Nitric oxide activation facilitated by cooperative multimetallic electron transfer within an iron-functionalized polyoxovanadate-alkoxide cluster.

A series of NO-bound, iron-functionalized polyoxovanadate-alkoxide (FePOV-alkoxide) clusters have been synthesized, providing insight into the role of multimetallic constructs in the coordination and activation of a substrate. Upon exposure of the heterometallic cluster to NO, the vanadium-oxide metalloligand is oxidized by a single electron, shuttling the reducing equivalent to the {FeNO} subunit to form a {FeNO}7 species. Four NO-bound clusters with electronic distributions ranging from [VV3VIV2]{FeNO}7 to [VIV5]{FeNO}7 have been synthesized, and characterized via 1H NMR, infrared, and electronic absorption spectroscopies. The ability of the FePOV-alkoxide cluster to store reducing equivalents in the metalloligand for substrate coordination and activation highlights the ultility of the metal-oxide scaffold as a redox reservoir.

Prospective role of indigenous Exiguobacterium profundum PT2 in arsenic biotransformation and biosorption by planktonic cultures and biofilms.

AIMS: The aim of this study was to analyse arsenic (As) transformation and biosorption by indigenous As-resistant bacteria both in planktonic and biofilm modes of growth. METHODS AND RESULTS: As-resistant bacteria were isolated from industrial waste water and strain PT2, and identified as Exiguobacterium profundum through 16S rRNA gene sequencing was selected for further study. As transformation and biosorption by E. profundumPT2 was determined by HPLC-ICP-MS analysis. Planktonic cultures reduced 3·73 mmol l-1 As5+ into As3+ from artificial waste water effluent after 48-h incubation. In case of biosorption, planktonic cultures and biofilms exhibited 25·2 and 29·4 mg g-1 biomass biosorption, respectively. As biosorption kinetics followed Freundlich isotherm and pseudo second-order model. Biofilm formation peaked after 3 days of incubation, and in the presence of As stress, biofilm formation was significantly affected in contrast to control (P < 0·05). Homogeneous nature of mature biofilms with an increased demand of nutrients was revealed by minimum roughness and maximum surface to biovolume ratio measured through CLSM analysis. CONCLUSION: Indigenous As-resistant E. profundumPT2 was found capable of As transformation and biosorption both in the form of planktonic cultures and biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: Indigenous biofilm forming E. profundum PT2 revealing As biosorption and biotransformation potential is presented an eco-friendly and cost-effective source for As remediation that can be implemented for waste water treatment.

Antibacterial isoeugenol coating on stainless steel and polyethylene surfaces prevents biofilm growth.

AIMS: Pathogenic bacteria can spread between individuals or between food items via the surfaces they share. Limiting the survival of pathogens on surfaces, therefore, presents an opportunity to limit at least one route of how pathogens spread. In this study, we propose that a simple coating with the essential oil isoeugenol can be used to circumvent the problem of bacterial transfer via surfaces. METHODS AND RESULTS: Two commonly used materials, stainless steel and polyethylene, were coated by physical adsorption, and the coatings were characterized by Raman spectroscopy, atomic force microscopy and water contact angle measurements. We quantified and visualized the colonization of coated and uncoated surfaces by three bacteria: Staphylococcus aureus, Listeria monocytogenes and Pseudomonas fluorescens. No viable cells were detected on surfaces coated with isoeugenol. CONCLUSIONS: The isoeugenol coating prepared with simple adsorption proved effective in preventing biofilm formation on stainless steel and polyethylene surfaces. The result was caused by the antibacterial effect of isoeugenol, as the coating did not diminish the adhesive properties of the surface. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study demonstrates that a simple isoeugenol coating can prevent biofilm formation of S. aureus, L. monocytogenes and P. fluorescens on two commonly used surfaces.

Osteopontin adsorption to Gram-positive cells reduces adhesion forces and attachment to surfaces under flow.

The bovine milk protein osteopontin (OPN) may be an efficient means to prevent bacterial adhesion to dental tissues and control biofilm formation. This study sought to determine to what extent OPN impacts adhesion forces and surface attachment of different bacterial strains involved in dental caries or medical device-related infections. It further investigated if OPN's effect on adhesion is caused by blocking the accessibility of glycoconjugates on bacterial surfaces. Bacterial adhesion was determined in a shear-controlled flow cell system in the presence of different concentrations of OPN, and interaction forces of single bacteria were quantified using single-cell force spectroscopy before and after OPN exposure. Moreover, the study investigated OPN's effect on the accessibility of cell surface glycoconjugates through fluorescence lectin-binding analysis. OPN strongly affected bacterial adhesion in a dose-dependent manner for all investigated species (Actinomyces naeslundii, Actinomyces viscosus, Lactobacillus paracasei subsp. paracasei, Staphylococcus epidermidis, Streptococcus mitis, and Streptococcus oralis). Likewise, adhesion forces decreased after OPN treatment. No effect of OPN on the lectin-accessibility to glycoconjugates was found. OPN reduces the adhesion and adhesion force/energy of a variety of bacteria and has a potential therapeutic use for biofilm control. OPN acts upon bacterial adhesion without blocking cell surface glycoconjugates.

Physicochemical characterization of fish protein adlayers with bacteria repelling properties.

Materials coated with aqueous fish protein extracts can reduce bacterial adhesion, but the mechanism behind the observed effect is not fully understood. In this study we explore the physicochemical properties of fish muscle protein adlayers on four substrates: gold, stainless steel, polystyrene and silicon dioxide. The aims were (i) to determine if the anti-adhesive effect is independent of the underlying substrate chemistry, (ii) to link the physicochemical properties of the adlayer to its ability to repel bacteria, and (iii) to elucidate the mechanism behind this effect. The main proteins on all surfaces were the muscle proteins troponin, tropomyosin, and myosin, and the lipid binding protein apolipoprotein. The quantity, viscoelasticity, and hydration of the protein adlayers varied greatly on the different substrates, but this variation did not affect the bacterial repelling properties. Our results imply that these proteins adsorb to all substrates and provide a steric barrier towards bacterial adhesion, potentially providing a universal antifouling solution.

Colonization of the oral cavity by probiotic bacteria.

The aim of this study was to investigate if three probiotic bacteria present in the milk product Cultura Dofilus® naturell could be detected in saliva and on oral mucosal surfaces, and if they colonized dental surfaces in situ in 8 caries-inactive individuals after 8 daily exposures to the milk product for up to 3 days. Bacteria were identified by fluorescence in situ hybridization and confocal laser scanning microscopy. While probiotic bacteria were present sporadically in the oral cavity on mucosal surfaces and in saliva after 3 days of frequent use of the probiotic milk, they were not detected on dental surfaces. Probiotic bacteria may thus contribute to general oral health, but their potential role in biofilm-induced dental diseases remains unclear.

Enzymatic generation of hydrogen peroxide shows promising antifouling effect.

The antifouling (AF) potential of hydrogen peroxide (H(2)O(2)) produced enzymatically in a coating containing starch, glucoamylase, and hexose oxidase was evaluated in a series of laboratory tests and in-sea field trials. Dissolved H(2)O(2) inhibited bacterial biofilm formation by eight of nine marine Proteobacteria, tested in microtiter plates. However, enzymatically produced H(2)O(2) released from a coating did not impede biofilm formation by bacteria in natural seawater tested in a biofilm reactor. A field trial revealed a noticeable effect of the enzyme system: after immersion in the North Sea for 97 days, the reference coating without enzymes had 35-40 barnacles, 10% area coverage by diatoms and 15% area coverage by tunicates. The enzyme containing coating had only 6-12 barnacles, 10% area coverage by diatoms and no tunicates. The enzyme system had a performance similar to a copper-based commercial coating and thus appears to have potential as a non-persistent AF agent.

Impact of nitrate addition on biofilm properties and activities in rising main sewers.

Anaerobic sewer biofilm is a composite of many different microbial populations, including sulfate reducing bacteria (SRB), methanogens and heterotrophic bacteria. Nitrate addition to sewers in an attempt to control hydrogen sulfide concentrations affects the behaviour of these populations, which in turn impacts on wastewater characteristics. Experiments were carried out on a laboratory reactor system simulating a rising main to determine the impact of nitrate addition on the microbial activities of anaerobic sewer biofilm. Nitrate was added to the start of the rising main during sewage pump cycles at a concentration of 30 mg-N L(-1) for over 5 months. While it reduced sulfide levels at the outlet of the system by 66%, nitrate was not toxic or inhibitory to SRB activity and did not affect the dominant SRB populations in the biofilm. Long-term nitrate addition in fact stimulated additional SRB activity in downstream biofilm. Nitrate addition also stimulated the activity of nitrate reducing, sulfide oxidizing bacteria that appeared to be primarily responsible for the prevention of sulfide build up in the wastewater in the presence of nitrate. A short adaptation period of three to four nitrate exposure events (approximately 10 h) was required to stimulate biological sulfide oxidation, beyond which no sulfide accumulation was observed under anoxic conditions. Nitrate addition effectively controlled methane concentrations in the wastewater. The nitrate uptake rate of the biofilm increased with repeated exposure to nitrate, which in turn increased the consumption of biodegradable COD in the wastewater. These results provide a comprehensive understanding of the impact of nitrate addition on wastewater composition and sewer biofilm microbial activities, which will facilitate optimization of nitrate dosing for effective sulfide control in rising main sewers.

Tunable 3D and 2D polystyrene nanoparticle assemblies using surface wettability, low volume fraction and surfactant effects.

Polymer-based nanopatterning on metal surfaces is of increasing importance to a number of applications, including biosensors, bioelectronic devices and medical implants. Here we show that polycrystalline gold surfaces can be functionalized with monocomponent nanoparticle (NP) assemblies by a simple drop deposition method. Ordered 3D hexagonal close-packed structures consisting of 350 nm polystyrene (PS) NPs on hydrophobically modified gold surfaces from solutions of very low volume fraction (varphi = 0.0006) were obtained as a result of capillary force induced self-assembly, whilst 2D self-assembly of PS NPs was generated over large area on hydrophilic gold and TiO(2) surfaces by spin coating. Furthermore, we show that when Triton X-100 is added to the PS NP suspending medium longer range ordering is obtained. Our observations may initiate interesting applications in the areas of nanoengineering of metal-based sensors and as a means to design new nanostructures for biocompatible implant surfaces.

Adhesion of food-borne bacteria to stainless steel is reduced by food conditioning films.

AIMS: Preconditioning of stainless steel with aqueous cod muscle extract significantly impedes subsequent bacterial adhesion most likely due to repelling effects of fish tropomyosin. The purpose of this study was to determine if other food conditioning films decrease or enhance bacterial adhesion to stainless steel. METHODS AND RESULTS: Attachment of Pseudomonas fluorescens AH2 to stainless steel coated with water-soluble coatings of animal origin was significantly reduced as compared with noncoated stainless steel or stainless steel coated with laboratory substrate or extracts of plant origin. Coating with animal extracts also decreases adhesion of other food-relevant bacteria. The manipulation of adhesion was not attributable to growth inhibitory effects. Chemical analysis revealed that the stainless steels were covered by homogenous layers of adsorbed proteins. The presence of tropomyocin was indicated by appearance of proteins with similar molecular weight based in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in several extracts that reduced adhesion but also extracts not containing this protein reduced bacterial adhesion, indicating that several molecular species may be involved in the phenomenon. CONCLUSIONS: It is a common perception that food materials facilitate bacterial adhesion to surfaces; however, this study demonstrates that aqueous coatings of food origin may actually reduce bacterial adhesion. SIGNIFICANCE AND IMPACT OF THE STUDY: Compounds from food extracts may potentially be used as nontoxic coatings to reduce bacterial attachment to inert surfaces.

Nitrite effectively inhibits sulfide and methane production in a laboratory scale sewer reactor.

The production and emission of hydrogen sulfide and methane by anaerobic microoganisms in sewer systems is a well-documented problem. The effectiveness of nitrite in controlling sulfide and methane production was tested in a laboratory scale sewer reactor. Nitrite was continuously dosed in the reactor for 25 days at concentrations of 20-140mgN/L. No sulfide and methane accumulation was observed in the reactor in the presence of nitrite. A significant reduction was observed in the sulfate reduction and methane production capabilities of the biofilm. Nitrite also stimulated biological sulfide oxidation within the biofilm. The nitrite uptake rate of the reactor increased over the nitrite dosing period and nitrous oxide production was observed within the biofilm. When nitrite addition was stopped, sulfate reduction and methane production gradually resumed, and reached pre-nitrite addition levels after 2.5 months. The slow recovery suggests that nitrite can be applied intermittently for sulfide and methane control, which represents a key advantage over similar chemicals such as nitrate and oxygen. The study demonstrates nitrite addition as a promising and effective strategy for the management of sulfide and methane in sewers. Further investigation and optimization are still required before application in the field.

[Emergencies and urgent consultation in non-urban Swiss general practices]. / Dringliche Konsultationen und Notfälle im Notfalldienstkreis Möhlin-Wegenstettertal.

The upcoming shortage of general practitioners in Switzerland will be a big challenge for medical out-of-hours services. Regionally ver different exists only few datas about organisational matters of and problems seen in "out-of-hours" care and "urgent consultations". Our Pilot present the prevalence of "out-of-hours care" in a general practitioner setting describes and classifies the problems seen using ICPC-2.

Duration of smoking abstinence as a predictor for non-small-cell lung cancer survival in women.

BACKGROUND: Previous studies have attempted to investigate the impact of smoking cessation on lung cancer survival but have been limited by small numbers of former smokers and incomplete data. METHODS: Over a six-year period, 5229 patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) were enrolled in a prospective cohort of whom 2052 were former smokers. Patient's characteristics were obtained from medical records and a baseline interview. Vital status was determined through multiple sources. Cox proportional hazards models were used to estimate the effect of smoking abstinence on post-diagnosis mortality. RESULTS: For all patients with NSCLC, the median survival among never, former, and current smokers was 1.4 years, 1.3 years, and 1.1 years, respectively (P < 0.01). Female NSCLC patients had a significantly lower risk of mortality with a longer duration of smoking abstinence (RR per 10 years of smoking abstinence = 0.85; 95% CI: 0.75, 0.97). No effect of smoking abstinence on mortality was observed for women with SCLC or for men with either histologic group. CONCLUSIONS: The identification of smoking history as a prognostic factor in lung cancer survival supports previous research suggesting a direct biologic effect of smoking on survival. However, this effect may vary by sex and type of lung cancer.

Integration of titrimetric measurement, off-gas analysis and NOx- biosensors to investigate the complexity of denitrification processes.

The denitrification process, namely the reduction of nitrate (NO3-) to nitrogen gas (N2), often cannot be simply modelled as a single step process. For a more complete and comprehensive model the intermediates, particularly nitrite (NO2-) and nitrous oxide (N2O), need to be investigated. This paper demonstrates the integration of titrimetric measurements and off-gas analysis with on-line nitrite plus nitrate (NOx-) biosensors, highlighting the necessity of measuring process intermediates with high time-scale resolution to study and understand the kinetics of denitrification. Investigation of activated sludge from a full-scale treatment plant showed a significant accumulation of NO2-, which appeared to impact on the overall denitrification rate measured as NOx- reduction or N2 production. A different sludge obtained from a lab-scale bioreactor produced N2O instead of N2 as the end product of denitrification. The two examples both illustrate the complexity of denitrification and stress the need for the more versatile and detailed measurement procedures, as presented in this paper.

N-cadherin is involved in axon-oligodendrocyte contact and myelination.

We have analyzed the influence of the calcium-dependent cell adhesion molecule, N-cadherin, on events leading to CNS myelination. Interactions between axons and oligodendrocyte progenitor (OP) cells and the CG4 OP cell line were examined by video-microscopy. OPs cocultured with dorsal root ganglia explants migrated around the culture and formed numerous contacts with axons. The duration of these contacts depended on the morphology of the OP, with OPs containing four or more processes forming long-lasting contacts and OPs with three or fewer processes forming short-termed contacts. Treatment with N-cadherin function blocking peptides approximately halved the duration of contacts made by cells with four or more processes but contact times for cells with three or less processes were unaffected. The L7 cadherin-blocking antibody and calcium withdrawal had similar effects. Contacts with axons regenerating from explants of adult retina, which do not have N-cadherin on their surface was examined. The contact duration of OPs to adult retina axons was short and similar in length to those formed between OPs and dorsal root ganglion axons in the presence of cadherin blocking reagents. Oligodendrocyte myelination was examined in organotypic rat cerebellar slice cultures, taken before myelination at postnatal day 10 and then allowed to myelinate in vitro over 7 days. When incubated with an N-cadherin function-blocking peptide, myelination of Purkinje cell axons was reduced to about half of control levels, while control peptides were without effect. Cadherin-blockade did not prevent maturation of OPs, since oligodendrocytes showing myelin basic protein immunostaining were still found in these cultures. However, many of the cell processes did not colocalize with calbindin-positive axons. From these data we conclude that N-cadherin is important for the initial contact between a myelinating oligodendrocyte and axons and significantly contributes to the success of myelination.

Increased NCAM-180 immunoreactivity and maintenance of L1 immunoreactivity in injured optic fibers of adult mice.

The injury related expression of two axon-growth promoting cell adhesion molecules (CAMs), NCAM-180 which is developmentally downregulated and L1 which is regionally restricted, were compared in optic fibers in the adult mouse. The neuron-specific isoform of NCAM (NCAM-180) is present at very low levels in unlesioned adult optic axons. At 7 days after nerve crush, immunoreactivity was strongly and uniformly increased in optic axons within the nerve and throughout retina. Reactivity in surviving axons had returned to control levels at 4 weeks. To induce regrowth of adult retinal ganglion cell axons retinal explants were placed in culture. Strong NCAM-180 staining was observed on these regenerating optic axons. The neuronal cell adhesion molecule L1 is restricted to retina and to the unmyelinated segment of the optic nerve near the optic nerve head in unlesioned adult animals. Following nerve crush, L1 immunoreactivity was retained within retina and proximal nerve and novel staining was detected in the more distal segment of the optic nerve up to the lesion site where it persisted for at least eight months. The capacity of optic fibers to show increased NCAM-180 immunoreactivity and maintain L1 expression after a lesion may explain why these fibers exhibit relatively good potential for regeneration.

Regenerating optic fibers correct large-scale errors by random growth: evidence from in vivo imaging.

Regenerating optic fibers in goldfish make large-scale errors when they invade tectum and subsequently correct these to generate a projection with moderate retinotopic order by 1 month. The behavior of fibers underlying these extensive rearrangements is not well understood. To clarify this, we have imaged optic fibers in living adult goldfish at 2-4 weeks of regeneration. A small number of neighboring retinal ganglion cells were labeled with microinjections of DiI and imaged in the dorsal tectum with a cooled CCD camera on a fluorescence microscope for 5 to 8 hours. Nearly all fibers were simple unbranched processes and had endings that were highly dynamic showing both growth and retraction. Fibers from dorsal retina that normally innervate ventral tectum were frequently observed in dorsal tectum. These ectopic fibers oscillated more frequently between growth and retraction and retracted more often than ventral optic fibers. Like retinotopic fibers, ectopic fibers exhibited net growth but they showed no apparent directional preference toward their retinotopic position. In contrast, large errors along the anterior-posterior axis corresponding to nasal-temporal retina were rare and there was no differential behavior that distinguished these fibers.

Gradients of ephrin-A2 and ephrin-A5b mRNA during retinotopic regeneration of the optic projection in adult zebrafish.

Regeneration of optic axons in the continuously growing optic system of adult zebrafish was analyzed by anterograde tracing and correlated with the mRNA expression patterns of the recognition molecules ephrin-A2 and ephrin-A5b in retinal targets. The optic tectum and diencephalic targets are all reinnervated after a lesion. However, the rate of erroneous pathway choices was increased at the chiasm and the bifurcation between the ventral and dorsal brachium of the optic tract compared to unlesioned animals. Tracer application to different retinal positions revealed retinotopic reinnervation of the tectum within 4 weeks after the lesion. In situ hybridization analysis indicated the presence of rostral-low to caudal-high gradients of ephrin-A2 and ephrin-A5b mRNAs in unlesioned control tecta and after a unilateral optic nerve lesion. By contrast, the parvocellular superficial pretectal nucleus showed retinotopic organization of optic fibers but no detectable expression of ephrin-A2 and ephrin-A5b mRNAs. However, a row of cells delineating the terminal field of optic fibers in the dorsal part of the periventricular pretectal nucleus was intensely labeled for ephrin-A5b mRNA and may thus provide a stop signal for ingrowing axons. Ephrin-A2 and ephrin-A5b mRNAs were not detectable in the adult retina, despite their prominent expression during development. Thus, given a complementary receptor system in retinal ganglion cells, expression of ephrin-A2 and ephrin-A5b in primary targets of optic fibers in adult zebrafish may contribute to guidance of optic axons that are continuously added to the adult projection and of regenerating axons after optic nerve lesion.

Alpha1-antitrypsin deficiency and inflammatory bowel diseases.

OBJECTIVE: To evaluate a possible etiologic role of alpha1-antitrypsin deficiency (alpha1AD), most frequently caused by a Z allele mutation, in ulcerative colitis (UC) and Crohn disease (CD). PATIENTS AND METHODS: This retrospective study included 10 patients diagnosed with and/or treated for inflammatory bowel disease (IBD) between 1976 and 1997 and identified from the Mayo Clinic Medical Index System. All 10 patients had either alpha1AD and CD or alpha1AD and UC. The alpha1-antitrypsin (alpha1AT) types and levels were determined with isoelectric focusing testing. The allele types, representing genotypes, were designated PiZZ (or ZZ) for homozygotes and PiMZ (or MZ) for heterozygotes. RESULTS: Seven patients had UC: 4 were genotype ZZ and 3 MZ. Four of these 7 patients had emphysema, 2 had asthma, and 1 had chronic bronchitis. Five were cigarette smokers, but only 1 had smoked coincident with activity of her UC. Two of the UC patients never smoked, and 1 of these 2 had asthma. Three of the 10 patients had CD, 2 genotype ZZ and 1 MZ. Two of the 3 patients were long-term cigarette smokers, and both had emphysema. Nine of the 10 patients with UC and alpha1AD required surgery. CONCLUSIONS: The need for surgery in patients with UC and alpha1-AD may point to a unique phenotypic subgroup of patients with alpha1AD and severe UC. Further studies are required to substantiate the etiologic role of alpha1AD in IBD. Our observations, if confirmed by future studies, suggest that in patients with both IBD and chronic obstructive pulmonary disease, alpha1AD testing should be considered.