Étude comparative de la dégradation du bromoxynil et du bromoxynil heptanoate par photolyse UV et par oxydation chimique (H²O²/UV ; O³ ; Cl²)

Les dégradations du bromoxynil heptanoate et du bromoxynil ont été étudiées pour différents traitements chimiques (03, Cl2) et photochimiques (H202/W; W254) en milieu aqueux dilué. Les expériences ont été réalisées à pH 7 pour le bromoxynil (CO=5 10-5 mol 1-1) et à pH 4 pour le bromoxynil heptanoate (CO=10-6 mol 1-1) afin de limiter la réaction d'hydrolyse.Les résultats obtenus montrent une bonne dégradation de ces deux pesticides aussi bien par irradiation W que par oxydation chimique au chlore ou à l'ozone. L'ajout de peroxyde d'hydrogène dans le milieu n'augmente pas de façon significative l'efficacité du traitement par rapport à l'irradiation seule. Parmi tous les traitements étudiés, l'ozonation est le procédé le plus efficace.L'analyse par couplage GC-MS des produits de réaction au cours de l'irradiation UV a permis d'identifier quatre photoproduits correspondant à la substitution des atomes de brome soit par un atome d'hydrogène, soit par un groupement OH. Les produits identifés sont A: -3,4 dihydroxy -5 bromobenzonitrile; B: -3,4,5 trihydroxybenzonitrile; C: -3,4 dihydroxybenzonitrile; D: -4 hydroxybenzo- nitrile. Un schéma réactionnel de photodégradation du bromoxynil heptanoate a été proposé dans cette étude.In the aquatic environment hydrolysis and phototransformation processes are the main abiotic degradation routes of chemicals. The aim of this study is to investigate the degradation pathway of 2 pesticides (bromoxynil heptanoate and its hydrolysis product bromoxynil) by UV photolysis and by chemical oxidation. The chemical oxidation processes studied are ozonation chlorination and radical oxidation with OH radicals. These radicals are produced by photolysis of hydrogen peroxide.Bromoxynil heptanoate (-4 cyano -2,6 dibromophenyl heptanoate) is an ester which is quite unstable in aqueous medium. Preliminary experiments, carried out in diluted solution (C[inf]o=10-[sup]6 mol l-¹) and in phosphate buffer (µ=10-2 mol l-¹), showed that 20 to 25% of bromoxynil heptanoate is hydroIyzed after 24 hours at pH 7. The hydrolysis decreases strongly with pH; it is only 3 % at pH 4 after one day.In order to limit the hydrolysis reaction, the following experiments were carried out at pH 7 for bromoxynil (C[inf]o=5 10-[sup]5 mol l-¹) and at pH 4 for bromoxynil heptanoate (Co=10-[sup]6 mol l-¹). The pH was adjusted with a phosphate buffer.Absorption spectra of bromoxynil heptanoate and bromoxynil do not show any absorption band up to 320 nm (bromoxynil heptanoate l max=218, 290 nm; bromoxynil I max=222, 280 nm; fig. 1). Therefore, the removal of these two pesticides by direct photolysis with the sun light will be very small. The measurement of the quantum yield (number of molecules undergoing photodegradation transformation per number of photons absorbed by these molecules) in the UV region in both monochromatic and polychromatic lights (HPK, Philips; I[inf]0=1.48 10-[sup]8 Einstein sec-¹, indicates that these 2 compounds are easily eliminated by a UV irradiation treatment (10-2 < F < 10-¹ at I=254 nm and 290 nm).The irradiation of these two pesticides at 254 nm (low pressure vapor mercury lamp, l[inf]0=5.8 10-[inf]8 Einstein sec-¹) in the presence of hydrogen peroxide does not seem to significantly improve the efficiency of the treatment by UV irradiation alone. For example, the half life time of bromoxynil is 11 minutes by UV compared to 8 minutes when hydrogen peroxide is present. This small difference of reactivity of H2O2/UV system is due to the small quantity of H202 photolyzed during this irradiation time; at t=8 min only 1 % of H202 is decomposed.The oxidation of bromoxynil heptanoate and bromoxynil by ozonation was performed in a semi-batch reactor (Q=5 mg O3 min-¹). Results show that these two compounds are very reactive with ozone. 50 % of elimination was obtained after 5 and 2 minutes of ozonation for bromoxynil heptanoate and bromoxynil respectively. In both cases the transfer of ozone was the limiting factor.Finally chlorination of bromoxynil at a rate of 35.5 mg Cl2-l-¹ indicates that this pesticide is also oxidized by chlorine but the degradation rate is quite slow; a total degradation is observed after 90 min of reaction. Comparison of the different treatments studied shows that ozonation is certainly the most effective process. Only a few minutes with reasonable ozone doses are necessary to eliminate these pesticides from aqueous medium. The other treatment (UV, H2O2/UV, Cl2) can also be a good alternative for the removal of these compounds from water.For the different oxidation treatments, the HPLC analysis of the bromoxynil reaction mixture shows the formation of by-products. Only UV and H2O2/UV byproducts were identified in this work; but comparison of the retention times from the HPLC analysis indicates that certain by-products from ozonation are similar to the ones observed by UV and H202/UV oxidation. On the other hand, the products formed during chlorination, probably chlorinated products, have different retention times.The reaction intermediates werc identified by GC-MS analysis after 10 min of irradiation (with and without H2O2). This time corresponds to the maximum concentration of one of the photoproduct. Two kinds of compounds wers identified from the GC-MS analysis: hydroxylated compounds (-3,4 dihydroxy -5 bromobenzonitrile; -3,4,5 trihydroxybenzonitrile) and hydrogenated compounds (-3,4 dihydroxybenzonitrile; -4 hydroxybenzonitrile). In both cases the bromine atoms were substituted either by an H atom or by an OH group. A reaction mechanism of photodegradation of bromoxynil heptanoate is proposed in this study (Fig. 6)

Comparative Studies on Naturally Occurring Antikeratin Antibodies in Human Sera

Comparative studies on the specificity of the so-called antiepidermal antibodies (Abs) found in human sera were performed by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and immunoelectron microscopy (LEM). After a screening test by indirect immunofluorescence (IF), sera obtained from patients with various diseases and controls could be classified in 5 different groups according to the IF patterns on the epidermis: sera reactive with: (1) the stratum corneum (SC); (2) the upper layer (U-Cyt); (3) the whole epidermis (G-Cyt); (4) basal cells (B-Cyt); and (5) negative ones. By immunoblotting, all the 23 IF-positive sera were found to bind to one or more keratin bands, and did not show any reactivity with epidermal Nonidet P-40 soluble proteins. SC-Abs were mainly directed against a 67 kD Keratin band, whereas U-Cyt- and G-Cyt-Abs bound to both 58-56 kD and 67-63 kD keratins. B-Cyt-Abs reacted strongly with 63 kD keratins and slightly with a 50 kD band. Antikeratin Abs were detected by immunoblotting even in the IF-negative sera. The ELISA study showed that sera with high IF titers contained high levels of antikeratin Abs. In the IEM study using sera containing U-Cyt- or B-Cyt-Abs, 2 distinct reaction patterns were demonstrated: U-Cyt-Abs stained tonofilaments of suprabasal keratinocytes, while B-Cyt- Abs characteristically reacted with those of basal cells. Moreover, SC-, U-Cyt-, and G-Cyt-Abs were absorbed out by insoluble epidermal proteins, and B-Cyt-Abs were decreased in titer after the absorption test. The present study provides strong evidence that most, though not all, human antiepidermal Abs are directed against different keratin polypeptides, and that antikeratin Abs commonly occur in almost all human sera

Cervical squamous carcinoma cells are resistant to the combined action of tumor necrosis factor-α and histamine whereas normal keratinocytes undergo cytolysis

<p>Abstract</p> <p>Background</p> <p>Previous reports showed that mast cells can typically be found in the peritumoral stroma of cervix carcinomas as well as in many other cancers. Both histamine and TNF-α are potent preformed mast cell mediators and they can act simultaneously after release from mast cells. Thus, the effect of TNF-α and histamine on cervical carcinoma cell lines was studied.</p> <p>Methods and results</p> <p>TNF-α alone induced slight growth inhibition and cell cycle arrest at G0/G1 phase in SiHa cells, but increased their migration. Histamine alone had no effect on cells. In addition, TNF-α and histamine in combination showed no additional effect over that by TNF-α alone, although SiHa cells were even pretreated with a protein synthesis inhibitor. Furthermore, TNF-α-sensitive ME-180 carcinoma cells were also resistant to the combination effect of TNF-α and histamine. In comparison, TNF-α or histamine alone induced growth inhibition in a non-cytolytic manner in normal keratinocytes, an effect that was further enhanced to cell cytolysis when both mediators acted in combination. Keratinocytes displayed strong TNF receptor (TNFR) I and II immunoreactivity, whereas SiHa and ME-180 cells did not. Furthermore, cervix carcinoma specimens revealed TNF-α immunoreactivity in peritumoral cells and carcinoma cells. However, the immunoreactivity of both TNFRs was less intense in carcinoma cells than that in epithelial cells in cervical specimens with non-specific inflammatory changes.</p> <p>Conclusion</p> <p>SiHa and ME-180 cells are resistant to the cytolytic effect of TNF-α and histamine whereas normal keratinocytes undergo cytolysis, possibly due to the smaller amount of TNFRs in SiHa and ME-180 cells. In the cervix carcinoma, the malignant cells may resist this endogenous cytolytic action and TNF-α could even enhance carcinoma cell migration.</p

Seroprevalence of 34 Human Papillomavirus Types in the German General Population

The natural history of infections with many human papillomavirus (HPV) types is poorly understood. Here, we describe for the first time the age- and sex-dependent antibody prevalence for 29 cutaneous and five mucosal HPV types from 15 species within five phylogenetic genera (alpha, beta, gamma, mu, nu) in a general population. Sera from 1,797 German adults and children (758 males and 1,039 females) between 1 and 82 years (median 37 years) were analysed for antibodies to the major capsid protein L1 by Luminex-based multiplex serology. The first substantial HPV antibody reactions observed already in children and young adults are those to cutaneous types of the genera nu (HPV 41) and mu (HPV 1, 63). The antibody prevalence to mucosal high-risk types, most prominently HPV 16, was elevated after puberty in women but not in men and peaked between 25 and 34 years. Antibodies to beta and gamma papillomaviruses (PV) were rare in children and increased homogeneously with age, with prevalence peaks at 40 and 60 years in women and 50 and 70 years in men. Antibodies to cutaneous alpha PV showed a heterogeneous age distribution. In summary, these data suggest three major seroprevalence patterns for HPV of phylogenetically distinct genera: antibodies to mu and nu skin PV appear early in life, those to mucosal alpha PV in women after puberty, and antibodies to beta as well as to gamma skin PV accumulate later in life

Genetics of immunoglobulin-A vasculitis (Henoch-Schönlein purpura): An updated review

Immunoglobulin-A vasculitis (IgAV) is classically a childhood small-sized blood vessel vasculitis with predominant involvement of the skin. Gastrointestinal and joint manifestations are common in patients diagnosed with this condition. Nephritis, which is more severe in adults, constitutes the most feared complication of this vasculitis. The molecular bases underlying the origin of IgAV have not been completely elucidated. Nevertheless, several pieces of evidence support the claim that genes play a crucial role in the pathogenesis of this disease. The human leukocyte antigen (HLA) region is, until now, the main genetic factor associated with IgAV pathogenesis. Besides a strong association with HLA class II alleles, specifically HLA-DRB1 alleles, HLA class I alleles also seem to influence on the predisposition of this disease. Other gene polymorphisms located outside the HLA region, including those coding cytokines, chemokines, adhesion molecules as well as those related to T-cells, aberrant glycosylation of IgA1, nitric oxide production, neoangiogenesis, renin-angiotensin system and lipid, Pyrin and homocysteine metabolism, may be implicated not only in the predisposition to IgAV but also in its severity. An update of the current knowledge of the genetic component associated with the pathogenesis of IgAV is detailed in this review.Acknowledgements: RL-Mis supported by the Miguel Servet I programme of the Spanish Ministry of Economy and Competitiveness through the grant CP16/ 00033. FG is recipient of a Sara Borrell postdoctoral fellowship from the “Instituto Carlos III de Salud” at the Spanish Ministry of Health (Spain) (CD15/00095). SR-M is supported by funds from the RETICS Program (RIER) (RD16/0012/0009). FDC is supported by the Ramón y Cajal programme of the Spanish Ministry of Economy and Competitiveness through the grant RYC-2014-16458

Evidence that involucrin, a marker for differentiation, is oxygen regulated in human squamous cell carcinomas

Hypoxia is associated with poor prognosis in squamous cell carcinomas affecting both local control and distant spread (Hockel et al., 1996a, 1996b, 1999; Nordsmark et al, 1996; Fyles et al, 2002; Kaanders et al, 2002). Local control is believed to depend on local radiation response while distant spread is thought to depend, at least in part, on the induction of oxygen-regulated proteins. In order to test this, pimonidazole, an extrinsic marker for tissue hypoxia (Arteel et al, 1995; Kennedy et al, 1997; Varia et al, 1998; Raleigh et al, 1999), with prognostic value (Kaanders et al, 2002) was used to examine whether ORPs such as VEGF (Raleigh et al, 1998a), metallothionein (Raleigh et al, 2000), HIF-1α (Janssen et al, 2002), Glut-1 (Airley et al, 2003) and CAIX (Olive et al, 2001) were, in fact, associated with cellular hypoxia in human tumours. Unexpectedly, VEGF and metallothionein (MT) were not expressed in the majority of hypoxic cells in squamous cell carcinomas (Raleigh et al, 1998a, 2000) even though these ORPs were induced by hypoxia in experimental systems (Shweiki et al, 1992; Raleigh et al, 1998b; Murphy et al, 1999)

Production et régulation de VEGF, Vascular Endothelial Growth Factor, par les kératinocytes et les fibroblastes humains normaux

Parmi les facteurs impliqués dans le développement de l'érythème cutané, le facteur de perméabilité vasculaire (VPF/VEGF-A) qui constitue un puissant vasodilatateur, exerce un rôle majeur. Il est synthétisé de manière constitutive par les kératinocytes et les fibroblastes dermiques, et surexprimé in vivo en conditions inflammatoires, notamment par les cellules épidermiques. Notre étude a précisé la régulation de VEGF-A par des facteurs d'agression exogènes (UV), endogènes (cytokines pro-inflammatoires, facteurs de croissance) et des extraits végétaux dans des cultures primaires de kératinocytes et de fibroblastes humains normaux. Parallèlement, nous avons étudié l'expression des nouveaux membres de la famille VEGF, VEGF-B, -C et -D, par ces cellules activées sous l'action de facteurs de croissance ou du TNF . L'expression des différents VEGFs suggère un contrôle de l'angiogenèse et de la lymphangiogenèse cutanées par les principales cellules résidentes de la peau.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

REGULATION DES MEDIATEURS IMPLIQUES DANS L'ERYTHEME CUTANE PHOTO-INDUIT (APPROCHE IN VITRO (DOCTORAT : BIOLOGIE EN PHARMACOLOGIE CUTANEE))

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF