Present and future potential role of toxin-producing Synechococcus in the tropical region.

As anthropogenic induced temperature rises and nutrient loadings increase in fresh and brackish environments, the ecological function of the phytoplankton community is expected to favour the picocyanobacteria, of the genus Synechococcus. Synechococcus is already a ubiquitous cyanobacterium found in both freshwater and marine environments, notwithstanding that the toxigenic species still remains unexplored in many freshwaters. Their fast growth rate and their ability to produce toxins make Synechococcus a potential dominant player in harmful algal blooms under climate change scenarios. This study examines the responses of a novel toxin-producing Synechococcus (i.e., one belonging to a freshwater clade; the other belonging to a brackish clade) to environmental changes that reflect climate change effects. We conducted a series of controlled experiments under present and predicted future temperatures, as well as under various N and P nutrients loadings. Our findings highlight how Synechococcus can be altered by the differing reactions to increasing temperature and nutrients, which resulted in considerable variations in cell abundance, growth rate, death rate, cellular stoichiometry and toxin production. Synechococcus had the highest growth observed at 28 °C, and further increases in temperature resulted in a decline for both fresh and brackish waters. Cellular stoichiometry was also altered, where more nitrogen (N) per cell was required, and the plasticity of N:P was more severe for the brackish clade. However, Synechococcus become more toxic under future scenario. Anatoxin-a (ATX) saw the greatest spike when temperature was at 34 °C especially under P-enrichment conditions. In contrast, Cylindrospermopsin (CYN) was promoted at the lowest tested temperature (25 °C) and under N-limitation. Overall, both temperature and external nutrients are the dominant control over Synechococcus toxins production. A model was also created to assess Synechococcus toxicity to zooplankton grazing. Zooplankton grazing was reduced by two folds under nutrient limitation, but temperature accounted for very insignificant change.

Parameters of Oxidative Stress and Activity of Antioxidant Enzymes in the Saliva of Patients with Type 1 Diabetes Mellitus.

Glucose concentration in the saliva is increased in type 1 diabetes mellitus. This parameter directly correlates with markers of the disease in the blood serum. Increased concentration of 8-oxo-2'-deoxyguanosine (8-OHdG) and diene conjugates, markers of oxidative stress, and reduced activities of superoxide dismutase and catalase were also observed in this pathology. Correlation analysis revealed a strong positive correlation between glucose concentration and the levels of oxidative stress markers and a negative correlation between activity of antioxidant enzymes and glucose concentration. The results indicate that the level of 8-OHdG, diene conjugates, and superoxide dismutase and catalase activities can serve as diagnostic markers of pathophysiological changes in the body in type 1 diabetes mellitus.

Distressing psychotic-like experiences, cognitive functioning and early developmental markers in clinically referred young people aged 8-18 years.

PURPOSE: Neurocognitive difficulties and early childhood speech/motor delays are well documented amongst older adolescents and young adults considered at risk for psychosis-spectrum diagnoses. We aimed to test associations between unusual or psychotic-like experiences (PLEs), co-occurring distress/emotional symptoms, current cognitive functioning and developmental delays/difficulties in young people (aged 8-18 years) referred to Child and Adolescent Mental Health Services in South London, UK. METHODS: Study 1 examined receptive language, verbal learning and caregiver-reported speech and motor delays/difficulties in a sample of 101 clinically-referred children aged 8-14 years, comparing those reporting no PLEs (n = 19), PLEs without distress (n = 16), and PLEs with distress (n = 66). Study 2 tested associations of severity of distressing PLEs with vocabulary, perceptual reasoning, word reading and developmental delays/difficulties in a second sample of 122 adolescents aged 12-18 years with distressing PLEs. RESULTS: In Study 1, children with distressing PLEs had lower receptive language and delayed recall and higher rates of developmental delays/difficulties than the no-PLE and non-distressing PLE groups (F values: 2.3-2.8; p values: < 0.005). Receptive language (ß = 0.24, p = 0.03) and delayed recall (ß = - 0.17, p = 0.02) predicted PLE distress severity. In Study 2, the cognitive-developmental variables did not significantly predict PLE distress severity (ß values = 0.01-0.22, p values: > 0.05). CONCLUSION: Findings may be consistent with a cognitive-developmental model relating distressing PLEs in youth with difficulties in cognitive functioning. This highlights the potential utility of adjunctive cognitive strategies which target mechanisms associated with PLE distress. These could be included in cognitive-behavioural interventions offered prior to the development of an at-risk mental state in mental health, educational or public health settings.

Assessment of Human Health Risks in Tropical Environmental Waters with Microbial Source Tracking Markers.

Human specific microbial source tracking (MST) markers which are highly specific to human waste contamination offer the advantage of better association with human pathogens than traditional microbial indicators. However, the performance of these MST markers may vary across different geographical regions. The magnitude of MST markers also plays an important role in interpreting the health risks. This study aims to (i) validate the specificity and sensitivity of human markers for tropical urban catchments; (ii) identify the threshold concentrations of MST markers, i.e. human polyomaviruses (HPyVs), Bacteroides thetaiotaomicron (B. theta) and Methanobrevibacter smithii (M. smithii), that correspond to the acceptable gastrointestinal (GI) illness risks associated with swimming using the QMRA approach; and (iii) validate the threshold concentrations of MST markers using the surveillance data obtained from the tropical urban environment. Among the three MST markers, HPyVs showed the highest specificity (100%) to sewage samples, followed by M. smithii (97%) and B. theta (90%). All MST markers showed 100% sensitivity towards sewage contamination, with B. theta present in highest abundance in sewage, followed by HPyVs and M. smithii. This study demonstrates a risk-based framework to identify the threshold concentrations of MST markers associated with GI illness risks in environmental waters by considering two main influencing factors (i.e. decay and dilution factors). This study successfully validated the B. theta threshold concentration range (581 to 8073 GC/100 mL) with field data (370 to 6500 GC/100 mL) in estimating GI illness risks with an Enterococcus model. Field data showed that the MST markers at threshold concentrations were able to classify the safe level in more than 83% of the samples, according to GI illness risks from Enterococcus and adenovirus. The study also highlighted the lack of associations between MST markers and GI illness risks from norovirus. With comprehensive information on specificity, sensitivity and threshold concentrations of MST markers, increasing confidence can be placed on identifying human source contamination and evaluating the health risks posed in environmental waters in Singapore.

Correction to "Automatic Quality Assessment of Echocardiograms Using Convolutional Neural Networks: Feasibility on the Apical Four-Chamber View".

In the above paper [1], the first footnote should have indicated the following information: A. H. Abdi and C. Luong are joint first authors.

Using Pseudomonas aeruginosa PAO1 to evaluate hydrogen peroxide as a biofouling control agent in membrane treatment systems.

Hydrogen peroxide (H2 O2 ) is widely used in water treatment for biofouling control and, in conjunction with catalysts, as a powerful oxidant for contaminant destruction. H2 O2 could potentially serve as an antifouling agent in reverse osmosis systems in lieu of chlorine-based disinfectants. The dependence of the biocidal efficiency of H2 O2 on cell density, temperature and H2 O2 concentration by determining the growth, attachment and viability of the model bacterium Pseudomonas aeruginosa PAO1 was studied. For controlling growth of planktonic PAO1 cells, the minimally required H2 O2 concentration depends on the cell density and temperature. The effect of H2 O2 to remove the existing biofilm was found to be effective in the presence of a high concentration bicarbonate (8·4 g l-1 ), which forms peroxymonocarbonate, a strong oxidant and disinfectant. Treatment with H2 O2 -bicarbonate reduced the density of live PAO1 cells, removed extracellular polymeric substances and lowered the average biofilm thickness while maintaining the integrity of the membrane, suggesting that this type of treatment may be a suitable 'in-place-cleaning' procedure for biofouled membranes. SIGNIFICANCE AND IMPACT OF THE STUDY: H2 O2 is evaluated as a potential replacement for chlorine to control biofouling in membrane-based water treatment systems. The biocidal efficacy of H2 O2 was evaluated as a function of H2 O2 concentration, cell density and temperature using the model organism Pseudomonas aeruginosa PAO1. Results demonstrated that at low temperatures and low cell densities, bacterial growth and membrane biofouling can be prevented by low H2 O2 concentrations, and existing biofilms could be removed by H2 O2 -bicarbonate mixtures. Findings suggested that H2 O2 could be used as a low cost agent for prevention and controlling biofouling in reverse osmosis applications.

Risk assessment of noroviruses and human adenoviruses in recreational surface waters.

In the interest of public health and safety, this study aimed to quantify risks associated with the presence of noroviruses (NoV) and human adenoviruses (HAdV) in an urban catchment area in Singapore. Enteric viruses were quantified using QPCR. NoV were more prevalent in water samples than HAdV, and presented higher associated illness risks across all exposure scenarios. For primary contact recreation of adults and children, mean probability of illness were 0.0061 and 0.0089 for NoV, and 0.0028 and 0.0048 for HAdV. For secondary contact recreation, mean probability of illness were 0.0016 for NoV and 0.00068 for HAdV. Therefore, owing to their prevalence and associated risks, NoV are better suited as reference pathogens in recreational waters in Singapore.

Evaluation of FRNA coliphages as indicators of human enteric viruses in a tropical urban freshwater catchment.

This study aimed to evaluate the relationship between FRNA coliphages (FRNA GI to GIV) and human enteric viruses (human adenoviruses, HAdV, astroviruses, AstV, noroviruses, NoV, and rotaviruses, RoV) in a tropical urban freshwater catchment. Positive associations between human-specific coliphages and human viral pathogens substantiate their use as viral indicators and in microbial source tracking. Reverse transcription qPCR was used to measure the concentrations of viruses and FRNA coliphages in concentrated water samples. Environmental water samples were also analyzed for male-specific (F+) and somatic (Som) coliphages using plaque assay. The most abundant enteric virus was NoV (55%) followed by HAdV (33%), RoV (33%), and AstV (23%), while the most abundant FRNA genogroup was GI (85%) followed by GII (48%), GIV (8%) and GIII (7%). Concentrations of human-specific coliphages FRNA GII were positively correlated with NoV, HAdV, RoV, AstV, F+ and Som (τ = 0.5 to 0.3, P < 0.05) while concentrations of animal-specific coliphages FRNA GI were negatively correlated with HAdV and RoV (τ = -0.2, P < 0.05). This study demonstrates statistical relationships between human-specific coliphages and a suite of human enteric viruses in the environment.

Alternative fecal indicators and their empirical relationships with enteric viruses, Salmonella enterica, and Pseudomonas aeruginosa in surface waters of a tropical urban catchment.

The suitability of traditional microbial indicators (i.e., Escherichia coli and enterococci) has been challenged due to the lack of correlation with pathogens and evidence of possible regrowth in the natural environment. In this study, the relationships between alternative microbial indicators of potential human fecal contamination (Bacteroides thetaiotaomicron, Methanobrevibacter smithii, human polyomaviruses [HPyVs], and F+ and somatic coliphages) and pathogens (Salmonella spp., Pseudomonas aeruginosa, rotavirus, astrovirus, norovirus GI, norovirus GII, and adenovirus) were compared with those of traditional microbial indicators, as well as environmental parameters (temperature, conductivity, salinity, pH, dissolved oxygen, total organic carbon, total suspended solids, turbidity, total nitrogen, and total phosphorus). Water samples were collected from surface waters of urban catchments in Singapore. Salmonella and P. aeruginosa had significant positive correlations with most of the microbial indicators, especially E. coli and enterococci. Norovirus GII showed moderately strong positive correlations with most of the microbial indicators, except for HPyVs and coliphages. In general, high geometric means and significant correlations between human-specific markers and pathogens suggest the possibility of sewage contamination in some areas. The simultaneous detection of human-specific markers (i.e., B. thetaiotaomicron, M. smithii, and HPyVs) with E. coli and enterococcus supports the likelihood of recent fecal contamination, since the human-specific markers are unable to regrow in natural surface waters. Multiple-linear-regression results further confirm that the inclusion of M. smithii and HPyVs, together with traditional indicators, would better predict the occurrence of pathogens. Further study is needed to determine the applicability of such models to different geographical locations and environmental conditions.

[EFFECTS OF MELATONIN ON THE ACONITATE HYDRATASE ACTIVITY, CONTENT OF LIPID PEROXIDATION PRODUCTS AND SOME NON-ENZYMATIC ANTIOXIDANTS IN THE BLOOD OF PATIENTS WITH TYPE 2 DIABETES MELLITUS COMPLICATED BY STEATOHEPATITIS].

Type 2 diabetes mellitus complicated by steatohepatitis is accompanied by a decrease in aconitate hydratase activity, increase in the content of diene conjugates, decrease in the concentration of α-tocopherol, and change in the citrate level in the blood serum of patients, which is evidence of the development of oxidative stress as a result of the intensification of free radical oxidation of biosubstrates and decreasing degree of antioxidant defense of the organism. Combined therapy with melaxen provided a more significant change of the investigated parameters toward the norm (on the average by 36%, p 0.05) in comparison with basic treatment. This result was evidently associated with implementation of the antioxidant effect of melatonin, the level of which is corrected under the action of the drug employed.

[Effect of melaxen and valdoxan on free radical processes intensity, aconitate hydratase activity and citrate content in rats tissues under hyperthyroidism].

The influence of melaxen and valdoxan on the biochemiluminescence parameters, aconitate hydratase activity and citrate level in rats heart and liver during development of experimental hyperthyroidism has been investigated. Administration of these substances promoted a decrease of biochemiluminescence parameters, which had been increased in tissues of rats in response to the development of oxidative stress under hyperthyroidism. Aconitate hydratase activity and citrate concentration in rats liver and heart, growing at pathological conditions, changed towards control value after administration of the drugs correcting melatonin level. The results indicate the positive effect of valdoxan and melaxen on oxidative status of the organism under the development of experimental hyperthyroidism that is associated with antioxidant action of melatonin.

Surveillance of enteric viruses and coliphages in a tropical urban catchment.

An assessment of the occurrence and concentration of enteric viruses and coliphages was carried out in highly urbanized catchment waters in the tropical city-state of Singapore. Target enteric viruses in this study were noroviruses, adenoviruses, astroviruses and rotaviruses. In total, 65 water samples were collected from canals and the reservoir of the Marina catchment on a monthly basis over a period of a year. Quantitative PCR (qPCR) and single agar layer plaque assay (SAL) were used to enumerate target enteric viruses and coliphages in water samples, respectively. The most prevalent pathogen were noroviruses, detected in 37 samples (57%), particularly norovirus genogroup II (48%), with a mean concentration of 3.7 × 10(2) gene copies per liter. Rotavirus was the second most prevalent virus (40%) with a mean concentration of 2.5 × 10(2) GC/L. The mean concentrations of somatic and male-specific coliphages were 2.2 × 10(2) and 1.1 × 10(2) PFU/100 ml, respectively. The occurrence and concentration of each target virus and the ratio of somatic to male-specific coliphages varied at different sampling sites in the catchment. For sampling sites with higher frequency of occurrence and concentration of viruses, the ratio of somatic to male-specific coliphages was generally much lower than other sampling sites with lower incidences of enteric viruses. Overall, higher statistical correlation was observed between target enteric viruses than between enteric viruses and coliphages. However, male-specific coliphages were positively correlated with norovirus concentrations. A multi-level integrated surveillance system, which comprises the monitoring of bacterial indicators, coliphages and selected enteric viruses, could help to meet recreational and surface water quality criteria in a complex urbanized catchment.

[Effects of melaxen and valdoxan on the activity of glutathione antioxidant system and NADPH-producing enzymes in rat heart under experimental hyperthyroidism conditions].

The effects of melaxen and valdoxan on the activity of glutathione antioxidant system and some NADPH-producing enzymes have been studied under conditions of experimental hyperthyroidism in rat heart. Under the action of these drugs, reduced glutathione (GSH) content increased as compared to values observed under the conditions of pathology. It has been established that the activities of glutathione reductase (GR), glutathione peroxidase (GP), glucose-6-phosphate dehydrogenase, and NADP isocitrate dehydrogenase (increased under pathological conditions) change toward the intact control values upon the introduction of both drugs. The influence of melaxen and valdoxan, capable of producing antioxidant effect, leads apparently to the inhibition of free-radical oxidation processes and, as a consequence, the reduction of mobilization degree of the glutathione antioxidant system.

[The activity of glutathione antioxidant system at melaksen and valdoxan action under experimental hyperthyroidism in rats].

Investigation of glutathione antioxidant system activity and diene conjugates content in rats liver and blood serum at the influence of melaksen and valdoxan under experimental hyperthyroidism (EG) has been revealed. It has been established that the activities of glutathione reductase (GR), glutathione peroxidase (GP) and glutathione transferase (GT), growing at pathological conditions, change to the side of control value at these substunces introduction. Reduced glutathione content (GSH) at melaxen and valdoxan action increased compared with values under the pathology, that, obviously, could be associated with a reduction of its spending on the detoxication of free radical oxidation (FRO) toxic products. Diene conjugates level in rats liver and blood serum, increasing at experimental hyperthyroidism conditions, under introduction of melatonin level correcting drugs, also approached to the control meaning. Results of the study indicate on positive effect of melaxen and valdoxan on free radical homeostasis, that appears to be accompanied by decrease of load on the glutathione antioxidant system in comparison with the pathology.

[Effect of combined therapy with melaxen on lipid peroxidation rate and citrate content in blood serum of patients with drug-induced hepatitis diagnosis].

A combined therapy with melaxen led to a decrease in the activity of gamma-glutamyl transpeptidase and the level of diene conjugates in blood serum of patients with the drug-induced hepatitis developing on the background of administration of antituberculous preparations. These changes are indicative of pronounced antioxidant and hepatoprotective properties of the drug. In addition, there was a decrease in the content of citrate and a change in the activity of aconitate hydratase toward a normal level, which reflects a decrease in the degree of pathologic oxidative stress development and is evidence of the antiradical effect of melaxen.

[Peculiar properties of glutathione system and NADPH-generated enzymes functioning in blood of patients with drug-induced hepatitis under combined treatment with epifamin].

Activity of the glutathione antioxidant system has been studied in patients with drug-induced hepatitis treated with standart base therapy and combined with epifamin therapy. In blood serum of patients before treatment the decrease of reduced glutathione (GSH) level and the increase of glutathione peroxidase (GP) and glutathione reductase (GR) activities versus control were observed. Combined treatment with epifamin changed GSH level to the normal values. Treatment with epifamin was accompanied by pronounced increase in GP and GR activities compared with standard therapy. Activities of the NADPH-generated enzymes, glucose-6-phosphate dehydrogenase and NADP-isocitrate dehydrogenase, which decreased at this pathology, also demonstrated a more significant increase than standart treatment.

Prevalence and genetic diversity of waterborne pathogenic viruses in surface waters of tropical urban catchments.

AIMS: To study the virological quality of surface water from highly urbanized tropical water catchment areas and to determine predominant enteric viral genotypes in surface water. METHODS AND RESULTS: A wide range of human pathogenic viruses in urban surface waters was screened by nested PCR assays after concentration by ultrafiltration. Among the 84 water samples collected, at least one virus was detected in 70 (83·3%) of these samples. Noroviruses were determined to be the most prevalent enteric viruses detected in urban surface water samples, followed by astroviruses, enteroviruses, adenoviruses and hepatitis A viruses. The molecular characterization of environmental viral isolates suggested co-circulation of multiple genotypes of both noroviruses GI and GII, astroviruses and enteroviruses in urban surface waters. CONCLUSIONS: Human enteric viruses with great genetic diversity were detected in surface waters, indicating the presence of human origin of faecal contamination in highly urbanized water catchment areas.

[Intensity of free radical oxidation and superoxide dismutase activity in patients with drug hepatitis in combination therapy with melaxen or epifamin].

Intensity of free radical oxidation processes and superoxide dismutase activity at patients with drug-induced hepatitis at the combined therapy with melaxen or epifamin. Free radical homoeostasis state at patients with drug-induced hepatitis being on standard treatment, including hepatoprotectors, and the combined therapy with melaxen or epifamin has been investigated. Biochemiluminescence parameters in blood serum point out to intensification of free radical processes and inhibition of antioxidant defense of organism, at this time superoxide dismutase activity in blood serum increased. After leading of standard therapy a decline of oxidative stress expression was observed. Incorporation to base treatment of melaxen or epifamin accompanied by correction of antioxidant status of organism and provided more expressed antioxidant effect, that confirmed by changing of biochemiluminescence parameters and superoxide dismutase activity. Obviously, it is related to antiradical properties of melatonin the level of which is corrected under the action of these preparations.

Environmental surveillance and molecular characterization of human enteric viruses in tropical urban wastewaters.

AIMS: To study the prevalence and genotypes of waterborne pathogenic viruses in urban wastewaters in the tropical region. METHODS AND RESULTS: Viruses in wastewaters collected at three water reclamation plants in Singapore were studied by molecular methods. Over a 6-month sampling period, adenoviruses, astroviruses and both norovirus genogroups I (GI) and II (GII) were detected in 100% of the sewage and secondary effluent. Enteroviruses and hepatitis A viruses (HAV) were found in 94 and 78% of sewage, and 89 and 28% of secondary effluent, respectively. By using quantitative real-time PCR, estimated concentrations of astrovirus in the sewage were 1-2 orders of magnitude higher than those for adenovirus, noroviruses GI and GII. Genotyping of environmental isolates revealed multiple genotypes of GI and GII noroviruses. Coxsackieviruses A, astrovirus type 1 and adenovirus type 41 were prevalent. Norovirus GII/4 and coxsackievirus A24 isolates in wastewaters were closely related to respective outbreak strains isolated previously in Singapore. CONCLUSIONS: This study showed the widespread occurrence of all tested enteric virus groups in urban wastewaters. Genetic diversity of astroviruses, enteroviruses and noroviruses in the tropical region was observed. SIGNIFICANCE AND IMPACT OF THE STUDY: The high prevalence and great genetic diversity of human enteric viruses in urban wastewaters strongly supports the need of further comprehensive studies for evaluating the public health risk associated with viral pathogens in water environments.

Treating the right patient at the right time: Access to echocardiography in Canada.

The Canadian Cardiovascular Society is the national professional society for cardiovascular specialists and researchers in Canada. In the spring of 2004, the Canadian Cardiovascular Society Council formed the Access to Care Working Group ('Working Group') to use the best science and information available to establish reasonable triage categories and safe wait times for access to common cardiovascular procedures. The Working Group decided to publish a series of commentaries to initiate a structured national discussion on this important issue, and the present commentary proposes recommended wait times for access to echocardiography. 'Emergent' echocardiograms should be performed within 24 h, 'urgent' within seven days and 'scheduled' (elective) within 30 days. A framework for a solution-oriented approach to improve access is presented.