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1.
Geophys Res Lett ; 49(8): e2021GL096514, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35866058

RESUMO

Rivers transport contaminant microorganisms (including fecal indicator bacteria and human pathogens) long distances downstream of diffuse and point sources, posing a human health risk. We present a mobile-immobile model that incorporates transport as well as immobilization and remobilization of contaminant microbes and other fine particles during baseflow and stormflow. During baseflow conditions, hyporheic exchange flow causes particles to accumulate in streambed sediments. Remobilization of stored particles from streambed sediments occurs slowly during baseflow via hyporheic exchange flow, while remobilization is vastly increased during stormflow. Model predictions are compared to observations over a range of artificial and natural flood events in the dairy contaminated Topehaehae Stream, New Zealand. The model outputs closely matched timing and magnitude of E. coli and turbidity observations through multiple high-flow events. By accounting for both state-of-flow and hyporheic exchange processes, the model provides a valuable framework for predicting particle and contaminant microbe behavior in streams.

2.
Am J Transplant ; 15(10): 2739-49, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26014796

RESUMO

The full potential of islet transplantation will only be realized through the development of tolerogenic regimens that obviate the need for maintenance immunosuppression. Here, we report an immunotherapy regimen that combines 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide (ECDI)-treated donor lymphoid cell infusion (ECDI-DLI) with thymoglobulin, anti-interleukin-6 receptor antibody and rapamycin to achieve prolonged allogeneic islet graft survival in a nonhuman primate (NHP) model. Prolonged graft survival is associated with Treg expansion, donor-specific T cell hyporesponsiveness and a transient absence of donor-specific alloantibody production during the period of graft survival. This regimen shows promise for clinical translation.


Assuntos
Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto/imunologia , Imunossupressores/uso terapêutico , Transplante das Ilhotas Pancreáticas/imunologia , Isoantígenos/imunologia , Transfusão de Linfócitos/métodos , Linfócitos T Reguladores/imunologia , Animais , Quimioterapia Combinada , Rejeição de Enxerto/imunologia , Projetos Piloto , Primatas
3.
Am J Transplant ; 12(8): 2072-8, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22494812

RESUMO

The role of B cells in transplant tolerance remains unclear. Although B-cell depletion often prolongs graft survival, sometimes it results in more rapid rejection, suggesting that B cells may have regulatory activity. We previously demonstrated that tolerance induction by anti-CD45RB antibody requires recipient B cells. Here, we show that anti-CD45RB in combination with anti-TIM-1 antibody has a synergistic effect, inducing tolerance in all recipients in a mouse islet allograft model. This effect depends on the presence of recipient B cells, requires B-cell IL-10 activity, and is antigen-specific. These data suggest the existence of a regulatory B-cell population that promotes tolerance via an IL-10-dependent pathway.


Assuntos
Linfócitos B/imunologia , Tolerância Imunológica , Antígenos Comuns de Leucócito/imunologia , Proteínas de Membrana/fisiologia , Animais , Receptor Celular 1 do Vírus da Hepatite A , Camundongos , Camundongos Endogâmicos
4.
Methods ; 51(1): 56-65, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20123126

RESUMO

Full-grown Xenopus oocytes in first meiotic prophase contain an immensely enlarged nucleus, the Germinal Vesicle (GV), that can be injected with several hundred somatic cell nuclei. When the nuclei of mammalian somatic cells or cultured cell lines are injected into a GV, a wide range of genes that are not transcribed in the donor cells, including pluripotency genes, start to be transcriptionally activated, and synthesize primary transcripts continuously for several days. Because of the large size and abundance of Xenopus laevis oocytes, this experimental system offers an opportunity to understand the mechanisms by which somatic cell nuclei can be reprogrammed to transcribe genes characteristic of oocytes and early embryos. The use of mammalian nuclei ensures that there is no background of endogenous maternal transcripts of the kind that are induced. The induced gene transcription takes place in the absence of cell division or DNA synthesis and does not require protein synthesis. Here we summarize new as well as established results that characterize this experimental system. In particular, we describe optimal conditions for transplanting somatic nuclei to oocytes and for the efficient activation of transcription by transplanted nuclei. We make a quantitative determination of transcript numbers for pluripotency and housekeeping genes, comparing cultured somatic cell nuclei with those of embryonic stem cells. Surprisingly we find that the transcriptional activation of somatic nuclei differs substantially from one donor cell-type to another and in respect of different pluripotency genes. We also determine the efficiency of an injected mRNA translation into protein.


Assuntos
Blastodisco/metabolismo , Núcleo Celular/metabolismo , Técnicas Citológicas , Oócitos/citologia , Oócitos/metabolismo , Transcrição Gênica , Xenopus laevis/metabolismo , Animais , DNA/metabolismo , Camundongos , Modelos Biológicos , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Temperatura , Ativação Transcricional
5.
Trials ; 21(1): 357, 2020 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-32326980

RESUMO

BACKGROUND: Generalised anxiety disorder (GAD) is a chronic and disabling condition with considerable personal and economic impact. Cognitive behavioural therapy (CBT) is a recommended psychological therapy for GAD; however, there are substantial barriers to accessing treatment. Digital CBT, in particular smartphone-delivered CBT, has the potential to improve accessibility and increase dissemination of CBT. Despite the emerging evidence of smartphone-based psychological interventions for reducing anxiety, effect size scores are typically smaller than in-person interventions, and there is a lack of research assessing the efficacy of smartphone-delivered digital interventions specifically for GAD. METHODS: In the DeLTA trial (DigitaL Therapy for Anxiety), we plan to conduct a parallel-group superiority randomised controlled trial examining the efficacy of a novel smartphone-based digital CBT intervention for GAD compared to a waitlist control. We aim to recruit 242 adults (aged 18 years or above) with moderate-to-severe symptoms of GAD. This trial will be conducted entirely online and will involve assessments at baseline (week 0; immediately preceding randomisation), mid-intervention (week 3), post-intervention (week 6; primary end point) and follow-up (week 10). The primary objective is to evaluate the efficacy of the intervention on GAD symptom severity compared to a waitlist control at post-intervention. Secondary objectives are to examine between-group effects on GAD at follow-up, and to examine the following secondary outcomes at both post-intervention and follow-up: 1) worry; 2) depressive symptoms; 3) wellbeing; 4) quality of life; and 5) sleep difficulty. DISCUSSION: This trial will report findings on the initial efficacy of a novel digital CBT intervention for GAD. Results have the potential to contribute towards the evidence base for digital CBT for GAD and increase the dissemination of CBT. TRIAL REGISTRATION: ISRCTN, ISRCTN12765810. Registered on 11 January 2019.


Assuntos
Transtornos de Ansiedade/terapia , Ansiedade/terapia , Terapia Cognitivo-Comportamental/métodos , Intervenção Baseada em Internet , Aplicativos Móveis , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Sono , Smartphone , Resultado do Tratamento , Listas de Espera , Adulto Jovem
6.
Indoor Air ; 19(3): 268-77, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19302504

RESUMO

UNLABELLED: In this study the dominant filamentous actinobacteria occurring in water-damaged building materials were detected by culture and characterized by automated ribotyping and 16S rRNA gene sequencing. Fifty-two samples were taken from 20 water-damaged houses in four different countries. A total of 122 bacterial isolates were analyzed. Actinobacteria or thermoactinomycetes were present in 48% of the samples. The dominant genus was Streptomyces (58% of isolates), followed by Thermoactinomyces (23%), Laceyella (14%), Nocardiopsis (3%), Pseudonocardia (1%) and Saccharomonospora (1%). The most frequently detected species was the thermophilic Thermoactinomyces vulgaris (14 samples/4 countries). The most common streptomycetes were closely related to the heterogeneous species Streptomyces microflavus (7/2) or Streptomyces griseus (6/2). Automated ribotyping was a rapid tool for reliable characterization of these isolates. The spores of thermoactinomycetes and toxic substances of Nocardiopsis species and S. griseus may constitute a risk for human health. PRACTICAL IMPLICATIONS: Harmful microbes in indoor environments are a cause of public concern. To develop rapid and simple-to-use molecular biological methods to detect the presence of harmful actinobacterial species in water-damaged buildings more information about their occurrence in those materials is needed, which this study provides.


Assuntos
Actinobacteria/isolamento & purificação , Materiais de Construção/microbiologia , Micromonosporaceae/isolamento & purificação , Actinobacteria/classificação , Actinobacteria/genética , Inundações , Habitação , Humanos , Micromonosporaceae/classificação , Micromonosporaceae/genética , Dados de Sequência Molecular , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Ribotipagem
7.
S Afr Med J ; 109(8): 584-586, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31456553

RESUMO

BACKGROUND: Hepatitis E virus (HEV) genotypes 3 and 4 are zoonoses, with domestic pigs being the most important reservoir. A high anti- HEV IgG seroprevalence of 26 - 28% has been found in humans in Cape Town, South Africa (SA). Studies in industrialised countries have indicated a high prevalence of HEV in pigs and their associated food products. OBJECTIVES: To determine whether HEV could be found in pig-derived food products in Cape Town. METHODS: Pork-containing food products were purchased from supermarkets and butcheries around the Cape Town metropolitan area. HEV detection by polymerase chain reaction (PCR) was performed, and an amplified viral genome fragment was sequenced from positive samples. Phylogenetic analysis was done on the sequenced fragment. RESULTS: HEV was detected by PCR in 2/144 food samples - both were liver spread samples. One genome fragment sequence was obtained, which was closely related to HEV sequences obtained from humans in Cape Town. CONCLUSIONS: HEV can be found in pork-containing meat products available for sale in Cape Town, suggesting that these products could be a potential source of HEV transmission in our geographical area. Meat of pig origin should be thoroughly cooked before being consumed.


Assuntos
Vírus da Hepatite E/isolamento & purificação , Carne de Porco/virologia , Animais , Vírus da Hepatite E/genética , Humanos , Filogenia , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de RNA , África do Sul , Suínos
8.
NPJ Parkinsons Dis ; 3: 2, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28649602

RESUMO

The progressive nature of Parkinson's disease, its complex treatment regimens and the high rates of comorbid conditions make self-management and treatment adherence a challenge. Clinicians have limited face-to-face consultation time with Parkinson's disease patients, making it difficult to comprehensively address non-adherence. Here we share the results from a multi-centre (seven centres) randomised controlled trial conducted in England and Scotland to assess the impact of using a smartphone-based Parkinson's tracker app to promote patient self-management, enhance treatment adherence and quality of clinical consultation. Eligible Parkinson's disease patients were randomised using a 1:1 ratio according to a computer-generated random sequence, stratified by centre and using blocks of variable size, to intervention Parkinson's Tracker App or control (Treatment as Usual). Primary outcome was the self-reported score of adherence to treatment (Morisky medication adherence scale -8) at 16 weeks. Secondary outcomes were Quality of Life (Parkinson's disease questionnaire -39), quality of consultation for Parkinson's disease patients (Patient-centred questionnaire for Parkinson's disease), impact on non-motor symptoms (Non-motor symptoms questionnaire), depression and anxiety (Hospital anxiety and depression scale) and beliefs about medication (Beliefs about Medication Questionnaire) at 16 weeks. Primary and secondary endpoints were analysed using a generalised linear model with treatment as the fixed effect and baseline measurement as the covariate. 158 patients completed the study (Parkinson's tracker app = 68 and TAU = 90). At 16 weeks Parkinson's tracker app significantly improved adherence, compared to treatment as usual (mean difference: 0.39, 95%CI 0.04-0.74; p = 0.0304) with no confounding effects of gender, number of comorbidities and age. Among secondary outcomes, Parkinson's tracker app significantly improved patients' perception of quality of consultation (0.15, 95% CI 0.03 to 0.27; p = 0.0110). The change in non-motor symptoms was -0.82 (95% CI -1.75 to 0.10; p = 0.0822). 72% of participants in the Parkinson's tracker app group continued to use and engage with the application throughout the 16-week trial period. The Parkinson's tracker app can be an effective and novel way of enhancing self-reported medication adherence and quality of clinical consultation by supporting self-management in Parkinson's disease in patients owning smartphones. Further work is recommended to determine whether the benefits of the intervention are maintained beyond the 16 week study period.

10.
Water Sci Technol ; 51(9): 315-22, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16042273

RESUMO

The effect of biofilm on the attenuation of pathogen-sized particles from wastewater was compared for biofilms cultivated in a surface flow constructed wetland (SFW) and maturation pond (MP) The fate of fluorescently labelled microspheres (FLM) as surrogates for viruses (0.1 microm), bacteria (1 microm) and parasitic protozoa (4.5 microm dia) was investigated in microcosms in the presence or absence of biofilms. Rates of FLM removal from suspension were higher in the presence of biofilms for all particle sizes (kd 0.02-0.11 h(-1)) in MP and SFW microcosms with removal efficiency related to particle size and biofilm thickness and structure. Greater removal of 0.1 microm (79-81%), 1 microm FLM (92-96%) and 4.5 microm FLM (up to 98%) from suspension were found for microcosms containing thicker (autotrophic) biofilms grown in the MP or open water zone of the SFW. Lower removal of 43% (0.1 microm), 59% (1 microm) and 84% (4.5 microm) occurred in microcosms containing thinner heterotrophic biofilms from SFW vegetated zones. Providing surfaces for attachment of photosynthetic biofilms offers potential to enhance pathogen removal in open water systems. In vegetated systems, linkage to more oxic openwater zones may allow thicker and 'stickier' epiphytic biofilms to develop, improving pathogen interception and removal.


Assuntos
Biofilmes , Ecossistema , Fezes/microbiologia , Eliminação de Resíduos Líquidos/métodos , Animais , Bactérias/isolamento & purificação , Biodegradação Ambiental , Eucariotos/isolamento & purificação , Eucariotos/patogenicidade , Oxigênio , Vírus/isolamento & purificação , Microbiologia da Água
11.
Water Sci Technol ; 51(12): 107-10, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16114671

RESUMO

Advanced pond systems (APS), incorporating high-rate ponds, algal settling ponds, and maturation ponds, typically achieve better and more consistent disinfection as indicated by Escherichia coli than conventional waste stabilisation ponds. To see whether this superior disinfection extends also to enteric viruses, we studied the removal of somatic phages ('model' viruses) in a pilot-scale APS treating sewage. Measurements through the three aerobic stages of the APS showed fairly good removal of somatic phage in the summer months (2.2 log reduction), but much less effective removal in winter (0.45 log reduction), whereas E. coli was removed efficiently (> 4 logs) in both seasons. A very steep depth-gradient of sunlight inactivation of somatic phage in APS pond waters (confined in silica test tubes) is consistent with inactivation mainly by solar UVB wavelengths. Data for F-RNA phage suggests involvement of longer UV wavelengths. These findings imply that efficiency of virus removal in APS will vary seasonally with variation in solar UV radiation.


Assuntos
Fagos RNA/efeitos da radiação , Raios Ultravioleta , Vírus/efeitos da radiação , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Desinfecção , Fagos RNA/isolamento & purificação , Estações do Ano , Esgotos/microbiologia , Energia Solar , Vírus/isolamento & purificação , Microbiologia da Água
12.
Neuropsychologia ; 38(12): 1643-53, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11074087

RESUMO

This study documents a patient, SA, with an impairment of semantic memory arising as a result of Semantic Dementia (Pick's disease). The patient is impaired at deriving semantic knowledge from both words and pictures. However, his ability to derive semantic knowledge of countries is relatively spared compared to concrete nouns and famous people. The presence of a semantic deficit was used to investigate the role of semantics in reading and spelling. Several novel cueing/priming paradigms are reported which suggest that SA is able to use partial semantic knowledge to constrain his reading and spelling. These results are broadly consistent with the 'summation hypothesis' [27] and suggest that normal reading and spelling may take place by integrating both semantic information and knowledge of direct orthography-phonology correspondences.


Assuntos
Teoria Psicológica , Leitura , Semântica , Lobo Temporal/fisiopatologia , Comportamento Verbal/fisiologia , Atrofia/diagnóstico por imagem , Atrofia/patologia , Atrofia/fisiopatologia , Sinais (Psicologia) , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Fonética , Doença de Pick/fisiopatologia , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/patologia , Tomografia Computadorizada por Raios X
13.
J Immunol Methods ; 104(1-2): 191-4, 1987 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-3316392

RESUMO

A preliminary coating of the surface of polystyrene microtitre wells with anti-IgG Fc immunoglobulin improves the binding capacity of the wells for antibody and leads to a marked improvement in the reproducibility of immunoassays carried out in the wells. In an enhanced chemiluminescent enzyme immunoassay for oestradiol the binding capacity for oestradiol of wells precoated with anti-IgG Fc immunoglobulin and then coated with anti-oestradiol immunoglobulin was more than twice that of wells coated directly with anti-oestradiol immunoglobulin. Intra-assay precision in the precoated wells ranged from 1.3 to 4.0% compared to 2.9 to 6.7% (0-3200 fmol oestradiol) in wells which had not been precoated.


Assuntos
Estradiol/análise , Técnicas de Imunoadsorção , Anticorpos Anti-Idiotípicos/imunologia , Relação Dose-Resposta Imunológica , Estradiol/imunologia , Fragmentos Fc das Imunoglobulinas/imunologia , Medições Luminescentes , Plásticos
14.
Methods Biochem Anal ; 36: 179-208, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1552867

RESUMO

Antibody-enzyme conjugates are widely utilized in all spheres of specific analyte detection and measurement, and several trends are evident that will sustain, or even extend, this in the coming years. Of principal importance are the trends toward the development of simplified formats for the rapid and sensitive quantitation of a wide range of analytes without expensive or cumbersome instrumentation, and the exploitation of different types of enzyme and antibody molecules. Advances in hybridoma and recombinant genetics are enabling the practical manipulation of the theoretical repertoire of these reagents, facilitating their availability for a myriad of applications.


Assuntos
Anticorpos , Bioensaio , Enzimas , Técnicas Imunoenzimáticas
15.
J Clin Pathol ; 38(3): 317-9, 1985 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3919065

RESUMO

A sandwich enzyme immunoassay for plasma factor VIII related antigen has been developed which exploits a para-iodophenol enhanced chemiluminescent reaction to detect the horseradish peroxidase label. The assay entailed 15 min incubations with sample and with conjugate and had a detection limit of 0.12 mU. It showed good within batch precision (coefficient of variation = 2.95-5.8%) and results on a series of 57 specimens agreed with results obtained by immunoelectrophoresis (correlation coefficient = 0.97).


Assuntos
Antígenos/análise , Fatores de Coagulação Sanguínea/análise , Fator VIII/imunologia , Fator de von Willebrand/análise , Fator VIII/análise , Humanos , Técnicas Imunoenzimáticas , Medições Luminescentes
16.
Steroids ; 44(4): 317-28, 1984 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-6400058

RESUMO

A competitive enhanced luminescent enzyme immunoassay for serum progesterone is described, which is based on a 11 alpha-hydroxyprogesterone 11-hemisuccinyl-horseradish peroxidase conjugate and a black polystyrene microtitre plate sensitised with anti-progesterone IgG. Bound label was determined using a mixture of 4-iodophenol, luminol and peroxide, and the light emitted from the wells of the plate quantitated using a luminescent plate reader. The assay was sensitive (detection limit 0.5 pg), precise (CV 2.7 - 9.0% in the concentration range 4.3-67.7 nM) and showed good correlation (r = 0.99) with a conventional radioimmunoassay.


Assuntos
Peroxidase do Rábano Silvestre , Técnicas Imunoenzimáticas , Peroxidases , Progesterona/sangue , Humanos , Medições Luminescentes
17.
Ann Clin Biochem ; 25 ( Pt 3): 288-92, 1988 May.
Artigo em Inglês | MEDLINE | ID: mdl-3041904

RESUMO

Oestradiol in serum was determined with a simple enhanced chemiluminescent enzyme immunoassay. The assay is based on oestradiol labelled with horseradish peroxidase and the IgG fraction of an oestradiol antiserum coated on a black polystyrene microtitre plate. The enzyme activity of bound label was determined using a p-hydroxycinnamic acid-enhanced chemiluminescent reaction. The assay was sensitive (1.8 fmol/well), precise (intra- and inter-assay CV 4-10% and 8-12%, respectively for sample concentration in the range 122-1330 pmol/L) and showed good agreement with conventional radioimmunoassays (r = 0.99).


Assuntos
Estradiol/sangue , Soluções Tampão , Humanos , Técnicas Imunoenzimáticas , Indicadores e Reagentes , Medições Luminescentes , Radioimunoensaio
18.
Water Sci Technol ; 48(2): 97-104, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14510199

RESUMO

Parasite removal and low cost systems for wastewater treatment have become increasingly important requirements in developed and developing countries to safeguard public health from wastewater-associated intestinal diseases. Pilot and field-scale ponds and wetlands in Brazil and Egypt have been investigated for the fate and removal of eggs of human intestinal parasites from domestic wastewater. In northeast Brazil, parasite removal was investigated for a series of five waste stabilisation ponds treating raw wastewater. In Egypt, parasite removal was studied for Gravel Bed Hydroponic constructed wetlands treating partially treated wastewater. Influents to ponds and wetlands contained a variety of parasite helminth eggs (e.g. Ascaris, hookworm, Trichuris, and Hymenolepis spp.). The ponds consistently removed parasite eggs though rate of removal by individual ponds may have been related to influent egg numbers and extent of short-circuiting. Parasite eggs were reduced on average by 94% and 99.9% in the anaerobic and facultative ponds respectively. No eggs were found in effluent from the second maturation pond. In the wetland system, parasite removal varied with reedbed length. The majority of parasite eggs were retained within the first 25 m. Parasite eggs were reduced on average by 98% after treatment in 50 m beds and completely removed after treatment in 100 m beds.


Assuntos
Helmintos/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Animais , Biodegradação Ambiental , Brasil , Egito , Helmintos/patogenicidade , Óvulo
19.
Water Sci Technol ; 44(11-12): 191-8, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11804094

RESUMO

The removal of the protozoan parasite, Cryptosporidium parvum, from wastewaters is becoming of increasing importance in the UK, especially since contamination of raw waters by sewage effluents has been implicated in major waterborne outbreaks of cryptosporidiosis in recent years. Compared to conventional wastewater-treatment processes, constructed wetlands have demonstrated favourable removal rates for Cryptosporidium oocysts. The removal mechanisms, however, remain unknown. Predation by free-living ciliated protozoa, which are commonly found in constructed wetlands, was investigated as a possible mechanism for oocyst removal. In laboratory feeding experiments, ciliates (Euplotes patella, Stylonychia mytilus, Paramecium caudatum and an unidentified wetland ciliate species), were exposed to doses ranging from 10 to 10(6) oocysts/ml for between 5 and 60 minutes. Ciliate predatory activities were assessed by enumerating fluorescently labelled ingested oocysts using epifluorescence microscopy. Oocysts were found to be ingested by all species investigated. Paramecium demonstrated the highest mean ingestion rates (up to 170 oocysts/hr) followed by Stylonychia (up to 60 oocysts/hour). Euplotes and the wetland ciliate had lower mean grazing rates (4 and 10 oocysts/hr respectively). These results indicate that protozoan predation may be an important factor in the removal of Cryptosporidium oocysts from wastewaters in constructed wetlands.


Assuntos
Cilióforos , Cryptosporidium parvum , Ecossistema , Comportamento Predatório , Purificação da Água/métodos , Animais , Biodegradação Ambiental , Oócitos , Plantas , Dinâmica Populacional
20.
Water Sci Technol ; 47(3): 77-83, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12639009

RESUMO

Predation by free-living protozoa and rotifers was investigated as a possible mechanism for the removal of Cryptosporidium parvum oocysts in aquatic ecosystems including wastewater treatment plants. Free-living ciliated protozoa (Stylonychia mytilus, Paramecium caudatum and an unidentified wastewater wetland ciliate), an amoeba (Acanthamoeba culbertsoni) and rotifers, all commonly found in aquatic ecosystems, were exposed to varying doses of C. parvum oocysts. All organisms investigated ingested oocysts. Predation activity and rates of ingestion varied with predator species and prey density. Ciliated protozoa demonstrated greater predation activity than A. culbertsoni or rotifers when exposed to 2 x 10(5) oocyst/mL for up to 3 h. Greatest predation after 1 h exposure was observed in P. caudatum, the largest ciliate, with on average 1.9 oocysts/cell (range 0-9 oocysts/cell). Stylonychia mytilus and the wetland ciliate had a similar mean ingestion of around 0.3 oocysts/cell, with numbers internalised ranging from 0-3 oocysts/cell. Rotifers ingested on average 1.6 oocysts/individual (range 0-7 oocysts/individual) whilst amoebae ingested on average 1.8 oocysts/cell after 2 h exposure (up to 3 oocysts/cell). Grazing activity by P. caudatum was demonstrated at a variety of prey levels ranging from 9 to 9,000 oocysts. Numbers of oocysts internalised by Paramecium frequently exceeded the reported human infective dose of 30 oocysts. In general, numbers of internalised oocysts increased with incubation time of up to 20-30 min although the rate of accumulation was slower at lower dose levels. The significance of predation on the fate of Cryptosporidium oocysts in the environment is discussed.


Assuntos
Cryptosporidium , Eucariotos , Comportamento Predatório , Rotíferos , Microbiologia da Água , Purificação da Água , Abastecimento de Água , Animais , Ecossistema , Humanos , Oocistos , Dinâmica Populacional , Saúde Pública , Controle de Qualidade , Medição de Risco
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