Cervical cancer in the Hauts-Bassins region of Burkina Faso: Results of a screening campaign by visual inspection with acetic acid (VIA screening in Burkina Faso).

This study was conducted to describe the distribution of precancerous and cancerous lesions of the cervix uteri, enumerated during a mass screening in Burkina Faso. We conducted a cross-sectional study involving 577 women aged 18 to 60 years, carried out from November 23 to December 19, 2013, in the city of Bobo-Dioulasso and in the rural commune of Bama. Regarding the screening results, 89 participants (15.4%) were positive for pre-malignant cervical lesions. Chi-square testing and logistic regression analyses were conducted to identify the likelihood of cervical pre-cancer lesion in the women. Participants less than 29 years old were approximately 3 times more likely to have cervical lesions than participants >39 years. Participants who were parous (1-3 deliveries) and multiparous (four or more deliveries) were approximately 4 times more likely to present with cervical lesions than nulliparous women. Access to screening services is low in the Bobo-Dioulasso region. Further research should be conducted to understand the incidence and distribution of cervical precancerous and cancerous lesions in Burkina Faso.

Accuracy of CD64 expression on neutrophils and monocytes in bacterial infection diagnosis at pediatric intensive care admission.

The CD64 receptor has been described as an interesting bacterial infection biomarker. Its expression has not been studied in previously healthy children admitted to pediatric critical care unit (PICU). Our objective was firstly to describe the CD64 expression and secondly study its diagnostic accuracy to discriminate bacterial versus viral infection in this children. We made a prospective double-blind observational study (March 2016-February 2018). A flow cytometry (FC) was done from peripheral blood at PICU admission. We studied the percentage of CD64+ neutrophils and the CD64 mean fluorescence intensity (MFI) on neutrophils (nCD64) and monocytes (mCD64). Statistical analyses were performed with non-parametric tests (p < 0.05). Twenty children in the bacterial infection group (BIG) and 25 in the viral infection group (VIG). Children in BIG showed higher values of CD64+ neutrophils (p = 0.000), nCD64 (p = 0.001), and mCD64 (p = 0.003). In addition, CD64+ neutrophils and nCD64 expression have positive correlation with procalcitonin and C reactive protein. The nCD64 area under the curve (AUC) was 0.83 (p = 0.000). The %CD64+ neutrophils showed an AUC of 0.828 (p = 0.000). The mCD64 AUC was 0.83 (p = 0.003). The nCD64 and %CD64+ neutrophils also showed higher combined values of sensitivity (74%) and specificity (90%) than all classical biomarkers.In our series CD64 expression allows to discriminate between bacterial and viral infection at PICU admission. Future studies should confirm this and be focused in the study of CD64 correlation with clinical data and its utility as an evolution biomarker in critical care children.

The Living with Dysarthria group for post-stroke dysarthria: the participant voice.

BACKGROUND: The Living with Dysarthria group programme, devised for people with post-stroke dysarthia and family members, was piloted twice. Feedback from those who experience an intervention contributes to the evaluation of speech and language therapy programmes, giving the participant view of the intervention's value and guiding further developments. RESEARCH QUESTION: What feedback do participants in the Living with Dysarthria programme provide, informing on its perceived usefulness and guiding its future development? METHODS & PROCEDURES: Nine people with chronic dysarthria following stroke and four family members who completed the Living with Dysarthria programme all contributed to Focus Group (FG) discussion, transcribed and thematically analysed, and completed an Anonymous Questionnaire Evaluation (AQE), comprising closed statements and open questions. An anonymous descriptive adjective selection task (ADAST) was also used. OUTCOMES & RESULTS: The varied forms of feedback provided complementary information. Thematic analysis of FG data and AQE open question responses were configured around programme benefits, programme structure and content, and programme practicalities. Benefits associated with participation included learning and insight, being supported by peers and professionals, and improved speech and confidence. These are consistent with the main programme elements of education, support and speech practice. All activities were seen as relevant and positively received. Flexibility, recognition of and catering to individual needs were valued characteristics. The community location was approved by all. Most participants thought the format of eight weekly sessions of 2 h was appropriate. Responses to AQE closed statements provided almost unanimous confirmation of the very positive feedback conveyed in FG discussions. The main response to suggested improvements in AQEs was that the number of sessions should be increased. Feedback indicated that for a few individuals there was negative reaction to some facts about stroke, home practice tasks were difficult to complete, the person with dysarthria/family member pair may not be the optimum combination for paired practice activities and pre-programme information should be extended. The ADAST showed that the programme was enjoyable, interesting, stimulating and useful. CONCLUSIONS & IMPLICATIONS: Participant feedback indicates that group therapy, with family member participation, is a valid form of management for chronic post-stroke dysarthria. Education, peer and professional support, and speech practice are confirmed as relevant programme components. Consistent majority opinions were communicated in different situations and via varied mediums. Some individuals expressed views relevant to their own needs, and these responses also inform future implementation of the Living with Dysarthria programme.

Pediatric septic thrombosis of intracranial venous sinuses: from diagnosis to discharge. Twenty years of experience. / Trombosis séptica pediátrica de senos venosos intracraneales: del diagnóstico al alta. Veinte años de experiencia.

INTRODUCTION: Septic thrombosis of intracranial venous sinuses (STSV) is a rare and severe complication of cranial infections. MATERIALS AND METHODS: The main objective of this paper is to describe the clinical data, diagnostic procedures, treatment and evolution of a series of cases of STSV. In addition, the current literature is reviewed. Observational retrospective study by review of medical histories (January 1995-December 2016). The data collected were: clinical, analytical, epidemiological, microbiological, radiological, management and follow-up. A descriptive and statistical analysis of the data was done. RESULTS: Twelve children were included (86,832 admissions studied). They have a median age of 4.5 years (range 1-13) with a median time of symptoms of 6 days (range 1-25). At admission, the clinical data were: fever (11/12), vomiting (9/12) and headache (8/12). They also showed bad general status 12/12, 7/12 acute otitis media and 5/12 VI cranial nerve paresis. The lumbar puncture was pathological in 4/12. The most frequently microorganism isolated was Streptococcus sp. Prothrombotic mutations were confirmed on 2/12. Cranial computed tomography allowed diagnosis in 9/12; the magnetic resonance imaging achieves that in 12/12. Previous neurological signs or time to diagnosis did not influence the appearance of other image complications. All received antibiotic treatment, heparin 10/12 and 11/12 surgery. There were no sequels. CONCLUSION: In our series otitis, headache, vomiting and fever were prevalent. Complementary tests allowed the suspect but the definitive diagnosis was obtained by neuroimaging. There were no sequels and the therapies were mainly wide broad-spectrum antibiotics, heparin, and surgical.

TITLE: Trombosis séptica pediátrica de senos venosos intracraneales: del diagnóstico al alta. Veinte años de experiencia.Introducción. La trombosis séptica de los senos venosos intracraneales (TSSV) es una complicación rara y grave de las infecciones craneales. Materiales y métodos. El objetivo principal de este trabajo es describir los datos clínicos, procedimientos diagnósticos, tratamiento y evolución de una serie de casos de TSSV. Además, se revisa la bibliografía actual. Es un estudio retrospectivo observacional mediante revisión de historias médicas (enero de 1995-diciembre de 2016). Los datos recogidos fueron: clínicos, analíticos, epidemiológicos, microbiológicos, radiológicos, de manejo y de seguimiento. Se realizó un análisis descriptivo y estadístico de los datos. Resultados. Se incluyó a 12 niños (86.832 ingresos estudiados). La mediana de edad fue de 4,5 años (rango: 1-13), con un tiempo medio de síntomas de 6 días (rango: 1-25). En el momento de la admisión, los datos clínicos fueron: fiebre (11/12), vómitos (9/12) y dolor de cabeza (8/12). También mostraron mal estado general, 12/12; otitis media aguda, 7/12; y paresia del VI par craneal, 5/12. La punción lumbar fue patológica en 4/12. El microorganismo más frecuentemente aislado fue Streptococcus spp. Se confirmaron mutaciones protrombóticas en 2/12. La tomografía computarizada craneal permitió el diagnóstico en 9/12; la resonancia magnética lo logró en 12/12. Los signos neurológicos anteriores o el tiempo de diagnóstico no influyeron en la aparición de otras complicaciones de la imagen. Recibieron tratamiento antibiótico 12/12; heparina, 10/12; y cirugía, 11/12. No hubo secuelas. Conclusión. En nuestra serie, la otitis, el dolor de cabeza, los vómitos y la fiebre fueron frecuentes. Las pruebas complementarias permitieron el diagnóstico de sospecha, pero el diagnóstico definitivo se obtuvo por neuroimagen. No hubo secuelas y las terapias fueron principalmente antibióticos de amplio espectro, heparina y cirugía.

Respiratory and pharmacological management in severe acute bronchiolitis: Were clinical guidelines not written for critical care?

PURPOSE: The treatment applied for children admitted to the pediatric intensive care unit (PICU) for severe acute bronchiolitis may differ from general recommendations. The first objective of our study was to describe the treatments offered to these children in a Spanish tertiary PICU. The second objective was to analyse the changes in management derived from the publication of the American Academy of Pediatrics (AAP) bronchiolitis guideline in 2014. METHODS: This was a retrospective-prospective observational study conducted during two epidemic waves (2014-2015 and 2015-2016). The AAP guidelines were distributed and taught to PICU staff between both epidemic waves. RESULTS: A total of 138 children were enrolled (78 male). In the first period, 78 children were enrolled. The median age was 1.8 months (IQR 1.1-3.6). There were no differences between the management in the two periods, except for the use of high-flow oxygen therapy (HFOT); its use increased in the second period. Overall, 83% of patients received non-invasive ventilation or HFOT. Children older than 12 months received HFOT exclusively. In comparison, continuous positive airway pressure and bi-level positive airway pressure were used less during the period 2015-2016 (P=0.036). Regarding pharmacological therapy, 70% of patients received antibiotics, 23% steroids, 33% salbutamol, 31% adrenaline, and 7% hypertonic saline. The mortality rate was zero. CONCLUSIONS: Our PICU did not follow the AAP recommendations. There were no differences between the two periods, except in the use of HFOT. All children older than 12 months received HFOT exclusively. The rate of using invasive mechanical ventilation was also low.

Enhanced biotransformation of TCE using plant terpenoids in contaminated groundwater.

AIMS: To examine plant terpenoids as inducers of TCE (trichloroethylene) biotransformation by an indigenous microbial community originating from a plume of TCE-contaminated groundwater. METHODS AND RESULTS: One-litre microcosms of groundwater were spiked with 100 micromol 1(-1) of TCE and amended weekly for 16 weeks with 20 microl 1(-1) of the following plant monoterpenes: linalool, pulegone, R-(+) carvone, S-(-) carvone, farnesol, cumene. Yeast extract-amended and unamended control treatments were also prepared. The addition of R-carvone and S-carvone, linalool and cumene resulted in the biotransformation of upwards of 88% of the TCE, significantly more than the unamendment control (61%). The aforementioned group of terpenes also significantly (P < 0.05) allowed more TCE to be degraded than the remaining two terpenes (farnesol and pulegone), and the yeast extract treatment which biotransformed 74-75% of the TCE. The microbial community profile was monitored by denaturing gradient gel electrophoresis and demonstrated much greater similarities between the microbial communities in terpene-amended treatments than in the yeast extract or unamended controls. CONCLUSIONS: TCE biotransformation can be significantly enhanced through the addition of selected plant terpenoids. SIGNIFICANCE AND IMPACT OF THE STUDY: Plant terpenoid and nutrient supplementation to groundwater might provide an environmentally benign means of enhancing the rate of in situ TCE bioremediation.

Application of luminescent biosensors for monitoring the degradation and toxicity of BTEX compounds in soils.

AIMS: To assess the changes in acute toxicity and biodegradation of benzene, toluene, ethylbenzene and xylene (collectively referred to as BTEX) compounds in soil over time and compare the performances of biological and chemical techniques. METHODS AND RESULTS: Biological methods (lux-based bacterial biosensors, basal respiration and dehydrogenase activity) were related to changes in the concentration of the target compounds. There was an initial increase in toxicity determined by the constitutively expressed biosensor, followed by a continual reduction as degradation proceeded. The biosensor with the BTEX-specific promoter was most induced when BTEX concentrations were highest. The treatment with nutrient amendment had a significant increase in microbial activity, while the sterile control produced the lowest level of degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: Luminescent biosensors were able to monitor changes in contaminant toxicity and bioavailability in aqueous extracts from BTEX-impacted soils as degradation proceeded. The integration of biological tests with chemical analysis enables a fuller understanding of the biodegradation processes occurring at their relative rates. CONCLUSIONS: The biological methods were successfully used in assessing the performance of different treatments for enhancing natural attenuation of BTEX from contaminated soils. While, chemical analysis showed biodegradation of parent BTEX compounds in biologically active soils, the biosensor assays reported on changes in bioavailability and potentially toxic intermediate fractions as they estimated the integrative effect of contaminants.

Physiological and toxicological characterization of an engineered whole-cell biosensor.

Bioluminescence-based bacterial biosensors are often reported as reliable and efficient tools for risk assessment and environmental monitoring. However, there are few data comparing the metabolism of genetically engineered strains to the corresponding wild type. A pollutant-degrading bacterium capable of mineralising 2,4-dichlorophenoxyacetic acid (2,4-D), Burkholderia sp. strain RASC c2, was genetically engineered to produce light constitutively and tested for assessing the main causes of biodegradation constraint affected by growth rates, toxicity, bioavailability and metal speciation in complex environments. This research focuses on such aspects by characterizing two pollutant-degrading isolates, the wild type and the genetically engineered biosensor (lux-marked). Degradation and growth rates of both isolates were assessed with different concentrations of 2,4-D as the sole carbon source. Kinetic rates were affected by initial concentration of substrate and isolates showed distinct growth rates at different 2,4-D concentrations. Toxic effects of zinc and copper were also comparatively assessed using a dehydrogenase assay and light output. The isolates were sensitive to both metals and at similar EC(50) values. Therefore, bioluminescence response of the lux-marked isolate accurately reflected the toxic response of the parental organism towards zinc and copper, making it an ideal test-organism for assessing toxicity in the context of pollutant mineralization.

Rhizoremediation of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723.

Sphingobium chlorophenolicum is well known as a pentachlorophenol (PCP) degrader. The objective of this study was to evaluate PCP degradation in a loamy sandy soil artificially contaminated with PCP using phytoremediation and bioaugmentation. Measurements of PCP concentrations were carried out using high performance liquid chromatography analyses (HPLC). The toxic effect of PCP on plants was studied through the monitoring of weight plant and root length. The biodegradation of PCP by S. chlorophenolicum in soil was assessed with a bioluminescence assay of Escherichia coli HB101 pUCD607. Bacterial analyses were carried out by plating on Mineral Salt Medium (MSM) for S. chlorophenolicum, MSM for PCP-degrading/tolerant organisms and Trypticase Soy Broth Agar (TSBA) for heterotrophic organisms. The introduction of S. chlorophenolicum into soil with plants showed a faster degradation when compared to the non-inoculated soil. The monitoring of the plant growth showed a protective role of S. chlorophenolicum against the toxicity of PCP. The bioassay confirmed that initial toxicity was lowered while degradation progressed. There was a significant increase of organisms tested in the roots in comparison to those in the soil. This study showed that the presence of S. chlorophenolicum enhanced the PCP degradation in a loamy soil and also it had a protective role to prevent phytotoxic effects of PCP on plant growth. The combined use of bioaugmentation and plants suggests that the rhizosphere of certain plant species may be important for facilitating microbial degradation of pesticides in soil with important implications for using vegetation to stabilize and remediate surface soils.

Degradation and toxicity of phenyltin compounds in soil.

Although the fate of organotins has been widely studied in the marine environment, fewer studies have considered their impact in terrestrial systems. The degradation and toxicity of triphenyltin in autoclaved, autoclaved-reinoculated and non-sterilised soil was studied in a 231 day incubation experiment following a single application. Degradation and toxicity of phenyltin compounds in soil was monitored using both chemical and microbial (lux-based bacterial biosensors) methods. Degradation was significantly slower in the sterile soil when compared to non-sterilised soils. In the non-sterilised treatment, the half-life of triphenyltin was 27 and 33 days at amendments of 10 and 20 mg Sn kg(-1), respectively. As initial triphenyltin degradation occurred, there was a commensurate increase in toxicity, reflecting the fact that metabolites produced may be both more bioavailable and toxic to the target receptor. Over time, the toxicity reduced as degradation proceeded. The toxicity impact on non-target receptors for these compounds may be significant.

Linking biosensor responses to Cd, Cu and Zn partitioning in soils.

Soils bind heavy metals according to fundamental physico-chemical parameters. Bioassays, using bacterial biosensors, were performed in pore waters extracted from 19 contrasting soils individually amended with Cd, Cu and Zn concentrations related to the EU Sewage Sludge Directive. The biosensors were responsive to pore waters extracted from Zn amended soils but less so to those of Cu and showed no toxicity to pore water Cd at these environmentally relevant amended concentrations. Across the range of soils, the solid-solution heavy metal partitioning coefficient (K(d)) decreased (p<0.01) with increasing amendments of Cu and Zn; Cu exhibited the highest K(d) values. Gompertz functions of Cu and Zn, K(d) values against luminescence explained the relationship between heavy metals and biosensors. Consequently, biosensors provide a link between biologically defined hazard assessments of metals and standard soil-metal physico-chemical parameters for determining critical metal loadings in soils.

Trombosis séptica pediátrica de senos venosos intracraneales: del diagnóstico al alta. Veinte años de experiencia / Pediatric septic thrombosis of intracranial venous sinuses: from diagnosis to discharge. Twenty years of experience

Introducción: La trombosis séptica de los senos venosos intracraneales (TSSV) es una complicación rara y grave de las infecciones craneales. Materiales y métodos: El objetivo principal de este trabajo es describir los datos clínicos, procedimientos diagnósticos, tratamiento y evolución de una serie de casos de TSSV. Además, se revisa la bibliografía actual. Es un estudio retrospectivo observacional mediante revisión de historias médicas (enero de 1995-diciembre de 2016). Los datos recogidos fueron: clínicos, analíticos, epidemiológicos, microbiológicos, radiológicos, de manejo y de seguimiento. Se realizó un análisis descriptivo y estadístico de los datos. Resultados: Se incluyó a 12 niños (86.832 ingresos estudiados). La mediana de edad fue de 4,5 años (rango: 1-13), con un tiempo medio de síntomas de 6 días (rango: 1-25). En el momento de la admisión, los datos clínicos fueron: fiebre (11/12), vómitos (9/12) y dolor de cabeza (8/12). También mostraron mal estado general, 12/12; otitis media aguda, 7/12; y paresia del VI par craneal, 5/12. La punción lumbar fue patológica en 4/12. El microorganismo más frecuentemente aislado fue Streptococcus spp. Se confirmaron mutaciones protrombóticas en 2/12. La tomografía computarizada craneal permitió el diagnóstico en 9/12; la resonancia magnética lo logró en 12/12. Los signos neurológicos anteriores o el tiempo de diagnóstico no influyeron en la aparición de otras complicaciones de la imagen. Recibieron tratamiento antibiótico 12/12; heparina, 10/12; y cirugía, 11/12. No hubo secuelas. Conclusión: En nuestra serie, la otitis, el dolor de cabeza, los vómitos y la fiebre fueron frecuentes. Las pruebas complementarias permitieron el diagnóstico de sospecha, pero el diagnóstico definitivo se obtuvo por neuroimagen. No hubo secuelas y las terapias fueron principalmente antibióticos de amplio espectro, heparina y cirugía.(AU)

Introduction: Septic thrombosis of intracranial venous sinuses (STSV) is a rare and severe complication of cranial infections. Materials and methods: The main objective of this paper is to describe the clinical data, diagnostic procedures, treatment and evolution of a series of cases of STSV. In addition, the current literature is reviewed. Observational retrospective study by review of medical histories (January 1995-December 2016). The data collected were: clinical, analytical, epidemiological, microbiological, radiological, management and follow-up. A descriptive and statistical analysis of the data was done. Results: Twelve children were included (86,832 admissions studied). They have a median age of 4.5 years (range 1-13) with a median time of symptoms of 6 days (range 1-25). At admission, the clinical data were: fever (11/12), vomiting (9/12) and headache (8/12). They also showed bad general status 12/12, 7/12 acute otitis media and 5/12 VI cranial nerve paresis. The lumbar puncture was pathological in 4/12. The most frequently microorganism isolated was Streptococcus sp. Prothrombotic mutations were confirmed on 2/12. Cranial computed tomography allowed diagnosis in 9/12; the magnetic resonance imaging achieves that in 12/12. Previous neurological signs or time to diagnosis did not influence the appearance of other image complications. All received antibiotic treatment, heparin 10/12 and 11/12 surgery. There were no sequels. Conclusion: In our series otitis, headache, vomiting and fever were prevalent. Complementary tests allowed the suspect but the definitive diagnosis was obtained by neuroimaging. There were no sequels and the therapies were mainly wide broad-spectrum antibiotics, heparin, and surgical.(AU)

CD64 expression on monocytes and granulocytes in pediatric acute appendicitis scenario: A pilot study in pediatric critical care / Expresión de CD64 en monocitos y granulocitos en apendicitis aguda: estudio piloto en cuidados intensivos pediátricos

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Development and application of bioluminescent Caenorhabditis elegans as multicellular eukaryotic biosensors.

We describe a novel approach to assess toxicity to the free-living nematode Caenorhabditis elegans that relies on the ability of firefly luciferase to report on endogenous ATP levels. We have constructed bioluminescent C. elegans with the luc gene under control of a constitutive promoter. Light reduction was observed in response to increasing temperature, concentrations of copper, lead and 3,5-dichlorophenol. This was due to increased mortality coupled with decreased metabolic activity in the surviving animals. The light emitted by the transgenic nematodes gave a rapid, real-time indication of metabolic status. This forms the basis of rapid and biologically relevant toxicity tests.

Toxicity of the bacterial luciferase substrate, n-decyl aldehyde, to Saccharomyces cerevisiae and Caenorhabditis elegans.

This study determined that the bacterial luciferase fusion gene (luxAB) was not a suitable in vivo gene reporter in the model eukaryotic organisms Saccharomyces cerevisiae and Caenorhabditis elegans. LuxAB expressing S. cerevisiae strains displayed distinctive rapid decays in luminescence upon addition of the bacterial luciferase substrate, n-decyl aldehyde, suggesting a toxic response. Growth studies and toxicity bioassays have subsequently confirmed, that the aldehyde substrate was toxic to both organisms at concentrations well tolerated by Escherichia coli. As the addition of aldehyde is an integral part of the bacterial luciferase activity assay, our results do not support the use of lux reporter genes for in vivo analyses in these model eukaryotic organisms.

Correlation between cannabinoid mediated effects on paired pulse depression and induction of long term potentiation in the rat hippocampal slice.

Cannabinoids cause an increase in synaptic transmission via gamma-aminobutyric acid (GABA) receptors and this may be the mechanism by which activation of CB1 receptors blocks the induction of long-term potentiation (LTP). To test this hypothesis, we used paired pulse depression (PPD) of CA1 population spike responses recorded in the rat hippocampal slice as an index of GABA-ergic feedback inhibition, to establish whether the effects of a stereoselective CB1 receptor agonist on GABA-ergic transmission and LTP were correlated. The active isomer, WIN55212-2, blocked the induction of LTP and suppressed PPD over the concentration range 250 nM-5 microM, whereas the inactive isomer, WIN55212-3, was inactive at 5 microM. The effects of 5 microM WIN55212-2 on both LTP and PPD were completely blocked by the CB1 receptor antagonist SR141716A (5 microM). The results show that the effects are correlated in that both suppression of PPD and blockade of induction of LTP are probably mediated by CBI receptors. However, the suppression in PPD suggests that WIN55212-2 caused a decrease in GABA-ergic feedback transmission which would be expected to facilitate, rather than block, the induction of LTP. We therefore conclude that the blockade of LTP by cannabinoids is not via upregulation of GABA-ergic synaptic transmission.

Lux-biosensor assessment of pH effects on microbial sorption and toxicity of chlorophenols.

Lux-marked bacterial biosensors and a commercial toxicity testing bacterial strain (Microtox) were exposed to 2,4-dichlorophenol (DCP) and the light output response measured. Increasing DCP concentrations caused a decrease in light output in all three biosensors with an order of sensitivity (in terms of luminescence decrease over the DCP concentration range) of Pseudomonas fluorescens < Escherichia coli < Microtox. Adsorption of DCP to E. coli was measured using uniformly ring labelled [14C]DCP and found to be very rapid. The effect of pH on toxicity and adsorption was also investigated. Low pH values increased the amount of DCP adsorbed to the cell and increased the toxicity of DCP.

Feasibility of using prokaryote biosensors to assess acute toxicity of polycyclic aromatic hydrocarbons.

The aim of this study was to assess the acute toxicity of polycyclic aromatic hydrocarbons using lux-marked bacterial biosensors. Standard solutions of phenanthrene, pyrene and benzo[a]pyrene were produced using 50 mM hydroxpropyl-beta-cyclodextrin solution which contained each respective polycyclic aromatic hydrocarbon at 6.25 times the aqueous solubility limit of the compound. The polycyclic aromatic hydrocarbon solutions were incubated with each of the biosensors for 280 min and the bioluminescence monitored every 20 min. Over the incubation time period, there was no significant decrease in bioluminescence in any of the biosensors tested with the exception of Rhizobium leguminosarum biovar trifolii TA1 luxAB. In this series of incubations, there was a dramatic increase in bioluminescence in the presence of phenanthrene (2.5 times) and benzo[a]pyrene (3 times) above that of the background control (biosensor without polycyclic aromatic hydrocarbon) after 20 min. Over the next 3 h, bioluminescence decreased to that of the control. An ATP assay was carried out on the biosensors to assess if uncoupling of the oxidative phosphorylation mechanisms in the respiratory chain of the cells had occurred. However, it was found that the polycyclic aromatic hydrocarbons had no effect on the organisms indicating that there was no uncoupling. Additionally, mineralisation studies using 14C-labelled polycyclic aromatic hydrocarbons showed that the biosensors could not mineralise the compounds. This study has shown that the three polycyclic aromatic hydrocarbons tested are not acutely toxic to the prokaryotic biosensors tested, although acute toxicity has been shown in other bioassays. These results question the rationale for using prokaryote biosensors to assess the toxicity of hydrophobic chemicals, such as polycyclic aromatic hydrocarbons.

On-line microbial biosensing and fingerprinting of water pollutants.

The potential for biosensors to contribute to on-line toxicity testing for monitoring of water quality is currently constrained both by the relevance of the biosensors available and the technology for biosensor delivery. This paper reports the use of novel slow release biosensor delivery for on-line monitoring instrumentation, with environmentally relevant bacteria for both simple toxicity testing and more complex toxicity fingerprinting of industrial effluents. The on-line toxicity test, using bioluminescence-based biosensors, proved to be as sensitive and reliable as the corresponding batch test, with comparable contaminant EC(50) values from both methods. Toxicity fingerprinting through the investigation of the kinetics (dose-response) and the dynamics (response with time) of the biosensor test response proved to be diagnostic of both effluent type and composition. Furthermore, the slow release of biosensors immobilised in a polyvinyl alcohol (PVA) matrix greatly improved biosensor delivery, did not affect the sensitivity of toxicity testing, and demonstrated great potential for inclusion in on-line monitoring instrumentation.