Bases moléculaires et cellulaires de l'invasion des cellules épithéliales intestinales par Shigella flexneri

A key step in the pathogenesis of shigellosis is the capacity of the causative bacteria, shigellae, to invade colonic and rectal epithelial cells in humans. This invasive process encompasses several steps: entry into epithelial cells by induction of a macropinocytic event caused by secreted Ipa proteins. The bacterium then escapes from the vacuole and reaches the cytoplasmic compartment in which it divides rapidly and becomes motile via the expression of a surface protein, IcsA, whose polar localization achieves directed polymerization of actin filaments that push the bacterial body forward. Bacteria then engage the inner face of the cellular membrane in the junctional area and form protrusions allowing their passage into the adjacent cell. Lysis of the double membrane eventually allows access to the cytoplasmic compartment of the adjacent cell, thus providing the bacterium with a very efficient mechanism of epithelial colonization.     

Sur l'accumulation de nickel et de cobalt par les Charaées

Chara vulgaris was cultivated in a natural medium containing nickel and cobalt chloride.Growth increased in a culture solution containing Ni and Co in small amounts. Tissue analysis showed that the levels of Ni and Co in the dry matter were high. The two ions are found here as insoluble compounds, which explains why Chara vulgaris is an organism resistant to metal pollution.Université de Dijon, Laboratoire de Nutrition minérale des Végétaux     

Caractérisation d'une hémopexine sérique de truite par utilisation d'une protéine recombinante

Rainbow trout hemopexin was produced by Sf9 cells through the Baculovirus system; the protein is released into the culture medium. It has been purified through two successive chromatographic steps: ion exchange (MonoQ) and chelation (Zn⁺ affinity). Treatment of the protein by N-glycosidase F reduced its relative mass by 3 000, demonstrating N-glycosylation. Spectrophotometric analysis in the Soret band of protein + hemin mixture revealed characteristics of a hemoprotein (oxidized: λ = 413 nm, dithionite-reduced: λ = 422 nm); the titration curve suggested a 1:1 molar ratio. An anti tHx antiserum was produced; it detected an intense band in the trout serum, but also in the serum of two perciforms: gilt-head sea bream and sea bass; it did not cross-react with the serum of the phylogenetically distant eel.     

Caractérisation combinée par TEP au 18F-FDG et par IRM des lésions hépatiques dans l’échinococcose alvéolaire

Positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) can be used to evaluate parasitic activity in alveolar echinococcosis (AE) as visualization of host–parasite immune reaction around the lesions. We performed a retrospective interpretation of PET and MR (magnetic resonance) images in 24 patients with AE to compare the results of metabolic imaging to Kodama et al. anatomical classification. All patients underwent hepatic MRI and dual-time point FDG-PET (1 hour and 3 hours after injection), improving sensitivity of standard FDG-PET in AE. The comparison of the images showed perilesional ¹⁸F-FDG uptake in all seven patients with type 1 (multiple microcysts without a solid component) and type 2 (multiple microcysts with a solid component) lesions and in ten of 12 patients with type 3 lesions (a solid component surrounding cysts and microcysts). No abnormal perilesional uptake was observed at standard and delayed PET acquisitions in two of 12 patients with type 3 lesions and in all five patients with type 4 (a solid component without microcysts) and type 5 (a large liquid cavity without microcysts) lesions. Our study demonstrates a strong correlation between anatomical “microcystic” aspect and metabolic activity of AE lesions in 89.5% of cases. Thus, microcysts and metabolic perilesional activity seem correlated to parasite activity, which suggests an important role to combined follow-up of AE patients, through multimodality imaging using MRI and ¹⁸F-FDG-PET scan.     

Traitement par ultrasons focalisés du cancer localisé de la prostate: Résultats carcinologiques et pronostic sexuel

Introduction

Since 1999, a therapeutic device using High Intensity Focused Ultrasound (HIFU) technology has been marketed in Europe for the treatment of localized prostate cancer. Clinical and technical development was designed to provide a minimally invasive alternative for these patients. The purpose of this study was to evaluate the efficacy of HIFU therapy for localized prostate cancer and its impact on sexual function.

Material and Methods

HIFU technology is based on a convergent beam of high intensity ultrasound that creates a sudden and sharp increase in temperature (85°C to 100°C) in the tissues at the focal point. This leads to a precise lesion in the tissue, adjustable from 19 to 24 mm in height and 2 mm in diameter. Successive displacements of the focal point are computer-driven, allowing treatment of a defined volume. All patients were treated with the ABLATHERM® device (EDAP SA, France); they were treated using the device prototypes between 1993 to 1999 and then with the marketed machine. The treatment procedure was improved from 2000 onwards with the combination of transurethral resection of the prostate (TURP) in order to reduce post-treatment catheter time. A nerve-sparing procedure was also tested in 2002. The selected population included 120 patients considered to be potentially curable with clinical stage T1–T2 prostate cancer and an initial PSA < 10 ng/ml (group 1). A larger group of 167 patients with an initial PSA < 30 ng/ml was also considered (group 2). All patients were not candidates for surgery due to their age or comorbidities. In the two groups, clinical failure was defined by the need for administration of an adjuvant prostate cancer treatment (hormone deprivation or external radiation). Disease progression, or biochemical failure, was strictly defined as any evidence of residual cancer on follow-up biopsies (regardless of the PSA level), or 3 successive increases of the PSA level (with negative follow-up biopsies), with a velocity > 0.75 ng/ml/year. Disease-free survival rates were calculated using the Kaplan-Meier method. Survival rates were compared using the log-rank test. The impact of HIFU treatment on sexual function was assessed by a questionnaire in 70 patients who underwent standard HIFU treatment and in 28 patients in whom a nerve-sparing procedure was performed.

Results

Patient baseline characteristics (± SD) were, in group 1 and group 2 respectively: mean age: 71.2 (± 5.34) years and 71.8 (± 5.11) years; clinical stage: T1 for 61 patients and T2 for 59 patients in group 1, and T1 for 77 patients, T2 for 85 patients and T3 for 5 patients in group 2; mean initial PSA level: 5.67 (± 2.47) ng/ml and 9.30 (± 6.01) ng/ml; Gleason score: 2–6 for 77 patients and 7–10 for 43 patients in group 1, and 2–6 for 98 patients, 7 for 44 patients, and 8–10 for 25 patients in group 2; mean prostate volume: 33.6 (± 16.5) ml and 34.4 (± 16.7) ml, respectively. Mean follow-up was 27 months (range: 3–96 months) in group 1, and 23 months (range: 3–90 months) in group 2. In group 1, a residual cancer was diagnosed in 17 patients, but only 6 patients needed adjuvant treatment due to a significant rise of the PSA level (hormone deprivation: n=2, external radiation: n=4), leading to a clinical success rate of 95%. Similarly, in group 2, 36 patients presented with positive follow-up biopsies, and 21 of them required adjuvant treatment (hormone deprivation: n=10, external radiation: n=11), leading to a clinical success rate of 87.5%. The disease-free survival rates (previously defined on the combined biopsy and PSA criteria) were 76.9% and 66% in group 1 and 2, respectively. In addition, the disease-free survival rate in group 2 was stratified according to the initial prognosis risk level: 85% in low-risk patients (i.e. patients with clinical stage T1–T2a and PSA < 10 ng/ml and Gleason score < 7), 67.5% in intermediate-risk patients (i.e. clinical stage T2b or PSA 10–20 ng/ml or Gleason score = 7), and 42% in high-risk patients (i.e. clinical stage T2c or PSA > 20 ng/ml or Gleason score > 7). In the overall population, 70 patients had normal sexual function prior to HIFU treatment; 25 patients (36%) still had erections allowing sexual intercourse with penetration after treatment. A nerve-sparing procedure was also performed in 28 potent patients: 43% of these patients had persistent erections allowing sexual intercourse with penetration after treatment, indicating that this nerve-sparing procedure still needs to be improved.

Conclusion

The efficacy results observed after HIFU treatment are similar to those observed after other non-surgical treatments for prostate cancer. After complete HIFU treatment of the gland, more than 1/3 of patients still reported erections allowing sexual intercourse with penetration; these results must be interpreted for an elderly population (mean age: 72 years). A nerve-sparing procedure is currently being perfected and tested.     

Activité cholinestérasique des corpuscules sensoriels cutanés de Herbst et de Grandry

Résumé L'activité cholinestérasique (ChE) a été étudiée dans les corpuscules de Herbst et de Grandry du bec de canard par la méthode de Karnovsky. Le BW 284 C 51, l'iso-OMPA et l'ésérine ont été utilisés comme inhibiteurs. Une activité cholinestérasique non spécifique (nsChE) a été identifiée dans les corpuscules. Elle est présente dès le début de leur différenciation.Corpuscule de Herbst: l'activité nsChE est localisée dans les cellules du bulbe interne (citernes périnucléaires, reticulum endoplasmique granulaire, vésicules associées à l'apppareil de Golgi) et à la surface de la membrane plaamique des cellules du bulbe interne et de la terminaison nerveuse.Corpuscule de Grandry: l'activité nsChE est localisée dans les cellules satellites (citernes périnucléaires, reticulum endoplasmique granulaire) et à la surface de la membrane plasmique des cellules satellites, des cellules de Grandry et de la terminaison nerveuse.Une forte activité nsChE a été mise en évidence dans certaines zones de contact entre les cellules dites sensorielles (cellules du bulbe interne et de Grandry) et les terminaisons nerveuses. Une réaction positive a été observée au niveau des mitochondries des cellules satellites et de la terminaison nerveuse du corpuscule de Grandry, et dans des vésicules du réticulum endoplasmique lisse des terminaisons nerveuses.Aucune activité ChE n'a été détectée dans les cellules capsulaires, les cellules de l'espace interne, les cellules de Grandry, et dans les vésicules synaptiques.Ces résultats ont été discutés en relation avec ce que l'on sait sur l'activité ChE des autres types de corpuseules sensoriels. La signification fonctionnelle de cette activité ChE et le problème de l'origine des différentes catégorics cellulaires qui constituent les corpuscules de Herbst et de Grandry ont été envisagés.

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Cholinesterase activity in the Herbst and Grandry cutaneous sensory corpusclesHistochemical study at the light and electron microscope

Summary Cholinesterase activity (ChE) was localized in the Herbst and Grandry cutaneous sensory corpuscle of the duck beak with Karnovsky's method. Controls with BW 284 C 51, iso-OMPA and eserine were carried out. A non-specific cholinesterase activity (nsChE) was identified in the corpuscles. This enzyme activity is present from the beginning of their differenciation.Herbst corpuscle: nsChE activity was localized in the inner bulb cells (perinuclear cisterna, granular endoplasmic reticulum, vesicles associated with the Golgi complex) and along the plasma membrane of inner bulb cells and nerve ending.Grandry corpuscle: nsChE activity was localized in the satellite cells (perinuclear cisterna, granular endoplasmic reticulum) and along the plasma membrane of satellite cells, Grandry cells, and nerve ending.A high nsChE activity was evident in certain zones of contact between the so-called sensory cells (inner bulb and Grandry cells) and the nerve endings. A positive reaction was seen in mitochondria of satellite cells and nerve ending for the Grandry corpuscle, and in smooth endoplasmic vesicles of the nerve endings.No ChE activity was detected in capsular cells, inner space cells, Grandry cells and in synaptic vesicles.These results are discussed in relation with what is known about ChE activity of other sensory corpuscles. The functional significance of this ChE activity and the problem of the origin of the different cells of Herbst and Grandry corpuscles have been considered.

     

Toxicité aigüe et bioconcentration du lindane et de la deltaméthrine par les tetards de Rana temporaria et les gambusies (Gambusia affinis)

Acute toxicity and bioconcentration capacities of lindane and deltamethrin were studied in Rana temporaria tadpoles and in mosquitofish. These studies show that the toxicity of deltamethrin is about 100 to 1 000 times greater than that of lindane and bioconcentration factors are very different for these two insecticides. The bioconcentration factor of lindane, a stable chemical, low volatility, hydrophobic and a poorly metabolized molecule is considerable in either static or flow through contamination systems. For deltamethrin, an quickly metabolized molecule, this factor is weak or null. Moreover a comparison of various methods of contamination (static or flow through systems) showed that the experimental conditions of exposure to the insecticide strongly influence the concentration in the tested species.

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Toxicité aigüe et bioconcentration du lindane et de la deltaméthrine par les tetards de Rana temporaria et les gambusies (Gambusia affinis)