Toxic effects and bioaccumulation of cadmium in the aquatic oligochaete Tubifex tubifex.

Although Tubifex tubifex (Oligochaeta, Tubificida) has been proposed as a test organism for ecotoxocological studies, very few data concerning sublethal toxicity and bioaccumulation are available on this worm. The aims of this work were to assess the toxicity of cadmium, one of the most toxic metals frequently encountered in polluted areas, on T. tubifex and the ability of the worm to accumulate this metal. Acute toxicity was analyzed by measurement of the 96-h LC(50) and daily survival rates. Results indicated that T. tubifex undergoes an adaptation period to Cd, the duration of which decreases with increasing Cd concentration. The various parameters affecting toxicity are discussed. Sublethal toxicity was studied by scanning electron microscopy. Observations revealed that Cd induced autotomy of the caudal region and mucus production. Autotomy is proposed as a criterion for sublethal toxicity. The results of bioaccumulation studies revealed that Cd is highly and rapidly taken up by the worm, suggesting involvement of efficient detoxification mechanisms. Consequently, the ability to accumulate large amounts of Cd may represent a potential toxicological risk to predators of the worm if Cd is accumulated in bioavailable forms.

Persisting Haemophilus influenzae strains induce lower levels of interleukin-6 and interleukin-8 in H292 lung epithelial cells than nonpersisting strains.

Nonencapsulated Haemophilus influenzae strains isolated from patients with chronic bronchitis can be divided into those that persist in the lower respiratory tract and those that do not. We tested the hypothesis that persisting and nonpersisting strains differ in the extent to which they activate epithelial cells to produce two potent inflammatory mediators, interleukin (IL)-6 and IL-8. A suspension of 10(7) and 10(8) colony forming units (cfu) x mL(-1) of H. influenzae, persisting and nonpersisting, induced a dose- and time-dependent production of IL-6 and IL-8 by the human pulmonary mucoepidermoid carcinoma-derived cell line H292, but levels of IL-6 were lower after exposure to persisting H. influenzae (p<0.05). IL-8 production showed a similar trend (p<0.02; analysis of variance). H. influenzae bacteria that adhered to H292 cells were equally distributed over persisting and nonpersisting isolates and induced IL-6 and IL-8 levels similar to their nonadhering counterparts. The difference between persisting and nonpersisting H. influenzae was not due to cytotoxic, antimetabolic or antiproliferative effects on H292 cells. Furthermore, pre-exposure of cells to persisting and nonpersisting isolates did not block subsequent IL-1beta-induced IL-6 production. We conclude that persisting clinical isolates induce less interleukin-6 and interleukin-8 in H292 cells than nonpersisting isolates, probably because they excrete lower amounts of a stimulus of H292 cells. The stimulus is heat stable, hydrophilic and nonproteinous and probably not lipopolysaccharide alone. These findings support the suggestion that some strains of Haemophilus influenzae that persist in the airways of patients, may do so because they induce only a weak inflammatory response.

Nedocromil sodium in obstructive airways disease: effect on symptoms and plasma protein leakage in sputum.

In patients with asthma or chronic obstructive pulmonary disease, there is chronic airway inflammation with increased leakage of plasma proteins into the airway lumen, which can be reduced by inhaled glucocorticosteroids. Nedocromil sodium is an anti-inflammatory drug, and we questioned whether it also affects the leakage of plasma proteins. In a double-blind placebo-controlled study we investigated the effect of 12 weeks of treatment with nedocromil on forced expiratory volume in one second (FEV1), provocative concentration of histamine causing a 20% fall in FEV1 (PC20), peak flow, symptom scores, and plasma protein leakage in sputum, in 31 patients with obstructive airways disease and sputum production (mean (range) FEV1 61% of predicted (42-87%); geometric mean (range) PC20 0.39 (0.04-2.9) mg x mL(-1)). As a measure for plasma protein leakage we calculated the relative coefficients of excretion (RCE) of proteins from serum to the soluble phase of sputum. There was a small increase in morning and evening peak flow (p<0.05) and a decrease in night-time bronchodilator use (p<0.02) in favour of nedocromil. The RCE of alpha2-macroglobulin to albumin significantly decreased after treatment with nedocromil (p=0.03). The results show limited clinical efficacy of nedocromil in our study group. They further suggest that the anti-inflammatory properties of nedocromil extend to inhibition of plasma protein leakage into the airways.

Effects of platinum (Pt4+) on Lumbriculus variegatus Müller (Annelida, Oligochaetae): acute toxicity and bioaccumulation.

The acute toxicity and bioaccumulation (rates, kinetic) of tetravalent platinum in Lumbriculus variegatus under different physicochemical conditions (temperature and total water hardness) were investigated. Increased Pt4+ concentration (from 0.05 to 50 mg/L), exposure (up to 30 days), temperature (from 4 to 20 degrees C) and decreasing water hardness (from 300 to 0 mg/L CaCO3) increased Pt toxicity. The metal accumulated at a constant rate that was concentration, temperature and time dependent. The median lethal concentration (96h LC50) varied greatly from 0.397 mg/L in distilled water to 30 mg/L in the hard water from Champagne. Thus, L. var. can tolerate high levels of Pt. As a result, L. var. can be used in the laboratory to analyze mechanisms of adaptation to the induced stress and in the field as an indicator of Pt pollution.

Analysis of plasma-protein leakage and local secretion in sputum from patients with asthma and chronic obstructive pulmonary disease.

In order to assess the usefulness of sputum analysis in studying plasma-protein exudation and local secretion of proteins in the airways, we measured specific proteins in the sputum sol phase (SSP) and sputum gel phase (SGP) from patients with stable asthma or chronic obstructive pulmonary disease (COPD). Protein levels in SSP showed relatively small variations between two subsequent visits of each patient (n = 22), as also reflected by intraclass correlation coefficients above 0.79. Protein levels differed between SSP and SGP, but inclusion of the SGP data did not affect the variation of protein levels in sputum. The degree of plasma-protein leakage was estimated from the relative coefficients of excretion (RCE) of alpha 2-macroglobulin and albumin (QA2M/QALB), and of alpha 2-macroglobulin and ceruloplasmin (QA2M/QCP), which do not depend on variable dilution of sputum. Despite the heterogeneity of the study group of 26 patients with asthma (atopic [13] smokers [13], including five patients using inhaled steroids), QA2M/QALB and QA2M/QCP correlated both with bronchial hyperreactivity (Spearman rank: r = -0.45 and r = -0.36, p < 0.05) and with blood eosinophil counts (r = 0.37 and 0.56, p < 0.05). We conclude that protein levels in SSP are relatively constant in patients with stable asthma or COPD; in patients with asthma, the plasma-protein leakage, as measured with the RCE in SSP, appears to correlate with indirect indices of airway inflammation.