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At least 865 records · Page 48Linked to original sources
PubMed2006

Alteration of foot temperature in diabetic neuropathy: is it another piece of puzzle?

Poor glycaemic control and the duration of diabetes mellitus are known to accelerate development and progression of neuropathy. Diabetic co-morbidities: hypertension and hyperlipidaemia, have been postulated to associate with development of neuropathy. A diabetic foot with low temperature and frequent exposure to low temperature environment has recently been hypothesized to be at higher risk to develop early neuropathy. This cross-sectional study is undertaken to identify risk factors for diabetic neuropathy and the association between foot temperature and development of diabetic neuropathy by using simple clinical examination in the outpatient setting. From April 18, to April 30, 2005, universal sampling method was used to select 134 diabetic patients (type 1 or type 2 for >1 year) with peripheral neuropathy. Excluded are those with chronic alcoholism, drug-induced neuropathy, dietary history of vitamin B deficiency and family history of porphyria and hereditary sensorimotor neuropathy. The patient's duration of diabetes, glycaemic control status and the presence of co-morbids: hypertension and hyperlipidemia, were recorded. The temperature of the foot was measured by using thermo buddy. Of 134 patients representing Malaysian ethnic distribution with an equal number of males and females, 20.1% were in the age group of 61 to 65 years and, 85.1% and 67.9% belonged to lower socioeconomic and educational groups respectively. Associations between diabetic neuropathy and glycaemic control (p = 0.018) and duration of diabetes (p < 0.05) were significant. However, hypertension, hyperlipidaemia and low foot temperature were not significantly associated with development of diabetic neuropathy. Poor glycaemic control is significantly associated with diabetic neuropathy. Foot temperature alteration is merely an effect of autonomic neuropathy with a cold foot is attributed to co-existing peripheral arterial disease.

Adult↗
PubMed2005

A dynamic population model to investigate effects of climate on geographic range and seasonality of the tick Ixodes scapularis.

A dynamic population model of Ixodes scapularis, the vector of a number of tick-borne zoonoses in North America, was developed to simulate effects of temperature on tick survival and seasonality. Tick development rates were modelled as temperature-dependent time delays, calculated using mean monthly normal temperature data from specific meteorological stations. Temperature also influenced host-finding success in the model. Using data from stations near endemic populations of I. scapularis, the model reached repeatable, stable, cyclical equilibria with seasonal activity of different instars being very close to that observed in the field. In simulations run using data from meteorological stations in central and eastern Canada, the maximum equilibrium numbers of ticks declined the further north was the station location, and simulated populations died out at more northerly stations. Tick die-out at northern latitudes was due to a steady increase in mortality of all life stages with decreasing temperature rather than a specific threshold event in phenology of one life stage. By linear regression we investigated mean annual numbers of degree-days >0 degrees C (DD>0 degrees C) as a readily mapped index of the temperature conditions at the meteorological stations providing temperature data for the model. Maximum numbers of ticks at equilibrium were strongly associated with the mean DD>0 degrees C (r2>0.96, P<0.001), when the Province of origin of the meteorological station was accounted for (Quebec>Ontario, beta=103, P<0.001). The intercepts of the regression models provided theoretical limits for the establishment of I. scapularis in Canada. Maps of these limits suggested that the range of southeast Canada where temperature conditions are currently suitable for the tick, is much wider than the existing distribution of I. scapularis, implying that there is potential for spread. Future applications of the model in investigating climate change effects on I. scapularis are discussed.

Animals↗
PubMed2006

Ice-active characteristics of soil bacteria selected by ice-affinity.

As an initial screen for microorganisms that produce ice-active macromolecules, ice-affinity was used to select microorganisms from soil consortia originating from three temperate regions. Once selected and subsequently purified to single colonies, these microbes were putatively identified by 16S ribosomal RNA sequencing and assayed for various ice-active properties. Ice-affinity selection appeared to select for bacteria with ice-associating activities: inhibition of ice recrystallization; ice nucleation; ice shaping. Although none of these activities were observed in Paenibacillus amyloliticus C8, others such as Chryseobacterium sp. GL8, demonstrated both ice recrystallization inhibition and ice-shaping activities. Pseudomonas borealis DL7 was classified as a type I ice nucleator, Flavobacterium sp. GL7, was identified as a type III ice nucleator and Acinetobacter radioresistens DL5 demonstrated ice recrystallization inhibition. In all, 19 different culturable bacteria were selected from the thousands of microbes in late-summer collected soil samples. Many of the selected microbes have been previously reported in glacial ice cores or polar sea ice, and of five isolates that were further characterized, four showed ice-associating activities. These results indicate the significant potential of ice-affinity selection even with temperate climate soils, suggesting that sampling in more extreme and remote areas is not required for the isolation of ice-active bacteria.

Acinetobacter↗
PubMed2004

Microbial life in permafrost.

Hydrogenotrophic and acetoclastic methanogenesis was measured at temperatures between 5 and -16.5 degrees C with H14CO3- and 14CH3CO2- as substrates in Siberian permafrost soils. The rate of methane formation was reduced approximately 2-fold over the temperature range from 5 to -1.8 degrees C. For the most active sample "a" temperature dependence of CH4, production at negative temperatures was approximately a 100-fold reduction for a range of -1.8 to -16.5 degrees C for both substrates. According to the Arrhenius equation, the activation energy of methane generation from bicarbonate and acetate for the temperature interval -5 to -16.5 degrees C was reduced by a factor of 3 and 1.5, respectively, in comparison with the temperatures above zero. In the experiments we tested the geological time series, showing the ability of microorganisms to carry out redox reactions after thousands to millions years of existence in permafrost. From the Climate Change point of view, it is important that the recovered organisms are quickly involved anew in present-day ecological processes after instances of permafrost thawing, and may be vital in nutrient recycling and in the production and consumption of greenhouse gases over a large portion of the Earth's surface. From an exobiological point of view, the terrestrial permafrost, inhabited by cold adapted microbes and protecting the cells against unfavorable conditions, can be considered as an extraterrestrial model. The methanogenic bacteria and their metabolic end-products found in the Earth's permafrost provide a range of analogues that could be used in the search for possible ecosystems and potential inhabitants on extraterrestrial cryogenic bodies free of oxygen.

Acetates↗
PubMed1997

Potential effects of climatic change on radiological doses from disposal of Canadian nuclear fuel waste.

The environmental assessment of deep geologic disposal of Canadian nuclear fuel waste considers many processes that could affect radionuclide transport to humans over thousands of years. Climatic change is an important feature that will occur over these long times. Glaciation will likely occur within the next 100,000 years over much of Canada, and its impact on radiological doses has been assessed previously. In the present study, we investigate the potential effect of short-term climatic change, usually associated with global warming caused by increases in atmospheric trace gases. We study the main biosphere transport pathways causing a radiological dose to humans from 129I, which is the most important radionuclide in disposal of Canadian used nuclear fuel. Irrigation of a garden with contaminated well water is the main pathway and it can be affected by changes in temperature and precipitation. A cold, wet climate decreases the need for irrigation, and this decreases the radiological dose. A drastic climatic change, such as an increase in temperature from 10 to 20 degrees C and decrease in precipitation from 0.3 to 0.2 m during the growing season, is estimated to increase the dose by a factor of four. This is a relatively small change compared to the range of doses that arise from the variability and uncertainty in many of the parameters used in the environmental assessment models. Therefore, it is likely that the results of probabilistic dose assessment models can include the consequences of short-term climatic change.

Agriculture↗
PubMed1994

A model for the evolution of CO2 on Mars.

We have constructed a model that predicts the evolution of CO2 on Mars from the end of the heavy bombardment period to the present. The model draws on published estimates of the main processes believed to affect the fate of CO2 during this period: chemical weathering, regolith uptake, polar cap formation, and atmospheric escape. Except for escape, the rate at which these processes act is controlled by surface temperatures which we calculate using a modified version of the Gierasch and Toon energy balance model (1973, J. Atmos. Sci. 30, 1502-1508). The modifications account for the change in solar luminosity with time, the greenhouse effect, and a polar and solar equatorial energy budget. Using published estimates for the main parameters, we find no evolutionary scenario in which CO2 is capable of producing a warm (global mean temperatures>250 K) and wet (surface pressures>30 mbar) early climate, and then evolves to present conditions with approximately 7 mbar in the atmosphere, <300 mbar in the regolith, and <5 mbar in the caps. Such scenarios would only exist if the early sun were brighter than standard solar models suggest, if greenhouse gases other than CO2 were present in the early atmosphere, or if the polar albedo were significantly lower than 0.75. However, these scenarios generally require the storage of large amounts of CO2 (>1 bar) in the carbonate reservoir. If the warm and wet early Mars constraint is relaxed, then we find best overall agreement with present day reservoirs for initial CO2 inventories of 0.5-1.0 bar. We also find that the polar caps can a profound effect on how the system evolves. If the initial amount of CO2 is less than some critical value, then there is not enough heating of the poles to prevent permanent caps from forming. Once formed, these caps control how the system evolves, because they set the surface pressure and, hence, the thermal environment. If the initial amount of CO2 is greater than this critical value, then caps do not form initially, but can form later on, when weathering and escape lower the surface pressure to a point at which polar heating is no longer sufficient to prevent cap formation and the collapse of the climate system. Our modeling suggests this critical initial amount of CO2 is between 1 and 2 bar, but its true value will depend on all factors affecting the polar heat budget.

Atmosphere↗
PubMed2004

Synthesis of effects in four Arctic subregions.

An assessment of impacts on Arctic terrestrial ecosystems has emphasized geographical variability in responses of species and ecosystems to environmental change. This variability is usually associated with north-south gradients in climate, biodiversity, vegetation zones, and ecosystem structure and function. It is clear, however, that significant east-west variability in environment, ecosystem structure and function, environmental history, and recent climate variability is also important. Some areas have cooled while others have become warmer. Also, east-west differences between geographical barriers of oceans, archipelagos and mountains have contributed significantly in the past to the ability of species and vegetation zones to relocate in response to climate changes, and they have created the isolation necessary for genetic differentiation of populations and biodiversity hot-spots to occur. These barriers will also affect the ability of species to relocate during projected future warming. To include this east-west variability and also to strike a balance between overgeneralization and overspecialization, the ACIA identified four major sub regions based on large-scale differences in weather and climate-shaping factors. Drawing on information, mostly model output that can be related to the four ACIA subregions, it is evident that geographical barriers to species re-location, particularly the distribution of landmasses and separation by seas, will affect the northwards shift in vegetation zones. The geographical constraints--or facilitation--of northward movement of vegetation zones will affect the future storage and release of carbon, and the exchange of energy and water between biosphere and atmosphere. In addition, differences in the ability of vegetation zones to re-locate will affect the biodiversity associated with each zone while the number of species threatened by climate change varies greatly between subregions with a significant hot-spot in Beringia. Overall, the subregional synthesis demonstrates the difficulty of generalizing projections of responses of ecosystem structure and function, species loss, and biospheric feedbacks to the climate system for the whole Arctic region and implies a need for a far greater understanding of the spatial variability in the responses of terrestrial arctic ecosystems to climate change.

Animals↗
PubMed2005

The potential impact of climate change on infectious diseases of Arctic fauna.

Climate change is already affecting Arctic species including infectious disease agents and greater changes are expected. Some infectious diseases are already increasing but future changes are difficult to predict because of the complexity of host-agent-environment relationships. However mechanisms related to climate change that will influence disease patterns are understood. Warmer temperatures will benefit free living bacteria and parasites whose survival and development is limited by temperature. Warmer temperatures could promote survivability, shorter development rates and transmission. Insects such as mosquitoes and ticks that transmit disease agents may also benefit from climate change as well as the diseases they spread. Climate change will have significant impacts on biodiversity. Disease agents of species that benefit from warming will likely become more prevalent. Host species stressed by changing environmental conditions may be more vulnerable to disease agents. Warming could lead to increased agriculture and other economic opportunities in the Arctic bringing people, domestic food animals, pets and invasive species and their disease agents into Northern regions. Climate warming may also favor the release of persistent environmental pollutants some of which can affect the immune system and may favor increased rates of some diseases.

Acclimatization↗
PubMed1995

Ventilation in homes infested by house-dust mites.

Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.

Air Pollution, Indoor↗
PubMed1999

Diaphyseal cross-sectional geometry of the Boxgrove 1 Middle Pleistocene human tibia.

Cross-sectional geometric analysis of the early Middle Pleistocene human tibia from Boxgrove, West Sussex, U.K. reveals a mosaic pattern relative to other archaic Homo tibiae. The specimen has relatively low percent cortical area within its cross sections. However, it exhibits the high mediolateral strength characteristic of archaic Homo tibiae. Scaled solely to tibial length it is robust, similar to those of the Neandertals and above those of early modern and pre-Late Pleistocene African and Asian humans. However, given ecogeographically-patterned variance in relative tibial length and body laterality, it is most likely that it exhibits a level of robusticity within the range encompassed by Late Pliocene to Late Pleistocene archaic Homo combined with arctic body proportions. Given its association with late interglacial cool temperate climatic indicators, the inferred body proportions of the Boxgrove hominid were probably promoted by their minimal level of cultural buffering, requiring a significant biological conservation of body heat.

Animals↗
PubMed1996

British weather: conversation topic or serious health risk?

Britain is renowned for low indoor winter temperatures and a high rate of excess winter deaths and a causal association has been drawn between the two. A lack of priority given to energy efficiency here is often justified in terms of the mild climate. However, it can be shown that British climatic features may be related to poor health as long as poor standards of construction and insulation prevail. Legislation should therefore be implemented to improve standards both for new housing and refurbishment of much existing housing stock, not only for reasons of energy conservation but also for community health.

Acclimatization↗
PubMed1999

Temperature-dependent expression of cytochrome-c oxidase in Antarctic and temperate fish.

Seasonal acclimation versus permanent adaptation to low temperatures leads to a differential response in the expression of cytochrome-c oxidase (CCO) in temperate and Antarctic eelpouts. Although eurythermal eelpout from the North Sea (Zoarces viviparus) displayed a cold-induced rise of CCO activity in white muscle, enzyme activity in the cold stenothermal Antarctic eelpout Pachycara brachycephalum failed to reflect such a compensatory increase. In Antarctic eelpout, CCO activity correlates with transcript levels of mitochondrial encoded subunits of CCO (CCO I and CCO II), whereas cold-acclimated eelpout from the North Sea show lower enzyme activities than expected on the basis of mitochondrial mRNA levels. In these animals, CCO expression at low temperatures may be limited either by nuclear CCO transcripts or by posttranscriptional processes. These may comprise translation of the subunits or assembly of the CCO holoenzyme. mRNA levels of CCO IV, one of the nuclear encoded subunits, increased strongly during cold acclimation, indicating that the expression of CCO is likely not message limited in cold-acclimated Z. viviparus. Our data suggest that seasonal cold acclimation of Z. viviparus results in a modification of the relationship between transcription and translation or posttranslational processes. In permanently cold-adapted P. brachycephalum, on the other hand, CCO expression shows similar characteristics as in the warm-acclimated confamilial species, e.g., low levels of enzyme activity correlated with low levels of mitochondrial message.

Acclimatization↗
PubMed2002

Human impacts on the tundra-taiga zone dynamics: the case of the Russian lesotundra.

The tundra-taiga zone is considered not only as a natural ecotone, but as a unique fringe zone with socioeconomic peculiarities. This holistic approach enables us to analyze several significant types of human impacts (industrial impacts and those associated with renewable resources development, including traditional reindeer herding and human settlements) and their role in the displacement of the lesotundra zone. In Russia, there is much evidence of deforestation and ecosystem degradation in different regions of the lesotundra zone and the northern taiga which borders the lesotundra zone. One indicator of this is that in the Archangelsk region and the Komi Republic, the observed current southern border of the lesotundra zone lies 40-100 km to the south of the southern boundary of the Protection Belt of Pretundra Forests, established in 1959. Human impacts also displace the northern boundary of the lesotundra zone (the boundary with the tundra zone) to the south. As a result, according to published estimations, the total area of human-made tundra and lesotundra stretching from the Kola Peninsula to Chukotka, is c. 470-500,000 km2. The increases in man-made tundra lead to negative consequences for the sociocultural sustainability of the lesotundra zone, a decrease in the quality of life (notably for permanent residents and native people and increases in mortality and depopulation. It cannot be predicted with any certainty that climate warming in the tundra-taiga zone will lead to a northward movement of the boreal forest treeline. We need also to consider the human impacts discussed in this article, which may actually lead to a southward movement of the lesotundra zone.

Agriculture↗
PubMed2001

Problems of combined chronic pathology in newcomers of the north.

The problem of a combination of diseases is of great in the clinical treatment of internal diseases. Syntropy is of great significance to the northern population. A total of 617 patients living in Yakutia were studied. Analysing the combination of chronic pathology by means of the international classification of diseases was revealed that 7.4% of patients have only one nosological form and 55.1% had been diagnosed with 5 and more nosologies. When analysing the combination of the classes of the international classification of diseases it was seen that patients with one class constituted 14.0%. At same time the number of classes of the diagnosed pathology comprised 3 and more in 44.3% of the patients. In our opinion the process of long human adaptation to severe climatic conditions leads to a decrease of the functional reserves in an organism and disadaptation in newcomers. It leads to the development of severe chronic polynosological pathology, pathogenesis of which is defined by the for need complex of disadaptive disorder.

Adaptation, Biological↗
PubMed2006

[The rhythms of arterial pressure and heart rate in individuals with arterial hypertension under the conditions of Far North].

The circadian and ultradian rhythms of blood pressure (BP) and heart rate (HR) were studied by means of 24-hour BP monitoring in patients with arterial hypertension (AH) and practically healthy people working in Far North shifts. The subjects were 418 men. The main group consisted of 177 men aged 18 to 59 working in trans-polar shifts in Yamburg, Tyumen region, latitude 57 North. The comparison group included 158 residents of a moderate climatic zone (Tyumen, latitude 57 North). The control group consisted of 83 practically healthy men, of whom 43 worked in Far North shifts, and 40 were residents of Tyumen. The groups were comparable by age, AH duration, and office systolic and diastolic BP (SBP; DBP). The study demonstrates that even healthy people working in Far North shifts display high BP variability and the decrease of the stability and power of SBP, DBP and HR circadian rhythms due to the reduction of the amplitude, contribution of the rhythm to the total variability, and the increase of the amplitude of high-frequency harmonics of the spectrum (a manifestation of extracircadian dissemination), which may be a sign of accelerated ageing and biological age increase, and may facilitate AH development. Development of AH under the extreme conditions of Far North shifts, unlike the conditions of moderate climatic zones, is accompanied by progressive BH variability increase, the worsening of the chronological structure of SBP and DBP, the increase of extracircadian dissemination, which can be of both clinical and prognostic significance.

Adolescent↗
PubMed2004

Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system.

Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net effects of climate change on terrestrial feedbacks to the climate system. This uncertainty applies to magnitude, and even direction of some of the feedbacks.

Arctic Regions↗
PubMed1978

[Problems arising from the health status evaluation and certification of diseases developed in countries with different climatic conditions].

Based on the Polish regulations, the authors present problems and difficulties in qualification for business departures into the tropics, as well as diagnostic and certification procedures related to those whose health has been injured during their business trip to the tropics. The authors postulate a greater attention to be paid to this problem and explanation of some doubts resulting from interpretation of operative regulations.

Cold Climate↗