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PubMed1994

Reduced mite allergen levels in dwellings with mechanical exhaust and supply ventilation.

Seventy similar bungalows constructed between 1968 and 1970 in the same suburban area of Stockholm were investigated regarding the content of house dust mite allergen, absolute indoor humidity, type of ventilation and basement construction. Houses with mechanical exhaust and supply ventilation had an indoor humidity above 7 g/kg less often than houses without this type of ventilation (Odds ratio 0.1, 95% confidence interval 0.0-0.2). Furthermore, only five of the 24 houses with exhaust and supply ventilation contained mattress dust mite allergen concentrations exceeding the median value (98.5 ng/g) compared with 30 of 46 hours which did not have such ventilation (odds ratio = 0.1, C.I. 0.0-0.5). Houses with both natural ventilation and crawl space basement harboured significantly less mattress mite allergen than houses having the same type of ventilation, but with a concrete slab basement. In a cold temperature climate, type of building construction and ventilation seem to be important for the occurrence of house dust mite allergens in dwellings. Our results indicate that modern energy-efficient houses should be equipped with mechanical exhaust and supply ventilation to reduce indoor air humidity during the dry winter months and the risk of mite infestation.

Air Pollution, Indoor↗
PubMed2005

Isolation by distance and post-glacial range expansion in the rough-skinned newt, Taricha granulosa.

Allozymes and mitochondrial DNA sequences were used to examine the phylogeographical history of the rough-skinned newt, Taricha granulosa, in western North America. Nineteen populations were analysed for allozyme variation at 45 loci, and 23 populations were analysed for cytochrome b sequence variation. Both data sets agree that populations in the southern part of the range are characterized by isolation by distance, whereas northern populations fit the expectations of a recent range expansion. However, the northern limit of isolation by distance (and the southern limit of range expansion) is located in Oregon State by the mtDNA data, and in Washington State by the allozyme data. Nevertheless, both data sets are consistent with the known Pleistocene history of western North America, with phylogenetically basal populations in central and northern California, and a recent range expansion in the north following the retreat of the Cordilleran ice sheet 10,000 years ago. Additionally, a population in Idaho, previously considered introduced from central California based on morphometric analyses, possesses a distinct mtDNA haplotype, suggesting it could be native. The relevance of these results for Pacific Northwest biogeography is discussed.

Animals↗
PubMed1991

Sudden infant deaths and cold weather: was the rise in infant mortality in 1986 in England and Wales due to the weather?

Using the daily number of deaths due to sudden infant death syndrome in England and Wales from 1979 to 1985, and the daily temperature recorded at the London Weather Centre, two models were constructed, one including a temperature term and one without it, and the models used to predict the mortality in 1986. It was found that the model using temperature had a slightly better predictive power and successfully accounted for the increased mortality in February 1986. Thus, we conclude that the excess mortality of February 1986 was associated with the unusually cold weather during that month.

Cold Climate↗
PubMed2006

Low growth temperatures modify the efficiency of light use by photosystem II for CO2 assimilation in leaves of two chilling-tolerant C4 species, Cyperus longus L. and Miscanthus x giganteus.

Two C4 plants, Miscanthus x giganteus and Cyperus longus L., were grown at suboptimal growth temperatures and the relationships between the quantum efficiencies of photosynthetic electron transport through photosystem II (PSII) (PSII operating efficiency; Fq'/Fm') and CO2 assimilation (phiCO2) in leaves were examined. When M. x giganteus was grown at 10 degrees C, the ratio of the PSII operating efficiency to phiCO2 increased relative to that found in leaves grown at 14 and 25 degrees C. Similar increases in the Fq'/Fm': phiCO2 occurred in the leaves of two C. longus ecotypes when the plants were grown at 17 degrees C, compared to 25 degrees C. These elevations of Fq'/Fm': phiCO2 at low growth temperatures were not attributable to the development of anthocyanins, as has been suggested for maize, and were indicative of the operation of an alternative sink to CO2 assimilation for photosynthetic reducing equivalents, possibly oxygen reduction via a Mehler reaction, which would act as a mechanism for protection of PSII from photoinactivation and damage. Furthermore, in M. x giganteus grown at 10 degrees C, further protection of PSII was effected by a 20-fold increase in zeaxanthin content in dark-adapted leaves, which was associated with much higher levels of non-photochemical quenching of excitation energy, compared to that observed in leaves grown at 14 and 25 degrees C. These differences may explain the long growing season and remarkable productivity of this C4 plant in cool climates, even in comparison to other C4 species such as C. longus, which occur naturally in such climates.

Adaptation, Physiological↗
PubMed1982

Penguin egg-white and polar fish blood-serum proteins.

The development of, and findings in, a long-term research program on penguin proteins and polar fish blood proteins are described. Two of the egg-white proteins from the Adelie penguin (Pygoscelis adeliae) have unique properties: a glycoprotein named penalbumin that is a major constituent with some characteristics similar to ovalbumin, and an ovomucoid with strong inhibitory capacity for subtilisin as well as for bovine trypsin and alpha-chymotrypsin. The antifreeze glycoproteins from Antarctic fish (Trematomus borchgrevinki and Dissostichus mawsoni) and an Arctic fish (Boreogadus saida) appear to function noncolligatively by lowering the freezing temperature without affecting the melting point. Current evidence indicates that the antifreeze glycoprotein functions at the ice-solution interface, either on the ice surface or in a transition layer between the solution and the ice.

Animals↗
PubMed1995

Viable fungi in indoor air in homes and schools in the Sør-Varanger community during winter.

The present study investigated the content of fungal aerospores in homes and schools of house-dust-mite (HDM)-sensitized and control children in a subarctic area. During winter, airborne microfungi were collected from the homes and schools of 19 HDM-sensitized children and 19 nonatopic controls, all living in the community of Sør-Varanger, northern Norway. The samples were cultivated and microfungal growth was identified microscopically. Indoor humidity, temperature, and carbon dioxide (CO2) concentrations were measured. Housing conditions and sociodemographic and symptom data were obtained by a questionnaire. Penicillium was the most common microfungus in both homes and schools, followed by various yeasts, Aspergillus, Cladosporium, and Mucor. The number of infected homes was equal in the HDM-sensitized group and the control group, but aerospore counts were higher in the HDM-sensitized group than in the control group. The lowest aerospore counts were found in the schools. High aerospore counts also appeared to be related to high indoor humidity. The keeping of pets and damp indoor conditions were more frequent in homes of HDM-sensitized children than in the control group, whereas parental smoking and carpeting occurred with equal frequency in both groups. This indicates that no allergy sanitation measures had been undertaken, especially in the homes of the HDM-sensitized children.

Air Pollution, Indoor↗
PubMed2006

Glacial refugia and the phylogeography of Steller's sea lion (Eumatopias jubatus) in the North Pacific.

Mitochondrial DNA sequence data were used to examine the phylogeographic history of Steller's sea lions (Eumetopias jubatus) in relation to the presence of Plio-Pleistocene insular refugia. Cytochrome b and control region sequences from 336 Steller's sea lions reveal phylogenetic lineages associated with continental refugia south of the ice sheets in North America and Eurasia. Phylogenetic analysis suggests the genetic structure of E. jubatus is the result of Pleistocene glacial geology, which caused the elimination and subsequent reappearance of suitable rookery habitat during glacial and interglacial periods. The cyclic nature of geological change produced a series of independent population expansions, contractions and isolations that had analogous results on Steller's sea lions and other marine and terrestrial species. Our data show evidence of four glacial refugia in which populations of Steller's sea lions diverged. These events occurred from approximately 60,000 to 180,000 years BP and thus preceded the last glacial maximum.

Animals↗
PubMed1992

The hemoglobins of Notothenia angustata, a temperate fish belonging to a family largely endemic to the Antarctic Ocean.

The blood of the teleost Notothenia angustata contains a major hemoglobin (Hb 1, over 95% of the total), accompanied by a minor component (Hb 2). The two hemoglobins have identical beta chains and differ in their alpha chains. The primary structure of both hemoglobins has been established through the elucidation of the complete amino acid sequence of the three chains. The study of the oxygen-binding properties shows that Hb 1 displays the Bohr and Root effects and has high affinity for organic phosphates. N. angustata belongs to the family Nototheniidae, suborder Notothenioidei. Unlike the vast majority of nototheniid species, which live in isolation in the Antarctic Ocean and have developed cold adaptation, N. angustata inhabits the waters of southern New Zealand and is not cold adapted. Although some hematological parameters typically favour oxygen transport in a temperate environment, the hemoglobin multiplicity and structural and functional features closely resemble those of the Antarctic species of the same family and suborder. Thus, N. angustata may be considered as a link between temperate and Antarctic habitats. The hypothetical separation history of N. angustata from the Antarctic species of the same family is discussed in the light of the present findings.

Acclimatization↗
PubMed1992

The overwintering of Fasciola hepatica eggs under semi-arid and temperate Mediterranean climate (Madrid, Spain).

In this experimental work, conducted over two consecutive years (1988 and 1989), we have analyzed the overwintering possibilities of Fasciola hepatica eggs deposited in winter in a semi-arid and temperate Mediterranean area (Madrid, Spain). Eggs did not survive for more than a week in faeces at environmental moisture conditions. In contrast, over a 75% of the eggs maintained in permanently wet faeces survived winter temperatures, showing no high mortality until important thermic increment from June. The success of overwintering was higher in eggs arrested in wet faeces than included in water (55% "versus" 20% of hatching in spring), and it was unrelated to the deposition time (excretion in early or late winter). The hatching period of overwintered eggs started in May, at the same time as those excreted in early spring. Therefore, overwintering of eggs will have an effect on the level but not on the start of the spring contamination with miracidia. The dry winters of this semi-arid area greatly restrict the overwintering eggs contamination to soils next to streams, ponds or irrigation channels.

Animals↗
PubMed1989

Jogger's phimosis.

Explore the source record for details and available documents.

Athletic Injuries↗
PubMed2006

Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length.

Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea, Pinus, Abies and Larix) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote (A), x-axis placement (beta) and rate of change (kappa). A strong linear relationship was found between the constants beta and kappa for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.

Canada↗
PubMed2006

Increased ectomycorrhizal fungal abundance after long-term fertilization and warming of two arctic tundra ecosystems.

Shrub abundance is expected to increase with enhanced temperature and nutrient availability in the Arctic, and associated changes in abundance of ectomycorrhizal (EM) fungi could be a key link between plant responses and longer-term changes in soil organic matter storage. This study quantifies the response in EM fungal abundance to long-term warming and fertilization in two arctic ecosystems with contrasting responses of the EM shrub Betula nana. Ergosterol was used as a biomarker for living fungal biomass in roots and organic soil and ingrowth bags were used to estimate EM mycelial production. We measured 15N and 13C natural abundance to identify the EM-saprotrophic divide in fungal sporocarps and to validate the EM origin of mycelia in the ingrowth bags. Fungal biomass in soil and EM mycelial production increased with fertilization at both tundra sites, and with warming at one site. This was caused partly by increased dominance of EM plants and partly by stimulation of EM mycelial growth. We conclude that cycling of carbon and nitrogen through EM fungi will increase when strongly nutrient-limited arctic ecosystems are exposed to a warmer and more nutrient-rich environment. This has potential consequences for below-ground litter quality and quantity, and for accumulation of organic matter in arctic soils.

Arctic Regions↗
PubMed1987

Heterococcus endolithicus sp. nov. (Xanthophyceae) and other terrestrial Heterococcus species from Antarctica: morphological changes during life history and response to temperature.

Strains of Heterococcus endolithicus sp. nov., H. pleurococcoides Pitschmann, H. caespitosus Vischer, and H. protonematoides Vischer isolated from terrestrial habitats in Antarctica were studied in culture. Morphology of the algae changes with stage in life history. The characteristic branching patterns are not present in very young or old cultures. Filament formation is suppressed when cultures are grown outside their optimal temperature range.

Antarctic Regions↗
PubMed1998

Geographic distribution of constipation in the United States.

OBJECTIVE: Despite its frequent occurrence, the etiology of constipation has remained poorly understood. The influence of widely accepted risk factors such as inadequate dietary fiber intake, immobility, insufficient fluid intake, and poor muscle tone is unclear. This study examined the geographic distribution of constipation among Medicare beneficiaries to identify potential environmental risk factors. METHODS: All Medicare beneficiaries with a diagnosis of constipation were extracted from the total Health Care Financing Administration data file of 1987 and stratified by sex, race, and state of residence. The population of each state by sex, race, and age >65 yr served as the denominator to calculate sex- and race-specific morbidity rates. RESULTS: A distinct geographic distribution was observed. When stratified by individual states, hospital discharges for constipation were more common in rural as compared with urban states. Constipation also appeared to be more common in northern and in poorer states. CONCLUSION: The distinct geographic pattern of constipation suggests the influence of three global environmental factors: rural living, colder temperature, and lower socioeconomic status.

Aged↗