Airborne exposure to wheat allergens: measurement by human immunoglobulin G4 and rabbit immunoglobulin G immunoassays.

BACKGROUND: Exposure to airborne wheat allergens in the bakery trade is associated with a high risk of occupational allergy and asthma. Control and reduction of allergen exposure require relatively simple but reliable monitoring techniques. We developed new rabbit IgG-based enzyme immunoassays (EIA) for wheat allergens, which might be a convenient alternative for the thus far used human IgG4 inhibition assay. METHODS: The reactivity and specificity of rabbit antibodies were assessed by EIA and immunoblotting, and compared with those of IgE from wheat-sensitized bakers, and with the antibodies used in the IgG4 inhibition EIA. An IgG inhibition and a sandwich EIA were developed for analysis of airborne dust samples. RESULTS: Human IgG4 and rabbit IgG inhibition EIAs had comparable sensitivities, with limits of detection (LOD) between 18 and 88 ng/mL, while the sandwich EIA was much more sensitive (LOD<0.2 ng/mL). Human IgG4 and rabbit IgG reacted in immunoblotting with most of the IgE-binding wheat proteins, although with quantitative differences. All three assays showed a strong reaction with wheat proteins, and some cross-reactivity with rye and barley, but were further highly specific for cereal flour proteins. Concentrations measured with the three EIAs in 432 airborne dust samples were highly correlated (r>0.95) and their absolute values showed less than 10-20% differences. CONCLUSION: The rabbit IgG EIAs are valid substitutes for the human IgG4 inhibition EIA, with important practical advantages. The inhibition EIA is recommended for routine wheat allergen measurements. The sandwich EIA may be used to measure low allergen levels, as in short task-related exposure measurements or in subfractions of airborne dust samples.

Enzyme exposure in the British baking industry.

OBJECTIVES: Enzymes are commonly used in the baking industry, as they can improve dough quality and texture and lengthen the shelf life of the final product. There is little published information highlighting exposure to enzymes (other than fungal alpha-amylase) in the baking industry, therefore the purpose of this study was to identify antibodies and develop assays for the measurement of a variety of such enzymes in samples of airborne flour dust. METHODS: Polyclonal antibodies to bacterial amylase, glucose oxidase and amyloglucosidase were identified and developed into ELISA assays. The assays showed limited cross-reactivity with other enzymes commonly used in the baking industry. RESULTS: We measured levels of airborne enzymes in 195 personal air samples taken from a sample of 55 craft baking establishments. We were able to detect amyloglucosidase in 9% (16/184) of the samples, fungal alpha-amylase in 6% (11/171), bacterial alpha-amylase in 7% (13/195). However, we were unable to detect glucose oxidase in any of the samples. Measurements for protease enzymes were not carried out. Median levels in detectable samples of amyloglucosidase, fungal alpha-amylase and bacterial amylase were similar at 10.3, 5.3 and 5.9 ng/m(3), respectively. These figures represent the total enzyme protein (active and inactive) measured. CONCLUSIONS: There are few data in the literature regarding sensitization and exposure-response relationships to these enzymes, and indeed there is often a lack of information within the industry as to the precise enzyme content of particular baking ingredients. As a precautionary measure, all enzymes are regarded as having the potential to cause respiratory sensitization. Consequently, exposures need to be controlled to as low a level as reasonably practicable, and future investigation may highlight the importance of measuring a variety of enzyme exposures and standardizing these methodologies to inform approaches to adequate control.

Upper limb disability in HAVS cases--how does it relate to the neurosensory or vascular elements of HAVS?

AIMS: Hand-arm vibration syndrome (HAVS) consists of vascular, neurosensory and musculoskeletal components, characterized by symptoms that include Raynaud's phenomenon, tingling and numbness in the hands. However, there has been little published data on the effects of HAVS on the capability to carry out normal daily tasks. We have investigated the application of the widely-used disability, arm, shoulder and hand (DASH) disability questionnaire that reflects functionality problems in the upper extremities, as well as symptoms, in a HAVS cohort. METHODS: The cohort consisted of 118 males who, as a part of their health surveillance, had been referred for further assessment and Stockholm workshop staging. This process involved medical interview, physical examination and quantitative tests covering neurosensory function, manual dexterity and handgrip strength. RESULTS: The relationship between DASH outcome metric and a combination of quantitative tests reflecting a range of abnormalities found in HAVS, supports the validity of this questionnaire in HAVS studies. The data suggest that HAVS cases have a greater level of upper extremity disability compared with a general population. The study confirms that disability in HAVS is very largely related to sensorineural Stockholm workshop staging, rather than vascular staging. Any influence of vibration-induced Raynaud's phenomenon on upper extremity disability is related to the frequency of blanching attacks rather than their extent across the digits. CONCLUSION: This study strengthens the importance of identifying and preventing the exacerbation of the neurosenory component of HAVS, that unlike the blanching attacks of the vascular component does not have such an obvious pathognomic signal.

The changing distribution of occupational asthma: a survey of supermarket bakery workers.

In the UK, since the mid 1980s, supermarkets have accounted for an increasing volume of bread production. Occupational asthma among employees who produce bread from raw ingredients in supermarkets has not been previously investigated. A cross-sectional survey was undertaken involving 239 (71%) employees from 20 different supermarket bakeries. The work-related symptoms were investigated by using questionnaires and measuring the radioallergosorbent test serum-specific immunoglobulin (Ig)E to flour and fungal alpha-amylase. A total of 89 employees underwent whole-shift personal measurement of dust exposure. The geometric mean dust exposure for bakers was 1.2 mg x m(-3), which was higher than for other bakery employees. A total of 37 (15%) employees also reported work-related chest symptoms. Serum IgE to flour was present in 24 (11%) employees and to fungal alpha-amylase in nine (4%) employees. The combination of work-related chest symptoms and specific IgE was found in six (9%) bakers, one (4%) manager and two (3%) assistants. One-quarter of all employees, but half of bakers and managers, had previously worked for different, mainly small, bakeries. This population of bakery workers has important levels of sensitisation and work-related respiratory symptoms, despite low levels of dust exposure. Changes in the location and process of bread manufacture have led to a change in the distribution of bakers' asthma in the UK.

Exposure to flour dust in UK bakeries: current use of control measures.

OBJECTIVES: In May 2001, a maximum exposure limit (MEL) for flour dust was set in the UK at 10 mg/m(3) [8 h time-weighted average (TWA)] with a short-term exposure limit (STEL) of 30 mg/m(3) (15 min reference period). The purpose of this study was to produce a benchmarking baseline of current control measures and exposure levels, in addition to assessing the provision of training and the knowledge of the UK regulations amongst the bakeries. METHODS: A total of 208 long-term personal inhalable dust samples (8 h TWA) were collected from workers in 55 bakeries (covering a wide range of industry types and sizes) between October 2002 and December 2003 in England, Wales and Scotland. Standardized occupational hygiene reports were produced for each establishment to provide information about the site (such as the size of the bakery) and the control measures employed (including ventilation, good working practices, knowledge of UK regulations and the extent of training provided). RESULTS: Median inhalable dust exposure (8 h TWA) for the bakery workers was 3.7 mg/m(3) (75th percentile at 7.7 mg/m(3)) and 17% of the dust results exceeded the MEL. Although information about the MEL has been available in the trade press and through recognised trade associations, only 27% of the bakeries were aware of the MEL and STEL. Mixed model regression analysis suggested that determinants of higher exposure included the job category (particularly weighing/sieving or mixing), medium to large bakery size (50 or more employees) and bakeries being located in Scotland. However, having an appointed safety representative was associated with lower exposure. CONCLUSIONS: The conclusions derived here are based upon the use of a statistical model, but clearly, if bakeries and individuals employ good working practices, with correct use of local exhaust ventilation, they should be able to comply with the MEL.

The diagnostic value of finger systolic blood pressure and cold-provocation testing for the vascular component of hand-arm vibration syndrome in health surveillance.

BACKGROUND: Hand-arm vibration syndrome (HAVS) is a complex condition with vascular, sensorineural and musculoskeletal components. A number of quantitative tests have been used for assisting in the diagnosis of HAVS and grading disease severity. AIMS: To investigate and compare the diagnostic value of finger systolic blood pressure (FSBP) and rewarming of finger skin temperature (FST) following cold-provocation testing, in the assessment of vascular HAVS. METHODS: Twenty-four individuals with vascular HAVS (Stockholm Workshop stage 2 or 3V) and 22 control subjects underwent FSBP measurements at 30, 15 and 10 degrees C and monitoring of FST following immersion of the hands in water at 15 degrees C for 5 min. RESULTS: There was a significant reduction in median FSBP% in the vascular HAVS group in the change in FSBP from 30 to 15 degrees C adjusted for brachial blood pressure (FSBPC%). There was no difference in the median time for FST to rewarm by 4 degrees C between HAVS cases and controls. The sensitivity and specificity of FSBP to discriminate between the groups varied between 44 and 61% and 91 and 95%, respectively. The sensitivity and specificity for the time for FST to rewarm by 4 degrees C were 71 and 77%. CONCLUSIONS: There is little evidence that the described form of finger rewarming after cold-provocation testing is a useful diagnostic test for vascular HAVS, although it may have some moderate influence in ruling out vascular problems. Based on our data, the FSBP may also have limited use in confirming a positive diagnosis of vibration-induced vascular problems. The higher specificity of the FSBP test suggests it may have some value in ruling out the vascular component of HAVS. The data from this study do not confirm the diagnostic power of FSBP for the vascular component of HAVS reported by a few other investigators.

Prevalence of sensitisation to cellulase and xylanase in bakery workers.

AIMS: To assess the prevalence of sensitisation to a range of exogenous fungal enzymes used in bakeries, and determine the relation between sensitisation and work related symptoms. METHODS: Serum samples (n = 135) from a previous cross sectional study investigating the prevalence of respiratory symptoms and sensitisation to dust components, were reanalysed for specific IgE to the mixed enzymes cellulase, hemicellulase, and xylanase. RESULTS: Eight (6%) of sera tested had detectable specific IgE to mixed enzymes (excluding fungal alpha-amylase) and 16 (12%) to fungal alpha-amylase. A significant increase (p = 0.03) in nasal symptoms was found in those workers sensitised to enzymes (including alpha-amylase and the mixed enzymes, but with or without sensitisation to wheat flour) when compared to those sensitised to wheat flour alone. Both groups had significantly greater levels of nasal symptoms in comparison to those with no evidence of sensitisation. CONCLUSIONS: The association between specific IgE to mixed enzymes, and an increased prevalence of nasal symptoms in individuals sensitised to enzymes, highlights the importance of measuring sensitisation to the full range of exogenous enzymes used in the baking industry, as well as to wheat flour.

Mechanisms of isocyanate sensitisation. An in vitro approach.

Although there is an abundance of clinical evidence which suggests that the inhalation of isocyanates can induce occupational asthma, the immunological basis for the disease is not understood. We have investigated immune cell responses to isocyanate using the cell line mono-mac-6, by measuring the production of hydrogen peroxide, and the expression of ICAM-1 following challenge with isocyanates and their corresponding amines. We observed an increase in the levels of intracellular peroxide, in addition to an upregulation of ICAM-1 expression (P<0.05), following cell stimulation with isocyanates, which was not apparent following stimulation with amines. From the results of this study we hypothesise that the production of reactive oxygen species (ROS) by monocytic cells at the site of exposure to an isocyanate may have two potential outcomes. The first is that the ROS may contribute to tissue damage at the site of inflammation, and then secondly, it is possible this production of hydrogen peroxide may also induce the upregulation of adhesion markers on monocytic cells, specifically ICAM-1, which may potentiate the infiltration and adhesion of cells at the site of inflammation.

Measurement of personal exposure to aerosols of Nephrops norvegicus (scampi) using a monoclonal-based assay.

BACKGROUND: The industrial processing of scampi (Nephrops norvegicus) generates bioaerosols which can cause occupational respiratory disease in exposed individuals. The objective of this study was to develop a monoclonal antibody-based immunoassay to measure scampi proteins collected using standard personal air sampling methods. METHODS: A monoclonal antibody was generated which predominantly bound to a single 97 Kd scampi protein, which we have shown to be a major allergen. This protein was shown by SDS PAGE immunoblotting to be present in various aqueous extracts from wastes produced during scampi processing. A quantitative immunoslotblot method was developed to quantify scampi from air sample filters. RESULTS: We demonstrated the utility of this method by showing a significant difference (P = 0.015) in the level of exposure of two groups of 12 workers processing scampi at a traditional open workstation (GM = 607 ng m(-3)) and at an enclosed workstation (GM = 451 ng m(-3)). CONCLUSION: We conclude that this assay can be used, in conjunction with health surveillance, to monitor exposure and the efficacy of measures to reduce exposure to airborne scampi allergen in an occupational environment.

The development of an antibody to trimellitic anhydride.

Acid anhydrides are a group of highly reactive chemicals used widely in the formulation of paints and plastics. Exposure to acid anhydrides causes several occupational lung diseases such as pneumonititis and asthma. Whilst anhydrides, specifically trimellitic anhydride (TMA), have been shown to bind to lung tissue in an animal model, further investigation has been hampered by the lack of a reagent which would enable the identification of primary target proteins for the binding of TMA. Our objective was to develop an antibody to TMA which would enable in vitro studies of TMA interactions with lung epithelial proteins. We developed a monoclonal antibody which binds solely to TMA. We have demonstrated that the antibody can be used to detect TMA bound to different human proteins with little non-specific binding to unconjugated proteins. We then exposed cells of the A549 lung epithelial cell line to TMA in vitro and have shown by western blotting that binding occurs in the 20-35 Kd weight range. We have developed a specific and sensitive reagent to detect TMA bound to proteins. We have used this to show that when TMA is incubated with a lung epithelial cell line, that the TMA binds to proteins with a restricted molecular weight range. These results suggest that the current paradigm for the detection of IgE to small molecular weight reactive chemicals, which presupposes that the chemical binds to serum albumin, may need further investigation.

Development and validation of a monoclonal based immunoassay for the measurement of fungal alpha-amylase: focus on peak exposures.

The inhalation of flour dust has been implicated in the induction of sensitisation and elicitation of respiratory symptoms, such as asthma in bakers. In addition to the cereal allergens present in wheat flour, enzymes in flour improvers, in particular fungal alpha-amylase, are now known to be a significant cause of respiratory allergy in the baking industry.A monoclonal antibody based enzyme-linked immunoassay (ELISA) was developed using two monoclonal antibodies that recognised two distinct epitopes of the fungal alpha-amylase enzyme. The ELISA had an inter-assay variation of 12.0% at 1360 pg/ml and 12.8% at 564 pg/ml and intra-assay variation of 4.9% at 1340 pg/ml and 6.1% at 504 pg/ml. The assay had a sensitivity of 200 pg/ml. Competitive inhibition assays confirmed that the monoclonal antibodies had no cross reactivity with other enzymes used in the baking industry and could distinguish added fungal alpha-amylase from cereal amylase. We assessed the levels of exposure to dust, total protein and fungal alpha-amylase in four UK bakeries ranging in size and technical capabilities. Within the bakeries we surveyed, workers were exposed to variable levels of inhalable dust (0.8-39.8 mg/m3), total protein (0-5.7 mg/m3) and fungal alpha-amylase (0-29.8 ng/m3). Consecutive 15 min personal samples taken over a 1 h period demonstrated that the ELISA could measure fungal alpha-amylase exposure in such a 15 min period. Short term peak exposures to fungal alpha-amylase could be identified which may contribute to the sensitisation in individuals who appear to have low exposure levels if measured over a full shift period.

Colophony: an in vitro model for the induction of sensitization.

BACKGROUND: The potential of colophony fumes from soldering flux to induce asthma has been known since the 1970s, however, no direct in vitro or in vivo evidence has been reported. The present study investigated the potential of colophony to stimulate human phagocytic cells to produce reactive oxygen species. METHODS: The human cell line HL-60 was differentiated to produce cells with a monocyte-like and a neutrophil-like phenotypes. A number of procedures were used to confirm the phenotype of these differentiated cells including morphology, esterase activity, flow cytometry and phagocytosis. The potential of colophony to stimulate human phagocytic cells to produce reactive oxygen species was monitored using flow cytoenzymology. RESULTS: We were able to show that intracellular peroxide levels were increased in both monocyte-like and neutrophil-like cells, but not in undifferentiated HL-60 cells following the addition of colophony. CONCLUSIONS: The resin acid epoxides and hydroperoxides which have been suggested to be sensitizers in contact allergy, are degraded during the soldering process. However, conditions for the oxidation of colophony may occur in vivo as a result of the colophony-induced oxidative burst from neutrophils and monocytes. These oxidation products may then interact with body proteins to further initiate immune responses. Therefore for the preparation of low molecular weight chemical (LMWC)-protein conjugates, consideration must be taken to determine whether the LMWC is undergoing a reaction in vivo before it is interacting with body proteins.

Common mistakes in managing metabolic disorders.

Three mistakes are commonly made in managing metabolic disorders. 1. Oral fluids may be pushed to treat simple volume depletion. However, almost all fluids used for this purpose are sodium-poor and do not restore salt and water balance. 2. The physician may not be aware of common causes of hypophosphatemia, such as hyperventilation, sepsis, stress, use of antacids or diuretics, and alcoholism. If the patient is not monitored adequately, severe hypophosphatemia may develop with serious consequences. 3. Low serum bicarbonate levels may be attributed to metabolic acidosis only, when in actuality metabolic acidosis may coexist with respiratory alkalosis. Arterial blood gas studies differentiate the conditions and direct attention to the cause of respiratory alkalosis when present.

Potassium imbalance: causes and prevention.

The amount of potassium normally found in the serum is less than 2% of the total body amount. Thus, the serum potassium level is not the ideal indicator of potassium activity in the body. Potassium homeostasis or imbalance is a function of changes in input, changes in output, and shifts of potassium between the serum and the intracellular fluid. Most significant hyperkalemia is associated with renal impairment, either glomerular or tubular; hypokalemia in many instances is causally related to increased renal potassium losses. Such losses can be sequentially measured and the information used to prevent potassium depletion. The key to understanding and treating potassium imbalance is to know which patients are at risk, what the physiologic consequences of hypokalemia and hyperkalemia are, and how to use urinary potassium measurements and the ECG for prevention rather than relying on the serum potassium level only.

Listeria cerebritis: relapse of infection in renal transplant patients.

In 3 cases of Listeria cerebritis, two of the patients had relapse with cerebritis after antimicrobial therapy for acute Listeria septicemia or meningitis. Each had received ten to 14 days of intravenous penicillin. Relapse occurred with fever and sudden focal cerebral dysfunction. Brain scans showed focal uptake; arteriograms and computerized tomography were normal. Cerebrospinal fluids were nondiagnostic; blood cultures yielded Listeria in two patients. Penicillin treatment for six weeks produced rapid clinical responses that were complete in one and minimal residual in two. Progress brain scans were normal. A relapse rate of 35% is reported in transplant patients with Listeria meningitis and/or bacteremia who are treated for less than three weeks; to our knowledge, cerebritis in such patients has not been reported previously. High-dose penicillin or ampicillin therapy for four to six weeks is recommended for Listeria infections in this select group.

Staphylococcal sepsis in patients on chronic hemodialysis regimens: intravenous treatment with vancomycin given once weekly.

Five patients on chronic hemodialysis regimens were hospitalized with six episodes of Staphylococcus aureus septicemia. Three of the patents acquired the infection during home dialysis, and it was related to the hemodialysis circulatory-access site in four. Initial therapy was methicillin sodium. Vanomycin hydrochloride was given in a 1-gm, single, weekly dose as the sole antibiotic after a short interval (mean, three days). Five of the six episodes were treated successfully. Staphylococcus epidermidis grew in blood cultures obtained during one of the treatments. The advantages of this regimen included a more prompt ambulation and the discontuation of constant infusions in patients with no peripheral veins available.