. Placentas from Berkeley stock rats (3,800 m) were heavier than those from the other groups, and fetal hematocrits from these animals were reduced.     

Pollen distribution at elevations above 1000 m inSwitzerland

In Switzerland the concentration of allergenic pollendecreases with increasing elevation of the samplingsite of the Swiss pollen measuring network. The aim ofthis study was, to compare the pollen concentrationsof five different localities in the Swiss Alps and inthe Jura mountains, to get an idea of the differencesin the pollen abundance in altitudes above 1000 m. Theinvestigated localities are: La Chaux-de-Fonds(1040 m), Wiesen (1420 m), Davos (1600 m), Samedan(1705 m) and Gütsch (2287 m). These pollen sumswere compared to the Swiss plateau (Basel 273 m).Basel, La Chaux-de-Fonds and Wiesen show clearlyhigher pollen values than Davos, Samedan andGütsch. Pollen concentrations of Corylus,Alnus glutinosa-type and Fraxinus arereduced with increasing altitude and are only a smallproblem for allergies above 1000 m. Betulapollen are also reduced in the higher localities, butthere still occur many days with high pollenconcentrations. Especially Betula pollen frommedium range transport can play an important role forallergies in higher localities. The total grass pollensum does not decrease up to an altitude of 1500 m. Thegrass pollen concentration depends more on factorslike composition of the local grassland, land use andwind situation.Pollen concentrations at higher elevations isinfluenced by the local vegetation, a reduced pollenproduction, land use, topography, exposition, windvelocity and wind direction. These factors modify thepollen concentration considerably. Due to the complextopography of the Prealps and Alps, it is thereforenot possible to propose a general rule of pollenreduction with increasing altitude.     

Women at altitude: energy requirement at 4,300 m.

To test the hypotheses that prolonged exposure to moderately high altitude increases the energy requirement of adequately fed women and that the sole cause of the increase is an elevation in basal metabolic rate (BMR), we studied 16 healthy women [21.7 +/- 0.5 (SD) yr; 167.4 +/- 1.1 cm; 62.2 +/- 1.0 kg]. Studies were conducted over 12 days at sea level (SL) and at 4,300 m [high altitude (HA)]. To test that menstrual cycle phase has an effect on energetics at HA, we monitored menstrual cycle in all women, and most women (n = 11) were studied in the same phase at SL and HA. Daily energy intake at HA was increased to respond to increases in BMR and to maintain body weight and body composition. Mean BMR for the group rose 6.9% above SL by day 3 at HA and fell to SL values by day 6. Total energy requirement remained elevated 6% at HA [ approximately 670 kJ/day (160 kcal/day) above that at SL], but the small and transient increase in BMR could not explain all of this increase, giving rise to an apparent "energy requirement excess." The transient nature of the rise in BMR may have been due to the fitness level of the subjects. The response to altitude was not affected by menstrual cycle phase. The energy requirement excess is at present unexplained.     

Part B Frequency distribution of positive and negative small ion concentrations,based on many years' recordings at two mountain stations located at 740 and 1780 m ASL

Conclusions There is no doubt that positive and negative ion concentrations are influenced by meteorological conditions. But this dependence on weather is due to the given atmospheric content and size of aerosol particles which the small ions attach to (Lassen and Rau, 1960). Consequently, minimum values are found in fog and low visibility, respectively, high values at high visibility, fair weather without precipitation, but also during foehn conditions. However, the latter are in no way distinguished by special features compared to other weather conditions that favor the increase of ion concentrations. This relates to ion concentrations of both signs as well as the ratio from positive to negative concentrations.On the basis of an extensive data material it was possible to confirm again what has been observed long time ago (Reiter, 1960). Weather-dependent effects of foehn ften claimed but never convincingly proved —can no longer be explained by abnormal ion conditions. This conception should once and for all be put to the realm of stories. Advertisements from the commercial side according to which strong excess and high concentrations of negative ions will generate a well-being like that in high mountains or other open countrysides are completely unfounded. It even needs to be pointed out that in a mountainous region during fair weather the ratio of the small ion concentration is shifted more towards positive ions. Similarly, this is true of conditions in roof-gardens and even balconies of multi-storey buildings.     

Osmoregulation in the Extremely Euryhaline Marine Micro-Alga Chlorella autotrophica

Chlorella autotrophica (Clone 580) grows over the external salinity range of 1 to 400% artificial sea water (ASW), can photosynthesize over the range from 1 to 600% ASW, and survives the complete evaporation of seawater. The alga grown at high salinities shows an increase in cell volume and a small decrease in cell water content. Measurements of ion content were made by neutron activation analysis on cells washed in isoosmotic sorbitol solutions which contained a few millimolar of major ions to prevent ion leakage. Cells grown at various ASW concentrations contain large quantities of sodium, potassium, and chloride ions. Measurements of cations associated with cell wall and intracellular macromolecules were made to determine intracellular concentration of free ions. The proline content of cells increases in response to increases in external salinity. Cells in 300% ASW contain 1500 to 1600 millimolar proline.     

Specific ion concentration as a factor in barotolerant protein synthesis in bacteria.

The degree of barotolerance exhibited by Pseudomonas fluorescens and Pseudomonas bathycetes in vitro polyphenylalanine-synthesizing systems can be modified by altering the concentrations of specific ions in the reaction mixture. Hybrid-protein-synthesizing systems, utilizing all the possible S-100 supernatant fluid and ribosome combinations from Escherichia coli, P. fluorescens, and P. bathycetes, were tested for barotolerance under conditions of low (16 mM Mg2+ plus 0 mM Na+) and high (150 mM Na+ plus 60 mM Mg2+) ion concentrations. The results reveal that barotolerant synthesis is a characteristic determined by the origin of the ribosome. Systems utilizing E. coli ribosomes are barosensitive at both low and high ion concentrations, P. fluorescens ribosomes barotolerant under both conditions, and P. bathycetes ribosomes barosensitive at low and barotolerant at high ion concentrations. Therefore, certain concentrations of specific ions will increase barotolerance, but only if the ribosomes are capable of functioning at high pressures.     

Granular pneumocytes and altitude: A stereological evaluation

Summary Stereological analysis demonstrates that the granular pneumocytes of mice native to high altitude (4660 m) are significantly larger than those of the same species (Phyllotis darwini) living at sea level. Such cells have larger nuclei and a significantly greater volume of mitochondria. There are both more and larger lamellar bodies in high altitude granular pneumocytes, resulting in about four times more surfactant per cell at high altitude.     

Acute in vitro hypoxia and high-altitude (4,559 m) exposure decreases leukocyte oxygen consumption

Hypoxia impairs metabolic functions by decreasing activity and expression of ATP-consuming processes. To separate hypoxia from systemic effects, we tested whether hypoxia at high altitude affects basal and PMA-stimulated leukocyte metabolism and how this compares to acute (15 min) and 24 h of in vitro hypoxia. Leukocytes were prepared at low altitude and ～24 h after arrival at 4559 m. Mitochondrial oxygen consumption (JO?) was measured by respirometry, oxygen radicals by electron spin resonance spectroscopy, both at a Po? = 100 mmHg (JO?,???) and 20 mmHg (JO?,??). Acute hypoxia of leukocytes decreased JO? at low altitude. Exposure to high altitude decreased JO?,???, whereas JO?,?? was not affected. Acute hypoxia of low-altitude samples decreased the activity of complexes I, II, and III. At high altitude, activity of complexes I and III were decreased when measured in normoxia. Stimulation of leukocytes with PMA increased JO?,??? at low (twofold) and high altitude (five-fold). At both locations, PMA-stimulated JO? was decreased by acute hypoxia. Basal and PMA-stimulated reactive oxygen species (ROS) production were unchanged at high altitude. Separate in vitro experiments performed at low altitude show that ～75% of PMA-induced increase in JO? was due to increased extra-mitochondrial JO? (JO?(,res); in the presence of rotenone and antimycin A). JO?(,res) was doubled by PMA. Acute hypoxia decreased basal JO?(,res) by ～70% and PMA-stimulated JO?(,res) by about 50% in cells cultured in normoxia and hypoxia (1.5% O?; 24 h). Conversely, 24 h in vitro hypoxia decreased mitochondrial JO?,??? and JO?,??, extra-mitochondrial, basal, and PMA-stimulated JO? were not affected. These results show that 24 h of high altitude but not 24 h in vitro hypoxia decreased basal leukocyte metabolism, whereas PMA-induced JO? and ROS formation were not affected, indicating that prolonged high-altitude hypoxia impairs mitochondrial metabolism but does not impair respiratory burst. In contrast, acute hypoxia impairs respiratory burst at either altitude.     

Intrusion of airborne pollen through open windows and doors

The importance of the transport of pollen by air movement into houses was evaluated using six to eight simultaneously collecting rotorod-type samplers, creating either a sampler line from outdoors to inside the room, or a sampler grid inside a room. The number of incoming pollen grains was highly dependent on the outdoor concentration. The highest concentrations inside (1–2 m distance) and outside (1 m) the room were 600 and 3,250 grains/m³, respectively, in the Betula pollen season and 1,980 and 5,080 grains/m³ in the Pinus season. The pollen concentration and the indoor/outdoor (I/O) ratio decreased as the distance from the ventilation opening increased. Inside the room at a distance of 1–2 m 28%, and at a distance of 3–5 m 12%, of the outside concentration was recorded. In the lower part of the opening the mean proportion was 63% and in the upper part of the opening it was 40%. Efficient ventilation with two open windows increased the I/O ratio and enabled the pollen to spread throughout the room. During the Pinus pollen season 3–35% of the outdoor concentration was simultaneously recorded at six locations inside the room with two open windows and only 0.1–3.6% with one open window. At the same point in the room the I/O ratio varied from <1 to 35%, depending on the sampling conditions. Only a minor effect on the I/O ratio was found between small and large ventilation windows and the door, although it was expected that more air and pollen grains would come indoors through a larger opening.     

Muscle accounts for glucose disposal but not blood lactate appearance during exercise after acclimatization to 4,300 m.

We hypothesized that the increased blood glucose disappearance (Rd) observed during exercise and after acclimatization to high altitude (4,300 m) could be attributed to net glucose uptake (G) by the legs and that the increased arterial lactate concentration and rate of appearance (Ra) on arrival at altitude and subsequent decrease with acclimatization were caused by changes in net muscle lactate release (L). To evaluate these hypotheses, seven healthy males [23 +/- 2 (SE) yr, 72.2 +/- 1.6 kg], on a controlled diet were studied in the postabsorptive condition at sea level, on acute exposure to 4,300 m, and after 3 wk of acclimatization to 4,300 m. Subjects received a primed-continuous infusion of [6,6-D2]glucose (Brooks et al., J. Appl. Physiol. 70: 919-927, 1991) and [3-13C]lactate (Brooks et al., J. Appl. Physiol. 71:333-341, 1991) and rested for a minimum of 90 min, followed immediately by 45 min of exercise at 101 +/- 3 W, which elicited 51.1 +/- 1% of the sea level peak O2 uptake (65 +/- 2% of both acute altitude and acclimatization peak O2 uptake). Glucose and lactate arteriovenous differences across the legs and arms and leg blood flow were measured. Leg G increased during exercise compared with rest, at altitude compared with sea level, and after acclimatization. Leg G accounted for 27-36% of Rd at rest and essentially all glucose Rd during exercise. A shunting of the blood glucose flux to active muscle during exercise at altitude is indicated. With acute altitude exposure, at 5 min of exercise L was elevated compared with sea level or after acclimatization, but from 15 to 45 min of exercise the pattern and magnitude of L from the legs varied and followed neither the pattern nor the magnitude of responses in arterial lactate concentration or Ra. Leg L accounted for 6-65% of lactate Ra at rest and 17-63% during exercise, but the percent Ra from L was not affected by altitude. Tracer-measured lactate extraction by legs accounted for 10-25% of lactate Rd at rest and 31-83% during exercise. Arms released lactate under all conditions except during exercise with acute exposure to high altitude, when the arms consumed lactate. Both active and inactive muscle beds demonstrated simultaneous lactate extraction and release. We conclude that active skeletal muscle is the predominant site of glucose disposal during exercise and at high altitude but not the sole source of blood lactate during exercise at sea level or high altitude.     

Glucoregulatory hormones in man at high altitude

Concentrations of glucose, lactic acid, free fatty acid (FFA), insulin, cortisol and growth hormone (GH) in the blood were monitored in 15 euglycaemic men (sojourners, SJ) at sea level (SL) and while at altitudes of 3500 m and 5080 m, in acclimatised low landers (ALL) and in high altitude natives (HAN). In SJ, blood glucose and insulin concentrations showed a significant increase on the 3rd and 7th day after arrival at high altitude (HA), thereafter returning to sea level values and remaining the same during the entire period of their stay at 3500 m. Subsequently, on arrival at higher altitude (5080 m) the glucose concentrations again showed an increase over the preceding values and returned to SL values on day 41 while at 5080 m. A significant increase in cortisol concentrations was seen on day 3 after arrival at HA and the increased levels were maintained until day 21 at 3500 m. The cortisol concentrations on day 30 after arrival at 5080 m came down to SL values and remained unchanged thereafter. No appreciable change in GH and FFA was seen during the sojourn at HA. On the other hand, blood lactic acid concentration decreased significantly. There was no difference between the fasting glucose concentrations in ALL at 3500 m and in HAN at 3500 m and 4200 m compared to values of SJ at SL, whereas ALL at 4200 m had higher glucose values. Concentrations of plasma insulin and GH in ALL and HAN were higher than the values of SJ at SL, whereas cortisol values did not show any difference. These observations indicated that at HA the glucose values were high for the insulin concentration observed and might have been due to increased secretion of GH by the pituitary gland.     

Headache at high altitude is not related to internal carotid arterial blood velocity

The cause of headache in persons going to high altitude is unknown. Relatively severe hypoxemia in susceptible subjects could induce large increases in cerebral blood flow that then could initiate the headache. Thus we measured noninvasively, by Doppler ultrasound, changes in internal carotid arterial blood velocity (velocity) in 12 subjects in Denver (1,600 m) and repeatedly up to 7 h at a simulated altitude of 4,800 m (barometric pressure = 430 Torr). Six subjects, selected because of prior history of high-altitude headache, developed comparatively severe headache at 4,800 m, and four subjects, without such history, remained well. Two subjects developed moderate headache. Velocity at 4,800 m did not correlate with symptom development, arterial O2 saturation, or end-tidal PCO2. Also, neither velocity nor blood pressure was consistently elevated above the Denver base-line values. During measurements of hypercapnic ventilatory response in Denver, velocity increased linearly with end-tidal PCO2, confirming that our Doppler method could demonstrate an increase. Also, 30 min of isocapnic or poikilocapnic hypoxia caused small increases in velocity (+8 and +6%) during the base-line measurement at low altitude. Although even a small increase in cerebral perfusion could contribute to headache symptoms at high altitude, cerebral blood flow does not appear to play a primary role.     

Changes in plasma lipids and lipoprotein cholesterol during a high altitude mountaineering expedition (4800 m)

Effects of high altitude exposure on plasma lipids and lipoprotein cholesterol were studied in 8 mountaineers who spent 3 weeks at the Annapurna IV base camp (4800 m) after a 12 day trek. In spite of the moderate physical exertion at the camp, the loss of body weight was more pronounced during the stay at high altitude than during the trekking period. Compared with baseline values observed at sea level, marked reductions in plasma cholesterol (-27%) and phospholipids (-19%) were found 3 days after arrival at the camp and persisted during the next 17 days. A less marked fall in plasma triglycerides occurred, weakly significant at the end of the stay. Because there were no relevant changes in very low density lipoproteins or in high density lipoprotein (HDL)-cholesterol, the low plasma cholesterol levels at the high altitude resulted mainly from the reduction in low density lipoprotein (LDL)-cholesterol: the mean HDL/LDL cholesterol ratio changed from 0.39 at sea level to 0.63 at the end of the stay at 4800 m. Fluctuations in LDL-cholesterol were not concomitant with those in body weight and were independent of the exercise training during the expedition. This study shows moreover that the early drop in LDL-cholesterol was associated with an opposite change in plasma levels of catecholamines and thyroid hormones. Taking into account that such hormonal responses are classically observed at high altitude, the concomitant decrease in LDL-cholesterol might be interpreted as being a relevant adaptative response to hypoxic conditions at high altitude.     

Responses of calves to a simulated altitude of 5000 m

Six calves were exposed in succession 12 days at 400 m altitude (control), 12 days at a simulated altitude of 5000 m in a low pressure chamber (experimental), and 14 days at 400 m altitude (recovery). Exposure to 5000 m produced the following changes: intake of feed and water decreased by 47 and 35% respectively, and body weight gain ceased. Rectal temperature rose by 0.4°C. Heart rate increased by 65%. Respiratory rate and blood pH increased moderately. There was an S-shaped rise of haematocrit (from 33 to 45%), which was paralleled by blood viscosity. Plasma viscosity showed a sharp, but transient rise. Short term measurements made during ascent to and descent from 5000 m altitude, both lasting for four hours, showed that some of the changes developed rapidly.     

Possible influence of cell walls upon ion concentrations at plasma membrane surfaces. Toward a comprehensive view of cell-surface electrical effects upon ion uptake, intoxication, and amelioration

Plant uptake of ions, intoxication by ions, and the alleviation of intoxication by other ions often correlate poorly with ion concentrations in the rooting medium. By contrast, uptake, intoxication, and alleviation correlate well with ion concentrations at the plasma membrane (PM) surface computed as though the PM were bathed directly in the rooting medium with no effect from the cell wall (CW). According to two separate lines of analysis, a close association of CWs and PMs results in a slight increase in cation concentrations and a slight decrease in anion concentrations at the PM surface compared with concentrations when the CW is separated or has no effect. Although slightly different, the ion concentrations at the PM surface computed with and without close association with the CW are highly correlated. Altogether, the CW would appear to have a small effect upon ion uptake by the PM or upon intoxication or alleviation of intoxication originating at the PM surface. These analyses have been enabled by the recent evaluation of parameters required for the electrostatic models (Gouy-Chapman-Stern and Donnan-plus-binding) used to compute electrical potentials and ion concentrations in CWs and at PM surfaces.     

Dispersal in microbes: fungi in indoor air are dominated by outdoor air and show dispersal limitation at short distances

The indoor microbiome is a complex system that is thought to depend on dispersal from the outdoor biome and the occupants'' microbiome combined with selective pressures imposed by the occupants'' behaviors and the building itself. We set out to determine the pattern of fungal diversity and composition in indoor air on a local scale and to identify processes behind that pattern. We surveyed airborne fungal assemblages within 1-month time periods at two seasons, with high replication, indoors and outdoors, within and across standardized residences at a university housing facility. Fungal assemblages indoors were diverse and strongly determined by dispersal from outdoors, and no fungal taxa were found as indicators of indoor air. There was a seasonal effect on the fungi found in both indoor and outdoor air, and quantitatively more fungal biomass was detected outdoors than indoors. A strong signal of isolation by distance existed in both outdoor and indoor airborne fungal assemblages, despite the small geographic scale in which this study was undertaken (<500 m). Moreover, room and occupant behavior had no detectable effect on the fungi found in indoor air. These results show that at the local level, outdoor air fungi dominate the patterning of indoor air. More broadly, they provide additional support for the growing evidence that dispersal limitation, even on small geographic scales, is a key process in structuring the often-observed distance–decay biogeographic pattern in microbial communities.     

Nocturnal periodic breathing at altitudes of 6,300 and 8,050 m

Nocturnal periodic breathing was studied in eight well-acclimatized subjects living at an altitude of 6,300 m [barometric pressure (PB) 350-352 Torr] for 3-5 wk and in four subjects during one night at 8,050 m altitude (PB 281-285 Torr). The measurements at 6,300 m included tidal volume by inductance plethysmography, arterial O2 saturation by ear oximetry (calibrated by arterial blood samples), electrocardiogram (ECG), and electrooculogram. At 8,050 m, periodic breathing was inferred from the cyclical variation in heart rate obtained from a night-long ECG record. All subjects at 6,300 m altitude showed well-marked periodic breathing with apneic periods. Cycle length averaged 20.5 s with 7.9 s apnea. Minimal arterial O2 saturation averaged 63.4% corresponding to a PO2 of approximately 33 Torr, i.e., approximately 6 Torr lower than the normal value at rest during daytime. This was probably the most severe hypoxemia of the 24-h period. At 8,050 m altitude, the cycle length averaged 15.4 s, much longer than predicted by a theoretical model. Cyclical variations in heart rate caused by periodic breathing occurred in all subjects, but abnormal cardiac rhythms such as ventricular premature contractions were uncommon. The severe arterial hypoxemia caused by periodic breathing may be an important determinant of tolerance to these great altitudes.