Rôle pathogène des mouches

Flies are pathogenic for human for many reasons. They can carry a lot of germs (bacterium, virus, parasites). Flies are exceptional intermediate host of parasites (Thelazia). Some are vectors of diseases, as glossina which transmit sleeping sickness, and the tabanidae the loiasis. But the most frequent pathogenicity is due to the larvae, which are under the skin or in natural cavities, as eyes, ears and nose.These myiasis are provoked by different flies as Musca, Cordylobia, Dermatobia, Gasterophilus or Hypoderma. Lucilia is useful because it cleans the wounds. Diagnosis of myiasis is set up by the extraction of the larva and its typing, and in some cases of visceral myiasis by the serodiagnosis. There is only a symptomatic treatment.     

Apoptose et pouvoir pathogène des bactéries

A growing number of bacterial pathogens and their toxins is shown to be able to cause apoptosis of their target cells. It looks as if the goal is for the microorganism to delete cells of the innate immune system such as macrophages in order to achieve survival within infected tissues. An alternative goal may be to initiate inflammation. Activation of caspase-1, a cysteine protease activating IL-1b and causing the apoptotic death of infected cell accounts for this dual function. This is the case for Shigella, a bacterial species whose capacity to cause apoptotic death of macrophages has been studied in details. For most of the pathogens causing apoptosis of their target cells, three major questions remain unanswered: what are the precise mechanisms inducing programmed cell death? Does this process occur in vivo? What is the advantage for the pathogen?     

Différenciation de l'origine exogène ou endogène de produits dopants par l'analyse isotopique du carbone

Carbon isotope analysis by isotope ratio mass spectrometry (IRMS) has a great analytical potential in anti-doping control. Indeed, standard analysis based on the identification an quantification of molecules come up against the specific problem of endogenous compounds because no obvious diagnostic of illicit abuse of these compounds can be obtained from their presence or concentration in urine. After the separation of the molecules by gas chromatography, IRMS offers the possibility to distinguish between exogenous and endogenous origin by the precise determination of the 13C/12C (the two stable carbon isotope) ratio value of these molecules.A brief presentation of the continuous flow isotope ratio mass spectrometer instrumentation is made and the principle of the differentiation between exogenous and endogenous origin of doping compounds is presented. In particular, the important contribution of this technique for the detection of exogenous testosterone intake is detailed. The trend of this technique for other steroid hormones such as endogenous anabolic steroids or corticosteroids and the perspective of its development in anti-doping control are also evoked.     

Le diagnostic biologique de la coqueluche : culture,PCR ou sérologie ?

Because of the whooping cough resurgence, currently observed in France, in non vaccinated infants contaminated by adults, very often clinically atypical, whooping cough biological diagnosis are necessary. Those diagnosis are either direct, like culture or PCR, or indirect, such as measurement of agglutinins by agglutination or of anti-toxin antibodies by ELISA or western blot analysis in the serum of the patients. Culture is a rather unexpensive and reimbursed diagnosis, while PCR is expensive and not reimbursed. PCR is a more sensitive technique than culture, but culture should not be given up being the only technique allowing to follow evolution of B. pertussis isolates under the effect of vaccinal strategies. Agglutination is unexpensive non reimbursed technique, while immunoassay is expensive but reimbursed. The type of diagnosis will be chosen according to the patient's age and immune condition.     

Les transporteurs d'oxygène à base d'hémoglobine

The modified hemoglobins are not true blood substitutes because they do not possess the complex functions of erythrocytes. They are oxygen carriers only with a short intravascular life, adapted for temporary use. Three types of modified hemoglobin solutions have been designed, prepared from human or bovine hemoglobin or by genetic engineering. These hemoglobins are highly purified to eliminate trace amounts of stroma, lipids and endotoxins, which are responsible for acute toxicity. They are modified by internal cross linking between the monomers, or by binding to macromolecules. Afterwards, they can be polymerized or encapsulated in liposomes. The purpose of these modifications is to increase oxygen delivery to tissue, to reduce the dissociation into monomers and to guard against oxydation into methemoglobin. The modified hemoglobin solutions are essentially used in hemorrhagic shock and perioperative hemodilution. These oxygen carriers could be used by some athlets to increase their results in particular during endurance sports. But these hemoglobins are different enough from physiologic hemoglobins (normal or pathological), so they could be easily detected in blood samples.