Disorders of iron metabolism account for some of the most common human diseases. Cellular iron homeostasis is maintained by iron regulatory proteins (IRP)-1 and 2 through their binding to
cis
...-regulatory iron-responsive elements (IREs) in target mRNAs. Mouse models with IRP deficiency have yielded valuable insights into iron biology, but the physiological consequences of gain of IRP function in mammalian organisms have remained unexplored. Here, we report the generation of a mouse line allowing conditional expression of a constitutively active IRP1 mutant (IRP1*) using Cre/Lox technology. Systemic activation of the IRP1* transgene from the
Rosa26
locus yields viable animals with gain of IRE-binding activity in all the organs analyzed. IRP1* activation alters the expression of IRP target genes and is accompanied by iron loading in the same organs. Furthermore, mice display macrocytic erythropenia with decreased hematocrit and hemoglobin levels as well as impaired erythroid differentiation. Thus, inappropriately high IRP1 activity causes disturbed body iron distribution and erythropoiesis. This new mouse model further highlights the importance of appropriate IRP regulation in central organs of iron metabolism. Moreover, it opens novel avenues to study diseases associated with abnormally high IRP1 activity, such as Parkinson’s disease or Friedreich’s ataxia.
Context. The optical ring-like structure detected by Arp (1965) around M 81 (commonly referenced as “Arp's loop”) represents one of the most spectacular features observed in nearby galaxies. Arp's ...loop is commonly interpreted as a tail resulting from the tidal interaction between M 81 and M 82. However, since its discovery the nature of this feature has remained controversial. Aims. Our primary purpose was to identify the sources of optical and infrared emission observed in Arp's loop. Methods. The morphology of Arp's loop has been investigated with deep wide-field optical images. We also measured its colors using IRAS and Spitzer-MIPS infrared images and compared them with those of the disk of M 81 and Galactic dust cirrus that fills the area where M 81 is located. Results. Optical images reveal that this peculiar object has a filamentary structure characterized by many dust features overlapping M 81's field. The ratios of far-infrared fluxes and the estimated dust-to-gas ratios indicate the infrared emission of Arp's loop is dominated by the contribution of cold dust that is most likely from Galactic cirrus. Conclusions. The above results suggest that the light observed at optical wavelengths is a combination of emission from i) a few recent star-forming regions located close to M 81, where both bright UV complexes and peaks in the HI distribution are found, ii) the extended disk of M 81 and iii) scattered light from the same Galactic cirrus that is responsible for the bulk of the far-infrared emission.
Background: House dust mites are common sources of indoor allergens. In Reykjavik, Iceland, 9% of the young adult population had serum‐specific IgE to Dermatophagoides pteronyssinus. Sensitization ...to mites is usually assumed to be due to exposure to house dust mites in the indoor environment. This investigation was carried out to measure the concentrations of house dust mite allergens and to investigate which species of mites were present in beds in Iceland.
Methods: A total of 197 randomly selected adults were visited at home using the European Community Respiratory Health Survey (ECRHS) II Indoor protocol. Dust samples were collected from mattresses for measurement of house dust mite allergen concentrations and to estimate the number and type of house dust mites. Additional samples from mattresses and floors were collected from the homes of 10 patients with positive skin prick tests (SPT) to D. pteronyssinus. House dust mite allergen concentrations were measured using ELISA and examination of mite species was carried out using microscopy. Climatic parameters were assessed using psychrometer readings in the bedrooms and outdoors.
Results: We found two single mite specimens, both D. pteronyssinus, in two dust samples. Mite allergen analyses indicated that two other dust samples had Der f 1 results close to the cut‐off of 0.1 μg/g of dust. No samples were positive for Der p 1. In an additional collection of dust from the homes of 10 SPT‐positive patients no Dermatophagoides spp. were found.
Conclusions: Reykjavik citizens are exposed to extremely low amounts of house dust mite allergens in their homes. Possible alternative sources for sensitization are discussed, such as bird nests, exposure from travelling abroad, or other mites or invertebrates that cross‐react with house dust mite allergens. Our findings suggest that exposures other than to house dust mites indoors are possible sources of mite allergen exposure.
Summary
Background Knowledge of the occurrence of house dust mites (HDM) and their allergens in domestic locations is important when planning intervention.
Objective The aim of this study was to ...describe the distribution of HDMs and their allergens before intervention in multiple locations in the homes of newly diagnosed HDM‐allergic patients with a known high Der 1 concentration in their mattress dust.
Methods Dust was collected from ten locations in the homes of eight HDM‐allergic patients. Dust was analysed for allergen content with ELISAs for Der f 1, Der p 1 and Der m 1; and HDM were counted. Total allergen concentrations (µg Der 1/g dust) were expressed as the sum of Der f 1, Der p 1 and Der m 1.
Results On mattresses the median concentration was 86 µg Der 1/g dust (range 30–288) and 188 mites/g dust (range 12–1910). Der 1 exceeded 10 µg/g dust in mattresses (8/8), duvets/pillows (3/8), a bedroom carpet (1/1), a living room carpet (1/6), upholstered furniture (2/8) and a curtain (1/5). Uncarpeted floors, upholstered furniture, bookshelves and walls had significantly lower Der 1 concentration than the mattresses. The relative contribution of Der p 1, Der f 1 or Der m 1 to Der 1 was related to homes, rather than to the location. Der m 1 only occurred in minute amounts.
Conclusion For HDM intervention, our results indicate that priority should be given to the removal of allergens from mattresses, and in addition from carpets, duvets/pillows and upholstered furniture. Dust from walls, uncarpeted floors, bookshelves and curtains appear to contribute insignificantly to the domestic HDM allergen load.
The plant parasitic mite Penthaleus major (Dugès) occurs as a pest on perennial grasses in hayfields in Iceland, northern Norway, and southern Greenland. In these areas it appears as a summer ...phenomenon, contrary to more southern locations, where it appears as a pest on winter crops. Up to 500 individuals of P. major were collected per day in pitfall traps. Spring application of 44 ml/ha of permethrin and 5 ml of deltamethrin significantly reduced but did not eliminate the populations of P. major the following weeks. In addition to this immediate effect, spring application also decreased the mite populations in the fall and even the following spring. Additional effects might be obtained by earlier spring application. Despite a significant reduction in mite populations and reduction in visible plant damage, significant differences on dry matter yield were rarely registered. A side effect of application was a small but significant reduction in potassium-content of the yield, and the reduction in mite population was accompanied by a corresponding reduction in the number of spiders.
Results from vacuum collected samples from a patient's environment may support the diagnosis of mite allergy. High estimates of mites or mite allergens do show that a patient is exposed. Low ...estimates are harder to interpret. Estimates may be low due to dust dynamics or to the behaviour of the mites, which, according to their biology, can be present or almost absent in the samples. A survey is given of the nature of these obstacles to proportionality between sample results and the exposure which might be experienced by a patient during a period of time. To reduce the problems of false-negative estimates of exposures from single samples, series of samples collected weeks apart may improve the significance of diagnoses.
Summary
Sensitization to house dust mites, storage mites and other common inhalation allergens was studied in 144 farmers using SPT and RAST. The study population was selected from a random sample of ...808 farmers and consisted of 47 persons who had declared themselves to suffer from asthma, 63 persons who had reported respiratory symptoms, and 34 healthy persons without respiratory symptoms. The most prevalent RAST was towards storage mites and was found in 17% of farmers who suffered from asthma and was estimated to occur in 5% of the random sample of farmers. A positive RAST to house dust mites was found in 17% of farmers who reported to suffer from asthma. Sensitization to pollens, animal dander and grain species was rare. A positive RAST to moulds was not found. There was a strong association between a positive RAST to house dust mites and a positive RAST to storage mites (odds ratio 21.0). A positive RAST to storage mites was significantly associated with living in a dwelling in the past which was recalled as damp (odds ratio 4.9). A high number of house dust mites was found in nearly all dwellings (median count 148 mites/0.1 g dust) and a high number of storage mites was found in some dwellings. This study suggests that in humid and temperate regions of Europe, allergy to storage mites in farmers is not caused exclusively by occupational exposure but damp housing conditions and indoor exposure to storage mites may also be important.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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