Home About us Contact
|
Home About us Contact | ||
|
|
||
High Altitude (high + altitude)
Selected AbstractsMalaria at High AltitudeJOURNAL OF TRAVEL MEDICINE, Issue 3 2000Rachel A. Bishop No abstract is available for this article. [source] The influence of management regime and altitude on the population structure of Succisapratensis: implications for vegetation monitoringJOURNAL OF APPLIED ECOLOGY, Issue 4 2001Christoph Bühler Summary 1,Environmental change and land use may alter the vegetation typical of wetland habitats. However, commonly used techniques for vegetation monitoring that are based on species composition are often not suitable to detect gradual changes in the structure of vegetation at an early stage. In this study we tested if this methodical deficiency could be overcome by observation of the stage structure of a perennial target species. 2,We studied the density and frequency distribution of four phenological stages of the perennial plant Succisapratensis in 24 calcareous fens in eastern Switzerland. These fens differed in management type (mowing, cattle-grazing) and altitude (low, medium, high). Among grazed fens, the intensity of management was quantified by direct observation. Species composition and canopy structure of the plant community surrounding S. pratensis were also measured. 3,High altitude had a positive effect on the density of adult plants of S. pratensis only in mown fens, whereas in grazed fens adult density was highest at medium altitude. 4,Local densities of seedlings and vegetative adults within a fen were higher in mown than in grazed fens, and lower in fens of the lowest altitude level than of the two higher ones. However, there were no differences in the relative proportions of all four phenological stages among main factors except that significantly fewer seedlings occurred in fens of the lowest altitude level. 5,It is the intensity rather than the mere type of management regime that is crucial for shaping populations of S. pratensis: for grazed fens, there is a negative relationship between intensity of grazing and density of adult plants of S. pratensis. Moreover, the number, the relative proportion of seedlings and the seed-set are all negatively correlated with grazing intensity. 6,The species composition of the plant community, but not its physical structure, was significantly related to the relative proportion of seedlings of S. pratensis, which supports the indicator qualities of the target species. 7,Monitoring the population structure of one or several target species provides important indicator information about the stability of a whole plant community. For the target-species approach we propose to use characteristic but frequently and steadily occurring species instead of rare or endangered ones. [source] Extreme altitude mountaineering and Type 1 diabetes; the Diabetes Federation of Ireland Kilimanjaro ExpeditionDIABETIC MEDICINE, Issue 9 2001K. Moore Abstract Aims To examine the effects of extreme altitude mountaineering on glycaemic control in Type 1 diabetes, and to establish whether diabetes predisposes to acute mountain sickness (AMS). Methods Fifteen people with Type 1 diabetes and 22 nondiabetic controls were studied during the Diabetes Federation of Ireland Expedition to Kilimanjaro. Daily insulin requirements, blood glucose estimations and hypoglycaemic attacks were recorded in diaries by the people with diabetes. The performance of blood glucose meters at altitude was assessed using standard glucose solutions. Symptoms of acute mountain sickness were recorded daily by people with diabetes and by the nondiabetic controls using the Lake Louise Scoring Charts. The expedition medical team recorded the incidence of complications of altitude and of diabetes. The final height attained for each individual was recorded by the expedition medical team and verified by the expedition guides. Results The final altitude ascended was lower in the diabetic than the nondiabetic group (5187 ± 514 vs. 5654 ± 307 m, P= 0.001). The mean daily insulin dose was reduced from 67.1 ± 28.3,32.9 ± 11.8 units (P < 0.001), but only 50% of recorded blood glucose readings were within the target range of 6,14 mmol/L. There were few hypoglycaemic attacks after the first two days of climbing. Both blood glucose meters tested showed readings as low as 60% of standard glucose concentrations at high altitude and low temperatures. The Lake Louise questionnaires showed that symptoms of AMS occurred equally in the diabetic and nondiabetic groups. There were two episodes of mild diabetic ketoacidosis; two of the diabetic group and three of the nondiabetic group developed retinal haemorrhages. Conclusions People with Type 1 diabetes can participate in extreme altitude mountaineering. However, there are significant risks associated with this activity, including hypoglycaemia, ketoacidosis and retinal haemorrhage, with the additional difficulties in assessing glycaemic control due to meter inaccuracy at high altitude. People with Type 1 diabetes must be carefully counselled before attempting extreme altitude mountaineering. Diabet. Med. 18, 749,755 (2001) [source] Haematological and respiratory gas changes in horses and mules exercised at altitude (3800 m)EQUINE VETERINARY JOURNAL, Issue S36 2006H. M. GREENE Summary Reason for performing study: Despite the common use of equids as visitors to high altitude mountainous environments, there are a paucity of carefully orchestrated scientific approaches. Further, again as a function of a common perceived advantage of mules over horses in these similar environments there are needs for controlled comparisons between these 2 equids. Objective: To measure haematological and respiratory function in horses and mules at low altitude (225 m), at rest and post exercise. In addition the rate and magnitude of these changes were followed over a 13 day period at high altitude (3800 m) to contrast acclimatisation. Methods: Resting and exercise venous blood samples (1 min post exercise) were obtained from 6 horses and 5 mules housed at 225 m (LA) and then transported to 3800 m (HA) for 13 days. The standardised exercise tests at both LA and HA consisted of trotting (3.0 m/sec) up an incline (6%) for 2 km. Data were analysed with repeated measures ANOVA (comparison of altitude acclimatisation and species) for changes in haematological and respiratory gases. Results: At low altitude, no group differences were found with both resting (P=0.69) and exercising (P=0.74) heart rates. Resting PCV was 8% lower in the mules (P=0.02) and 20% lower during exercise (P=0.02). Horses had significantly higher 2,3-diphosphoglycerate (2,3-DPG)/g Hb at both rest (P=0.003) and exercise (P=0.03). Exercise at HA increased PCV (P=0.03) in both groups, but the increase was attenuated in the mules compared to horses. The increase with 2,3-DPG/g Hb was expressed at HA in both groups (P=0.001) and was also attenuated in mules (P=0.03). Both groups were alkalotic compared to LA (P=0.001), and there were no group differences (P = 0.95). Conclusion: Of the variables measured, the most notable distinction between species was identified for only PCV and 2,3-DPG with both higher in horses, at both LA and HA. While the attenuated response of PCV in mules for the same exercise might argue for an improved adaptation to altitude, the lower 2,3-DPG might not. Other variables during the exercise bout were not different between species. [source] Regulation of cerebral blood flow in mammals during chronic hypoxia: a matter of balanceEXPERIMENTAL PHYSIOLOGY, Issue 2 2010Philip N. Ainslie Respiratory-induced changes in the partial pressures of arterial carbon dioxide and oxygen play a major role in cerebral blood flow (CBF) regulation. Elevations in (hypercapnia) lead to vasodilatation and increases in CBF, whereas reductions in (hypocapnia) lead to vasoconstriction and decreases in CBF. A fall in (hypoxia) below a certain threshold (<40,45 mmHg) also produces cerebral vasodilatation. Upon initial exposure to hypoxia, CBF is elevated via a greater relative degree of hypoxia compared with hypocapnia. At this point, hypoxia-induced elevations in blood pressure and loss of cerebral autoregulation, stimulation of neuronal pathways, angiogenesis, release of adenosine, endothelium-derived NO and a variety of autocoids and cytokines are additional factors acting to increase CBF. Following 2,3 days, however, the process of ventilatory acclimatization results in a progressive rise in ventilation, which increases and reduces , collectively acting to attenuate the initial rise in CBF. Other factors acting to lower CBF include elevations in haematocrit, sympathetic nerve activity and local and endothelium-derived vasoconstrictors. Hypoxia-induced alterations of cerebrovascular reactivity, autoregulation and pulmonary vascular tone may also affect CBF. Thus, the extent of change in CBF during exposure to hypoxia is dependent on the balance between the myriad of vasodilators and constrictors derived from the endothelium, neuronal innervations and perfusion pressure. This review examines the extent and mechanisms by which hypoxia regulates CBF. Particular focus will be given to the marked influence of hypoxia associated with exposure to high altitude and chronic lung disease. The associated implications of these hypoxia-induced integrative alterations for the regulation of CBF are discussed, and future avenues for research are proposed. [source] Allometric relationships between lamina area, lamina mass and petiole mass of 93 temperate woody species vary with leaf habit, leaf form and altitudeFUNCTIONAL ECOLOGY, Issue 4 2008Guoyong Li Summary 1The allometric scaling relationship between lamina and lamina support has rarely been examined, such that its significance to plant life-history strategies has not been fully explored and understood so far. We investigated the sizes of leaf lamina and petiole for 93 temperate broad-leaved woody species at two altitudes of a southwestern mountain, and analysed the scaling relationship in relation to leaf habit (evergreen vs. deciduous), leaf form (simple- vs. compound-leaved species), and habitat type (low vs. high altitude). 2Significant allometric scaling relationships were found between petiole mass and lamina mass, and between petiole mass and lamina area, with common slopes of 0·872 and 0·742, respectively, both significantly departed from the value of 1·0. The results of phylogenetic comparative analyses were in accordance with the observed positive scaling relationships. 3The evergreen species were found to have a greater petiole mass than the deciduous at a given lamina area; whilst a contrasting pattern was observed between lamina mass and petiole mass, in which the evergreens had a greater biomass allocation to lamina for the same petiole mass relative to the deciduous. 4The compound-leaved species were observed to be significantly greater in both lamina area and lamina support (including petioles, rachis and petiolules) than the simple-leaved species, whereas the former had a smaller lamina area or lamina mass at a given petiole mass than the latter. 5The plants from the high altitude had less lamina area at a given petiole investment compared to those from the lower altitude, likely due to the large mechanic and transporting requirements of petioles in the species at high altitude. 6Our results indicate that petioles serve as an adverse forcing on the maximization of lamina area and lamina biomass and that the allometric relationship between lamina and lamina support varies with leaf habit, leaf form and habitat. [source] Trends in aquatic macrophyte species turnover in Northern Ireland , which factors determine the spatial distribution of local species turnover?GLOBAL ECOLOGY, Issue 5 2004Einar Heegaard ABSTRACT Aim, The study examined qualitative predictions of ecological theories in relation to the spatial distribution of species turnover of aquatic macrophytes, through the following parameters: (1) distance between lakes (2) chemical conditions of the lakes (3) chemical differences between the lakes, and (4) the lake size. Location, 562 lakes dispersed throughout Northern Ireland were analysed. Methods, To obtain species turnover estimates independent of richness, the average distance between focal lakes and their five nearest neighbours in ordination space (DCA) was standardized by the species richness in a Generalized Additive Model (GAM). The relationships between species turnover and ecological (chemical condition, chemical difference, distance between lakes, and lake-size) and geographical parameters (latitude, longitude, and altitude) were analysed using GAM. Results, The results indicate that the pattern in species turnover is a combination of the chemical conditions and the distance between the lakes, including the interaction term. The effects of chemical heterogeneity and lake size parameters were both positive but weak. In general, increased distance and decreased ionic concentration contribute to increased turnover. The influence of distance on species turnover is strongest at low and high altitude, and at mid-elevation the species turnover is mainly driven by the chemical conditions. Towards the north there is an increasing influence of distance, whereas in the south the chemical conditions have their strongest influence. Conclusions, There is a need for components from several established ecological theories to explain the spatial trends in species turnover within Northern Ireland. Central theories in this particular study are the population/metapopulation dynamics, the continuum concept, and the species-pool concept. [source] Life history of a mule (c. 160 AD) from the Roman fort Biriciana/Weißenburg (Upper Bavaria) as revealed by serial stable isotope analysis of dental tissuesINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2010T. E. Berger Abstract The presence of the osseous remains of at least four mules in a garbage dump at the Roman fort of Biriciana near the town of Weißenburg, Upper Bavaria, dating to c. 160 AD, raised the question as to whether mule breeding was already performed to the north of the Alps during the Middle Roman Empire, or whether these animals still had to be imported from the Mediterranean. Serial analyses of the dental enamel and dentine of a lower fourth premolar and the surrounding alveolar bone of a mandible of a mule in terms of stable strontium isotopic ratios of the apatite, and stable carbon and oxygen isotope ratios of the structural carbonate, were carried out to test whether this individual moved long distances during its lifetime. Since isotopic ratios obtained by serial analysis can be correlated with consecutive ontogenetic stages, it can be assumed that this particular individual experienced significant changes in terms of diet and environmental parameters after its eighth year of life. These changes included a period of residence in a region of high altitude, most likely the Alps considering the location of the Roman fort where the mule was found. The isotopic data obtained do not contradict the assumption that this animal was bred and raised in northern Italy, to frequent later in its adult life the Alps and finally perish at Biriciana/Weißenburg. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hypoxia and oxidation levels of DNA and lipids in humans and animal experimental modelsIUBMB LIFE, Issue 11 2008Peter Møller Abstract The objective of this review was to evaluate the association between hypoxia and oxidative damage to DNA and lipids. Evaluation criteria encompassed specificity and validation status of the biomarkers, study design, strength of the association, dose-response relationship, biological plausibility, analogous exposures, and effect modification by intervention. The collective interpretation indicates persuasive evidence from the studies in humans for an association between hypoxia and elevated levels of oxidative damage to DNA and lipids. The levels of oxidatively generated DNA lesions and lipid peroxidation products depend on both the duration and severity of the exposure to hypoxia. Largest effects are observed with exposure to hypoxia at high altitude, but other factors, including ultraviolet light, exercise, exertion, and low intake of antioxidants, might contribute to the effect observed in subjects at high altitude. Most of the animal experimental models should be interpreted with caution because the assays for assessment of lipid peroxidation products have suboptimal validity. © 2008 IUBMB IUBMB Life, 60(11): 707,723, 2008 [source] Villous trophoblast growth in pregnancy at high altitudeJOURNAL OF ANATOMY, Issue 5 2002T. M. Mayhew The trophoblastic epithelium of placental villi exhibits continuous turnover. Phases of proliferation, recruitment, maturation, terminal differentiation (apoptosis) and extrusion exist in steady state and occur in distinctive spatial compartments, viz. cytotrophoblast cells (CT), syncytiotrophoblast (ST), syncytial knots (SK), denudation sites (DEN) and syncytial fragments. Hypoxia in vitro stimulates CT proliferation but inhibits recruitment into ST. Pregnancy at high altitude (HA) is associated with reduced birthweight and provides a convenient model of preplacental (hypobaric) hypoxia. HA placentas show impoverished villous growth and changes in the incidences of CT cells and SK regions. Here we examine placentas from Amerindian and nonindigenous women who completed full-term pregnancies at low altitude (LA; 400 m; n = 25) and high altitude (HA; 3600 m; n = 45) in Bolivia. We test the hypothesis that HA pregnancy disturbs the epithelial steady state as reflected in the relative volumes and surfaces of trophoblast compartments. Masson trichrome stained tissue sections and microscopical fields were generated by uniform random sampling. Point and intersection counts were used to estimate the volumes and surface areas of nonsyncytial knots (nonSK), SK regions, syncytial bridges (SB) and denudation sites (DEN). Absolute values were compared by 2-way analyses of variance to resolve altitudinal from ethnic effects. At LA, trophoblast comprised about 85% nonSK, 8% SK, 5% SB and 3% CT by volume. Its maternal surface area comprised about 91% nonSK, 5% SK, 2% SB, and 3% DEN. Apart from CT (the fractional volume of which increased to 4%, P < 0.05), relative volumes of trophoblast compartments did not alter significantly at HA. However, there was a roughly 30% reduction in absolute volume of trophoblast at HA (P < 0.001) which could be explained mainly by a decrease in volume of nonSK regions (P < 0.001). The volume of CT was unaltered. Absolute surface areas of villi also declined at HA (by 20%, P < 0.01) and, again, this was attributed mainly to nonSK. The findings confirm that poor villous growth is partly due to failure of trophoblast to attain the growth seen at LA. The reduced trophoblastic growth occurs despite an increase in relative volume of CT cells (consistent with previously reported increases in proliferative activity) and, probably, by a combination of compromised syncytial fusion and continuing extrusion of syncytial fragments. [source] The amounts and deposition patterns of fibrin-type fibrinoid at the villous surface are altered in pregnancy at high altitudeJOURNAL OF ANATOMY, Issue 5 2002T. M. Mayhew In pregnancy at high altitude, there is preplacental (hypobaric) hypoxia and intrauterine fetal growth is restricted. Previous studies on placentas from Amerindian and nonindigenous women completing term pregnancies at low (LA; 400 m) and high (HA; 3600 m) altitudes in Bolivia showed that HA placentas had smaller surface areas of villi and smaller volumes of fibrin type fibrinoid (FTF). Recently we devised a stereological method for testing whether perivillous FTF (pFTF) is randomly distributed at the surface of villous trophoblast. Here the method is applied to test 2 experimental hypotheses: [1] deposition of pFTF is nonrandom regardless of altitude and [2] deposition patterns differ between altitudes. Uniform random samples of microscopical fields were drawn from Masson trichrome stained sections and intersection counts used to estimate the surface areas of, and patterns of pFTF on, 4 regions of trophoblast: nonsyncytial knots (nonSK), syncytial knots (SK), syncytial bridges (SB) and denudation sites (DEN). Absolute areas were compared by 2-way analyses of variance. Expected and observed distributions were compared by (2 and contingency table analyses. At LA the mean (SEM) volume of FTF was 8.4 (1.54) cm3 and villous surface area was 7.0 (0.43) m2. At HA FTF volume was reduced by about 50% (P < 0.01) and villous surface by 20% (P < 0.01). The surface composition of trophoblast in LA placentas was nonSK (91%), SK (5%) and SB and DEN (both less than 3%). Relative surfaces were not significantly altered in HA placentas but, due to the impoverished growth of villi at HA, the changes represented a real decline in absolute surface of nonSK. At HA, the total surface of pFTF on trophoblast decreased by about 40%, from 4430 (564) cm2,2570 (406) cm2 (P < 0.01). At both altitudes pFTF deposition was preferentially found at DEN (12-fold greater than expected for a random distribution). Pattern differences were detected between altitudes. In HA placentas the amount of pFTF deposited on nonSK regions was about 45% less (P < 0.05); apparent changes on SK and SB regions were not significant. These histometric findings suggest that the coagulation-fibrinolysis steady state is altered at HA and favours greater fibrinolysis. At least some of the fibrinolytic or anticoagulant activity seems to reside in or on thinner regions of villous trophoblast and the placenta may be a relatively privileged site in terms of fibrinolysis. Also, reduced deposition of pFTF is probably linked to changes in the steady state of trophoblast turnover which seems to be perturbed in HA pregnancies. [source] Seasonality and host utilization of the invasive fruit fly, Bactrocera invadens (Dipt., Tephritidae) in central TanzaniaJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2006M. W. Mwatawala Abstract:, The temporal occurrence of the invasive and economically important pest fruit fly, Bactrocera invadens was studied in three agro-ecological areas of Morogoro Region, central Tanzania, during 2004,2005. Weekly and monthly trappings were carried out with methyl eugenol, protein bait and synthetic food attractant. Bactrocera invadens was permanently present at low and mid-altitudes (380,520 m a.s.l.) with peak periods coinciding with the fruiting season of mango (Mangifera indica) and guava (Psidium guajava). At high altitude (1650 m a.s.l.) its incidence was only temporal and apparently the result of dispersal from lower altitudes after the mango fruiting season. Rearing results showed mango, loquat (Eriobotrya japonica), guava and grapefruit (Citrus × paradisi) to be the favoured commercial host fruits. Other Citrus species, cucurbits, papaya (Carica papaya) and avocado (Persea americana) were less favoured. [source] The influence of geographic and morphometric factors on the distribution of water bird species in small high altitude tropical man made reservoirs, Central Rift Valley, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Francis Mwaura Abstract Variability in waterfowl characteristics among eight high altitude (2040,2640 m) small shallow (0.065,0.249 km2; 0.9,3.1 m) reservoirs in the escarpment zone along the central rift valley in Kenya between Naivasha and Nakuru towns were studied between 1998 and 2000. The aim of the study was to establish whether the geographic status of small reservoirs in terms of altitude and surface gradient can affect the characteristics of their birdlife in terms of bird counts and species numbers. The study also aimed at establishing whether reservoir bird counts and species number can be predicted by reservoir morphometric factors especially water depth, surface area, length of shoreline and area-shoreline ratio. The other aim was to determine the influence of local environment especially distance from the nearest natural lakes, and house density on the birdlife. The findings showed that geographic location of the reservoirs in terms of altitude and landscape had a strong influence on birdlife whereby reservoirs in higher altitude and flat plateau landscape were found to support higher bird species and counts. Larger and deeper reservoirs were richer in water bird species but small and shallow reservoirs were superior in terms of both bird species and counts. Reservoirs with more coarse, irregular and highly erratic shorelines had higher species number than those with smooth and well-rounded shorelines. The reservoir birdlife was found to be influenced by the number of farm houses near the waterbodies and also the distance from the nearby rift valley lakes. The results showed that both geographic and morphometric considerations are necessary in the establishment of new reservoirs especially for utilization in birdlife conservation and ecotourism. Résumé Entre 1998 et 2000, nous avons étudié la variabilité des caractéristiques de l'avifaune aquatique de huit petits réservoirs peu profonds (0,065,0,249 km²; 0,9,3,1 m) de haute altitude (2040,2640 m) dans la région de l'escarpement de la Rift Valley située entre Naivasha et Nakuru, au Kenya. L'objectif de cette étude était d'établir si le statut géographique de réservoirs petits en termes d'altitude et de gradient de surface peut affecter les caractéristiques de leur avifaune en ce qui concerne le nombre d'oiseaux et d'espèces. L'étude visait aussi àétablir si l'on peut prédire la densité des oiseaux et le nombre d'espèces d'après les facteurs morphométriques du réservoir, et en particulier la profondeur de l'eau, la superficie de la surface, la longueur des berges et le rapport entre la superficie et la longueur de berges. L'autre objectif était de déterminer plus spécialement l'influence de la distance par rapport aux lacs naturels les plus proches et celle de la densité des habitations sur l'avifaune. Les résultats ont montré que la situation géographique des réservoirs en termes d'altitude et de paysage avait une forte influence sur l'avifaune, en ceci que les réservoirs de plus haute altitude et situés dans un paysage de plateau régulier accueillaient un plus grand nombre d'espèces et une plus forte densité d'oiseaux. Les réservoirs plus étendus et plus profonds étaient plus riches en espèces d'oiseaux d'eau, et les réservoirs plus petits et moins profonds étaient supérieurs en termes de nombre d'espèces d'oiseaux et de densité. Les réservoirs dont les berges étaient accidentées, instables et irrégulières avaient un nombre d'espèces plus élevé que ceux dont les berges étaient bien délimitées et planes. On a découvert que l'avifaune d'un réservoir était influencée par le nombre d'exploitations agricoles situées près du plan d'eau et aussi par la distance qui le séparait des lacs les plus proches de la Rift Valley. Les résultats ont montré qu'il faut tenir compte des données géographiques et morphométriques pour établir de nouveaux réservoirs, spécialement s'ils sont destinés à la conservation de l'avifaune et au tourisme. [source] Comparison of maternal and newborn outcomes of Tibetan and Han Chinese delivering in Lhasa, TibetJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 6 2008Suellen Miller Abstract Aim:, To compare maternal and neonatal outcomes of Tibetan and Han Chinese women delivering vaginally at high altitude (3650 meters) in Lhasa, Tibet Autonomous Region, People's Republic of China. Method:, Comparative analysis of data from a prospective observational study of Tibetan (n = 938) and Han Chinese (n = 146) women delivering at three hospitals between January 2004 and May 2005. Results:, Han Chinese women had higher rates of pre-eclampsia/gestational hypertension than Tibetan women, (10.3% vs 5.9%, P = 0.04). There was no difference in rates of postpartum hemorrhage between Tibetan and Han women (12.8% vs 17.1%, P = 0.15). Han newborns weighed significantly less than Tibetan newborns (P < 0.01), and were twice as likely to be small for gestational age, (24.5% vs 11.6%, P < 0.01). Tibetan newborns were less likely to have poor neonatal outcomes than Han newborns (P < 0.01). Conclusion:, In high altitude deliveries in Tibet, adverse outcomes were significantly more common among Han Chinese. [source] Prevalence and Severity of Dental Caries in Adolescents Aged 12 and 15 Living in Communities with Various Fluoride ConcentrationsJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 1 2007América Patricia Pontigo-Loyola DrO Abstract Objectives: To determine the experience, prevalence, and severity of dental caries in adolescents naturally exposed to various fluoride concentrations. Methods: A cross-sectional census was conducted on 1,538 adolescents aged 12 and 15 years living at high altitude above sea level (>2,000 m or >6,560 ft) in above-optimal fluoridated communities (levels ranging from 1.38 to 3.07 ppm) of Hidalgo, Mexico. Sociodemographic and socioeconomic data were collected using questionnaires. Two previously trained and standardized examiners performed the dental exams. Results: Caries prevalence was 48.6 percent and mean of decay, missing, and filling teeth (DMFT) for the whole population was 1.15 ± 1.17. In terms of severity, 9.6 percent of the adolescents had DMFT , 4, and 1.7 percent had ,7. The significant caries index (SiC) was 2.41 in the group of 12-year-olds, and 3.46 in the 15-year-olds. Higher experience and prevalence were observed in girls, in children with dental visit in the past year, those in the wealthiest socioeconomic status (SES) (quartiles 2, 3, and 4), those whose locale of residence is in San Marcos and Tula Centro, and in fluorosis-free children and those with moderate/severe fluorosis. In an analysis of caries severity (DMFT , 4), both adolescents with very mild/mild and moderate/severe dental fluorosis have higher caries severity. Conclusions: The results indicated that caries experience, prevalence, and severity as well as SiC index among 12- and 15-year-old adolescents were relatively low. Sociodemographic and socioeconomic variables commonly associated with dental caries were also observed in Mexican adolescents. Unlike other studies, we found that caries increased with higher SES. Fluoride exposure (measured through fluorosis presence) does not appear to be reducing the caries prevalence (DMFT > 0) or caries severity (DMFT , 4) in these high-altitude communities. [source] Effects of slope exposure, altitude and yield on coffee quality in two altitude terroirs of Costa Rica, Orosi and Santa María de DotaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2005Jacques Avelino Abstract This study assessed the effects of slope exposure, altitude and yield on several cup quality criteria of coffees from two altitude terroirs of Costa Rica, Orosi (between 1020 and 1250 m above sea level) and Santa María de Dota (between 1550 and 1780 m above sea level). East-facing slopes gave beverages with generally superior attributes, probably owing to better exposure to morning sunlight. These beverages were mainly more acid: at Orosi an acidity score of 2.73 out of 5 was obtained (3.64 for Santa María de Dota) for eastern exposures, as opposed to 2.36 on average (3.28 for Santa María de Dota) for other exposures. In addition, a positive relation was found between altitude and taster preferences in both terroirs. A negative relation was also found between yield and beverage acidity at Santa María de Dota, where some coffee trees produced up to 13 kg of coffee cherry. Coffees from Orosi were characterised by a floral flavour, which depended on slope exposure, whilst coffees from Santa María de Dota displayed a chocolate taste, which was more marked at high altitude. In both terroirs the caffeine, trigonelline, fat, sucrose and chlorogenic acid contents were not well correlated with the sensory characteristics. Copyright © 2005 Society of Chemical Industry [source] Fagus sylvatica forest vegetation in Greece: Syntaxonomy and gradient analysisJOURNAL OF VEGETATION SCIENCE, Issue 1 2001Erwin Bergmeier Abstract. This is the first comprehensive study on Fagus sylvatica s.l. forest communities in Greece. It is based on the multivariate analysis of more than 1100 relevés throughout the distribution area of Fagus in Greece, 60 % of which have been sampled within the last 15 years. The data were compiled from all relevant literature and from unpublished field studies. Prior to data analysis, taxonomic and floristic inaccuracies in older literature have been corrected, and some taxa aggregated. Status and distribution of Fagus in Greece, as well as historical and silvicultural aspects, are outlined. Classification resulted in 16 vegetation types defined by species composition, of which 10 units are ranked as association (of which two were described as new) or community, with six subcommunities included. Synonyms from the literature are given to all types. The floristic structure of the data set is displayed by a synoptic table and by DCA ordination. Community differentiation follows a complex edaphic-climatic-phytogeographic pattern. Apart from Fagus sylvatica ssp. orientalis forests of warm and dry habitats and low to medium altitudes which are related to deciduous Quercus forests, four Fagion community groups are distinguished which represent different habitat types: (1) cool, humid, mesotrophic; (2) cool, acidic; (3) high altitude, calcareous; (4) medium altitude, moderately warm and dry. The communities may be assigned to three regional suballiances, viz. (a) Doronico orientalis-Fagenion at medium altitudes of North-Central and East-Central Greece; (b) Doronico columnae-Fagenion in the far north and at high altitudes southward to East-Central Greece; (c) Geranio striati-Fagenion in the Northwest. Various types of thermophilous beech forest are assigned to (a) and (c), acidic forest to (b), and mesic Fagus forest to (b) and (c). [source] Gene expression in peripheral arterial chemoreceptorsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002Estelle B. Gauda Abstract The peripheral arterial chemoreceptors of the carotid body participate in the ventilatory responses to hypoxia and hypercapnia, the arousal responses to asphyxial apnea, and the acclimatization to high altitude. In response to an excitatory stimuli, glomus cells in the carotid body depolarize, their intracellular calcium levels rise, and neurotransmitters are released from them. Neurotransmitters then bind to autoreceptors on glomus cells and postsynaptic receptors on chemoafferents of the carotid sinus nerve. Binding to inhibitory or excitatory receptors on chemoafferents control the electrical activity of the carotid sinus nerve, which provides the input to respiratory-related brainstem nuclei. We and others have used gene expression in the carotid body as a tool to determine what neurotransmitters mediate the response of peripheral arterial chemoreceptors to excitatory stimuli, specifically hypoxia. Data from physiological studies support the involvement of numerous putative neurotransmitters in hypoxic chemosensitivity. This article reviews how in situ hybridization histochemistry and other cellular localization techniques confirm, refute, or expand what is known about the role of dopamine, norepinephrine, substance P, acetylcholine, adenosine, and ATP in chemotransmission. In spite of some species differences, review of the available data support that 1) dopamine and norepinephrine are synthesized and released from glomus cells in all species and play an inhibitory role in hypoxic chemosensitivity; 2) substance P and acetylcholine are not synthesized in glomus cells of most species but may be made and released from nerve fibers innervating the carotid body in essentially all species; 3) adenosine and ATP are ubiquitous molecules that most likely play an excitatory role in hypoxic chemosensitivity. Microsc. Res. Tech. 59:153,167, 2002. © 2002 Wiley-Liss, Inc. [source] Immunology highlights at high altitude: review of the fourth EAACI-GA2LEN Davos MeetingALLERGY, Issue 10 2006J. Gutermuth The field of allergy is moving fast. To keep pace with the underlying immunologic mechanisms, the 4th EAACI-GA2LEN Davos meeting on ,Basic Immunology Research in Allergy and Clinical Immunology' was organized in Grainau, Germany, February 16th,19th, 2006 by the Immunology Section of the European Academy of Allergy and Clinical Immunology and the ZAUM , Center for Allergy and Environment, Technical University Munich, with generous support from GA2LEN. Recent advances and new insights on innate and adaptive immunity, environmental factors influencing immune responses, immune regulation and allergic inflammation were presented by keynote speakers and selected participants. [source] Winter down-regulation of intrinsic photosynthetic capacity coupled with up-regulation of Elip-like proteins and persistent energy dissipation in a subalpine forestNEW PHYTOLOGIST, Issue 2 2006C. Ryan Zarter Summary ,,Overwintering, sun-exposed and photosynthetically inactive evergreens require powerful photoprotection. The goal of this study was to seasonally characterize photosynthesis and key proteins/components involved in electron transport and photoprotection. ,,Maximal photosystem II (PSII) efficiency and photosynthetic capacity, amounts of zeaxanthin (Z), antheraxanthin (A), pheophytin and proteins (oxygen-evolving 33 kDa protein (OEC), PSII core protein D1 and subunit S (PsbS) protein, and members of the early light-inducible protein (Elip) family) were assessed in five conifer species at high altitude and in ponderosa pine (Pinus ponderosa) at moderate altitude during summer and winter. ,,Relative to summer, winter down-regulation of photosynthetic capacity and loss of PSII efficiency at the high-altitude sites were paralleled by decreases in OEC, D1, and pheophytin; massive nocturnal retention of (Z + A) and up-regulation of two to four proteins cross-reactive with anti-Elip antibodies; and no change in PsbS amount. By contrast, ponderosa pine at moderate altitude exhibited no down-regulation of photosynthetic capacity, smaller depressions in PSII efficiency, and less up-regulation of Elip family members. ,,These results support a function for members of the Elip family in the acclimation of sun-exposed needles that down-regulate photosynthesis during winter. A possible role in sustained photoprotection is considered. [source] The Vitamin D Status Among TibetansPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Gelsor Norsang UVB from the sun and intake from food are the only human sources of vitamin D. Tibet is a unique region for comparisons of these sources: (1) it lies at a low latitude and at a high altitude and has very large annual fluences of UVB; (2) the traditional Tibetan food is poor in vitamin D. Blood samples were taken from 63 persons of different age, with different occupations and staying at different places. UVB doses at these places were measured. The samples were analyzed by a standard radioimmune assay for determination of the serum concentration of 25 hydroxyvitamin D (25(OH)D). The main finding was that among nomads, there seems to be severe vitamin D deficiency (serum levels of 25(OH)D < 30 nm). We tentatively propose that the low level of 25(OH)D of nomads is related to their clothing and sun exposure habits. For persons of other occupations (students, teachers and farmers) the levels are higher, although a significant fraction of these persons also have lower levels than 75 nm, by many regarded as a limit for insufficiency related to a number of negative health conditions. The annual dose of vitamin D-generating UVB is about five times larger in Lhasa than in Oslo. Despite this, the average vitamin D status seems to be similar, except in the case of nomads. This phenomenon is certainly related to food habits. In conclusion, the 25(OH)D status among nomads in Tibet appears to be alarmingly low. However, for people of other occupations the status is more normal. [source] Nutritional, developmental, and genetic influences on relative sitting height at high altitude,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009Sara Stinson The study explores how nutritional status, developmental exposure to high-altitude hypoxia, and genetic ancestry influence relative sitting height in two groups of high-altitude Bolivian children aged 8 through 13 years of age: 253 rural Aymara children of very low socioeconomic status and 273 children of upper socioeconomic status from the capital city of La Paz. The rural Aymara children on average have longer trunks relative to stature, but there is also overlap in body proportions between the two groups of children. The 20% of each sample in the region of overlap was examined to investigate influences on relative sitting height. Nutritional effects on relative sitting height are suggested by the finding that Aymara children with relatively long legs are taller, heavier, and fatter than other Aymara children. Developmental and genetic influences on relative sitting height are suggested by the finding that high relative sitting heights in elite urban children are associated with a greater percentage of time lived at high altitude and with parents born in Bolivia. Separating developmental and ancestry effects is difficult because the two are closely interconnected in the urban children. The results of this study suggest that influences on growth in relative trunk and leg length are similar to those that affect other aspects of growth in Andean populations. They also highlight the fact that because relative sitting height gradually decreases prior to adolescence and then increases, the interpretation of variation in body proportions in children is not always straightforward. Am. J. Hum. Biol. 2009. © 2009 Wiley-Liss, Inc. [source] Evolutionary adaptation to high altitude: A view from in utero,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009Colleen Glyde Julian A primary focus within biological anthropology has been to elucidate the processes of evolutionary adaptation. Frisancho helped to move anthropology towards more mechanistic explanations of human adaptation by drawing attention to the importance of the functional relevance of human variation. Using the natural laboratory of high altitude, he and others asked whether the unique physiology of indigenous high-altitude residents was the result of acclimatization, developmental plasticity, and/or genetic adaptation in response to the high-altitude environment. We approach the question of human adaptation to high altitude from a somewhat unique vantage point; namely, by examining physiological characteristics,pregnancy and pregnancy outcome,which are closely associated with reproductive fitness. Here we review the potent example of high-altitude native population's resistance to hypoxia-associated reductions in birth weight, which is often associated with higher infant morbidity and mortality at high altitude. With the exception of two recent publications, these comparative birth weight studies have utilized surnames, self-identification, and/or linguistic characteristics to assess ancestry, and none have linked ,advantageous' phenotypes to specific genetic variations. Recent advancements in genetic and statistical tools have enabled us to assess individual ancestry with higher resolution, identify the genetic basis of complex phenotypes and to infer the effect of natural selection on specific gene regions. Using these technologies our studies are now directed to determine the genetic variations that underlie the mechanisms by which high-altitude ancestry protects fetal growth and, in turn, to further our understanding of evolutionary processes involved in human adaptation to high altitude. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] Developmental adaptation: Where we go from here,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009A. Roberto Frisancho The concept of developmental adaptation is a powerful framework that can be used for understanding the origin of population differences in phenotypic and genotypic biological traits. There is great deal of information describing how developmental responses can shape adult biological outcomes. Specifically, current research suggest that individuals developing in stressful environments such as high altitude will attain an adult enlarged residual lung volume that contribute to the successful cardiovascular adaptation of the high-altitude Andean native. Likewise, studies on the etiology of the metabolic syndrome indicate that development under poor nutritional environments elicit efficient physiological and metabolic responses for the utilization of nutrients and energy, which become disadvantageous when the adult environmental conditions provide abundant access to food and low energy expenditure. Epigenetic research in experimental animals and retrospective research in humans confirm that environmental influences during developmental period have profound consequences on the phenotypic expression of biological and behavioral traits during adulthood. Research on epigenetics is a productive direction for human biologists concerned with understanding the origins of human biological variability. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source] Control of the flexible annual/biennial life cycle of the heather psyllid Strophingia ericaePHYSIOLOGICAL ENTOMOLOGY, Issue 3 2001J. Butterfield Abstract.Strophingia ericae (Curtis) (Homoptera: Psylloidea) takes one or two years to complete its life cycle. In both cases eggs hatch over a prolonged period from midsummer, possibly extending into the following spring at high altitude, and instars overlap in time. Instar III is the predominant overwintering stage in the lowland, annual cycle, whereas in the upland, biennial cycle most first-year nymphs overwinter in instars I and II and most second-year nymphs in instar V. When moved to the laboratory, instars IV and V from a predominantly annual population showed accelerated development in response to elevated temperatures and to long days in both mid-winter and early spring. In the biennial life cycle, short autumn days retard instar V development but the response to photoperiod disappears by the end of winter. Exposure to LD 18 : 6 h retarded development of early instars in the annual population, resulting in an accumulation in instar III. The proportion of overwintering instars I and II rises with increase in altitude and moult to instar III becomes progressively delayed. Nymphs that reach instar III under long daylengths in the year following hatching are channelled towards the biennial cycle. Exposure of a predominantly biennial population to 15 °C and LD 18 : 6 h after midsummer, thus avoiding autumn conditions, promoted the rapid development of overwintered nymphs, switching the cycle from biennial to annual. [source] Antioxidant and DNA protecting properties of anti-fatigue herb Trichopus zeylanicusPHYTOTHERAPY RESEARCH, Issue 8 2005Binu Tharakan Abstract Chronic fatigue is considered a complex symptom for which currently there is no curative treatment available. Oxidative stress plays an important role in the etiology of fatigue and antioxidant treatment might be a valuable therapeutic approach. The Kani, a tribal high altitude living population in southern India, traditionally use the seeds of Trichopus zeylanicus to combat fatigue. In this study, the antioxidant properties of Trichopus zeylanicus were established on free radicals (DPPH and ABTS), its ability to reduce iron, lipoxygenase activity and hydrogen peroxide-induced lipid peroxidation. The effects of Trichopus zeylanicus on reactive oxygen species induced plasmid DNA (pBR322) cleavage were also investigated. Trichopus zeylanicus significantly scavenged free radicals, reduced lipid peroxidation and inhibited lipoxygenase activity. Trichopus zeylanicus also exhibited iron-chelating activity and inhibited reactive oxygen species induced DNA damage. Trichopus zeylanicus contains NADH, polyphenols and sulfhydryl compounds, which have the ability to scavenge reactive oxygen species suggesting that the antioxidant activity may be an important mechanism of action of Trichopus zeylanicus to combat fatigue. Copyright © 2005 John Wiley & Sons, Ltd. [source] Acute mountain sickness is associated with sleep desaturation at high altitudeRESPIROLOGY, Issue 4 2004Keith R. BURGESS Objective: This study was intended to demonstrate a biologically important association between acute mountain sickness (AMS) and sleep disordered breathing. Methodology: A total of 14 subjects (eight males, six females aged 36 ± 10 years) were studied at six different altitudes from sea level to 5050 m over 12 days on a trekking route in the Nepal Himalaya. AMS was quantified by Lake Louise (LL) score. At each altitude, sleep was studied by 13 channel polysomnography (PSG). Resting arterial blood gases (ABG) and exercise SaO2 were measured. Ventilatory responses (VR) were measured at sea level. Individual data were analysed for association at several altitudes and mean data were analysed for association over all altitudes. Results: ABG showed partial acclimatization. For the mean data, there were strong positive correlations between LL score and altitude, and periodic breathing, as expected. Strong negative correlations existed between LL score and PaO2, PaCO2, sleep SaO2 and exercise SaO2, but there was no correlation with sea level VR. There were equally tight correlations between LLs/PaO2 and LL score/sleep SaO2. The individual data showed no significant correlations with LL score at any altitude, probably reflecting the non-steady state nature of the experiment. In addition, mean SaO2 during sleep was similar to minimum exercise SaO2 at each altitude and minimum sleep SaO2 was lower, suggesting that the hypoxic insult during sleep was equivalent to or greater than walking at high altitude. Conclusions: It is concluded that desaturation during sleep has a biologically important association with AMS, and it is speculated that under similar conditions (trekking) it is an important cause of AMS. [source] Antioxidants reverse depression of the hypoxic ventilatory response by acetazolamide in manTHE JOURNAL OF PHYSIOLOGY, Issue 3 2006Luc J. Teppema The carbonic anhydrase inhibitor acetazolamide may have both inhibitory and stimulatory effects on breathing. In this placebo-controlled double-blind study we measured the effect of an intravenous dose (4 mg kg,1) of this agent on the acute isocapnic hypoxic ventilatory response in 16 healthy volunteers (haemoglobin oxygen saturation 83,85%) and examined whether its inhibitory effects on this response could be reversed by antioxidants (1 g ascorbic acid i.v. and 200 mg ,-tocopherol p.o.). The subjects were randomly divided into an antioxidant (Aox) and placebo group. In the Aox group, acetazolamide reduced the mean normocapnic and hypercapnic hypoxic responses by 37% (P < 0.01) and 55% (P < 0.01), respectively, and abolished the O2,CO2 interaction, i.e. the increase in O2 sensitivity with rising PCO2. Antioxidants completely reversed this inhibiting effect on the normocapnic hypoxic response, while in hypercapnia the reversal was partial. In the placebo group, acetazolamide reduced the normo- and hypercapnic hypoxic responses by 33 and 47%, respectively (P < 0.01 versus control in both cases), and also abolished the O2,CO2 interaction. Placebo failed to reverse these inhibitory effects of acetazolamide in this group. We hypothesize that either an isoform of carbonic anhydrase may be involved in the regulation of the redox state in the carotid bodies or that acetazolamide and antioxidants exert independent effects on oxygen-sensing cells, in which both carbonic anhydrase and potassium channels may be involved. The novel findings of this study may have clinical implications, for example with regard to a combined use of acetazolamide and antioxidants at high altitude. [source] Ketamine for emergency anaesthesia at very high altitude (4243 m above sea-level),ANAESTHESIA, Issue 9 2007M. P. W. Grocott Summary A 22-year-old woman presenting with postpartum haemorrhagic shock at 4243 m altitude required anaesthesia to identify and treat the source of bleeding. Slow intravenous administration of ketamine (0.5 mg.kg,1) resulted in deep anaesthesia and apnoea requiring hand ventilation for 5 min. Haemodynamic stability was maintained throughout the procedure. Haemostasis was achieved following uterine packing and suture of a second-degree vaginal tear and small cervical tear. Confusion and visual hallucinations occurred upon awakening but recovery was otherwise uneventful. Ketamine can be used for emergency anaesthesia in a wilderness environment over 4000 m but it is probable that the benefits outweigh the risks only where life or limb are acutely threatened. Careful titration of the administered dose is strongly advised, particularly in patients where hypovolaemia and/or hypoxaemia are present. The availability of airway management equipment and the skills to use them may significantly reduce the risks associated with anaesthetic administration at very high altitude. [source] Genetic mapping of quantitative trait loci affecting susceptibility in chicken to develop pulmonary hypertension syndromeANIMAL GENETICS, Issue 6 2005T. S. K. M. Rabie Summary Pulmonary hypertension syndrome (PHS), also referred to as ascites syndrome, is a growth-related disorder of chickens frequently observed in fast-growing broilers with insufficient pulmonary vascular capacity at low temperature and/or at high altitude. A cross between two genetically different broiler dam lines that originated from the White Plymouth Rock breed was used to produce a three-generation population. This population was used for the detection and localization of quantitative trait loci (QTL) affecting PHS-related traits. Ten full-sib families consisting of 456 G2 birds were typed with 420 microsatellite markers covering 24 autosomal chromosomes. Phenotypic observations were collected on 4202 G3 birds and a full-sib across family regression interval mapping approach was used to identify QTL. There was statistical evidence for QTL on chicken chromosome 2 (GGA2), GGA4 and GGA6. Suggestive QTL were found on chromosomes 5, 8, 10, 27 and 28. The most significant QTL were located on GGA2 for right and total ventricular weight as percentage of body weight (%RV and %TV respectively). A related trait, the ratio of right ventricular weight as percentage to total ventricular weight (RATIO), reached the suggestive threshold on this chromosome. All three QTL effects identified on GGA2 had their maximum test statistic in the region flanked by markers MCW0185 and MCW0245 (335,421 cM). [source] | ||||||||||||||||||||||||||||||||||||||||