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At least 145 records · Page 8Linked to original sources
PubMed1990

Case report of occupational asthma due to palisander wood dust and bronchoprovocation challenge by inhalation of pure wood dust from a capsule.

Occupational asthma due to exposure to exotic wood dust and to rosewood (Dalbergia family) has been reported earlier. This paper deals with a case of occupational asthma due to palisander wood dust (Dalbergia nigra) in a joiner who sanded and polished parts of musical instruments. The causal relationship was confirmed by a positive skin reaction to an allergenic preparation and a positive nonimmediate, late asthmatic reaction after inhalation challenge testing with pure palisander wood dust. A method of bronchoprovocation testing with an occupational allergen is presented. It proved to be a practical and advantageous method in its simplicity and single-blind application of placebo. It should, however, be used with great caution, in well-chosen cases in whom nonspecific bronchial reactivity is proved or recorded to be in normal ranges.

Asthma↗
PubMed1976

The size of airborne dust particles precipitating bronchospasm in house dust sensitive children.

We have assessed the effect of house-cleaning procedures on changes in airborne dust and bacteria counts and correlated these with respiratory function tests in 14 children with bronchial asthma who were known to have developed attacks at home, and who had positive skin tests to house dust and the house-dust mite. We have demonstrated that after cleaning procedures a positive and statistically significant correlation exists between the increase in the numbers of small particles, 2 mum. and less in diameter, in the environment, and reduction in mean peak flow. This indicates that particles of this size penetrate the bronchial tree and are the causative factor in the genesis of bronchospasm.

Asthma↗
PubMed1993

Does guanine concentration in house-dust samples reflect house-dust mite exposure?

Using specific ELISA extracts, we analyzed samples of pure mite cultures and house dust for group I allergens from Dermatophagoides pteronyssinus, D. farinae, and D. microceras. Correspondingly, we measured the concentration of guanine and xanthine by rigorous chemical methods. The pure mite cultures were used to correlate allergen levels with guanine levels. The house-dust samples one-sidedly contained more guanine than expected. This suggests that considerable amounts of guanine originate from non-house-dust mite sources and implies that guanine quantifications are of limited clinical value.

Allergens↗
PubMed2006

[Japanese administrative control level of respirable dust and determination of crystalline silica in dust].

In Japan, there are two commonly used regulations on respirable dust concentration: the Occupational Exposure Limit (OEL), recommended by the Japan Society for Occupational Health, and the Administrative Control Level (ACL). Both depend on the crystalline silica content in dust. Until 2004, the ACL for respirable dust conformed to the OEL. However, the ACL was revised in 2005 in light of the OEL and the American Conference of Governmental Industrial Hygienists (ACGIH)'s Threshold Limit Value (TLV), same value as National Institute for Occupational Safety and Health (NIOSH)'s Recommended Exposure Limit (REL). In this paper, the author intends to clarify the stringency of the current ACL by comparing it with the OEL and the ACGIH's TLV. In addition, the effect of the analytical error due to the phosphoric acid method in the current and former ACLs is shown.

Dust↗
PubMed2005

Bacterial contamination of indoor air, surfaces, and settled dust, and related dust endotoxin concentrations in healthy office buildings.

Endotoxin, a characteristic external fraction of the outer membrane from Gram-negative bacteria, continuously shed into the environment, is considered as an important risk factor for human health. Our purpose was to study the bacterial species contaminating healthy working environments. Airborne, working surfaces and carpet dust samples were collected from 25 offices. Bacterial species were identified with biochemical ApiSystem strips. Endotoxin concentrations in settled dust were measured with the kinetic chromogenic Limulus assay. The airborne bacterial level varied from 44-2,511, with a median of 277 cfu/m(3). Bacterial contamination on surfaces ranged from 1-1000, with 33 cfu/25 cm(2) as median value. On carpets, bacterial concentration ranged from 0.73-185 x 10(5) cfu/g, with 7.28 x 10(5) cfu/g as median value. Endotoxin concentration varied from 4.6-116.2 EU/mg, with a median of 20.3 EU/mg. Altogether, 501 bacterial strains were isolated. The species variability was greater in Gram-negative bacteria than in Gram-positive cocci with 41 versus 34 various species. In conclusion, people working in healthy offices can be exposed to large concentrations of airborne and dust bacteria and related endotoxin concentrations, giving a risk of work-related diseases.

Air Microbiology↗
PubMed1991

[Correlation between nasal polyposis and perennial allergy exemplified by house dust mite and house dust allergy].

A total of 139 patients with nasal polyps were investigated by a standardized history, intradermal skin test and nasal challenge to house dust mite allergy. The aim of the study was to assess the disputed role of perennial allergy in patients with nasal polyps using allergens to the house dust mite as an example. Using our diagnostic criteria we found allergy to house dust mite in 28% of all cases. We found this diagnosis in 44.8% of patients aged 10-39. We recommend, especially in this age group, an allergy test, if necessary with the appropriate therapy. Test correlations are illustrated in 174 patients who have been examined by the above methods. Good reproducibility was found by the nasal challenge, which led to the right diagnosis in 92%, compared with 81% by a standardized history. Therefore, it can be considered to be the key to the diagnosis of allergy.

Adolescent↗
PubMed1983

[Fibrogenic effect of anthracite dust compared with the effects of hard and bituminous coal dust on the lungs of albino rats].

In experiments on white rats the fibrogenic effects of the dust of anthracite and other types of coal, from the U.S.A. and Poland, were tested. What was found basing on hydroxyproline measurements in lungs was that the extent of fibrogenic effects of anthracite equals fibrogenic effects of bituminous coal dust containing 30% alpha-quartz. Non-anthracite coal dusts containing SiO2 crystalline phases (alpha-quartz) as an admixture--exhibit fibrogenic effects on white rats' lungs--proportional to free silica content. It is probable that fibrogenic effects of anthracite on the pulmonary tissue result from its structure and active free radicals.

Animals↗
PubMedDate not supplied

Characteristics of tantalum dust and dust generator for bronchography.

The two tantalum powders, "5mu" and "1.4mu", available from Fansteel Metals, are characterized with respect to particle size. Results show that these powders cannot be used directly for tantalum bronchography, but require fractionation to achieve a range of sizes for effective use in tantalum bronchography. This task can be accomplished with the BAHCO Micro Particle Classifier. The powder designated "1.4mu" is superior to the "5mu" powder because about 60% by weight can be salvaged by separation for use in bronchography, compared to only 7% by weight of the "5mu" powder. Theoretical considerations of particle deposition in the human respiratory tract indicate that the material obtained with throttle 16 of the BAHCO is best suited for tantalum bronchography. The dust generator is a good tool to deliver a dust cloud into the lung. The generator can operate for approximately 2 1/2 hours before the brush of the brush feed must be replaced; a procedure taking about 10 min. Additional maintenance is unnecessary. The breathing resistance of 1.1 inch of water imposed by the generator system, and which has to be overcome by the patient, is judged acceptable. The bronchograms obtained by introducing tantalum dust for 10 min into an artificially ventilated dog lung were clear, with deposition heaviest at bifurcations. These results suggest that the generator should now be used for human bronchography.

Animals↗
PubMed2001

Dust-acoustic modes in self-gravitating plasmas with dust size distributions.

Using a kinetic description, dust-acoustic waves are considered for dusty plasmas containing, besides the electrons and ions, dust particles with continuous mass (size) distributions. For broad size spectra, self-gravitational effects cannot be neglected anymore because in the competition between electromagnetic and gravitational forces, the scale tips over towards gravitation for the heavier dust grains. Self-gravitational effects are clearly interwoven with the grain size distribution and here the effects of different power-law size distributions on the propagation, damping, and instability of low-frequency waves are discussed.

Journal Article↗
PubMed2001

Effects of dust charge fluctuations on current-driven dust-ion-acoustic waves.

The effects of fluctuating grain charge on current-driven dust-ion-acoustic modes are investigated in the presence of various physical parameters which are varied in order to describe the behavior of the mode in detail. Variation of the charge clearly influences the ion-acoustic mode by changing of its frequency and growth rate. We report here the existence of a dust charge fluctuation mode in the system, and it is shown that the mode is unstable for a negative charge on the dust per unit volume not exceeding some critical value.

Journal Article↗
PubMed2002

Analysis of the particle interactions in a two-dimensional-plasma dust crystal and the use of dust as a probe of the time-averaged presheath electric field.

A method for measuring the interactions of dust particles within a two-dimensional (2D) layer in a plasma is presented, along with the use of dust as a probe for determining plasma presheath electric fields. Particle interactions were directly determined from the lateral compression of two-dimensional plasma dust crystals confined in a parabolic potential well. The shape of the parabolic potential well was confirmed by observing trajectories of single particles falling within the well. Particle trajectories were in good agreement with values calculated using gas temperatures derived from laser-induced-fluorescence measurements of the argon metastable velocity distributions and assuming diffusive gas scattering. Measured particle separations combined with an equation of state for the crystal were used to derive values for the plasma screening length and the charge on the particles. Screening lengths and charges were measured for a range of plasma power, pressure, and particle diameter (mass). Analysis of the particle heights and charge were used to derive the time-averaged electric fields at the edge of the rf driven plasma sheath. Measured electric fields were between 5 and 22 V/cm. For smaller particle diameters, the ion wind force was comparable to the force of gravity. These measurements showed that the particles are confined to the bulk-plasma side of the classical Bohm point.

Journal Article↗
PubMed2001

Experimental observation of vertically polarized transverse dust-lattice wave propagating in a one-dimensional strongly coupled dust chain.

Externally driven, vertically polarized transverse dust-lattice waves were observed in a one-dimensional strongly coupled dust chain levitated in the plasma-sheath boundary of a dc argon plasma at low gas pressure around 5 mtorr. Real and imaginary parts of the complex wave number were measured in the experiments. The experimental result clearly shows that the observed transverse dust-lattice wave propagates as a backward wave, which is in good agreement with the theoretical prediction.

Journal Article↗
PubMed1987

Some peculiarities of the pulmonary phagocytotic response: dust retention kinetics and silicosis development during long term exposure of rats to high quartz dust levels.

Rats were exposed to quartz dust (about 90 mg/m3) for five hours a day, five times a week either throughout the 48 weeks of the experiment or for a total of 40 weeks plus eight weeks of "rest." Cytological study of bronchoalveolar lavage showed that at a certain level of silicotic changes in the lungs, a pronounced breakdown in pulmonary dust clearance by macrophages could be observed. There was, however, a concomitant compensatory increase in the contribution to pulmonary phagocytosis by the neutrophil leukocytes (NL). As a result, pulmonary dust kinetics could be mathematically described using a constant clearance rate both throughout the 48 weeks of exposure and during the eight weeks after the end of the 40 week exposure. It is shown in a separate experiment that enhanced recruitment of NL into the airways may be due not only to an attractant effect of the products of macrophage breakdown (PMB) themselves but also to the release of an NL attractant factor by viable macrophages activated under influence of the PMB.

Animals↗
PubMed1975

Characteristics of lung dusts and their relation to dust exposure and pathological findings in the lungs.

Lung dusts were investigated, post-mortem, in twenty-five miners from mixed metal mines, tunnels, and quarries who had exposed to high concentrations of mixed dust containing about 20-25% free crystalline silica. The character of the relations found between the amount of quartz per 100 g dry tissue and the clinical, X-ray and pathological findings is similar to that established in coal miners. The difference lies in the fact that with equal amounts of quartz per 100 g dry tissue, there is less silicosis in coal miners than in our cases; the average residence time of retained dust is longer in coal miners, but its quartz per cent is lower.

Bulgaria↗
PubMed1997

The Melbourne house dust mite study: eliminating house dust mites in the domestic environment.

BACKGROUND: Hypersensitivity to house dust mite allergens is associated with increased asthma morbidity. Asthma severity appears to be related to the degree of mite allergen exposure. Short-term studies suggest that complete avoidance reduces disease severity. OBJECTIVE: The study was designed to assess the effect of different mattress covers and floor coverings on mite allergen concentrations in the homes of mite-sensitive children with asthma in the city of Melbourne, Australia. METHODS: Mite allergen Der p 1 concentration was measured on mattress covers, mattress surfaces, and carpeted and uncarpeted floors in 107 dwellings; and measurement was performed on three occasions over a 5-month period. After the first sampling, all mattress covers and impermeable encasements were permanently removed. RESULTS: The initial geometric mean concentrations of Der p 1 (micrograms per gram of fine dust) from the surfaces of sheepskin, wool, and cotton mattress coverings were greater than those from the surfaces of impermeable mattress encasements (116, 113, and 19 vs 0.4) (p < 0.001); corresponding concentrations on the underlying mattresses were 142, 38, 20, and 0.6, respectively (p < 0.05 to 0.001). At the end of the study these mattress surface concentrations were 79, 65, 9.7, and 3.1, respectively. In 24 dwellings an uncarpeted room was adjacent to a carpeted room. At each visit the concentration of Der p 1 in uncarpeted rooms was below the reported threshold for sensitization and significantly less than that in the adjacent carpeted room. CONCLUSION: In homes of children with asthma, "asthmogenic" concentrations of Der p 1 were found on nonencased mattresses and carpeted floors, but the use of impermeable mattress encasements and carpet exclusion were associated with concentrations of Der p 1 below the reported threshold for sensitization.

Adolescent↗
PubMed1998

The Melbourne House Dust Mite Study: long-term efficacy of house dust mite reduction strategies.

BACKGROUND: Asthma severity among mite-sensitized individuals appears to be related to the degree of mite allergen exposure. OBJECTIVES: The objective of this study was to assess the long-term effectiveness of mite avoidance measures in the homes of asthmatic children in Melbourne, Australia. METHODS: The concentration of house dust mite allergen (Der p 1) was measured on the child's mattress surfaces and bedroom floors in 85 homes on 10 occasions over a 16-month period. After the first three visits, all mattresses were covered with a semipermeable encasement, and carpeted bedroom floors were randomly allocated to regular applications of a placebo or an "anti-mite" shampoo. RESULTS: The concentration of Der p 1 recovered was initially high in the carpeted bedrooms (n = 66) (41.1, 95% confidence interval, 30.7 to 55.0 microg Der p 1 per gm) and mattresses (n = 85) (39.6, 27.2 to 57.7). During the initial observation period the concentration of mite allergen fell in the treatment, placebo, and parental control groups. During the seven treatment periods, no differences were seen between the Der p 1 concentrations in the groups using the "anti-mite" shampoo, placebo shampoo, or the parental control group (e.g., at visit 4; 12.6, 8.2 to 19.5; 14.8, 8.6 to 25.1; and 12.0, 8.1 to 17.7 microg/gm, respectively). In contrast, the concentration of Der p 1 in samples from uncarpeted floors and mattress encasements was low (4.1, 2.1 to 8.0 microg/gm and 4.2, 2.6 to 6.5 microg/gm, respectively) and insufficient dust for analysis was frequently obtained from these sites. CONCLUSIONS: There was no additional benefit from the use of an "anti-mite" shampoo. The absence of carpets and the use of mattress encasements was a useful long-term strategy for mite allergen avoidance.

Animals↗
PubMed2001

Effectiveness of laundry washing agents and conditions in the removal of cat and dust mite allergen from bedding dust.

BACKGROUND: There is limited information about the removal of allergens by laundry washing. OBJECTIVE: The purpose of this investigation was to determine the dynamics of the removal of mite allergen (Der p 1) and cat allergen (Fel d 1) from bed dust during simulated laundry processes. METHODS: Three studies were performed. The first compared combinations of 4 laundry agents (water alone, soap, detergent with enzymes, and detergent without enzymes), 4 temperatures (15 degrees, 25 degrees, 45 degrees, and 60 degrees C), and 3 extraction times (5, 20, and 60 minutes). The second study examined allergen extraction by 11 common brands of detergents at 25 degrees and 45 degrees C for 5 minutes. The third study compared 4 detergents containing enzymes before and after the denaturation of their enzymes. To measure the quantity of allergens extracted, each study used an ELISA assay as well as a more sensitive but semiquantitative Halogen immunoassay to detect any allergens remaining after the simulated laundry extraction. RESULTS: Study 1 showed that detergents extracted more of both Fel d 1 and Der p 1 than either soap or water alone and that almost all allergens were extracted within 5 minutes at 25 degrees. However, washing at 60 degrees C extracted slightly more Fel d 1 and denatured Der p 1, resulting in lower residual amounts of both allergens. Study 2 showed that all of the commercial detergents performed similarly. Study 3 showed that the presence of enzymes in detergent formulations did not produce a significant effect on the extraction of allergens. CONCLUSION: Using detergent solutions at 25 degrees for at least 5 minutes was sufficient to extract most mite and cat allergen from dust of bedding.

Allergens↗