Biomedical subjects

Britt-Marie Larsson

Publications and source records attributed to Britt-Marie Larsson.

10 recordsLinked to original sources

PubMed2006

History and results of the two inter-laboratory round robin endotoxin assay studies on cotton dust.

BACKGROUND: In the US cotton industry, airborne cotton dust levels are regulated, and other countries are moving to specify safety limits for airborne endotoxins. There is concern about potential respiratory health hazards associated with agricultural and other organic dusts. In laboratories, ranking which samples have high and low levels of endotoxin is usually in good agreement between laboratories. When different laboratories assay identical samples, the levels differ. The objective of this research was to evaluate the intra- and inter-laboratory variability for 13 laboratories measuring endotoxin in cotton dust. METHOD: Two inter-laboratory round robin endotoxin assay studies were conducted using cotton dust. In the first round robin, each laboratory used their normal in-house assay method and then used a common extraction protocol. In the second round robin, a common extraction protocol and endotoxin assay kit was used. RESULTS: The intra-laboratory results had small variations but inter-laboratory results had very high variations. The inter-laboratory results using a common extraction protocol showed reduced differences. Using the same extraction protocol and endotoxin assay kit, the intra-laboratory variation was small and inter-laboratory variation was reduced but not enough for inter-laboratory agreement. Most of the laboratories were able to discern between the high and low endotoxin concentration dusts. CONCLUSIONS: Standardization has reduced the differences in results between laboratories and possibly further standardization may bring closer inter-laboratory agreement.

Air Microbiology↗

PubMed2005

Interlaboratory evaluation of endotoxin analyses in agricultural dusts--comparison of LAL assay and mass spectrometry.

Endotoxin exposure is associated with wheeze and asthma morbidity, while early life exposure may reduce risk of allergy and asthma. Unfortunately, it is difficult to compare endotoxin results from different laboratories and environments. We undertook this study to determine if lipopolysaccharide (LPS) extraction efficiency could account for differences among laboratories. We generated and collected aerosols from chicken and swine barns, and corn processing. We randomly allocated side-by-side filter samples to five laboratories for Limulus assay of endotoxin. Lyophilized aliquots of filter extracts were analyzed for 3-hydroxy fatty acids (3-OHFAs) as a marker of LPS using gas chromatography-mass spectrometry. There were significant differences in endotoxin assay and GC-MS (LPS) results between laboratories for all dust types (p < 0.01). Patterns of differences between labs varied by dust type. Relationships between assay and GC/MS results also depended on dust type. The percentages of individual 3-OHFA chain lengths varied across labs (p < 0.0001) suggesting that each lab recovered a different fraction of the LPS available. The presence of large amounts of particle associated LPS and absence of a freezing thawing cycle were associated with lower correlations between LPS and bioactivity, consistent with an absence of Limulus response to cell-bound endotoxin. These data suggest that extraction methods affect endotoxin measurements. The LAL methods may be most suitable when comparing exposures within similar environments; GC-MS offers additional information helpful in optimizing sample treatment and extraction. GC-MS may be of use when comparing across heterogeneous environments and should be considered for inclusion in future studies of human health outcomes.

Aerosols↗

PubMed2005

Effects of 5-lipoxygenase inhibitor zileuton on airway responses to inhaled swine house dust in healthy subjects.

BACKGROUND: Inhalation of swine house dust induces acute airway inflammation and increased bronchial responsiveness in healthy subjects. OBJECTIVE: The aim of the study was to investigate whether 5-lipoxygenase products such as leukotrienes may have a role in this reaction. METHODS: Twenty-three healthy subjects were randomised into two groups receiving treatment with either zileuton (600 mg) or placebo four times a day. After 5 days of treatment, all subjects were exposed for 3h in a swine barn. Bronchial responsiveness, exhaled nitric oxide (NO), and mediators in nasal lavage (NAL), blood and urine were measured before and after the exposure. RESULTS: The exposure induced an increased bronchial responsiveness to methacholine in both groups with 2-3 doubling concentration steps, no significant difference between treatments. Leukotriene E(4) in urine increased significantly following exposure in the placebo group from 37.3 (29.1-45.6) (mean (95% confidence interval)) ng/mmol creatinine to 47.7 (36.3-59.0) ng/mmol creatinine (P<0.05), but not in the zileuton group. The post-exposure increase of LTB(4) levels in NAL fluid was totally abolished in the zileuton group (P<0.05 vs. the placebo). The levels of exhaled NO increased significantly (P<0.01), two-fold in both groups. The PGD(2) metabolite 9alpha, 11beta-PGF(2) increased in placebo-treated subjects (P<0.01; P<0.05 vs. zileuton), strengthening mast cell participation. Neutrophil counts and levels of IL-6 in peripheral blood increased in both groups, with a significantly larger increase in zileuton treated subjects (P<0.05 and P<0.001, respectively compared to placebo). CONCLUSIONS: Pre-treatment with clinically recommended doses of the 5-lipoxygenase inhibitor zileuton did not affect the increase of bronchial reactivity induced by swine dust exposure. The intervention totally abolished the LTB(4) release in NAL fluid, but only partially inhibited the formation of leukotrienes as monitored by urinary levels. The enhanced increase of neutrophils and IL-6 in peripheral blood in the zileuton group, suggests that inhibition of 5-lipoxygenase may have pro-inflammatory effects.

Adult↗

PubMed2005

Gender-related long-term effects in adult rats by perinatal dietary ratio of n-6/n-3 fatty acids.

Epidemiological studies in humans have shown that perinatal nutrition affects health later in life. We have previously shown that the ratio of n-6 to n-3 polyunsaturated fatty acids (PUFA) in the maternal diet affects serum leptin levels and growth of the suckling pups. The aim of the present study was to investigate the long-term effects of various ratios of the dietary n-6 and n-3 PUFA during the perinatal period on serum leptin, insulin, and triacylglycerol, as well as body growth in the adult offspring. During late gestation and throughout lactation, rats were fed an isocaloric diet containing 7 wt% fat, either as linseed oil (n-3 diet), soybean oil (n-6/n-3 diet), or sunflower oil (n-6 diet). At 3 wk of age, the n-6/n-3 PUFA ratios in the serum phospholipids of the offspring were 2.5, 8.3, and 17.5, respectively. After weaning, all pups were given a standard chow. At the 28th postnatal wk, mean body weight and fasting insulin levels were significantly increased in the rats fed the n-6/n-3 diet perinatally compared with the other groups. The systolic blood pressure and serum triacylglycerol levels were only increased in adult male rats of the same group. These data suggest that the balance between n-6 and n-3 PUFA during perinatal development affects several metabolic parameters in adulthood, especially in the male animals.

Aging↗

PubMed2004

Partial protection by respirators on airways responses following exposure in a swine house.

BACKGROUND: Exposure to swine dust leads to an intense airway inflammation and increased bronchial responsiveness. The purpose of the present study was to evaluate the effect of a respiratory protection device during exposure in a swine house. METHODS: Twenty-two subjects, 11 with a respirator, were exposed. Symptoms, body temperature, nasal lavage, and a bronchial metacholine challenge were performed before and 7 hr after exposure. For exposure assessment a nasal sampler was evaluated. RESULTS: The subjects with a respirator showed an attenuated inflammatory nasal response. An increase in bronchial responsiveness was observed in both groups, significantly greater in the unprotected group. The use of respirators reduced endotoxin exposure by more than 90% (assessed by nasal samplers). CONCLUSION: The use of a respirator attenuated the inflammatory response compared with an unprotected group. The minor effect on bronchial responsiveness suggests that gases and/or ultrafine particles may also be important factors.

Adult↗

PubMed2004

Acute respiratory effects of exposure to ammonia on healthy persons.

OBJECTIVES: This study investigated the acute respiratory effects of low ammonia exposure on healthy persons. METHODS: Twelve healthy persons underwent sham or ammonia (5 and 25 ppm) exposure randomly in an exposure chamber on three occasions. The exposure duration was 3 hours, 1.5 hours resting (seated) and 1.5 hours exercising (50 W on a bicycle ergonometer). Symptoms were registered repeatedly before, during, and after the exposure on visual analogue scales. Bronchial responsiveness to methacholine, lung function, and exhaled nitric oxide (NO) were measured before and 7 hours after the exposure. In addition, nasal lavage was performed, and peripheral blood samples were drawn before and 7 hours after the exposure. RESULTS: All the symptom ratings increased significantly during 25-ppm ammonia exposure as compared with the control exposure. The cumulative dose of methacholine causing a 20% decrease in forced expiratory volume in 1 second was lower (<1 concentration step of methacholine) for the exposure than for a pretrial control challenge. However, no difference was found between the control and ammonia exposures (P=0.33). The ammonia exposure did not significantly influence lung function or the exhaled NO levels. The total cell or interleukin-8 concentration in nasal lavage fluid did not change. The total leucocyte concentration in peripheral blood increased significantly (P<0.001) after both the sham and ammonia exposure, mainly due to an increase in neutrophils (P<0.001). Ammonia exposure did not significantly alter complement factor 3b in plasma. CONCLUSIONS: During ammonia exposure in an exposure chamber, symptoms related to irritation and central nervous effects increase and are constant with no signs of adaptation. Ammonia inhalation does not cause detectable upper-airway inflammation or increased bronchial responsiveness to methacholine in healthy persons.

Adult↗

PubMed2002

Airways inflammation after exposure in a swine confinement building during cleaning procedure.

BACKGROUND: Healthy volunteers exposed for 3 hr during weighing of pigs develop an airway inflammation characterized by a massive influx of neutrophilic granulocytes in the upper and lower airways and increased bronchial responsiveness to methacholine. The purpose of the present study was to investigate health effects from exposure during cleaning of the swine confinement building and to evaluate the effect of a respiratory protection device. METHODS: Sixteen subjects were exposed for 3 hr during cleaning of a swine confinement room with a high-pressure cleaner. Seven out of sixteen subjects were equipped with a mask during exposure. RESULTS: The bronchial responsiveness increased in all subjects following exposure, significantly more in the group exposed without a mask (P < 0.05). The cell concentration (mainly neutrophilic granulocytes) in nasal lavage fluid as well as the concentration of interleukin-8, increased significantly only in those subjects exposed without a respiratory protection device. In peripheral blood, an increase of neutrophilic granulocytes was observed in both groups, although it was significantly higher in the group without mask (P < 0.05). The inhalable dust level was 0.94 (0.74 - 1.55) mg/m(3) and respirable dust 0.56 (0.51-0.63) mg/m(3). CONCLUSION: Exposure to dust aerosols during the cleaning of the interior of a swine confinement building induces increased bronchial responsiveness and an acute inflammatory reaction in the upper airways. The use of a mask attenuated but did not abolish the inflammatory response. This suggests that gases and/or ultrafine particles in this environment could be important factors in the development of increased bronchial responsiveness.

Animal Husbandry↗

PubMed2002

Measuring health related quality of life in patients with rheumatoid arthritis--reliability, validity, and responsiveness of a Swedish version of RAQoL.

OBJECTIVE: To adapt the Rheumatoid Arthritis Quality of Life (RAQoL) questionnaire for Swedish patients and evaluate psychometric properties in a prospective study. METHODS: Reliability was assessed in 61 patients filling in RAQoL two times with one week's interval. 114 patients completed RAQoL and Nottingham Health Profile (NHP) on 2-3 occasions 6 months apart. Validity was evaluated comparing RAQoL-scores to disease-related variables and NHP subscales. Standardized response mean was applied to calculate responsiveness with the RA-related variables as external indicators of change. RESULTS: Test-retest reliability was high and internal consistency sufficient. RAQoL correlated as expected to NHP section scores. In a multivariate model the Stanford Health Assessment Questionnaire disability index (HAQ) and general health could explain 40% and disease activity measures 13% of the variance of RAQoL. Correlations between change scores of clinical variables and RAQoL and NHP were weak but positive. Standardized response means regarding change of disease activity, HAQ, and general health were small but in the same range for both RAQoL and NHP. CONCLUSION: The Swedish RAQoL had similar measurement properties as the original version. However, responsiveness regarding condition specific measures was not better than for the generic instrument NHP.

Arthritis, Rheumatoid↗

PubMed2002

Second inter-laboratory study comparing endotoxin assay results from cotton dust.

Previously, a large two-part inter-laboratory round robin endotoxin assay study was completed. This first study showed that when cotton dust samples, which are practically identical, are assayed for endotoxin that the intra- laboratory results had a very small variation while intra-laboratory results of the sample had a very high variation. In the first part of the study, each laboratory followed its own in-house assay protocol; but in the second part of the study, when the extraction protocol was standardized, the inter-laboratory results showed a lower variation, which suggested that with further standardization, further reduction of differences between laboratories might be achieved in order that results between laboratories would become more comparable. The results stimulated interest in extending the study to include cotton dust with two levels of endotoxin, standardization of the extraction protocol, and using the same assay kit from the same production lot. The results of this second round robin endotoxin assay study indicate that differences between laboratories are still high, but most of the laboratories could discern the cotton dusts with the different levels of endotoxin.

Chemistry Techniques, Analytical↗

PubMedDate not supplied

Comparison of endotoxin assays using agricultural dusts.

Endotoxins from gram-negative bacteria pose a significant respiratory hazard. Establishing dose-response relationships is problematic because there are no standard procedures for sampling and analysis. The goal of this study was to compare endotoxin analyses in six laboratories using Limulus-based assays for analysis of organic dusts from three agricultural environments: chicken barns, swine barns, and corn processing facilities. For each dust generation experiment 14 side-by-side air samples were collected on 37-mm glass fiber filters at flows of 1.8 L/min. Each laboratory was randomly allocated two filters from each of seven experiments per dust type. Three laboratories used the QCL-1000 endpoint assay, and three used the kinetic-QCL method. To eliminate variability among different lots, a single lot of Limulus amebocyte lysate for endpoint assays and one similar lot for kinetic assays was provided. Precision of assays performed within labs was very good, with pooled coefficients of variation for replicate samples ranging from 1 to 11% over all labs and all dust types. There were significant differences between laboratories for all three dust types (p < 0.01). The pattern of differences between labs varied by dust type. For chicken dust, labs using the endpoint method reported higher results than those using kinetic methods. For swine and corn dusts, labs using the kinetic method reported the highest endotoxin values. For chicken dust, results from all labs except A and B were highly correlated (r = 0.86-1.00). For swine dust, only labs B and E, and C and D were correlated. For corn, A, B, and D were significantly correlated with most other labs. In conclusion, statistical differences in performance between laboratories were apparent and may be related to the extraction and analytical methods. The results of this study will be useful for standardization of sampling and analysis of airborne endotoxin in agriculture.

Agriculture↗