Protective immunity against Ixodes ricinus induced by a salivary serpin.

Iris is a specific elastase inhibitor expressed in the salivary glands of the hard tick Ixodes ricinus. It belongs to the superfamily of serpins and interferes with both haemostasis and the immune response of the host. In this study, we first show that Iris is expressed in nymphs but not in the female midgut nor in males. We also show that Iris is present in the saliva. To examine its potency as anti-tick vaccine candidate, we set up three models of I. ricinus infestation on immunized animals: nymphs on mice, and adults and nymphs on rabbits. We report the rise of neutralizing antibodies following immunization of rabbits and mice. This comes with a significant protective immunity against ticks in rabbits only, resulting in a 30% mortality rate and a diminution of weight gain in both nymphs and adults and a prolongation of blood feeding time in adults. This is the first report on an anti-tick vaccine trial on I. ricinus using a protein able to interact with both host immunity and haemostasis, as a vaccinating antigen.

Esterases in marine dinoflagellates and resistance to the organophosphate insecticide parathion.

Esterases are involved in the susceptibility or resistance of organisms to organophosphate pesticides. We have examined the action of parathion on the marine dinoflagellates Crypthecodinium cohnii and Prorocentrum micans by looking at their esterases. One-dimensional gel electrophoresis, immunoblotting and cytochemistry plus image analysis were used to characterize the nature and distribution of the enzymes. Esterases were found in both species, but there appeared to be no particular intracellular localization. The esterase activity of the heterotrophic species Crypthecodinium cohnii was 30-fold greater than that of the autotrophic Prorocentrum micans and had an antigenic site in common with mosquito esterase. The resistance of Crypthecodinium cohnii to parathion was specific and reversible. Less parathion entered the parathion-resistant Crypthecodinium cohnii cells than the untreated control cells. Parathion-resistant cell extracts of Crypthecodinium cohnii analyzed after immunoblotting also contained an additional band of esterase activity. These results confirm the importance of esterases in toxicological studies of organophosphate insecticides, especially those of marine dinoflagellates.

Changes in ATP concentration, mitochondrial structures, and rhodamine 123 binding in two marine dinoflagellates cultured in the presence of parathion.

Parathion, an organophosphorous insecticide, is highly toxic to the two free-living marine dinoflagellates Prorocentrum micans Ehrenberg (autotrophic) and Crypthecodinium cohnii Biechler (heterotrophic). To study its non-antiacetylcholinesterase action we assessed its effect on the mitochondrial system, as shown by changes in intracellular ATP concentration and in rhodamine 123 fluorescence evaluated by image analysis. The technique of image analysis permits direct assessment of changes in the overall activity of mitochondria in living cells. Mitochondrial structures were also examined in the electron microscope. The three methods of investigation yielded complementary results. In P. micans, parathion noticeably altered mitochondria but did not significantly alter ATP concentrations. In C. cohnii, however, mitochondrial disturbance was slight, whereas ATP increased greatly. We think, therefore, that parathion has different effects on mitochondria in the two organisms, and in particular that it increases mitochondrial activity in C. cohnii.

Fluorescence induction used to measure parathion toxicity in the marine dinoflagellate Prorocentrum micans: a possible model for biodetection.

The marine dinoflagellate Prorocentrum micans Ehrenberg was used as a test organism to determine the conditions of use of fluorescence induction kinetic measurements in the study of parathion phytotoxicity. Measurements were taken of the kinetics of slow and fast fluorescence induction in whole cells and isolated chloroplast fragments at various concentrations of parathion. In both types of induction, the addition of parathion greatly decreased the fluorescence yield, indicating either inhibition of electron transport or physical changes. The action of parathion was a function of its concentration and was similar to the action of DCMU. Fluorescence induction was clearly less in isolated chloroplast fragments than in whole cells.

Environmental and health risks of hydroquinone.

Hazard assessment of hydroquinone has been evaluated from bibliographical and original data on the physicochemical properties, the environmental behavior, and the biological effects of this aromatic compound. Hydroquinone, which is produced in large amounts and widely used, must be considered as an environmental contaminant. However, it is not persistent. The ecotoxicity of this molecule, which must be linked to its physicochemical properties, varies from species to species. Its acute and chronic toxicity toward higher terrestrial organisms is moderate. Hydroquinone is estimated to be nonmutagenic by the Ames test but induces chromosome aberrations or karyotypic effects in eucaryotic cells. Carcinogenic and teratogenic potentials have been at present inadequately studied. The study underlines the complementarity of QSAR models and experimental approaches when an attempt is made to obtain ecotoxicological profiles of pollutants.

Action of the organophosphorous insecticide parathion on the free-living marine dinoflagellate Prorocentrum micans Ehrbg.

Growth of cultures of the dinoflagellate Prorocentrum micans Ehrbg. was slowed by parathion greater than 1 ppm. Parathion also decreased chlorophyll content and perturbed cellular ultrastructure, eliciting especially plastoglobuli in their chloroplasts. Toxicity of this organophosphorous insecticide is unlikely to be due to its anticholinesterase activity since P. micans appears not to contain cholinesterase. Fluorescence kinetics show that parathion affects the photosynthetic system, particularly photosystem II.

[Peripheral nerves in a case of lead neuropathy]. / Etude du nerf périphérique dans un cas de neuropathie saturnine.

A patient developed lead neuropathy with an asymmetrical distal weakness of the four limbs and sensory signs. Tap water contained high amounts of lead and biopsy confirmed the intoxication. The electromyogram was altered from the onset of the disorder and was still abnormal one year after treatment with EDTA, which however brought frank improvement. Biopsies were taken from nerves of the upper and lower limbs. Examination of teased nerve fibers showed the predominance of fibers of small diameter and segmental demyelinization with signs of remyelination in the lower limbs. Semi-thin sections demonstrated depopulation of large myelinated fibers, regeneration clusters and Schwann cells with globular nuclei. Electron microscopy showed myelin sheath alterations and neuritic lesions, some hyperactive Schwann cells. Main alterations were seen in basal membranes of Schwann cells of unmyelinated fibers and endoneuronal capillaries. Such alterations to our knowledge have never been reported in human peripheral lead neuropathy, but have been described after experimental intoxication. These findings together with recent experimental studies allow a discussion about the site of entry of lead into the nerve and about its site of action on the various constituents of the peripheral nerve.

[Ulcerative colitis associated with chronic atrophic polychondritis. One case (author's transl)]. / Recto-colite hémorragique associée à une polychondrite chronique atrophiante. Une observation.

A male patient has developed ulcerative colitis at the age of 70. Signs of chronic atrophic polychondritis appeared 9 months after the first attack. Subsequently, during the course of the disease each attack of ulcerative colitis was preceded by an exacerbation of polychondritis, which suggests a causal relationship rather than a chance association between the two conditions. The clinical response of polychondritis to sulfones in daily doses of 200 mg was satisfactory, but this dosage, which at present seems appropriate requires to be confirmed by further observations.

[Associated vertebral angioma and epidural cavernoma (author's transl)]. / Angiome vertébral associé à un cavernome épidural.

A 27 year old man developed a pyramidal syndrome with hypoesthesia up to the level of D8, over a period of two months. Radiographic examination revealed the presence of an angioma of D8. Selective angiography demonstrated that there was epidural invasion as well as an angioma of the vertebral body, and enabled embolization of the 2 pedicles of the lesion to be performed. This produced only a partial, temporary improvement, and a posterior epidural tumor was found and removed by operation. The histological appearance of the tumor was that of a cavernoma, and rapid and permanent recovery of normal neurological function was obtained after the operation. The authors discuss the pathogenicity of the neurological disorders associated with single bone angiomas, and the problems raised by their treatment.

[Action of cadmium on a free dinoflagellate Prorocentrum micans E: growth, cadmium absorption and cell modifications]. / Action du cadmium sur un dinoflagellé libre: Prorocentrum micans E.: croissance, absorption du cadmium et modifications cellulaires.

The study of the growth of Prorocentrum micans E. submitted to sublethal doses of cadmium demonstrated a high sensitivity of this Dinoflagellate to the polluant starting with concentration of 5 microgram/l. The uptake of cadmium was measured by pulse polarographic analysis of the filtered culture medium. Structural modifications, not apparent in living cells, are visible after fixation. The high sensitivity of Prorocentrum micans to cadmium, also its easy culture, makes it a suitable pollution indicator of this heavy metal.