Biodegradability of HCH in agricultural soils from Guadeloupe (French West Indies): identification of the lin genes involved in the HCH degradation pathway.

Banana has been a main agricultural product in the French West Indies (Guadeloupe and Martinique) since the 1960s. This crop requires the intensive use of pesticides to prevent attacks by insect pests. Chlorinated pesticides, such as hexachlorocyclohexane (HCH), chlordecone and dieldrin, were used until the beginning of the 1990s, resulting in a generalized diffuse contamination of the soil and water in the areas of banana production, hence the need to develop solutions for cleanup of the polluted sites. The aims of this work were (i) to assess lindane degradation in soil slurry microcosms treated with lindane at 10 mg/L and (ii) to detect the catabolic genes involved in the HCH degradation pathway. The soil slurry microcosm system showed a 40% lindane degradation efficiency at the end of a 30-day experiment. Lower lindane removal was also detected in the abiotic controls, probably caused by pesticide adsorption to soil particles. Indeed, the lindane concentration decreased from 6000 to 1330 ng/mL and from 800 to 340 ng/mL for the biotic and abiotic soils, respectively. Nevertheless, some of the genes involved in the HCH degradation pathway were amplified by polymerase chain reaction (PCR) from crude deoxyribonucleic acid (DNA) extracted from the Guadeloupe agricultural soil, suggesting that HCH degradation is probably mediated by bacteria closely related to the family Sphingomonadaceae.

[Role of general practioners in the follow-up of bariatric surgery in the province of Liege]. / La place et le rôle des médecins généralistes dans le suivi de chirurgie bariatrique en province de Liège.

This paper is concerned with the place and role of general practitioners in the follow-up of patients submitted to bariatric surgery in the province of Liège. The results of the analysis were compared with clinical practice guidelines published by the French Haute Autorité de Santé (HAS). Fifteen interviews were conducted with GPs who follow up operated patients. The results highlight the GPs' wish to fully participate in the follow-up of those patients. Their medical supervision is centered on the HAS clinical practice guidelines, taking into account the intake deficiencies as well as the patient's psychological experience. However, some aspects are disregarded, mainly because of a lack of theoretical knowledge (some biological parameters, pregnancy and contraception). The short consultation time along with the poor communication with the hospital multidisciplinary team were mentioned as obstacles to a good quality follow-up. Progress is still needed to reach the clinical practice guidelines. However, there is a wish to better collaborate. Organising coordination meetings between professionals along with an early implication of the GP - even before surgery - represent possible solutions.

Preparation and characterisation of raw chars and physically activated carbons derived from marine Posidonia oceanica (L.) fibres.

Industrial valorisation of low cost and renewable biomass as raw precursor of activated carbon for environmental applications is an interesting alternative to costly commercial activated carbons. In this study, the possible use of Mediterranean, Posidonia oceanica fibrous biomass, as a precursor for chars and physically activated carbons, is investigated. Firstly, the raw marine material was chemically and biochemically characterised throughout dry-basis elemental, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis. Then, several P. oceanica chars were prepared and characterised under different pyrolysis times and temperatures. In addition, physically activated carbons (PACs) were produced via water steam flow under various activation periods. The results showed that the pyrolysis induces the creation of pores at different levels with respect to the involved temperature. Thereafter, the physical activation tends to enhance the development of the porous structure. In that issue, the performed Brunauer-Emmett-Teller (BET) and Barrett-Joiner-Halenda (BJH) analysis revealed that the prepared PACs have a mainly mesoporous inner morphology with a varying fraction of micropores.

Adsorption studies of molasse's wastewaters on activated carbon: modelling with a new fractal kinetic equation and evaluation of kinetic models.

Adsorption kinetic of molasses wastewaters after anaerobic digestion (MSWD) and melanoidin respectively on activated carbon was studied at different pH. The kinetic parameters could be determined using classical kinetic equations and a recently published fractal kinetic equation. A linear form of this equation can also be used to fit adsorption data. Even with lower correlation coefficients the fractal kinetic equation gives lower normalized standard deviation values than the pseudo-second order model generally used to fit adsorption kinetic data, indicating that the fractal kinetic model is much more accurate for describing the kinetic adsorption data than the pseudo-second order kinetic model.

Activated carbon from vetiver roots: gas and liquid adsorption studies.

Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components in precursors for pyrolysed tropical fruit stones and seeds, Micropor. Mesopor. Mater. 59 (2003) 85-91]. The N(2) adsorption isotherm follows either the Freundlich law K(F)P(alpha) which is the small alpha equation limit of a Weibull shaped isotherm or the classical BET isotherm. The surface area of the activated carbons are determined using the BET method. The K(F) value is proportional to the BET surface area. The alpha value increases slightly when the burn-off increases and also when there is a clear increase in the micropore distribution width.

Adsorption studies of recalcitrant compounds of molasses spentwash on activated carbons.

Due to high levels of residual chemical oxygen demand (COD) in the effluent of molasses spentwash (MSW) after anaerobic treatment, acceptable COD levels for discharge cannot be achieved without some form of post-treatment. In this study, the particulate composition of molasses spentwash after anaerobic digestion (MSWD), is characterised as to its particle size distribution, using micro- and ultrafiltration and three activated carbons are characterised as to their ability to reduce significantly the COD of MSWD effluent. The activated carbons tested as adsorbent, were characterised by XPS spectroscopy, elemental analysis, surface area, pore size distribution, and acid-base titration using the Boehm's method. Adsorption of phenol, used here as a reference compound, and of some organic compounds contained in MSWD (gallic acid, tannic acid, and melanoidin, respectively), was studied. It was clearly demonstrated that an activated carbon with a significant distribution of both micropores and mesopores and a significant amount of macropores that are assumed to act as conduits providing access to micro- and mesopores, have a good adsorption efficiency for compounds such as tannic acid and melanoidins. It is a good adsorbent for melanoidin and coloured compounds of MSWD, which represents a large source of the aqueous pollution in sugar cane industries.

Parameters from a new kinetic equation to evaluate activated carbons efficiency for water treatment.

The fractal dimension of some commercial activated carbon (AC) was determined in the micro-, meso- and macropore range using mercury porosimetry and N(2) adsorption data. We studied the kinetic of adsorption of phenol, tannic acid and melanoidin on those ACs. The typical concentration-time profiles obtained here could be very well fitted by a general fractal kinetics equation q(n,alpha)(t)=q(e)[1-(1+(n-1)(t/tau(n,alpha))(alpha))(-1/(n-1))] deduced from recently new methods of analysis of reaction kinetics and relaxation. The parameter n is the reaction order, alpha is a fractional time index, q(e) measures the maximal quantity of solute adsorbed, and a "half-reaction time", tau(1/2), can be calculated, which is the time necessary to reach half of the equilibrium. The adsorption process on AC is clearly a heterogeneous process, taking place at the liquid-solid boundary, and the diffusion process occurs in a complex matrix with a fractal architecture as demonstrated here. In fact, these systems belong to what has been called "complex systems" and the fractal kinetic, which has been extensively applied to biophysics, can be a useful theoretical tool for study adsorption processes.

Localization and solubilization of the Iron(III) reductase of geobacter sulfurreducens

The iron(III) reductase activity of Geobacter sulfurreducens was determined with the electron donor NADH and the artificial electron donor horse heart cytochrome c. The highest reduction rates were obtained with Fe(III) complexed by nitrilotriacetic acid as an electron acceptor. Fractionation experiments indicated that no iron(III) reductase activity was present in the cytoplasm, that approximately one-third was found in the periplasmic fraction, and that two-thirds were associated with the membrane fraction. Sucrose gradient separation of the outer and cytoplasmic membranes showed that about 80% of the iron(III) reductase was present in the outer membrane. The iron(III) reductase could be solubilized from the membrane fraction with 0.5 M KCl showing that the iron(III) reductase was weakly bound to the membranes. In addition, solubilization of the iron(III) reductase from whole cells with 0.5 M KCl, without disruption of cells, indicated that the iron(III) reductase is a peripheral protein on the outside of the outer membrane. Redox difference spectra of KCl extracts showed the presence of c-type cytochromes which could be oxidized by ferrihydrite. Only one activity band was observed in native polyacrylamide gels stained for the iron(III) reductase activity. Excision of the active band from a preparative gel followed by extraction of the proteins and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of high-molecular-mass, cytochrome-containing proteins in this iron(III) reductase activity band. From these experimental data it can be hypothesized that the iron(III) reductase of G. sulfurreducens is a peripheral outer membrane protein that might contain a c-type cytochrome.

Contaminated environments in the subsurface and bioremediation: organic contaminants.

Due to leakages, spills, improper disposal and accidents during transport, organic compounds have become subsurface contaminants that threaten important drinking water resources. One strategy to remediate such polluted subsurface environments is to make use of the degradative capacity of bacteria. It is often sufficient to supply the subsurface with nutrients such as nitrogen and phosphorus, and aerobic treatments are still dominating. However, anaerobic processes have advantages such as low biomass production and good electron acceptor availability, and they are sometimes the only possible solution. This review will focus on three important groups of environmental organic contaminants: hydrocarbons, chlorinated and nitroaromatic compounds. Whereas hydrocarbons are oxidized and completely mineralized under anaerobic conditions in the presence of electron acceptors such as nitrate, iron, sulfate and carbon dioxide, chlorinated and nitroaromatic compounds are reductively transformed. For the aerobic often persistent polychlorinated compounds, reductive dechlorination leads to harmless products or to compounds that are aerobically degradable. The nitroaromatic compounds are first reductively transformed to the corresponding amines and can subsequently be bound to the humic fraction in an aerobic process. Such new findings and developments give hope that in the near future contaminated aquifers can efficiently be remediated, a prerequisite for a sustainable use of the precious-subsurface drinking water resources.

Inhibition of ascorbate oxidase by phenolic compounds. Enzymatic and spectroscopic studies.

Competitive inhibition by phenolic compounds of the ascorbic acid oxidation reaction catalyzed by ascorbate oxidase was investigated at pH 7.0 and 23.0 degrees C. Inhibition of p-nitrophenol is pH dependent over the range 5.0-8.0, with inhibitor binding favored at higher pH. Bulky substituents on the phenol nucleus reduce or prevent the inhibitory effect. The presence of phenol affects the binding characteristics of azide to the trinuclear cluster of the enzyme. In particular, binding of azide to type 2 copper is prevented, and the affinity of azide to type 3 copper is reduced. In addition, reduction of type 1 copper is observed upon prolonged incubation of ascorbate oxidase with excess phenol and azide, but not with phenol alone. It is proposed that binding of phenolic inhibitors occurs at or near the site where the substrate (ascorbate) binds. NMR relaxation measurements of the protons of phenols in the presence of ascorbate oxidase show paramagnetic effects due to the proximity of the bound inhibitor to a copper center, likely type 1 copper. Copper-proton distance estimates between this paramagnetic center and p-cresol or p-nitrophenol bound to ascorbate oxidase are between 4.4 and 5.9 A.

Study of the coordination chemistry of prostaglandin G/H synthase by resonance Raman spectroscopy.

Resonance Raman spectra of prostaglandin G/H synthase (PGHS) in its ferric and ferrous states have been obtained by Soret excitation. In native PGHS, which contained only 0.25 heme/monomeric apoprotein, the ferric heme was in a high-spin hexacoordinated state. The presence of a vibration at 289 cm-1 that was responsive to H(2)16O -> H(2)18O replacement was taken as evidence for the presence of a H-bonded H2O molecule as the sixth ligand of the Fe. A study, by CD and resonance Raman spectroscopy, of heme incorporation into the apoprotein showed that, for heme/protein ratios lower than 0.5, the heme was in the same ferric high-spin hexacoordinated state as in the native enzyme. For heme/protein ratios higher than 0.5, the concomitant formation of two minor species was observed: a low-spin hexacoordinated species which could be due to the axial coordination of a distal histidine to the Fe trans to its proximal histidine ligand; and a high-spin pentacoordinated species that corresponded to non-specific binding of the heme to the apoprotein. In the reduced state, the heme of PGHS contained a high-spin pentacoordinated Fe(II) with a histidine as the proximal ligand. However, this species shifted spontaneously towards a low-spin hexacoordinated Fe(II) species in which the iron was probably coordinated by a distal histidine as the sixth axial ligand. The PGHS Fe(II).CO derivative displayed an Fe-CO stretching mode at 529 cm-1, which is in the range observed for peroxidases. Such a high frequency could be due to H-bonding between the oxygen atom of the CO ligand and the distal histidine, His207. Since this histidine plays an important role, by coordination of Fe(II) or Fe(III) of PGHS and stabilization of the ligands of the Fe, H2O or CO by H-bonding, it is suggested that this histidine could also play a key role in the cleavage of the O-O bond of peroxides by peroxidases.

Studies on photoinactivation by various phthalocyanines of a free or replicating non-enveloped virus.

The non-enveloped picornaviruses, which are particularly resistant to physicochemical inactivation, include the aetiological agents of poliomyelitis, hepatitis A and E and infectious common cold (rhinovirus). In this work we used human rhinovirus type 5 (RV-5) cultivated in VERO cells to study the photoinactivating effects of several phthalocyanines and naphthobenzoporphyrazines. Free RV-5 was photoinactivated by aluminium trisulphonated naphthobenzoporphyrazine at 5 x 10(-8) M concentration. This photosensitizer was also active on replicating virus when the infected VERO cells were treated with 5 x 10(-6) M concentration followed by a very short illumination period. On the other hand, the ZnPc(3-MeO-Py)4 phthalocyanine, which possesses four positive charges, does not photoinactivate free rhinovirus, but this molecule protects VERO cells against RV-5 infection when added to the cultures before virus inoculation, in the presence or absence of subsequent illumination, and may therefore be considered as an antiviral agent in itself.

Reactions of prostaglandin H synthase with monosubstituted hydrazines and diazenes. Formation of iron(II)-diazene and iron(III)-sigma-alkyl or iron(III)-sigma-aryl complexes.

The reaction of p-chlorophenylhydrazine with prostaglandin H synthase (PGHS) Fe(III) under aerobic conditions leads to a partial destruction of the heme and to a new complex absorbing at 436 nm. This complex is also obtained by reaction of p-chlorophenyldiazene (pClPhN = NH) with PGHS Fe(III) under anaerobic conditions and by oxidation of the PGHS Fe(II)(pClPhN = NH) diazene complex by Fe(CN)6K3. The similarity between those reactions and those of arylhydrazines and aryldiazenes with other hemoproteins such as cytochrome P450 and hemoglobin and myoglobin, as well as the similarities between the spectroscopic and chemical properties of this complex and those of the sigma-aryl complexes of other hemoproteins such as hemoglobin and myoglobin, strongly suggested a PGHS Fe(III)-pClPh structure for this complex. It was completely established after the extraction of its heme, by butan-2-one at 0 degree C under neutral or acidic conditions, which led to the sigma-aryl PGHS-Fe(III)-pClPh complex and to N-phenylprotoporphyrin IX, respectively. A mechanism is proposed for the formation of the PGHS Fe(III) pClPh complex; it includes the reduction of PGHS Fe(III) into PGHS Fe(II) with formation of the diazene pClPhN = NH. This diazene can bind to PGHS Fe(II) or be oxidized with formation of pClPh free radicals. These radicals can react with PGHS Fe(II) to form the PGHS Fe(III)-pClPh complex or with the protein, or may initiate free radical oxidations which could lead to destruction of the heme or of the protein. Other alkylhydrazines or arylhydrazines also react with PGHS Fe(III) under aerobic conditions with the formation of PGHS Fe(III)-R or aryl (Ar) complexes and heme destruction. Alkylhydrazines such as methylhydrazine, which lead to very reactive alkyl radicals, lead to very low amounts of PGHS Fe(III)-R complex and high amounts of heme destruction, whereas arylhydrazines bearing electron-withdrawing substituents such as 3,4-dichlorophenylhydrazine, which lead to stabilized aryl radicals, lead to a high amounts of PGHS Fe(III)-Ar complex and low amounts of heme destruction.(ABSTRACT TRUNCATED AT 400 WORDS)

Phenylhydrazones as new good substrates for the dioxygenase and peroxidase reactions of prostaglandin synthase: formation of iron(III)-sigma-phenyl complexes.

Phenylhydrazones of various aromatic and aliphatic aldehydes or ketones act as good substrates of the dioxygenase reaction of prostaglandin synthase (PGHS). Corresponding alpha-azo hydroperoxides are formed as intermediates with maximum initial rates of O2 consumption between 8 and 230 mol (mol of PGHS)-1 s-1 for benzophenone and hexanal phenylhydrazone, respectively. The Km values for these reactions vary from 100 to 300 microM. These alpha-azo hydroperoxides are then converted to the corresponding alpha-azo alcohols by the peroxidase reaction of PGHS. During such oxidations of phenylhydrazones by PGHS, a new complex of this hemeprotein characterized by peaks at 438 and 556 nm is formed. This complex was obtained both by direct reaction of PGHS Fe(III) with phenyldiazene and by reaction of PGHS Fe(III) with phenylhydrazine in the presence of O2. By analogy to results previously reported for hemoglobin, myoglobin, catalase, and cytochrome P450, this species should be a sigma-phenyl PGHS FeIII-Ph complex. The PGHS FeIII-Ph complex should derive from an oxidation of the intermediate alpha-azo alcohol by PGHS Fe(III), cleavage of the resulting alkoxy radical with formation of a ketone (or aldehyde) and Ph*, and combination of PGHS Fe(II) with Ph*. Such an oxidation of alpha-azo alcohols by lipoxygenase-FeIII with formation of Ph* was reported previously. The formation of Ph* and of PGHS FeIII-Ph is likely the cause of the inhibitory effects previously reported for arylhydrazones toward PGHS.

Photodynamic properties of naphthosulfobenzoporphyrazines, novel asymmetric, amphiphilic phthalocyanine derivatives.

Metallo naphthosulfobenzoporphyrazines sulfonated to different degrees (M-NSBP) were prepared, and their potential as photosensitizers for the photodynamic therapy (PDT) of cancer was evaluated. M-NSBP can be viewed as hybrid molecules between sulfophthalocyanines and naphthalocyanines resulting in distinct differences in the absorption spectra between the mono-through tetrasulfonated derivatives. This feature greatly facilited their purification. Using V-79 Chinese hamster cells in vitro, the disulfonated derivatives were found slightly more photoactive than the hydrophilic trisulfonated derivatives while the monosulfonated derivative was inactive, in spite of a sixfold higher cell uptake. In the case of the di- and trisulfonated derivatives, differences in phototoxicity correlated well with their relative cell uptake. Substitution of Al for Zn had little effect on the extent of phototoxicity of the M-NSBP. In vitro PDT of the EMT-6 cells after in vivo dye administration, revealed a similar potency for direct cell killing between the di- and trisulfonated AlOH-NSBP, while the monosulfonated analog was inactive. PDT with the amphiphilic disulfonated AlOH-NSBP on the EMT-6 mammary tumor in BALB/c mice induced a significant tumor response, while the monosulfonated derivative was much less active.

Mixed acenannellated metallotetraazaporphins: a new class of amphiphilic photosensitizers for the photodynamic therapy of cancer.

The first synthesis of amphiphilic mixed acenannellated metallotetraazaporphins compounds, designed with the aim of improving cell membrane penetration, is described and the preliminary results on their photocytotoxicity are presented.