Health in dust belt cities and beyond-an essay by Nick Middleton

Desert dust is associated with morbidity and mortality, and distant spread means lessons for mitigating the harms can be found by looking beyond cities in arid regions, writes Nick Middleton

Monitoring daily events, coping strategies, and emotion during a desert expedition in the Middle East

Personnel operating in extreme environmental conditions are exposed to a variety of stressors. Whether a person adjusts to the conditions and is able to cope has implications for their psychological health. In previous extreme-environment work, temporal changes in stress, coping, and emotion have been reported. Building on previous studies, we used a diary methodology to explore temporal changes in and associations between daily events, coping strategies, and affect during a unique hyperarid desert expedition. Four participants undertaking a crossing of the Empty Quarter desert were recruited to the study. Participants completed pre-expedition, postexpedition, and 4-month follow-up questionnaires. A daily self-report diary was used to collect situational data. Time-based changes were analysed before testing predictive models linking events and coping strategies with affective responses. Findings suggest that participants had an overall positive experience. There were changes in both the events experienced and coping strategies used during the expedition. Variation in events and coping strategies significantly predicted fluctuations in positive and negative affect. Results offer valuable mechanistic information that could inform monitoring systems aimed at tracking psychological variables during operations in extreme environments. Results are discussed in relation to the novel context, diary methodology, and implications for those operating in extremes.

[Should a doctor take into consideration the influence of climatic factors? Deliberations on the occasion of the publication of a new monograph (the book of essays of arid medicine by Z.R. Zununov, I.H. Nurov, and S.Z. Zununova)]

The authors analyze the monograph of the Uzbek scientists professor Z.R. Zununov, I.H. Nurov, and S.Z. Zununova «Essays of arid medicine» (Tashkent: «KAMALAK-PRESS» publishing house, 2016;540). The book presents the results of the comprehensive bioclimatic assessment of the arid zones of Uzbekistan, their extreme climatic conditions (such as high intensity and solar radiation and the considerable duration of its period, dry air and summer heat, sandstorms (the so-called «Afghans»), and the great variety of the natural health-improving factors including mineral waters, microclimate of the speleotherapeutic cave, the desert dune sand, etc. The work is based on the authors' conceptual theory of «arid/meteorological stress syndrome», underlain by the hypothesis of the predominant role of hyperthermal weather hypoxia. A wide range of issues id discussed related to weather and climate adaptation of the healthy subjects (both indigenous and non-indigenous residents) and the patients suffering from ischemic heart disease, chronic obstructive pulmonary disease, and rheumatoid arthritis. Of special interest are the methods proposed for the correction of dysadaptive changes including the application of the natural balneotherapeutic factors existing in the arid zone (hydrogen sulphide and iodine-bromine balneotherapy, climatic therapy, speleotherapy, and psammotherapy (arenation). An important definitive conclusion at which the authors arrive is the necessity of the experimental observations in agreement with the requirements of the medico-biological ethics.

Effect of environmental factors on the germination and emergence of Salvia verbenaca L. cultivars (verbenaca and vernalis): An invasive species in semi-arid and arid rangeland regions

Salvia verbenaca (wild sage) is a commonly cultivated herbal medicine plant, which is native to the Mediterranean climate regions of Europe, Africa, Asia and the Middle East. However, it has become an invasive species in semi-arid and arid regions of southern Australia. Two varieties are present in this region, var. verbenaca and var. vernalis, each of which can be distinguished by differences in morphology and flowering period. Following trials to determine the optimum temperate regime for germination and response to light and dark, seeds of both varieties were tested for their response to variations in pH, moisture stress, salinity, and burial depth. The temperature and light trial was carried out using three different temperature regimes; 30/20°C, 25/15°C and 20/12°C, and two light regimes; 12 hours light/12 hours dark and 24 hours dark, with var. vernalis responding to relatively higher temperatures than var. verbenaca. The germination rate of neither species was significantly inhibited by complete darkness when compared to rates under periodic light exposure. Both varieties germinated at near optimum rates strongly to very strongly in all pH buffer solutions, from pH 5 to pH 10, but they responded most strongly at neutral pH. Var. vernalis showed slightly more tolerance to reduced moisture availability, moderate to strong salinity, and burial depth, compared to var. verbenaca. However, even a fairly shallow burial depth of 2 cm completely inhibited germination of both varieties. Thus, in circumstances where both varieties are present in a soil seedbank, var. vernalis could be expected to establish in more challenging conditions, where moisture is limited and salinity is ‘moderate to high’, implying that it is a more serious threat for invasive weed in conditions where crop plants are already challenged.

Exertional Heat Illness Resulting in Acute Liver Failure and Liver Transplantation

Heat illness remains a large medical burden for militaries around the world. Mitigating the incidence as well as the complications of heat illness must remain on the forefront of operational planning when operating in hot environments. We report the case of a 27-year-old male U.S. Marine who sustained a heat-related illness resulting in fulminant liver failure and permanent disability. The patient was transferred from the field to a civilian hospital. On hospital day 5, liver failure was identified. The patient was transferred to a transplant center, where he successfully received a liver transplant.

Impacts of ridge-furrow rainfall concentration systems and mulches on corn growth and yield in the semiarid region of China

BACKGROUND

Plastic-covered ridge-furrow farming systems for rainfall concentration (RC) improve the water availability for crops and increase the water use efficiency (WUE), thereby stabilizing high yields. In this study, we optimized the mulching patterns for RC planting to mitigate the risks of drought during crop production in semiarid agricultural areas. We conducted a 4-year field study to determine the RC effects on corn production of mulching in furrows with 8% biodegradable films (RCSB ), liquid film (RCSL ), bare furrow (RCSN ) and conventional flat (CF) farming.

RESULTS

We found that RC significantly (P > 0.05) increased the soil moisture in the top 0-100 cm layer and the topsoil temperature (0-20 cm) during the corn-growing period. Mulching with different materials in planting furrows further improved the rain-harvesting, moisture-retaining and yield-increasing effects of RC planting. Compared with CF, the 4-year average total dry matter amount per plant for RCSB , RCSL and RCSN treatments increased by 42.1%, 30.8% and 17.2%, respectively. The grain yield increased by 59.7%, 53.4% and 32.6%, respectively.

CONCLUSION

Plastic-covered ridge and furrow mulched with biodegradable film and liquid film is recommended for use in the semiarid Loess Plateau of China to alleviate the effects of drought on crop production. © 2015 Society of Chemical Industry.

Occurrence of triazole-resistant Aspergillus fumigatus with TR34/L98H mutations in outdoor and hospital environment in Kuwait

BACKGROUND

Invasive aspergillosis due to triazole-resistant Aspergillus fumigatus, a common airborne fungal pathogen, has emerged in some European and Asian countries, likely due to exposure to azole fungicides in the environment. This study determined the occurrence of triazole-resistant A. fumigatus in outdoor and hospital environment in Kuwait, a semi-arid desert country in Arabian Peninsula.

METHODS

Outdoor/indoor air, water and cotton swab samples were cultured on malt extract agar and A. fumigatus colonies were identified by phenotypic and molecular methods. Drug susceptibility of A. fumigatus isolates to itraconazole, posaconazole and voriconazole was carried out by an Etest and a broth microdilution method. Resistance mechanisms involving cyp51A mutations were probed by mixed-format real-time (MF-rt)-PCR assays. Triazole-resistant isolates were typed by nine-locus microsatellite analysis. A multiplex allele-specific (MAS)-PCR assay was developed for detection of L98H mutation in cyp51A.

RESULTS

Of 115 A. fumigatus isolates obtained from 362 environmental samples from across Kuwait, 8 isolates were resistant to itraconazole, posaconazole and voriconazole. All itraconazole-resistant isolates contained a 34-bp tandem repeat (TR34) in the promoter region and a L98H mutation at codon 98 (TR34/L98H) in cyp51A. These mutations were absent in all itraconazole-susceptible isolates. MAS-PCR accurately detected L98H mutation in all triazole-resistant isolates. Three microsatellite patterns were observed among resistant isolates with one pattern clustering with Indian clinical and environmental isolates.

CONCLUSIONS

Triazole-resistant A. fumigatus with TR34/L98H mutations in cyp51A is prevalent in Kuwait. Although triazole-resistant A. fumigatus has not yet been isolated from clinical specimens, its presence in the environment suggests that the possibility of susceptible individuals getting infected with such strains exists and may pose therapeutic challenges in its management.

Birth cohort study on the effects of desert dust exposure on children's health: protocol of an adjunct study of the Japan Environment & Children's Study

INTRODUCTION

Desert dust is estimated to constitute about 35% of aerosol in the troposphere. Desertification, climatic variability and global warming all can contribute to increased dust formation. This study aims to examine possible health effects of desert dust exposure on pregnant women and their children. The purpose of this report was to present the study protocol.

METHODS AND ANALYSIS

This 4-year birth cohort study began in 2011 as an adjunct study of the Japan Environment & Children's Study (JECS) involving three regions: Kyoto, Toyama and Tottori. The JECS participants of the three regions above who also agreed to participate in this adjunct study were enrolled prior to delivery. Light Detecting and Ranging (LIDAR) with a polarisation analyser, which can distinguish mineral dust particles from other particles, is used for exposure measurements. Outcomes are allergic symptoms for mothers and development of asthma and other allergic or respiratory diseases for their children. Data are acquired in a timely manner by connecting local LIDAR equipment to an online questionnaire system. Participants answer the online questionnaire using mobile phones or personal computers.

ETHICS AND DISSEMINATION

The study protocol was approved by the ethics committees of Kyoto University, University of Toyama and Tottori University. All participants provided written informed consent. The results of this study will be published in peer-reviewed journals and disseminated to the scientific community and general public.

TRIAL REGISTRATION NUMBER

UMIN000010826.

Mycoplasmal upper respiratory tract disease across the range of the threatened Mojave Desert tortoise: associations with thermal regime and natural antibodies

Most research of upper respiratory tract disease (mycoplasmal URTD) in the threatened Mojave Desert tortoise (Gopherus agassizii) has worked under the hypothesis that the pathogen, Mycoplasma agassizii, has a relatively consistent and predictable effect on tortoise populations across their natural range. In contrast, we hypothesized that multiple factors influence the prevalence of disease and analyzed biological and environmental variables that vary significantly across the Mojave Desert. We used multiple regression models to analyze associations between mycoplasmal URTD and the genetic structure of 24 tortoise populations, levels of natural antibody (NAb) to M. agassizii in tortoises (one component of the innate immune system), precipitation, and colder thermal regimes. We detected a significant, positive association between mean levels of NAb and seroprevalence to M. agassizii. We hypothesized that NAbs may provide tolerance to mycoplasmal infections and that more tolerant populations may act as host reservoirs of disease. We also detected significant associations between colder winters and mycoplasmal URTD, suggesting that colder winters may depress tortoise immune resistance against M. agassizii or enhance conditions for the growth of M. agassizii.

Pollen augments the influence of desert dust on symptoms of adult asthma patients

BACKGROUND

East Asian desert dust storms that occur during mainly spring are called Asian dust storms (ADS). Our objective was to study the association of pollen and ADS with symptoms of adult asthma patients in Japan.

METHODS

We designed a telephone survey to investigate the upper and lower respiratory, ocular, and skin symptoms of asthma patients during ADS in February, March, and December on 2009. Peak expiratory flow (PEF) was also measured from February to May.

RESULTS

We surveyed 106 patients in February, 101 patients in March, and 103 patients in December. In February and March, Japanese cedar and/or cypress pollen was also in the atmosphere during ADS, but no pollen was identified during December survey. Worsening of upper or lower respiratory, ocular, or skin symptoms was noted by 20.8% of patients in February, 33.7% in March, and 16.5% in December. Worsening of symptoms was significantly more common in March than in February or December. Two patients needed emergency treatment for exacerbation during ADS in March, but no patient needed hospitalization in any period. There was no significant difference of the daily morning PEF/personal best PEF ratio between ADS days and control days. However, in patients with worsening of upper and/or lower respiratory tract symptoms, the daily morning PEF/personal best ratio was significantly associated with the atmospheric level of particulate matter, but not with levels of pollen or other air pollutants.

CONCLUSIONS

Pollen augmented symptoms in adult asthma patients, but ADS on its own also were able to aggravate symptoms and pulmonary function.

A lysimeter study of nitrate leaching, optimum fertilisation rate and growth responses of corn (Zea mays L.) following soil amendment with water-saving super-absorbent polymer

BACKGROUND

Nitrate leaching and the resulting groundwater contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving super-absorbent polymer (SAP) for minimising NO(3)(-) leaching from soil and optimising corn growth and yield. Thirty-six undisturbed soil lysimeters were installed in a field lysimeter facility in drought-affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as the amount of NO(3)-leaching losses under different fertiliser (standard, medium or 75% and low, or 50% of conventional fertilisation rate) and SAP (control, 0; level-1, 15 kg ha(-1) and level-2, 30 kg ha(-1)) treatments.

RESULTS

Corn yield fell by 19.7% under medium and 37.7% under low fertilisation; the application of SAP increased yield significantly by 44.4% on level-1 and 80.3% on level-2. Similarly, plant height, leaf area, number of grains as well as protein, soluble sugar and starch contents in the grain also increased with SAP treatment. Application of SAP at 30 kg ha(-1) plus half of conventional fertilisation can reduce maximum (64.1%) nitrate leaching losses from soil.

CONCLUSIONS

Application of SAP at 30 kg ha(-1) plus only half the amount of conventional fertiliser rate (150 kg urea, and 50 kg each of superphosphate and potassium sulfate) would be a more appropriate practice both for minimising nitrate leaching and sustainable corn production under the arid and semiarid conditions of northern China.

Effectiveness of a water-saving super-absorbent polymer in soil water conservation for corn (Zea mays L.) based on eco-physiological parameters

BACKGROUND

The objective was to study soil water conservation and physiological growth of corn (Zea mays L.) using water-saving super-absorbent polymer (SAP) at 30 kg ha(-1). The effectiveness of SAP was studied under three irrigation levels (adequate, moderate and deficit) using a new type of negative hydraulic pressure controlled auto-irrigator in the years 2009 and 2010 in a greenhouse at Beijing, P.R. China.

RESULTS

Eight weeks after sowing, plant height and leaf area increased significantly by 41.6 and 79.6% under deficit irrigation for SAP treatment. The SAP had little effect on shoot dry mass under adequate and moderate irrigation but increased it significantly by 133.5% under deficit irrigation. Similarly, the efficiency of water use also increased by 97.1%. Leaf water potential under adequate and moderate irrigation differs slightly for SAP application, whereas under deficit irrigation the values were exceeded significantly by 27.8%. The superior growth and water use efficiency of corn treated with SAP under deficit irrigation was ascribed to maintenance of higher relative water contents in leaves as well as intercellular carbon dioxide concentration, net photosynthesis and transpiration rate.

CONCLUSIONS

Our results suggested that plant growth and different physiological activities are restricted by drought stress and the application of super-absorbent polymer could conserve soil water, making same available to plants for increased growth and biomass accumulation especially under severe water stress. Thus, application of SAP is a suitable soil management practice for the locations characterised by severe water stress.

Elemental composition of arbuscular mycorrhizal fungi at high salinity

We investigated the elemental composition of spores and hyphae of arbuscular mycorrhizal fungi (AMF) collected from two saline sites at the desert border in Tunisia, and of Glomus intraradices grown in vitro with or without addition of NaCl to the medium, by proton-induced X-ray emission. We compared the elemental composition of the field AMF to those of the soil and the associated plants. The spores and hyphae from the saline soils showed strongly elevated levels of Ca, Cl, Mg, Fe, Si, and K compared to their growth environment. In contrast, the spores of both the field-derived AMF and the in vitro grown G. intraradices contained lower or not elevated Na levels compared to their growth environment. This resulted in higher K:Na and Ca:Na ratios in spores than in soil, but lower than in the associated plants for the field AMF. The K:Na and Ca:Na ratios of G. intraradices grown in monoxenic cultures were also in the same range as those of the field AMF and did not change even when those ratios in the growth medium were lowered several orders of magnitude by adding NaCl. These results indicate that AMF can selectively take up elements such as K and Ca, which act as osmotic equivalents while they avoid uptake of toxic Na. This could make them important in the alleviation of salinity stress in their plant hosts.

Drought increases freezing tolerance of both leaves and xylem of Larrea tridentata

Drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. Drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. To test this hypothesis, we subjected Larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 °C. We measured survival, leaf retention, gas exchange, cell death, freezing point depression and leaf-specific xylem hydraulic conductance (k₁). Drought-exposed plants exhibited smaller decreases in gas exchange after exposure to -8 °C compared to well-watered plants. Drought also conferred a significant positive effect on leaf, xylem and whole-plant function following exposure to -15 °C; drought-exposed plants exhibited less cell death, greater leaf retention, higher k₁ and higher rates of gas exchange than well-watered plants. Both drought-exposed and well-watered plants experienced 100% mortality following exposure to -24 °C. By documenting the combined effects of drought and freezing stress, our data provide insight into the mechanisms determining plant survival and performance following freezing and the potential for shifts in L. tridentata abundance and range in the face of changing temperature and precipitation regimes.

Role of Saharan dust in the relationship between particulate matter and short-term daily mortality among the elderly in Madrid (Spain)

BACKGROUND

Saharan dust outbreaks are a common phenomenon in the Madrid atmosphere. The current Directive 2008/50 CE governing air quality in European cities, draws no distinction between which particulate matter (PM(10), PM(2.5) or PM(10-2.5)) would be the best indicator on days with/without Saharan dust intrusions. This study sought to identify the role played by Saharan dust in the relationship between particulate matter (PM(10), PM(2.5) and PM(10-2.5)) concentrations and daily mortality among the elderly in the city of Madrid.

METHODS

We conducted an ecological longitudinal time-series study on daily mortality among the over-75 age group, from 2003 to 2005. Poisson regression models were constructed for days with and without Saharan dust intrusions. The following causes of daily mortality were analysed: total organic causes except accidents (International Classification of Diseases-10th revision (ICD-10): A00-R99); circulatory causes (ICD-10: I00-I99); and respiratory causes (ICD-10: J00-J99). Daily mean PM(10), PM(2.5) and PM(10-2.5) levels were used as independent variables. Control variables were: other ambient pollutants (chemical, biotic and acoustic); trend; seasonalities; influenza epidemics; and autocorrelations between mortality series.

RESULTS

While daily mean PM(2.5) concentrations in Madrid displayed a significant statistical association with daily mortality for all the above causes on days without Saharan dust intrusions, this association was not in evidence for PM(10) or PM(10-2.5) in the multivariate models. The relative risks (RRs) obtained for an increase of 10 μg/m(3) in PM(2.5) concentrations were: 1.023 (1.010-1.036) for total organic causes; 1.033 (1.031-1.035) for circulatory causes; and 1.032 (1.004-1.059) for respiratory causes. On Saharan dust days, a significant statistical association was detected between PM(10) (though not PM(2.5) or PM(10-2.5)) and mortality for all 3 causes analysed, with RRs statistically similar to those reported for PM(2.5).

CONCLUSIONS

The best air quality indicators for evaluating the short-term health effects of particulate matter in Madrid are therefore PM(10) concentrations on days with, and PM(2.5) concentrations on days without Saharan dust outbreaks. This fact should be taken into account in a European Directive regulating ambient air quality in almost all countries in the Mediterranean area.

Variation of seed heteromorphism in Chenopodium album and the effect of salinity stress on the descendants

BACKGROUND AND AIMS

Chenopodium album is well-known as a serious weed and is a salt-tolerant species inhabiting semi-arid and light-saline environments in Xinjiang, China. It produces large amounts of heteromorphic (black and brown) seeds. The primary aims of the present study were to compare the germination characteristics of heteromorphic seeds, the diversity of plant growth and seed proliferation pattern of the resulting plants, and the correlation between NaCl stress and variation of seed heteromorphism.

METHODS

The phenotypic characters of heteromorphic seeds, e.g. seed morphology, seed mass and total seed protein were determined. The effects of dry storage at room temperature on dormancy behaviour, the germination response of seeds to salinity stress, and the effect of salinity on growth and seed proliferation with plants derived from different seed types were investigated.

KEY RESULTS

Black and brown seeds differed in seed morphology, mass, total seed protein, dormancy behaviour and salinity tolerance. Brown seeds were large, non-dormant and more salt tolerant, and could germinate rapidly to a high percentage in a wider range of environments; black seeds were salt-sensitive, and a large proportion of seeds were dormant. These characteristics varied between two populations. There was little difference in growth characteristics and seed output of plants produced from the two seed morphs except when plants were subjected to high salinity stress. Plants that suffered higher salinity stress produced more brown (salt-tolerant) seeds.

CONCLUSIONS

The two seed morphs of C. album exhibited distinct diversity in germination characteristics. There was a significant difference in plant development and seed proliferation pattern from the two types of seeds only when the parent plants were treated with high salinity. In addition, seed heteromorphism of C. album varied between the two populations, and such variation may be attributed, at least in part, to the salinity.

Reflective inserts to reduce heat strain in body armor: tests with and without irradiance

BACKGROUND

This study evaluated adding reflective thermal inserts (RTI) to reduce the physiological strain during exercise-heat stress with a radiant load. RTI were used with a U.S. Army desert battle dress uniform, body armor, and helmet.

METHODS

Four male volunteers attempted four trials (10 min rest followed by 100 min walking at 1.56 m x s(-1)). All trials were at 40.0 degrees C dry bulb (Tdb), 12.4 degrees C dew point (Tdp), 20% RH, and 1.0 m x s(-1) wind speed. On 2 d, there was supplementary irradiance (+1) with globe temperature (Tbg) = 56.5 degrees C and on 2 d there was no supplementary irradiance (-I) with Tbg approximately Tdb. Trial conditions were: 1) RTI and armor with supplementary irradiance (RA+I); 2) plain armor with supplementary irradiance (PA+I); 3) RTI and armor with no supplementary irradiance (RA-I); and 4) plain armor with no supplementary irradiance (PA-I).

RESULTS

Endurance times were not significantly different among trials. With one exception, armor and helmet interior and exterior surface temperatures were not significantly different between either RA+I and PA+I or RA-I and PA-I. Temperature on the inside of the helmet in RA+I (47.1 +/- 1.4 degrees C) was significantly lower than in PA+I (49.5 +/- 2.6 degrees C). There were no differences for any physiological measure (core temperature, heart rate, mean weighted skin temperature, forehead skin temperature, sweating rate, evaporative cooling, rate of heat storage) between either RA+I and PA+L or RA-I and PA-I.

CONCLUSIONS

Results showed no evidence that wearing RTI with body armor and helmet reduces physiological strain during exercise-heat stress with either high or low irradiance.

Atmospheric movement of microorganisms in clouds of desert dust and implications for human health

Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources.

20th-Century doubling in dust archived in an Antarctic Peninsula ice core parallels climate change and desertification in South America

Crustal dust in the atmosphere impacts Earth's radiative forcing directly by modifying the radiation budget and affecting cloud nucleation and optical properties, and indirectly through ocean fertilization, which alters carbon sequestration. Increased dust in the atmosphere has been linked to decreased global air temperature in past ice core studies of glacial to interglacial transitions. We present a continuous ice core record of aluminum deposition during recent centuries in the northern Antarctic Peninsula, the most rapidly warming region of the Southern Hemisphere; such a record has not been reported previously. This record shows that aluminosilicate dust deposition more than doubled during the 20th century, coincident with the approximately 1 degrees C Southern Hemisphere warming: a pattern in parallel with increasing air temperatures, decreasing relative humidity, and widespread desertification in Patagonia and northern Argentina. These results have far-reaching implications for understanding the forces driving dust generation and impacts of changing dust levels on climate both in the recent past and future.

Cognitive deterioration associated with an expedition in an extreme desert environment

BACKGROUND

Prolonged exposure to extreme environments may result in cognitive changes that may influence decision making ability and increasing risk of injury or death.

OBJECTIVE

To measure the cognitive performance of a healthy man as he completed a 17 day desert expedition.

METHOD

A computer based cognitive test battery, subjective cognitive rating scale, and measures of physical characteristics were used. Objective cognitive performance was compared with the performance of eight age matched men who remained in their own homes.

RESULTS

The speed of psychomotor, attentional, and executive functions decreased as the expedition progressed, but the accuracy of performance remained unaffected. Although some impairments were large, they resolved completely once the expedition was completed. Subjective ratings indicated that the subject had insight into his failing cognitive performance during the expedition.

CONCLUSIONS

Cognitive performance can be measured repeatedly throughout an expedition in an extreme environment. Cognitive impairment may occur.

Renal lithiasis: addressing the risks of austere desert deployments

INTRODUCTION

Renal lithiasis affects approximately 5% of the general population, with higher risks for men and increasing risks with increasing age. The forward deployment of the Air Force into austere desert environments with integration of the active duty, Reserves, and Guard presents increasing risks to mission accomplishment with the increased risk of developing renal lithiasis.

METHODS

This paper describes seven cases of presumed renal lithiasis in a deployed desert setting in Air Force personnel on flying status. Their status and the location of the base acted as a focus for a review of the literature on kidney stone causation, prevention, diagnosis, and management.

RESULTS/DISCUSSION

A review of the literature revealed that current military recommendations to hydrate in the field may not be sufficient for the primary prevention of kidney stones. Beverage choice may prove more useful for prevention. Situations precipitating voluntary dehydration need to be prevented. Although there are superior ways to diagnose renal lithiasis, in the deployed setting patient history and physical examination are usually the only available means. Ultrasound is a viable diagnostic option for use in the deployed setting based on its portability, affordability, and ease of use. Additions to the standard management of renal lithiasis, such as subcutaneous Lidocaine and heat may have value in the deployed setting if the supply of narcotics is limited.

CONCLUSION

In the deployed setting, hydration choices, the addition of portable ultrasound to the diagnostic process, and pain management with nontraditional therapies need to be explored.

[Spatial variability of soil moisture, nutrients, and productivity on slopeland in loessial semiarid region]

For the sustainable development and ecological construction in the loessial semiarid region, it is important to describe the variability of slopeland soil properties and the affecting factors of slopeland productivity. In this study, soil samples were taken from eroded steep slopeland, and leaf area index (LAI) and above-ground biomass (AGB) were measured at the sampling locations. The soil water content (WC) of 2 m depth at 20 cm intervals, and the soil organic matter (OM), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN) and available phosphorus (AP) contents of 0-20 and 20-40 cm soil layers were determined in the laboratory. The results showed that the majority of the properties was normally distributed, and the nutrient contents were higher in 0-20 cm than in 20-40 cm layer, but the variations of soil nutrients were much smaller in 0-20 cm than in 20-40 cm layer. Soil nutrients had a significantly larger variation than soil moisture. Soil nutrient contents in 20-40 cm layer kept increasing from upslope to downslope, while those in 0-20 cm layer varied slightly. Slope topography had more obvious impact on soil organic matter, total nitrogen and available phosphorus than other affecting factors. Soil water and nutrient contents on the shallow gully trough were notably higher than those on the upslope, but above-ground biomass was less than that on the upslope. Though longitudinal slope (35 degrees-45 degrees) was obviously larger than the horizontal one (5 degrees-10 degrees), horizontal slope position had a greater influence on soil nutrients, but much weaker effect on soil moisture than longitudinal direction. There were significant correlations between 0-120 cm soil moisture and 20-40 cm soil nutrients, and among soil nutrients except 0-20 cm soil available phosphorus. Slopeland position had a great impact on soil moisture and nutrients, but soil moisture and/or nutrients had no significant impact on above-ground biomass.

Respiratory illnesses in relation to military assignments in the Mojave Desert: retrospective surveillance over a 10-year period

Military training exercises are conducted routinely in the Mojave Desert. To determine whether assignment in this desert environment increases risk of respiratory illnesses, hospitalization rates were compared between two matched cohorts of soldiers during three intervals of follow-up during a 10-year surveillance period. The exposed cohort (N = 21,543) included all soldiers who were ever assigned to the Mojave Desert during the surveillance period. The control cohort (N = 86,172) included soldiers matched on demographic characteristics who were never assigned to the Mojave Desert during the surveillance period. Three follow-up intervals ("before," "during," "after") were defined relative to times when exposed soldiers were assigned to the desert. Rates of respiratory hospitalizations were similar between the cohorts for the "before" and "during" intervals but were higher in the exposed cohort for the "after" interval (rate ratio, 1.30; 95% confidence interval, 1.07-1.59). This difference was largely attributable to excess pneumonia and influenza hospitalizations in the exposed cohort. Healthy, young adults may have increased susceptibility to respiratory infectious illnesses after prolonged exposures to desert environments.

Atmospheric transport of mold spores in clouds of desert dust

Fungal spores can be transported globally in clouds of desert dust. Many species of fungi (commonly known as molds) and bacteria--including some that are human pathogens--have characteristics suited to long-range atmospheric transport. Dust from the African desert can affect air quality in Africa, Europe, the Middle East, and the Americas. Asian desert dust can affect air quality in Asia, the Arctic, North America, and Europe. Atmospheric exposure to mold-carrying desert dust may affect human health directly through allergic induction of respiratory stress. In addition, mold spores within these dust clouds may seed downwind ecosystems in both outdoor and indoor environments.

Effect of long-term dehydration on serum constituents in extreme climatic conditions in camel (Camelus dromedarius)

Eight healthy female adult camels were used to study the effect of long term dehydration on serum constituents in extreme climatic conditions viz. cold and hot. The dehydration phases were of 24 days in cold and 13 days in hot conditions. The changes in sodium, potassium, calcium and phosphorus were non significant (P > 0.05) while in chloride, glucose, total proteins, urea, bilirubin, cholesterol and creatinine were significant (P < or = 0.05) during dehydration phase. The mean values of all the constituents tended to return to normal as the rehydration phase advanced. Changes in sodium and potassium in dehydrated camels reflected that they were able to maintain the salt balance.

Contrasting responses to desiccation and starvation by eggs and neonates of two lepidoptera

We examined the effects of desiccation on eggs and first-instar larvae of two species of Lepidoptera, Grammia geneura (Arctiidae) and Manduca sexta (Sphingidae). Grammia geneura occurs primarily in grasslands and savannas of the southwestern United States; M. sexta co-occurs with G. geneura but also is cosmopolitan across much of the Western Hemisphere. Eggs of G. geneura exposed to 0% relative humidity (RH) lost water much less rapidly (7.6 microg d(-1); 2.4% d(-1)) than did eggs of M. sexta (79.5 microg d(-1); 5.7% d(-1)). Eggs of both species survived at rates exceeding 75% at both 0% and 85% RH. Neonates of the two species responded differently to desiccation and starvation. In 85% RH, larval G. geneura survived at high rates (>80%) without access to food or water up to day 17, and in 0% RH, they survived at rates exceeding 50% through the first 10 d. Larvae at 0% RH lost mass very slowly (7.2 microg d(-1); 2.9% d(-1)), which was attributable both to low rates of water loss and to an ability to reduce metabolic rate to low levels. Larval M. sexta, in contrast, had rates of mortality that were much higher: after 1 d, fewer than 30% were alive in either group, and by about 1.5 d, all were dead. Neonate M. sexta also lost mass much more rapidly at 0% RH, about 329 microg d(-1). Water from metabolism appeared to contribute significantly to the water budget of G. geneura but not of M. sexta. These data show that G. geneura and M. sexta can inhabit similar macroclimates via remarkably different physiologies.

[Effects of unarmed marching in dry-heat desert environment on the heat shock protein 27 in human blood]

To explore the variation of blood heat shock protein 27(HSP27) for unarmed marching in dry-heat environment, plasma HSP27 levels of 57 marchers and 14 controls were detected. The results revealed a significant difference between exposed and control groups (P < 0.01), and no significant difference among different time exposures at the same speed. HSP27 levels increased slightly with the increase of speed. During the second hour of marching, HSP27 levels were slightly lower, and kept steady in the third hour.

Host range and the maintenance of Haemonchus spp. in an adverse arid climate

Three Haemonchus species (Haemonchus contortus, Haemonchus placei and Haemonchus longistipes) live in sympatry in Sahelian areas such as Mauritania (West Africa). Four host species (dromedary, zebu cattle, sheep and goats) share the same pastures for several months per year. Experimental infection by H. contortus or H. placei was achieved only poorly in dromedaries, and H. contortus or H. longistipes infection failed to establish in zebu cattle. Conversely, H. placei and H. longistipes successfully infected sheep and goats. Under field conditions, mixed congeneric infections were very rare in dromedaries but frequent in zebu cattle (H. contortus represented 16% of Haemonchus spp. burden), in sheep (H. placei: 15%) and in goats (H. placei: 9% and H. longistipes: 6% of worms). The importance of the different host species was evaluated for Haemonchus spp.: small ruminants are the main hosts of H. contortus, dromedaries harboured the large majority of H. longistipes worms but 5% of them were found in goats which seemed to be additional hosts. The most striking finding was the role played by the small ruminants in the survival strategy of H. placei in Sahelian regions: 56% of the total of H. placei worms were found in sheep, 34% in goats and only 10% in zebu cattle. These results are consistent with the hypothesis that the extension of host range plays an important role in the survival strategy of H. placei, whereas H. longistipes or H. contortus might well survive utilising their usual hosts.

Environmental profile and critical temperature effects on milk production of Holstein cows in desert climate

The environmental profile of central Arizona is quantitatively described using meteorological data between 1971 and 1986. Utilizing ambient temperature criteria of hours per day less than 21 degrees C, between 21 and 27 degrees C, and more than 27 degrees C, the environmental profile of central Arizona consists of varying levels of thermoneutral and heat stress periods. Milk production data from two commercial dairy farms from March 1990 to February 1991 were used to evaluate the seasonal effects identified in the environmental profile. Overall, milk production is lower during heat stress compared to thermoneutral periods. During heat stress, the cool period of hours per day with temperature less than 21 degrees C provides a margin of safety to reduce the effects of heat stress on decreased milk production. Using minimum, mean and maximum ambient temperatures, the upper critical temperatures for milk production are 21, 27 and 32 degrees C, respectively. Using the temperature-humidity index as the thermal environment indicator, the critical values for minimum, mean and maximum THI are 64, 72 and 76, respectively.

Variability in intake and dehydration in young men during a simulated desert walk

Voluntary dehydration was examined in young unacclimatized men walking under simulated desert conditions. Thirty-three subjects (20-33 years) walked on a treadmill (4.82 km.h-1, 5% grade) for 30 min.h-1 for 6 h in a hot environment (40 degrees C db/26 degrees C wb, 4.02 km.h-1 windspeed). Cool (15 degrees C) water was provided ad libitum in canteens. Because thirst is stimulated and drinking should occur at about 2% body weight loss as body water, we used this criterion to identify two groups of individuals. Individuals who maintained body weight (BW) loss at less than 2% (0.44-1.88%) were defined as avid drinkers (D, n = 20) and those who exceeded the 2% BW loss (2.07-3.51%) despite the continual availability of cool (15 degrees C) water were called reluctant drinkers (RD, n = 13). RD consumed 31% less water (2.05 +/- 0.14 L) than D (2.98 +/- 0.12 L), and this resulted in a significantly greater BW loss in RD (2.65 +/- 0.11%) than D (1.16 +/- 0.11%). However, the only statistically significant differences in plasma indices of dehydration were the higher final plasma Na+ and protein levels in RD. Rectal temperature was higher in the RD, whereas final heart rates were unaffected. In the current study, about 40% of the young adult male subjects were reluctant to drink, and thus voluntarily dehydrated even when given cool water ad libitum during intermittent exercise in the heat. The reduced intake of these reluctant drinkers may be critical in predisposing them to increased risk of dehydration and heat injury.

Ecological upheavals with special reference to desertification and predicting health impact

This paper begins with an introduction that touches on the ecological upheavals of earthquakes, floods, as well as other upheavals that result from sudden huge crowding of people in one place such as in refugee situations and situations of a famine disaster. The point is made that for sudden emergencies the health impact will very much depend on the nature of traumatic physical damage on the people's bodies and property as well as the capacity with which response is organised for assessment of damage and medical management. A number of texts are mentioned with respect to management in emergencies, including health, feeding and water and the point made that familiarity with these texts provides a starting point in responding to emergencies. These have put together information on how one goes about organising the response to save lives. Also mentioned are the consequences of the approach taken to providing food in these situations; whether it is through distribution of dry ration to be taken home, or whether one is dealing with shelter situations. In this introduction, land degradation/desertification is mentioned as being the largest and possibly the most devastating ecological upheaval. The rest of the paper goes on to address this ecological upheaval of land degradation/desertification. The magnitude of this upheaval is presented. The contribution of overcultivation, overgrazing, deforestation and irrigation to desertification are discussed. The health consequence of this process is then presented and finally, there is a discussion on the challenges that social scientists and health professionals could help to address in order to bring about some appropriate interventions that would contribute to arresting and possibly reversing the desertification process.

Hydatid disease in children in Libya

Hydatid disease is a common condition in Libya. Between 1971 and 1976, hydatid disease accounted for 0.85% of total hospital admissions to Al-Jalah General Hospital, Benghazi. The incidence of hydatid disease reported in children below ten years of age was 11.7%. In this paper the experience of treating 56 children with hydatid disease is described. The presenting features, complications, surgical techniques and results are reported and discussed.

Epidemiology of heat illnesses during the Makkah Pilgrimages in Saudi Arabia

A review of the literature shows that our knowledge of the epidemiology of heat illnesses on a global and regional level is still lacking. Until now most of the information has come from the experience of European armies in hot environments. Recently increased interest has been shown following the epidemics of heat illnesses affecting civil communities in the United States. Of great importance and unique for the study of heat illness is the start of the hot cycle of the Makkah Pilgrimage which will continue for the next 15-16 years. Approximately two million people, the majority of whom are at great risk, will be exposed to the extremes of hot weather in May-September. Thousands of heat stroke cases are expected to occur. In this paper the conditions prevailing during the annual Makkah Pilgrimage are described as well as a review of the epidemiological and clinical findings observed by the author during the pilgrimages of 1980/81 when 176 cases and 467 cases of Heat Stroke were seen and treated respectively and a new physiological method of treatment of heat stroke which proved very successful in clinical field trials was introduced.