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Biomedical subjects

R D Tee

Publications and source records attributed to R D Tee.

At least 37 records · Page 2Linked to original sources
PubMed1994

Allergy to storage mites.

There is now much evidence of sensitization to storage mites in urban populations as well as in the well-documented rural populations. Sensitization is therefore not restricted only to those with occupational exposure. There appears to be a limited allergenic crossreactivity between storage mites and house dust mites, although both species also possess their own unique allergens. More research on identification and characterization of storage mite allergens and their crossreactivity is needed to understand their complexity. Such studies are necessary to obtain high quality extracts for diagnosis and possible immunotherapy. Development of immunoassays employing MoAbs will allow measurement of storage mite concentrations in workplaces and houses and the study of exposure-response relationships.

Allergens↗
PubMed1994

Measurement of airborne rat urinary allergen in an epidemiological study.

The suitability of radioallergosorbent test (RAST) inhibition to quantify occupational exposure to rat urinary aeroallergen (RUA) has been assessed. When using a constant pool of rat allergic sera, the reproducibility of the assay over 1 year was comparable to that reported for other immunoassays; at 50% RAST inhibition the inter-assay coefficient of variation (CV) was 7.0% and the intra-assay CV was 3.0%. The assay was highly specific for rat urine; mouse urine was 1100-fold less potent at inhibiting the rat urine RAST system. Significant inter-assay variation in the 'high' control was not due to batch variation and was relatively small when compared with the variation in RUA concentrations in the occupational environment. Measurement of workplace RUA exposure demonstrated that those directly involved in the care of rats experienced the highest RUA exposure of the nine occupational groups studied (animal technicians GM = 23.10 micrograms/m3), dead animals (e.g. post mortem GM = 1.60 micrograms/m3, scientists GM = 0.67 microgram/m3) and rat tissue (e.g. slide production GM = 0.04 microgram/m3). In view of the complexity of rat allergens, RAST inhibition is an appropriate method for the quantification of occupational exposure to rats.

Air Pollution, Indoor↗
PubMed1994

Determination of the size of airborne flour particles.

Air sampling was done in a UK bakery and a flour mill with an eight-stage cascade impactor to determine the size of airborne flour particles. The concentration of captured material was determined by a competitive inhibition radioimmunoassay. Comparison of the different sites revealed that 8.79% and 52.14% of the particles in the bakery dough-brake and roll-production areas had a diameter < or = 6.0 microns, respectively, and 19.7% of the particles in the flour mill packing area were of this size. We conclude that in dusty areas up to 20% of the airborne flour particles are of a diameter likely to allow them to be deposited in the bronchial airways and alveoli.

Air Pollutants, Occupational↗
PubMed1994

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to flour.

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to flour in bakeries or mills. Of 401 eligible workers in seven sites 344 (86%) were surveyed; symptoms assessed by self completed questionnaire, and sensitisation measured by the response to skin prick tests, were related to intensity of exposure both to total dust and to flour aeroallergen. Among 264 subjects without previous occupational exposure to flour, work related symptoms which started after first employment at the site were related to exposure intensity, especially when exposure was expressed in terms of flour aeroallergen. The relations with eye/nose and skin symptoms were independent of atopic status and cigarette smoking. Positive skin test responses to mixed flour and to alpha amylase were also more frequent with increasing exposure intensity, although this was confounded by atopic status. There was only a weak association between symptoms and specific sensitisation.

Adult↗
PubMed1994

Dust and flour aeroallergen exposure in flour mills and bakeries.

As part of an epidemiological study among workers exposed to flour total dust and flour aeroallergen concentrations were measured with personal samplers over a workshift in three large bakeries and four flour mills and packing stations. In the bakeries geometric means for total dust concentrations ranged from 0.4 mg/m3 in the bread wrapping area up to 6.4 mg/m3 at the dough brake. The flour aeroallergen concentrations ranged from 45.5 micrograms/m3 in the bread wrapping area up to 252.0 micrograms/m3 in the confectionary area. In the flour mills and packing stations the concentrations were higher with geometric means for total dust ranging from 0.5 mg/m3 in the office up to 16.9 mg/m3 for hygiene workers in an old mill. The flour aeroallergen concentrations ranged from 101.5 micrograms/m3 for transport workers up to 1728.2 micrograms/m3 for hygiene workers. The relation between total dust and flour aeroallergen concentrations varied for different areas and depended on the use of products other than flour.

Allergens↗
PubMed1994

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to laboratory rats.

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to laboratory rats. Of 366 eligible workers at four sites 323 (88%) were surveyed; symptoms assessed by self completed questionnaire and sensitisation measured by the response to skin prick tests were related to intensity of exposure both to total dust and to rat urinary aeroallergen. Among 238 workers, without previous occupational exposure to rats, work related symptoms, which started after first employment at the site were related to exposure intensity (expressed either in terms of dust or of aeroallergen) at the time of onset of symptoms. These relations were stronger in atopic subjects but were unrelated to smoking. Positive skin tests to rat urinary extract were also more frequent with increased exposure, a relation found in both atopic subjects and in smokers. There was a strong association between work related symptoms and specific sensitisation.

Adult↗
PubMed1994

Exposure to dust and rat urinary aeroallergens in research establishments.

As part of an epidemiological study rat urinary aeroallergen (RUA) and total dust concentrations were measured at three research establishments. Personal RUA measurements in nine exposure groups over a workshift showed highest exposure for animal technicians (geometric mean (GM) = 32.4 micrograms/m3) and lowest for workers in slide production and office (GM > or = 0.1 micrograms/m3). Except for slide production workers, contact with rats, their tissues, faeces, or urine comprised less than half the work shift. Exposure during contact with rats was considerably higher. Personal RUA measurements in nine task categories showed high RUA concentrations for handling rats (GM = 68.0 micrograms/m3) and cleaning out (GM = 53.6 micrograms/m3). Traces of RUA could still be measured in tearooms inside and near offices outside the animal houses. Total dust concentrations were low.

Allergens↗
PubMed1993

Analysis of rat urine proteins and allergens by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting.

BACKGROUND: In rats, urine has been identified as a major source of the allergens that cause laboratory animal allergy, an important occupational health problem. METHODS AND RESULTS: Urinary proteins and allergens of Wistar rats were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. Proteins excreted by male and female rats during puberty were similar and of low molecular weight. In adulthood, moderate increases in diffuse staining of 26 and 21 kd occurred in female urine. In males the 17 kd protein increased dramatically and the 23 and 21 kd proteins moderately. The urine excretion of high-molecular-weight proteins (75 to 63 kd) increased with age in males (females not studied). Immunoblot studies with six sera showed allergens in urine of male and female rats of all ages, three of which were present in all urine (75, 68, and 21 kd). Three allergens (17, 16, and 15 kd) in female urine may be allergenically similar to the 17 kd allergen in adult male urine. Adult male urine allergens were studied further with sera from 83 rat-hypersensitive subjects. Major allergens were identified at 23, 21, and 17 kd, and all sera had IgE to one or more of these proteins. Twenty-seven percent had IgE to 68 and 63 kd allergens. Minor allergens were identified at 75, 51, and 44 kd. CONCLUSIONS: Rat urine is an important source of the major allergens associated with rat hypersensitivity. Age and sex markedly influence the protein and allergenic constituents of rat urine.

Aging↗
PubMed1993

Investigation of possible adverse allergic reactions to mycoprotein ('Quorn').

Mycoprotein ('Quorn') is a food produced for human consumption from Fusarium graminearum. Crossreactivity studies showed that mycoprotein shared multiple common allergenic determinants with Aspergillus fumigatus and Cladosporium herbarum and some with Alternaria alternata. There is, therefore, a potential for mould allergic patients to react adversely to inhaled or ingested mycoprotein. Mycoprotein RAST screening of mycoprotein production workers was made during a 2 year period. Two of the production workers had specific RAST binding > or = 2% but none reported symptoms. Two of 10 patients referred to hospital following vomiting and diarrhoea after ingestion of mycoprotein had a mycoprotein skin-prick test weal > or = 2 mm but none had a significantly raised RAST. These largely negative results are important and reassuring because consumption of the product in the U.K. is now widespread and increasing.

Adult↗
PubMed1992

Specific immunological and bronchopulmonary responses following intradermal sensitization to free trimellitic anhydride in guinea pigs.

We have developed a guinea pig model of trimellitic anhydride-induced airway hypersensitivity responses. In one group of guinea pigs, injected intradermally with 0.1 ml 30% trimellitic anhydride (TMA), we examined the specificity of the bronchopulmonary response to TMA comparing the effect of intravenous TMA conjugated to guinea pig serum albumin (GPSA) with a control hapten (procion dye) protein conjugate (PD-GPSA). A significant increase in pulmonary inflation pressure (PIP) was provoked in sensitized animals following intravenous injection with TMA-GPSA (20%; 0-400, median; range) as compared to intravenous injection of PD-GPSA. In the second group we compared three different methods of sensitization: single injection of 0.1 ml of 0.3% TMA; four injections of 0.1 ml of 0.1% TMA; and a single high dose injection of 30% TMA. Following intravenous TMA-GPSA guinea pigs sensitized with a single injection 0.3% TMA had an increase in PIP of 395%; 220-600, while those given four repeat injections of 0.1% TMA had an increase in PIP of 343%; 315-490. These results were significantly higher than the increase in PIP (160%; 0-220) which occurred in guinea pigs sensitized with a single dose of 30% TMA. Four of 11 guinea pigs given low dose injections of TMA had bronchopulmonary responses to inhaled TMA-GPSA. All sensitized guinea pigs had specific IgG1 antibodies demonstrated by enzyme linked immunosorbent assay (ELISA) and confirmed by ELISA inhibition. Four guinea pigs sensitized by low dose injections of TMA had IgE antibodies demonstrated by passive cutaneous anaphylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Comparison of allergic responses to dust mites in U.K. bakery workers and Swedish farmers.

The IgE RAST response to Dermatophagoides pteronyssinus and four storage mites (Lepidoglyphus destructor, Tyrophagus putrescentiae, Glycyphaghus domesticus, and Acarus siro) was examined in 251 U.K. bakery workers and compared with that previously found in 440 Swedish farmers. Storage mites are found commonly in stored hay and grain so both these groups potentially encounter them in their work. In neither group of workers was a positive RAST (greater than or equal to 0.35 PRU) to D. pteronyssinus correlated with a positive RAST to a single storage mite. As in the Swedish farmers, significant though not strong correlations were found in the U.K. bakers between positive RAST responses to G. domesticus and L. destructor and to T. putrescentiae and L. destructor (P less than 0.05). Homologous and heterologous RAST inhibition studies showed there was low cross-reactivity between storage mites and D. pteronyssinus. L. destructor showed the least inhibition by the other antigens, suggesting it possessed the fewest common allergens. The most important difference in the IgE responses between the two groups was the much higher response to D. pteronyssinus in the U.K. bakers, which was not found in the Swedish farmers whose highest IgE response was to L. destructor.

Agriculture↗
PubMed1992

Reduction of airborne allergenic urinary proteins from laboratory rats.

Allergy and asthma caused by proteins of laboratory animals, particularly rats and mice, are the most important occupational health hazards for the scientists and technicians who work with such animals. The influence of different cage litters, cage design, and stock density on measured rat urinary aeroallergen (RUA) concentrations has been examined in a room housing male rats, to determine practical means to reduce allergen concentration in animal laboratories. Eight hour static air samples were taken at 2 1/min and the RUA concentrations measured by radioallergosorbent test (RAST) inhibition. High RUA concentrations occurred when the animals were housed on wood based, contact litter (geometric mean (GM) sawdust 7.79 micrograms/m3; woodchip 6.16 micrograms/m3). The use of noncontact absorbent pads was associated with a significant decrease in RUA concentrations (GM 2.47 micrograms/m3; p less than 0.0001). Rat urinary aeroallergen concentrations fell more than fourfold when the animals were housed on woodbased, contact litter in filter top cages rather than conventional open top cages (GM filter top 0.33 micrograms/m3; open top 1.43 micrograms/m3; p less than 0.0001). The number of rats (stock density) strongly influenced the RUA concentration and a linear relation was found between the log(e) allergen concentration and stock density under these study conditions. The measurement of airborne particle size on cleaning out days showed that all litter types generated similar sized particles: more than 80% of the RUA was carried on particles larger than 8 microns in diameter for all litter types. The findings suggest that the exposure of animal husbandry personnel to RUA may be substantially reduced by the avoidance of contact litter, the use of filter top cages (where suitable), and by keeping stock density to a minimum.

Air↗
PubMed1992

Immune response to flour and dust mites in a United Kingdom bakery.

In a study of 279 United Kingdom bakery workers a high prevalence of immunological response to storage mites was found. To determine whether this was the consequence of exposure to storage mites in bakery work, a population of salt packing workers was examined as a comparison group not at occupational risk of exposure to storage mites. Forty two per cent of both groups were atopic (had a positive skin prick response greater than negative controls to D pteronyssinus, grass pollen, or cat fur by 2 mm or more) and 33% had an immediate skin prick test response to at least one of four storage mites (L destructor, G domesticus, T putrescentiae, A Siro). A higher percentage of the salt packing workers than the bakery workers had a positive radioallergosorbent test (RAST) (greater than or equal to 0.35 PRU) to D pteronyssinus and to the four storage mites. Logistic regression analysis identified atopy as the most significant variable for a positive skin test and RAST response to storage mites in both groups of workers. RAST inhibition was used to analyse extracted area and personal air samples. Analysis of static area samples for aeroallergen showed immunological identity with flour but L destructor was found in only one of seven exposed filters. The concentration of airborne flour was related to exposure rank of perceived dustiness and gravimetric measurement of total dust. Nineteen out of 32 filters from workers in jobs with higher dust exposure (rank >/=6) had a level of > 10 microgram/m(3) flour whereas this concentrations was exceeded in only one of 23 filters from workers in low dust exposure (< rank 6). It is concluded that storage mites are not of special significance in allergic responses in bakery workers. The development of immunological (and airway) responsiveness to inhaled flour dust is increased in those exposed to higher concentrations of airborne allergen, which appears to be predominantly flour and not storage mites.

Air Pollutants, Occupational↗
PubMed1992

Bronchial hyperreactivity after inhalation of trimellitic anhydride dust in guinea pigs after intradermal sensitization to the free hapten.

We have developed in the guinea pig, an animal model of bronchial hyperreactivity provoked by inhalation of trimellitic anhydride (TMA) dust, a known cause of occupational asthma in humans, after intradermal sensitization to the free hapten. Male Dunkin-Hartley guinea pigs (n = 6) were injected intradermally with 0.1 ml of 30% TMA in corn oil. Control animals (n = 7) were injected with 0.1 ml corn oil alone. On Days 21 to 28 after sensitization, guinea pigs were challenged (nose only) to 12 mg/m3 of inhalable TMA dust for 30 min. Bronchial reactivity was measured in sensitized animals and in control animals at 8 h after exposure to the dust. We also measured bronchial reactivity in sensitized exposed guinea pigs at 2 h (n = 5) and at 24 h (n = 5). Pulmonary inflation pressure (PIP) was used to assess bronchopulmonary response. Blood samples were taken for assessment of IgG-1 antibodies to TMA conjugated to guinea-pig albumin. The concentration of acetylcholine required to induce a 100% increase in PIP was used to assess bronchial reactivity. The lungs were eviscerated for histologic examination. All guinea pigs injected intradermally with TMA had high titers of specific IgG-1 antibodies to TMA conjugated to guinea-pig albumin. There was a significant increase in bronchial reactivity in sensitized guinea pigs 8 h after exposure to the TMA dust compared with that in the control animals. There was also a significant eosinophilic inflammatory influx in the subepithelium of the sensitized groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗
PubMed1991

The effect of smoking on the development of allergic disease and specific immunological responses in a factory workforce exposed to humidifier contaminants.

The effects of smoking on the development of work related asthma and on the production of specific IgE and IgG antibodies to antigen from a contaminated humidifier are described for a sample of 258 workers from a printing factory. Current smoking was associated with low production of IgG antibody but with higher production of IgE antibody. No dose response for either antibody was found when numbers of cigarettes or pack-years smoked were considered. Work related asthma was detected in 12 workers by peak flow recordings. Six were current smokers and one was an ex-smoker. One subject with work related asthma had a high (and one a marginal) concentration of specific IgE to humidifier antigen.

Air Conditioning↗
PubMed1989

Total and anti-mycobacterial IgE levels in serum from patients with tuberculosis and leprosy.

A radioallergosorbent assay (RAST) was developed and used to determine the levels of IgE antibodies to soluble antigens of Mycobacterium tuberculosis (BCG vaccine strain) in sera from patients with tuberculosis and leprosy and in healthy control subjects. Total IgE levels in the same sera were quantitated with a commercial radioimmunoassay kit. Patients with tuberculosis and leprosy had higher total and specific IgE levels than the control groups but the overlap of levels in patients and controls was too great to render the difference diagnostically useful. Specific IgE levels were elevated in both tuberculosis and leprosy patients, suggesting that this antibody response is towards the shared mycobacterial antigens. No differences in total or specific IgE levels were found between healthy hospital workers occupationally exposed to patients with tuberculosis and factory workers who are not exposed.

Antibodies, Bacterial↗