Phagocytes from both vertebrate and invertebrate species use "coiling" phagocytosis.

Coiling phagocytosis has been observed previously only by chance, and there has been no systematic investigation of this uptake mechanism. Therefore, a comparative electron microscopical study was performed. Different human and murine cell populations, phagocytes from various vertebrate and invertebrate species, and predatory amoebae were incubated with Borrelia burgdorferi, one of the microbes known to induce coiling phagocytosis, to study the uptake mechanisms used. In this model, coiling phagocytosis was observed with both vertebrate and invertebrate species but not with amoebae. With cells from humans and mice, this uptake mechanism was restricted to phagocytic cells of myeloid origin. The coiled membrane gaps did not give rise to phagosomes; instead, membrane fusion was followed by membrane dissipation. Thus, coiling of B. burgdorferi apparently is an alternative uptake mechanism used by metazoan phagocytes, involving special membrane processing. However, coiling phagocytosis may show different features with different microbes.

Biological monitoring of pyrethroid metabolites in urine of pest control operators.

Due to their low mammalian toxicity but high insectical activity, pyrethroids are increasingly used for pest control. The objective of the present study was the development of a biological monitoring program to determine exposure to pyrethroids. A diastereoselective detection of the major pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid by capillary gas chromatography in combination with mass selective detection was applied. The limits of determination ranged between 0.5 and 1 microgram/l urine, depending on the metabolite concerned. It was demonstrated that pyrethroid metabolites were detectable in urine for a period of elimination up to 3.5 days after exposure to cyfluthrin. Fluorophenoxybenzoic acid was shown to be a suitable biomarker for exposure to cyfluthrin. The presented method was adequate for monitoring pyrethroids in occupationally exposed subjects.

Metabolism of (S)-bioallethrin and related compounds in humans.

Chrysanthemate insecticides like (S)-bioallethrin, natural pyrethins, and related pyrethroids are subjected to extensive hydrolytic and oxidative degeneration by the mammalian metabolism, leading to a complex series of metabolites partially conjugated and finally eliminated in the urine. The major oxidation products of chrysanthemic acid, cis-(E)- and trans-(E)-chrysanthemumdicarboxcylic acid (cis-(E) and trans-(E)-CDCA), were synthesized and their structures were established by nuclear magnetic resonance spectrometry (H1-NMR) and mass spectrometry (MS). Diastereoselective separation was by high performance liquid chromatography (HPLC) and capillary gas chromatography (GC). An analytical method for extraction and identification of CDCA from human urine was developed. Quantitation was by gas chromatography and electron-impact mass spectrometry (GC/MS). The limit of detection was 20 microg/l for cis-(E)-CDCA and 10 microg/l for trans-(E)-CDCA. To test the applicability of the presented method, urine samples of humans exposed to (S)-bioallethrin were investigated. Urinary peak excretion of trans-(E)-CDCA occurred within 24 h after exposure.

Induction of mitotic cell division distrubances and mitotic arrest by pyrethroids in V79 cell cultures.

Five pyrethroids (fenvalerate, deltamethrin, cypermethrin, permethrin, cyfluthrin) differing in their chemical purity were investigated on their cytotoxic effects, especially on their ability to induce mitotic cell division disturbances using Chinese hamster lung cells of line V79. The colony forming ability (CFA) resulted in distinct differences of the cytotoxic effect of the tested pyrethroids, whereby permethrin was found to be most toxic. With the exception of fenvalerate all tested pyrethroids gave rise to inhibition of cell cycle progression as shown by G2/M-arrest of synchronized V79 cells by flow cytometry as well as by the increase of the mitotic index as evaluated by light microscopy. The mitotic arresting activity could be attributed to the occurrence of abnormal mitotic figures such as initial and full C-metaphases. The results however indicate, that pyrethroids per se do not contribute to the cytotoxic effects but that other factors such as chemical impurities, source as well as manufacturing process and isomer composition may be responsible for the observed cytotoxic effects.

Biological monitoring of pyrethroids in blood and pyrethroid metabolites in urine: applications and limitations.

The objective of this study was to perform biological monitoring of subjects who are occupationally exposed to pyrethroids. The study group consisted of 30 pest control operators exposed to cyfluthrin, cypermethrin or permethrin. After exposure, 24-h urine samples were collected and 20 ml of blood was drawn. The pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid were determined in the urine samples (limit of detection: 0.5 micrograms/l) by GC MS and the pyrethroids in plasma (limit of detection: 5 micrograms) GC-ECD. The concentrations of metabolites in the urine of the pest control operators ranged between < 0.5 micrograms/l and 277 micrograms/l urine. The concentrations of cyfluthrin, cypermethrin and permethrin in the plasma were below the limits of detection (< 5 micrograms/l). To test if the metabolites are specific for pyrethroid exposure, they were determined in the urine of non-exposed subjects (n = 40). In no case could pyrethroid metabolites be detected. A cyfluthrin elimination experiment showed that cyfluthrin metabolites are eliminated following first-order kinetics (t 1/2 = 6.4 h). Storage experiments demonstrate that frozen urine samples (-21 degrees C) show no significant losses of metabolites within a year. In contrast, pyrethroids stored in plasma are susceptible to further biodegeneration.

Mitotic activity of the hemocytes in the tick Ixodes ricinus (Acari; Ixodidae).

The blood cells, or hemocytes, of Ixodes ricinus have been shown to recognize, attack, and phagocytose microorganisms invading the body cavity, or hemocoel, of this tick. Regulated proliferation and differentiation of hemocytes, also referred to as immunocytes, is basic to an effective immune response to invading microorganisms. Therefore, this study dealt with hemopoiesis in I. ricinus, the vector tick of the Lyme disease spirochete Borrelia burgdorferi. Histological evidence for the presence of hemopoietic tissue, a preferential proliferation site of hemocytes, is presented. Mainly the mitotic activity of free-floating hemocytes was examined. By means of microscopical photometry and flow cytometry, all three types of hemocytes in engorging female I. ricinus were found in different stages of the cell cycle. In the engorging tick, up to 40% of the hemocytes counted were in the S phase or the G2/M phase. From this study we conclude that the differentiated hemocyte types do not differentiate from stem cells in the adult tick. Moreover, microorganisms entering the hemocoel of engorging ticks are confronted with high numbers of hemocytes and, therefore, with an effective cellular immune response.

Ultrastructural localization of a sialic acid-specific hemolymph lectin in the hemocytes and other tissues of the hard tick Ixodes ricinus (Acari; Chelicerata).

Lectins have been suggested to function as pattern-recognition molecules in invertebrate immune mechanisms. A lectin from the hemolymph of the tick Ixodes ricinus with main specificity for sialic acid was characterized and antibodies directed against this lectin were prepared. In this study, these antibodies were used to localize the lectin in the tissues of I. ricinus. Immunoreactivity with poly- and monoclonal antibodies was detected in the granules of both types of granular hemocytes, at the membrane of hemocytes, and at the basal laminae surrounding the hemocoel. Furthermore, cells attached to the midgut, invaginations of Géné's organ, and granular inclusions of nephrocytes were labeled. The immunoreactivity detected in hemocytes and the hemocoel lining supports the idea that the hemolymph lectin may function as a recognition molecule in the immune system of I. ricinus. Another function could be protection of eggs that are coated with secretions by Géné's organ. The lectin activity could also be involved in transmission of Borrelia burgdorferi, the causative agent of Lyme borreliosis, and the tick-borne encephalitis virus.

[Gas chromatography and mass spectrometry method for detection of selected pyrethroid metabolites in urine]. / Gaschromatographische und massenspektrometrische Methode zum Nachweis ausgewählter Pyrethroidmetabolite im Urin.

Pyrethroids are increasingly used indoors, because of their low mammalian toxicity but high insecticidal activity. Indoor application of pyrethroids, which is often carried out without adequate expert knowledge, may lead to high pesticide residues, often combined with health hazards for the people concerned. Objective of the present study is the development of a method for a biological monitoring to determine internal exposure to pyrethroids. Major pyrethroid metabolites were detected in urine by capillary gas chromatography in combination with mass selective detection (MSD). For the metabolites, the limits of determination range between 0.5 and 1 microgram/L urine. Our results so far demonstrate the detectability of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (DVCA) and 3-phenoxybenzoic acid (3-PBA) in urine during a period of elimination of 48 hours after exposure to cypermethrin. In this paper the method is exemplary illustrated by one exposed person (pest control operator).

Human dose-excretion studies with the pyrethroid insecticide cyfluthrin: urinary metabolite profile following inhalation.

1. Nine male volunteers were exposed to the pyrethroid insecticide cyfluthrin. The study was performed in an exposure room, where an aerosol containing cyfluthrin was sprayed to obtain atmospheres with mean cyfluthrin concentrations of 160 and 40 micrograms/m3. Four volunteers were exposed for 10, 30 and 60 min at 160 micrograms/m3 and another five volunteers were exposed for 60 min at 40 micrograms/m3. For 160 micrograms/m3 exposure urine samples were collected before and immediately after exposure as well as for the periods 1-2, 2-3, 3-4, 4-5, 5-6, 6-12 and 12-24 h after exposure. For 40 micrograms/m3 exposure urine samples were collected before and 2 h after exposure. 2. The main urinary cyfluthrin metabolites, cis-/trans-3-(2,2-dichlorovinyl)-2,2-dimethylycyclopropane carboxylic acid (DCCA) and 4-fluoro-3-phenoxybenzoic acid (FPBA), were determined. The limit of detection (LOD) for all metabolites was 0.0025 microgram in an urine sample of 5 ml (0.5 microgram/l). After inhalative exposure of 40 micrograms cyfluthrin/m3 air for 60 min, the amount of metabolites in urine collected in the first 2 h after exposure was less than the LOD, namely 0.14 microgram for cis-DCCA, 0.15-0.28 microgram for trans-DCCA and 0.12-0.23 microgram for FPBA. 3. Of the metabolites, 93% was excreted within the first 24 h (peak excretion rates between 0.5 and 3 h) after inhalative exposure of 160 micrograms/m3. The mean half-lives were 6.9 h for cis-DCCA, 6.2 h for trans-DCCA and 5.3 h for FPBA. 4. The mean trans-:cis-DCCA ratio was 1.9 for the time course as well as for each subject. 5. The amount of metabolites in urine depends on the applied dose, on the exposure time and shows interindividual differences.