Apport de la tomographie par émission de positons au 18F-fluorodéoxyglucose (TEP-FDG) dans la prise en charge du cancer du canal anal

ObjectiveTo evaluate the contribution of FDG-PET in the management of anal carcinoma, with special emphasis on its impact on therapeutic strategy.Materials and methodsFrom March 2005 to August 2008, 48 PET were performed on 43 patients with anal epidermoid carcinoma, in initial staging (IS: 20 exams), therapeutic response assessment (TRA: 11), and recurrence assessment (RA: 17). We compared initial therapeutic strategies defined on conventional assessment results, to final ones chosen after PET.ResultsPET revealed lesions that were undetected by conventional investigation in 23% of cases (IS: 25%; TRA: 18%; RA: 23%) and cleared suspicious lesions in 21% of cases (IS: 10%; TRA: 18%; RA: 35%). It influenced the therapeutic strategy, and sometimes even modified it radically, in 44% of cases (IS: 35%; TRA: 54%; RA: 47%). This therapeutic impact was stronger in settings with diagnostic ambiguity, in which PET allowed to specify the diagnosis and to orientate consequently the therapeutic choice.ConclusionPET is interesting in the management of anal carcinoma, especially in uncertain diagnostic settings, in which the metabolic information brought allows to influence the therapeutic choice in almost half of the cases.     

Evidence that the capsule around mycobacteria grown in axenic media contains mycobacterial antigens: implications at the level of cell envelope architecture

The intracellular growth of pathogenic mycobacteria has been linked to the presence of an electron transparent zone (ETZ or capsule), which surrounds the phagocytized bacteria and prevents the diffusion of lysosomal enzymes in infected macrophages. Recently, it was suggested that this capsule may be a bacterial structures, even being present in test tube-grown pathogenic mycobacteria (FEMS Microbiol. Lett. 1988, 56, 225-230). In the present paper, we show that under special fixation and embedding conditions, this capsule was clearly observed among 7 strains of mycobacteria grown in axenic media and also in M. leprae extracted and purified from experimentally infected armadillo or nude mice. In the case of bacteria treated likewise but subject to a prior dehydration step, this capsular structure disappeared suggesting its lipidic nature. Ultrathin sections of M. intracellular after immunolabelling showed for the first time that this capsule obtained mycobacterial antigens confirming its mycobacterial origin. It is suggested that the mycobacterial capsule may be formed of inert lipids, in which surface antigens are embedded.     

Electron cytochemistry of mycobacteria: Evidence that strongly acidic sulfate groups are present on the surface of H37Rv (virulent) strain ofMycobacterium tuberculosis

Cytochemical characterization of mycobacterial surfaces was carried out on virulent (H37Rv) and avirulent (H37Ra) strains ofMycobacterium tuberculosis. The results were quantified and compared with those obtained with three colony types of the opportunistic pathogenMycobacterium avium. Mycobacterium aurum, a rapidly growing, nonpathogenic species, served as a model for the cytochemical methods. Concanavalin A (ConA) reacted with -d-mannose and -d-glucose residues, whereas negative charged residues were detected with either the ionized ferritin (CF) or the colloidal ferric hydroxide (CIH) method. Strongly acidic sulfate groups were detected by their selective blockage with alcian blue (AB) at pH 1 prior to the CIH labeling at pH 1.8. Weakly acidic groups were demonstrated by AB blockage at pH 2.5 prior to staining with CF stain. Except forM. aurum, all other strains showed a marked heterogeneity in regard to the abundance of their surface labeling. Accessible sulfate groups were present on the cell surface of the virulent H37Rv strain ofM. tuberculosis, but not on the avirulent strain H37Ra. Distribution of ConA receptors, on the other hand, was unrelated to the virulence or pathogenicity of the bacterial strain.     

Lampetra (Eudontomyzon) gracilis,a synonym of Eudontomyzon danfordi

Synopsis Evidence is presented which suggests that the nonparasitic lamprey, Lampetra (Eudontomyzon) gracilis Kux, 1965, is conspecific with the parasitic lamprey Eudontomyzon danfordi Regan, 1911. The diagnostic characters of the holotype and of the non-type material of E. gracilis are features found in E. danfordi specimens in their second and final year of adult life, thereby making the former a junior synonym of the latter.     

Expression of c-myc protooncogene in rat lens cells during development,maturation and reversal of galactose cataracts

It is well established that normal patterns of epithelial cell proliferation and metabolism, and of fiber cell differentiation and maturation are essential for the maintenance of transparency in the ocular lens. Several factors, including exposure to high levels of sugars, have been known to result in the compromise of lens transparency. For example, initiation of lens cell damage by galactose induces lens epithelial cells to proliferate. Elevated levels of c-myc mRNA have usually been correlated with rapid cell growth and increased entry of cells into the S phase. Therefore, changes in c-myc mRNA levels may provide an early indication of the stimulation of lens epithelial cells to proliferate and differentiate, which has been postulated to be an early and important event in response to lens cell injury by galactose. By Northern blot hybridization analysis we quantitated c-myc mRNA levels in the lens capsule epithelia of rats (1) exposed to galactose, and (2) undergoing a partial recovery from the galactose-induced cell damage. At the onset of lens cell damage, we find c-myc mRNA to elevate to 6-fold by 24 hr, and by 48 hr decreases to about 3-fold the normal levels. During recovery, c-myc mRNA continues to be expressed at high levels approaching a 10-fold increase by day 12, then decreasing to levels of about 8-fold the control by day 30. The 24 h transitory elevation in c-myc mRNA in lens epithelial cells is in accord with our previous observations on the 24 h increase in MP26, crystallin and aldose reductase mRNAs following a high influx of galactose. Therefore, the elevation in c-myc mRNA as well suggest that galactose appears to cause lens cells to undergo an early transitory period of gene induction following the exposure of lens cells to galactose.     

Biochemical and pharmacologic properties of the Ca2+ channel of skeletal muscle: appearance during myogenesis and the relation between its structure and function

Two distinct and interdependent binding sites for inhibitors of voltage-dependent Ca2+ channels have been identified. They include one site for molecules of the 1,4-dihydropyridine serie such as nitrendipine, nifedipine or PN200-110 and one site for a chemically heterogenous group of compounds comprising verapamil, D600 and desmethoxyverapamil, bepridil and diltiazem. Ca2+ binds to its own coordination site which is distinct from the receptor site for organic Ca2+ channel inhibitors. The molecular size of the native [3H] nitrendipine receptor of transverse tubule membrane, brain and heart, have been determined using the radiation inactivation technique. The [3H] nitrendipine receptor is found to have a Mr of 210,000 +/- 20,000. CHAPS solubilization and purification indicate that the dihydropyridine receptor contains polypeptides of apparent molecular weights of 142,000, 32,000 and 33,000 which copurifie with (+) [3H] PN200-110 binding activity. Two stages in which there is an increased binding of [3H]nitrendipine have been observed during chick myogenesis. The first one occurs during embryonic life and has the same properties as in the in vitro development. The second stage occurs near hatching and corresponds to a large increase in the number of nitrendipine receptors. This increase is accompanied by a decrease in the affinity of nitrendipine for its receptor by a factor of 4 to 10. The second stage of development is partly under innervation control and its expression is modulated by the intracellular cyclic AMP content. The two dihydropyridines Bay K8644 and CGP 28932 work preferentially on polarized membranes. 45Ca2+ flux experiments yielded results which are in good agreement with electrophysiological, contraction and binding data obtained with rat cardiac cells and skeletal muscle cells.     

Estrogen and androgen production by purified Leydig cells of mature boars

Purified Leydig cells were obtained from testes of mature male pigs by collagenase treatment and mechanical dispersion, followed by Percoll (0-90%) density gradient centrifugation. The cells recovered at 40-45% Percoll were applied to a second gradient of 15 ml of Percoll (10-60%) to yield three bands, one major and two lesser in numbers of cells. Incubations were then made with 0.25-1.0 X 10(6) cells at 34 degrees C for 3 h in 95% O2: 5% CO2, with or without human chorionic gonadotrophin (hCG) added to the medium. Steroid concentration was determined by radioimmunoassays. The steroids measured in the media were testosterone, dehydroepiandrosterone sulfate (DHAS) and estrone sulfate (E1S). Lesser amounts of dehydroepiandrosterone (DHA) and estrone (E1) were found. Stimulation by hCG led to an increase in apparent steroid production for all steroids, including estrogens, with the greatest quantities seen with DHAS (greater than 200 ng/1 X 10(6) cells/3 h). Cells in the major band gave the best response. These results show that Leydig cells are a significant site of estrogen production in the boar testis and that this organ is a source of an abundant supply of such cells.     

Selective modification of coupling factor 1 in spinach chloroplast thylakoids by a fluorescent maleimide

N-(1-Anilinonaphthyl-4)maleimide (ANM) has been used to modify coupling factor 1 (CF1), the terminal coupling factor of photophosphorylation in chloroplasts. As with other monofunctional maleimides, incubation of thylakoids with ANM in the light, but not in the dark, causes energy transfer inhibition of photophosphorylation. In the dark, sites on both the gamma and epsilon subunits of CF1 are modified. The light-accessible site is also on the gamma subunit. Trypsin digestion of the enzyme after dithiothreitol activation reveals that the dark-and light-accessible sites on the gamma subunit are different amino acid residues. Fluorescence of ANM bound at the dark-and light-accessible sites has been measured after isolation of CF1 from thylakoids. The fluorescence emission maximum of ANM at the light-accessible site is blue-shifted and the quantum yield is increased 2-fold relative to ANM bound at dark-accessible sites. On the soluble enzyme, fluorescence polarization is high and equivalent for ANM bound at both dark-and light-accessible sites. Fluorescence energy transfer from a tryptophan in a hydrophilic region of the epsilon subunit to ANM bound to the epsilon subunit but not to the gamma subunit has been observed. The significance of these observations is discussed with respect to the structure of the gamma subunit and its role in conformational transitions within CF1 that occur during energization of the membrane.     

Proton and carbon-13 nuclear magnetic resonance spectroscopy of diastereoisomeric 3- and 17 beta-tetrahydropyranyl ether derivatives of estrone and estradiol

Protection of 3- and 17 beta-hydroxyl groups of estrone and estradiol as tetrahydropyranyl ether derivatives led to mixtures of 2'(R)- and 2'(S)-diastereoisomers which were separated by crystallization (3-tetrahydropyranyl ethers), or by thin-layer chromatography (17-tetrahydropyranyl ethers), and characterized by 1H and 13C nuclear magnetic resonance (NMR). Assignments for NMR signals of estradiol 3,17 beta-ditetrahydropyranyl ether were facilitated by comparison with those of its 15 zeta, 16 zeta-dideuterio analog and by 2D 1H-13C heteroshift correlation experiments. Diastereoisomers of 3-tetrahydropyranyl ether derivatives could be identified through the 13C NMR doublet signals of the anomeric C-2' and the aromatic C-4 carbon atoms in CDCl3. Diastereoisomers of 17-tetrahydropyranyl ether derivatives were recognized from characteristic modifications of 1H NMR signals of H-2', H-6', H-1, H-17, and 18-CH3 protons as well as from the 13C NMR doublet signals corresponding to C-2', C-4', C-6', C-12, C-13, C-16, and C-17 carbon atoms. Low-temperature experiments showed a splitting of the C-2', C-6', and C-17 13C NMR signals of each of the two 17-tetrahydropyranyl ether isomers. The downfield signal (equatorial conformer) of the three resulting doublets was more intense for the 17-tetrahydropyranyl ether 2'(S)-isomer, whereas the upfield signal (axial conformer) was more intense for the 2'(R)-isomer.