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At least 973 records · Page 54Linked to original sources
PubMed2000

Mites and birds: diversity, parasitism and coevolution.

Ectoparasites play important roles in the lives of birds. Among these parasites, mites offer unique potential because of their extraordinary ecological and evolutionary diversity. However, the basic biology of most mites is poorly understood, and misleading extrapolations are sometimes made from better studied systems involving lice and fleas. Most importantly, not all bird-associated mites are parasitic; indeed, recent research suggests that some might even be beneficial. Here, we summarize what is known about the diversity of bird-mite relationships, and highlight how mites provide an ideal tool for the study of host life histories, sexual selection, immunocompetence and cospeciation.

Journal Article↗
PubMed1996

Density patterns of gall mites (Acarina:Eriophyidae) in a polluted area.

Trends in the densities of six species of gall mites on European aspen (Populus tremula) and on two birch species (Betula pubescens and B. pendula) were compared in an air pollution gradient from the Harjavalta copper-nickel smelter, SW Finland. The densities of gall mites on both birch species decreased towards the smelter and were negatively correlated with the levels of copper and nickel in the birch leaves. In contrast, the densities of aspen mites correlated neither with distance from the pollution source nor with the content of heavy metals in aspen leaves. Both birch and aspen trees tended to produce smaller leaves near the smelter, but a significant correlation between gall mite densities and site-specific leaf areas was only found for one species of mite.

Journal Article↗
PubMed2004

[Allergy to house dust mites: allergy independent symptoms dominate].

A sensitisation to allergens has not always a clinical relevance. Therefore, the history has an uppermost importance for defining the relevance of a sensitisation. In contrast to the history in seasonal rhino-conjunctivitis, which causes typical complains in a restricted time period patients with house dust mite allergy seem to have less defined complaints. To define the most relevant symptoms of this frequent allergy, we evaluated 35 patients with clearly defined house dust mite allergy by a questionnaire and evaluated the same questionnaire also in a control group of 18 patients without sensitisation or asthma. The symptoms described in the patient group confirm that symptoms of house dust mite allergy are frequently not related to a direct allergen exposure. Some patients complained about itchy red eyes in the morning, but the majority of symptoms occurred independent from allergen exposure. These are blocked nose as well as exercise induced asthma. These symptoms are present all year around and are not only restricted to mite exposed areas. They are probably related to the underling eosinophilic inflammation. Thus exercise induced asthma and blocked nose are symptoms, which may indicate a mite allergy, particular in younger patients.

Adolescent↗
PubMed2003

The plant MITE mPing is mobilized in anther culture.

Transposable elements constitute a large portion of eukaryotic genomes and contribute to their evolution and diversification. Miniature inverted-repeat transposable elements (MITEs) constitute one of the main groups of transposable elements and are distributed ubiquitously in the genomes of plants and animals such as maize, rice, Arabidopsis, human, insect and nematode. Because active MITEs have not been identified, the transposition mechanism of MITEs and their accumulation in eukaryotic genomes remain poorly understood. Here we describe a new class of MITE, called miniature Ping (mPing), in the genome of Oryza sativa (rice). mPing elements are activated in cells derived from anther culture, where they are excised efficiently from original sites and reinserted into new loci. An mPing-associated Ping element, which has a putative PIF family transposase, is implicated in the recent proliferation of this MITE family in a subspecies of rice.

Base Sequence↗
PubMed2002

Allergen-induced bronchial inflammation in house dust mite-allergic patients with or without asthma.

BACKGROUND: It is presently unknown which factors determine the occurrence and persistence of asthma in house dust mite-allergic individuals. The level of allergen-specific IgE antibodies does not seem to be decisive for asthmatic symptoms. Moreover, levels of exposure to mite allergens do not seem to differ significantly between asthmatic and non-asthmatics individuals. AIM: It was hypothesized that the presence or absence of asthmatic symptoms in house dust mite-allergic patients is associated with quantitative or qualitative differences in the cellular bronchial inflammatory response during the late phase of the allergic reaction. This hypothesis was tested in the bronchial allergen challenge model. MATERIAL AND METHODS: Whole lung challenges with house dust mite extract were performed in 52 house dust mite-allergic subjects, of whom 26 had asthma and 26 had perennial rhinitis without asthmatic symptoms. Primary outcomes were parameters for bronchial inflammation in serial samples of induced sputum (cell differentials, eosinophil cationic protein (ECP), interleukin-8 (IL-8), myeloperoxydase (MPO)). In addition, lung function, non-specific bronchial hyper-responsiveness and serial blood samples (eosinophils and IL-5) were analysed. RESULTS: At baseline sputum eosinophils and ECP were similar in both groups but neutrophils and IL-8 were higher in asthmatics. The early bronchoconstriction after allergen challenge was similar in asthma and non-asthmatic rhinitis (median decrease in FEV1: asthma -31.7% vs. non-asthmatics -29.1%, P > 0.1). The late phase bronchoconstriction was significantly greater in asthma (median decrease in FEV1: asthma -27.6% vs. non-asthmatics -18.9%, P = 0.02). Induction of bronchial hyper-responsiveness was similar in both groups. Bronchial allergen challenge elicited significant increases in sputum eosinophils and ECP, which were indistinguishable for both groups (P > 0.1 and P = 0.07, respectively). In contrast, higher numbers of neutrophils persisted in asthma 24h after challenge and were accompanied by significant increases in IL-8 and MPO, which were absent in non-asthmatics (difference between groups P = 0.007 and P = 0.05, respectively). CONCLUSION: Allergen challenge inducedvery similar increases in eosinophils and ECP in induced sputum in allergic asthmatics and in allergic non-asthmatic patients. The difference in bronchial inflammation between asthma and non-asthmatic rhinitis appeared to be more closely related to indices for neutrophilic inflammation.

Adolescent↗
PubMed2003

Control of exposure to mite allergen and allergen-impermeable bed covers for adults with asthma.

BACKGROUND: The effectiveness of avoidance of house-dust-mite allergen (Dermatophagoides pteronyssinus 1 [Der p1]) in the management of asthma is uncertain. METHODS: We conducted a double-blind, randomized, placebo-controlled study of allergen-impermeable bed covers involving 1122 adults with asthma. The primary outcomes were the mean morning peak expiratory flow rate over a four-week period during the run-in phase and at six months and the proportion of patients who discontinued inhaled corticosteroid therapy as part of a phased-reduction program during months 7 through 12. Der p1 was measured in mattress dust in a 10 percent random subsample of homes at entry and at 6 and 12 months. RESULTS: The prevalence of sensitivity to dust-mite allergen was 65.4 percent in the group supplied with allergen-impermeable bed covers (active-intervention group) and 65.1 percent in the control group supplied with non-impermeable bed covers. The concentration of Der p1 in mattress dust was significantly lower in the active-intervention group at 6 months (geometric mean, 0.58 microg per gram vs. 1.71 microg per gram in the control group; P=0.01) but not at 12 months (1.05 microg per gram vs. 1.64 microg per gram; P=0.74). The mean morning peak expiratory flow rate improved significantly in both groups (from 410.7 to 419.1 liters per minute in the active-intervention group, P<0.001 for the change; and from 417.8 to 427.4 liters per minute in the control group, P<0.001 for the change). After adjustment for base-line differences (by analysis of covariance), there was no significant difference between the groups in the peak expiratory flow rate at six months (difference in means, active-intervention group vs. control group, -1.6 liters per minute [95 percent confidence interval, -5.9 to 2.7] among all patients [P=0.46] and -1.5 liters per minute [95 percent confidence interval, -6.9 to 3.9] among mite-sensitive patients [P=0.59]). There was no significant difference between the groups in the proportion in whom complete cessation of inhaled corticosteroid therapy was achieved (17.4 percent in the active-intervention group and 17.1 percent in the control group) or in the mean reduction in steroid dose, either among all patients or among mite-sensitive patients. CONCLUSIONS: Allergen-impermeable covers, as a single intervention for the avoidance of exposure to dust-mite allergen, seem clinically ineffective in adults with asthma.

Adrenal Cortex Hormones↗
PubMed2001

P instability factor: an active maize transposon system associated with the amplification of Tourist-like MITEs and a new superfamily of transposases.

Miniature inverted-repeat transposable elements (MITEs) are widespread and abundant in both plant and animal genomes. Despite the discovery and characterization of many MITE families, their origin and transposition mechanism are still poorly understood, largely because MITEs are nonautonomous elements with no coding capacity. The starting point for this study was P instability factor (PIF), an active DNA transposable element family from maize that was first identified following multiple mutagenic insertions into exactly the same site in intron 2 of the maize anthocyanin regulatory gene R. In this study we report the isolation of a maize Tourist-like MITE family called miniature PIF (mPIF) that shares several features with PIF elements, including identical terminal inverted repeats, similar subterminal sequences, and an unusual but striking preference for an extended 9-bp target site. These shared features indicate that mPIF and PIF elements were amplified by the same or a closely related transposase. This transposase was identified through the isolation of several PIF elements and the identification of one element (called PIFa) that cosegregated with PIF activity. PIFa encodes a putative protein with homologs in Arabidopsis, rice, sorghum, nematodes, and a fungus. Our data suggest that PIFa and these PIF-like elements belong to a new eukaryotic DNA transposon superfamily that is distantly related to the bacterial IS5 group and are responsible for the origin and spread of Tourist-like MITEs.

Base Sequence↗
PubMed2002

House dust mite allergen levels in German day-care centers.

We investigated the levels of the major house dust mite allergens, Der p 1 and Der f 1, in dust collected from various locations in 41 day-care centers from two German cities (Düsseldorf and Bonn). One hundred and thirty-seven (96%) of 143 samples yielded detectable amounts of house dust mite allergen (range, < 15-85,000 ng/g; interquartile range, 210-1,480 ng group I allergen [sum of Der p 1 and Der f 1]/g dust), and 24 (17%) of the samples (8/34 mattresses; 11/46 cushions/soft toys; 5/43 carpeted floors, 0/20 smooth floors) exceeded the proposed "threshold" level of 2,000 ng/g dust in 18 (44%) of 41 day-care centers. Der p 1 and Der f 1 could be detected in nearly an equal number of samples. The highest concentrations of house dust mite allergens were found in dust from mattresses (geometric mean, 1,103 ng/g dust) and cushions/soft toys (geometric mean, 1,004 ng/g dust). The allergen load per unit area from carpeted floors exceeded that from smooth floors by more than two orders of magnitude. In comparison with dust samples from private homes within the same geographical area, the mite allergen levels in mattress dust (RR, 0.34; CI95, 0.18-0.64) and floor dust (RR, 0.21; CI95, 0.09-0.49) from day-care centers were significantly lower (p < 0.001). We conclude that day-care centers should be included as potential places of additional exposure to house dust mite allergens if avoidance measures are taken.

Allergens↗
PubMed1995

The diet of the parasitic mite Trichosurolaelaps crassipes Womersley, 1956 and its potential to act as a disease vector.

The anatomy of the gaster of Trichosurolaelaps crassipes is illustrated. Protonymphs, deutonymphs and adults were all seen with a scarlet gut and gave strongly positive results to occult blood tests. Host blood cells were identified in a gut smear from a female mite. An adult female gut could hold about 7.1 x 10(-6) ml. The mite was seen frequenting small open skin lesions. Gram-negative bacteria identified in the mite's gut are most likely to be endosymbionts. Mite larvae have their gastric caeca invaded by these bacteria before birth. There is a potential for this mite to act as a weak vector of disease from one possum to another.

Journal Article↗
PubMed2002

Leaf cell and tissue damage of cucumber caused by twospotted spider mite (Acari: Tetranychidae).

To quantify the damage caused by twospotted spider mite, Tetranychus urticae Koch, feeding on cucumber, Cucumis sativus L., leaf-cell and -tissue damage was assessed. On the abaxial leaf surface, adult T. urticae could feed through the spongy parenchyma and part of the palisade parenchyma of the leaf, while immature T. urticae could feed only through the sponge parenchyma. T. urticae punctured individual epidermal cells and consumed the contents of the mesophyll cells. Injured leaves had more empty space in the spongy parenchyma and fewer chloroplasts per cell. Damage also occurred even in the adjacent uninjured parenchyma cells without additional T. urticae feeding injury. Net photosynthetic rate, total chlorophyll content, and greenness of the leaf were significantly affected by feeding as quantified by mite-days. The percent loss of these parameters increased linearly or nonlinearly as mite-days increased, regardless of mite developmental stages. At 1,000 mite-days per 6 cm2, net photosynthetic rate was reduced by approximately 50 and 95%, total chlorophyll content was reduced by approximately 55 and 80%, and greenness was reduced by approximately 50 and 80% by feeding by immature and adult T. urticae, respectively.

Animals↗
PubMed2004

Altered physiology in worker honey bees (Hymenoptera: Apidae) infested with the mite Varroa destructor (Acari: Varroidae): a factor in colony loss during overwintering?

The ectoparasitic mite Varroa destructor (Anderson & Trueman) is the most destructive pest of the honey bee, Apis mellifera L., in Europe and the United States. In temperate zones, the main losses of colonies from the mites occur during colony overwintering. To obtain a deeper knowledge of this phenomenon, we studied the mites' impact on the vitellogenin titer, the total protein stores in the hemolymph, the hemocyte characteristics, and the ecdysteroid titer of adult honey bees. These physiological characteristics are indicators of long-time survival and endocrine function, and we show that they change if bees have been infested by mites during the pupal stage. Compared with noninfested workers, adult bees infested as pupae do not fully develop physiological features typical of long-lived wintering bees. Management procedures designed to kill V. destructor in late autumn may thus fail to prevent losses of colonies because many of the adult bees are no longer able to survive until spring. Beekeepers in temperate climates should therefore combine late autumn management strategies with treatment protocols that keep the mite population at low levels before and during the period when the winter bees emerge.

Acari↗
PubMed2005

Effects of various anti-asthmatic agents on mite allergen-pulsed murine bone marrow-derived dendritic cells.

BACKGROUND: Dendritic cells (DCs) play an important role in the immune response and are critically involved in asthma. beta2-agonists could potentially exacerbate type 2 T helper (Th2) cell-mediated immune response. OBJECTIVES: To determine the effects of various anti-asthmatic agents on DCs function both in vitro and in vivo. METHODS: Murine bone marrow-derived DCs were pulsed with mite allergen in the presence of pranlukast, salbutamol, salmeterol or fluticasone. These DCs were then inoculated intranasally into naïve mice to induce allergic airway inflammation in vivo. RESULTS: Pranlukast reduced IL-10 and increased IL-12, while fluticasone reduced both IL-10 and IL-12 production by mite allergen-pulsed DCs. Allergic airway inflammation in pranlukast- and fluticasone-treated and mite allergen pulsed DCs-harbouring mice was attenuated and such response was associated with inhibition of Th2 response in the airway. Salbutamol did not alter cytokine production, while salmeterol reduced IL-12 production by mite allergen-pulsed DCs. Lung pathology in beta2-agonist-harbouring mice was comparable with those of mite allergen-pulsed DCs-harbouring mice. CONCLUSIONS: Our results indicate that leukotriene receptor antagonists and corticosteroids inhibit DCs-induced Th2 skewed immune response, and that short- and long-acting beta2-agonists do not modify DCs-induced allergic airway inflammation.

Albuterol↗
PubMed2005

Mite allergen induces nitric oxide production in alveolar macrophage cell lines via CD14/toll-like receptor 4, and is inhibited by surfactant protein D.

BACKGROUND: Previously, we have found that dust mite allergens can directly activate alveolar macrophages (AMs), induce inflammatory cytokines, and enhance T-helper type 2 cytokine production. A molecule of innate immunity in the lung, surfactant protein D (SP-D), is able to bind mite allergens and alleviates allergen-induced airway inflammation. OBJECTIVES: This study was aimed at investigating the activation pathway of mite allergen (Dermatophagoides pteronyassinus, Der p)-induced nitric oxide (NO) production by AMs, and the role of SP-D in the modulation of activated AMs by mite allergens. METHODS: Porcine SP-D was purified from bronchoalveolar lavage fluids of Lan-Yu mini-pigs, by affinity chromatography on maltose-sepharose. NO production, inducible expression of lipopolysaccharides (LPS)-related binding and responding surface receptors complex, CD14 and toll-like receptor 4 (TLR4), as well as inducible NO synthase (iNOs) and nuclear factor-kappaB activation were studied in two AMs cell lines, MH-S (BALB/c strain),and AMJ2-C11 (C57BL/6 strain), and one peritoneal macrophage cell line (RAW264.7), after stimulation with LPS, or Der p. RESULTS: LPS and Der p elicited different responses of NO production in the different cell lines, and the response might depend upon the expression of the cell surface CD14/TLR4 complex in different genetic backgrounds of macrophage cell lines. Pretreatment of macrophages with SP-D could inhibit NO production from Der p or LPS-stimulated alveolar macrophages. CONCLUSION: Mite allergen-induced alveolar macrophage activation is mediated by CD14/TLR4 receptors and can be inhibited by SP-D; it further supports the concept that SP-D may be an important modulator of allergen-induced pulmonary inflammation.

Animals↗
PubMed2006

Characterization of glutathione S-transferase from dust mite, Der p 8 and its immunoglobulin E cross-reactivity with cockroach glutathione S-transferase.

BACKGROUND: Sensitization to mite and cockroach allergens is common, and diagnosis and therapy of allergy can be further complicated by the presence of allergen isoforms and panallergens. Purified recombinant and native allergens are useful for studies to resolve such problems. OBJECTIVE: To assess the allergenicity of native and recombinant mite glutathione S-transferase (GST) (Der p 8) and study the IgE cross-reactivity between Der p 8 and cockroach GST. METHODS: Der p 8 cDNA encoding a new isoform was isolated and expressed in yeast. Native Der p 8 was affinity purified from mite extract. IgE reactivity to native and recombinant Der p 8 was assessed by ELISA using sera from allergic subjects from Taiwan, Singapore and Malaysia. IgE cross-reactivity between Der p 8 and cockroach GST was examined by IgE inhibition assays. RESULTS: Our Der p 8 cDNA encoded a basic isoform (pI=8.5) containing six polymorphic residues located at positions 46, 106, 149, 160, 167 and 184. At least 8 isoforms of native Der p 8 were detected by two-dimensionalgel and immunoblot analyses. Sera from Taiwanese asthmatics showed 96% and 84% IgE reactivity to native Der p 8 and recombinant Der p 8, respectively. Native Der p 8 showed 75% and 65% IgE reactivity with sera from Malaysia and Singapore, respectively. CONCLUSIONS: A high frequency of sensitization to mite GST among allergic subjects was observed but the titres of IgE reactivity were low. The IgE cross-reactivity between mite and cockroach GST suggests that GST is a panallergen.

Adolescent↗
PubMed2006

Usefulness of specific immunotherapy in patients with atopic dermatitis and allergic sensitization to house dust mites: a multi-centre, randomized, dose-response study.

BACKGROUND: The effect of specific immunotherapy (SIT) on eczema in atopic dermatitis is not known. Therefore, a multi-centre, randomized dose-response trial, double-blind with respect to the efficacy of a biologically standardized depot house dust mite preparation was performed. METHODS: Eighty-nine adults with a chronic course of atopic dermatitis, SCORAD >or=40 and allergic sensitization to house dust mites [CAP-FEIA >or=3] were included, of whom 51 completed the study. Subcutaneous SIT with a house dust mite preparation (Dermatophagoides pteronyssinus/D. farinae) applying maintenance doses of 20, 2,000 and 20,000 SQ-U in weekly intervals for 1 year. The main outcome measures addressed the change of the SCORAD as average of the values after 9 and 12 months of SIT in comparison with the value at baseline. RESULTS: The SCORAD declined in the three dose groups in a dose-dependent manner (P = 0.0368, Jonckheere-Terpstra test) and was significantly lower in the two high-dose groups (2,000, 20,000 SQ-U) compared with the low-dose group of 20 SQ-U (P = 0.0379, U-test) after 1 year of SIT. The use of topical corticosteroids was significantly reduced with higher doses (P = 0.0007, Mantel-Haenszel chi-square test). CONCLUSIONS: Allergen-SIT for 1 year with a house dust mite preparation is able to improve the eczema in patients with atopic dermatitis who are sensitized to house dust mite allergens and reduces the need for topical corticosteroids. SIT may be valuable in the treatment of this chronic skin disease.

Adolescent↗
PubMed2006

Inhaled formaldehyde exposure: effect on bronchial response to mite allergen in sensitized asthma patients.

BACKGROUND: Formaldehyde, an indoor air pollutant, is known to be an irritant and an etiologic factor in occupational asthma. An epidemiologic study suggests that it may also increase the risk of childhood asthma for concentrations above 60 microg/m(3). AIM: To evaluate the influence of pre-exposure to low-dose formaldehyde (100 microg/m(3) in 30 min according to the World Health Organization's recommended maximum value for indoor environments) on bronchial response to Dermatophagoides pteronyssinus. METHOD: Nineteen asthmatic subjects were included. Each subject underwent a mite allergen bronchial challenge test immediately after a standardized exposure in a chamber to formaldehyde or air (random order). Induced sputum were collected 24 h before and after mite challenge. RESULTS: After formaldehyde inhalation, patients developed an immediate bronchial response at a significantly lower dose of mite allergen than after air exposure (the geometric mean PD(20) for Der p 1 was 34.3 ng after formaldehyde and 45.4 ng after placebo, P = 0.05). The late-phase reaction, expressed as the maximum fall in forced expiratory volume in 1 s (FEV(1)) from baseline, was significantly higher after formaldehyde (15%vs 11%, P = 0.046). CONCLUSION: Our study demonstrated that exposure to low levels of formaldehyde significantly enhanced bronchial responsiveness to mite allergen in mite-sensitized subjects with asthma.

Adult↗
PubMed2006

Total serum IgE and IgE antibodies specific to house dust mite found in two aged-matched cohorts of children with and without otitis media with effusion.

OBJECTIVES: To determine whether otitis media with effusion (OME) is associated with elevated serum immunoglobulin E (IgE) and IgE specific for house dust mite. DESIGN: Forty-seven children who had evidence of bilateral OME, both otoscopically and on tympanometry, on two separate occasions, 3 months apart were admitted for ventilation tubes. Forty-eight children admitted for minor eye surgery who had otoscopically normal ears and no history of middle ear problems were used as controls. Bloods samples were taken under anaesthesia. Total IgE and IgE radioallergosorbent test (RAST) to house dust mite was measured by the Pharmacia Unicap 100 system. The results from the two groups were compared. SETTING: Birmingham Children's Hospital. PARTICIPANTS: Children between the ages of 3 and 10. Children with Down's syndrome, cleft lip and palate, ciliary abnormalities, known immunodeficiencies and cardiac abnormalities were excluded. MAIN OUTCOME MEASURES: Total IgE and RAST to house dust mite. A RAST of >0.35 was taken to be positive. RESULTS: There was no statistical difference between the control and study groups for the total IgE. Six children from both study and control groups had a raised house dust mite RAST. There was no difference in the levels between either group. CONCLUSIONS: Our findings indicate that there is no direct relationship between OME and biochemical evidence of allergy, specifically to house dust mite.

Allergens↗
PubMed1996

Living on leaves: mites, tomenta, and leaf domatia.

Structures on the surfaces of leaves strongly affect phylloplane mites. Glandular trichomes defend against some plant parasites but can also mire predators. However, leaves with tomenta of nonglandular trichomes are often inhabited by large populations of predatory mites. Tufts of hairs and other minute structures in the vein axils are called leaf domatia. Comparative observations and experimental data demonstrate that leaves with domatia have enhanced levels of predatory mites. By accumulating predatory mites, leaf domatia act as a kind of constitutive defense against herbivores. Mites benefit from leaf domatia by securing a safe place for oviposition and molting. Like several other plant structures, leaf domatia are the manifestation of a long-term and mutually beneficial interaction between plants and arthropods.

Journal Article↗