8,297 research outputs found

    Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae

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    The estuarine genus Pfiesteria has received considerable attention since it was first identified and proposed to be the causative agent of fish kills along the mid-Atlantic coast in 1992. The presumption has been that the mechanism of fish death is by release of one or more toxins by the dinoflagellate. In this report, we challenge the notion that Pfiesteria species produce ichthyotoxins. Specifically, we show that (i) simple centrifugation, with and without ultrasonication, is sufficient to detoxify water of actively fish-killing cultures of Pfiesteria shumwayae, (ii) organic extracts of lyophilized cultures are not toxic to fish, (fit) degenerate primers that amplify PKS genes from several polyketide-producing dinoflagellates failed to yield a product with A shumwayae DNA or cDNA, and (iv) degenerate primers for NRPS genes failed to amplify any NRPS genes but (unexpectedly) yielded a band (among several) that corresponded to known or putative PKSs and fatty acid synthases. We conclude that P. shumwayae is able to kill fish by means other than releasing a toxin into bulk water. Alternative explanations of the effects attributed to Pfiesteria are suggested

    Establishing a Statistical Link between Network Oscillations and Neural Synchrony

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    Pairs of active neurons frequently fire action potentials or “spikes” nearly synchronously (i.e., within 5 ms of each other). This spike synchrony may occur by chance, based solely on the neurons’ fluctuating firing patterns, or it may occur too frequently to be explicable by chance alone. When spike synchrony above chances levels is present, it may subserve computation for a specific cognitive process, or it could be an irrelevant byproduct of such computation. Either way, spike synchrony is a feature of neural data that should be explained. A point process regression framework has been developed previously for this purpose, using generalized linear models (GLMs). In this framework, the observed number of synchronous spikes is compared to the number predicted by chance under varying assumptions about the factors that affect each of the individual neuron’s firing-rate functions. An important possible source of spike synchrony is network-wide oscillations, which may provide an essential mechanism of network information flow. To establish the statistical link between spike synchrony and network-wide oscillations, we have integrated oscillatory field potentials into our point process regression framework. We first extended a previously-published model of spike-field association and showed that we could recover phase relationships between oscillatory field potentials and firing rates. We then used this new framework to demonstrate the statistical relationship between oscillatory field potentials and spike synchrony in: 1) simulated neurons, 2) in vitro recordings of hippocampal CA1 pyramidal cells, and 3) in vivo recordings of neocortical V4 neurons. Our results provide a rigorous method for establishing a statistical link between network oscillations and neural synchrony

    Simultaneous determination of natural and synthetic steroid estrogens and their conjugates in aqueous matrices by liquid chromatography / mass spectrometry

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    An analytical method for the simultaneous determination of nine free and conjugated steroid estrogens was developed with application to environmental aqueous matrices. Solid phase extraction (SPE) was employed for isolation and concentration, with detection by liquid chromatography/mass spectrometry (LC/MS) using electrospray ionisation (ESI) in the negative mode. Method recoveries for various aqueous matrices (wastewater, lake and drinking water) were determined, recoveries proving to be sample dependent. When spiked at 50 ng/l concentrations in sewage influent, recoveries ranged from 62-89 % with relative standard deviations (RSD) < 8.1 %. In comparison, drinking water spiked at the same concentrations had recoveries between 82-100 % with an RSD < 5%. Ion suppression is a known phenomenon when using ESI; hence its impact on method recovery was elucidated for raw sewage. Both ion suppression from matrix interferences and the extraction procedure has bearing on the overall method recovery. Analysis of municipal raw sewage identified several of the analytes of interest at ng/l concentrations, estriol (E3) being the most abundant. Only one conjugate, estrone 3-sulphate (E1-3S) was observe

    Eosinophilic and neutrophilic leukemoid reaction in a woman with spindle cell sarcoma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>We report a case of a patient with marked eosinophilia and neutrophilia as a manifestation of a spindle cell sarcoma.</p> <p>Case presentation</p> <p>A 41-year-old African American woman presented with an enlarging, painful mass in her right knee area. Four years previously, she had had a mass similar to this diagnosed as an osteosarcoma, and had undergone a radical resection and hinge-knee replacement. Before the surgery, she was treated with neoadjuvant docetaxel and gemcitabine. A biopsy was taken from the recurrent mass, and histological examination revealed high-grade soft-tissue sarcoma. The patient received no further treatment. Complete blood counts revealed a white blood cell (WBC) count of 13.6 to 17.9 × 10<sup>9</sup>/L, with neutrophils being 8.2 to 10.9 × 10<sup>9</sup>/L and eosinophils 1.8 to 1.9 × 10<sup>9</sup>/L. At readmission six months later, WBC was 126.7 × 10<sup>9</sup>/L, with neutrophils being 57.02 × 10<sup>9</sup>/L and eosinophils 60.82 × 10<sup>9</sup>/L. The eosinophils peaked at 77.79 × 10<sup>9</sup>/L two days later. Evaluations for allergies, infection, and autoimmune mechanisms were negative. Bone marrow revealed increased eosinophils without blasts. After resection, blood counts abruptly decreased to the normal range. Pathology confirmed high-grade spindle cell sarcoma. Approximately one year after resection, the patient was readmitted with metastatic disease to her lungs. During this presentation, her eosinophil and neutrophil count was again increased. WBC was 107.8 × 10<sup>9</sup>/L, with eosinophil count of 47.43 × 10<sup>9</sup>/L and neutrophil count of 44.10 × 10<sup>9</sup>/L. Interleukin-5 was normal, and granulocyte–macrophage colony-stimulating factor (GM-CSF) was elevated at 208.8 (normal < 4.8).</p> <p>Conclusion</p> <p>In our case, the patient had eosinophilia and neutrophilia associated with a spindle cell sarcoma, possibly representing a paraneoplastic syndrome secondary to GM-CSF. There were no signs of infectious, allergic, or autoimmune causes for the eosinophilia or neutrophilia. Even though the occurrence of eosinophilia and neutrophilia with malignancy is rare, patients who have either condition without an apparent cause should be checked for malignancy.</p

    Cancer screening and preventative care among long-term cancer survivors in the United Kingdom

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    BACKGROUND: Long-term cancer survivors in the United Kingdom are mostly followed up in a primary care setting by their general practitioner; however, there is little research on the use of services. This study examines whether cancer survivors receive adequate screening and preventative care in UK primary care. PATIENTS AND METHODS: We identified a cohort of long-term survivors of breast, colorectal and prostate cancer with at least a 5-year survival using the General Practice Research Database, with controls matched for age, gender and practice. We compared adherence with cancer screening and the use of preventative care between cancer survivors and controls. RESULTS: The cancer survivors' cohort consisted of 18 612 breast, 5764 colorectal and 4868 prostate cancer survivors. Most cancer survivors receive cancer screening at the same levels as controls, except for breast cancer survivors who were less likely to receive a mammogram than controls (OR=0.78, 95% CI: 0.66-0.92). Long-term cancer survivors received comparable levels of influenza vaccinations and cholesterol tests, but breast (OR 0.81, 95% CI: 0.74-0.87) and prostate cancer survivors (OR=0.70, 95% CI: 0.57-0.87) were less likely to receive a blood pressure test. All survivors were more likely to receive bone densitometry. CONCLUSION: The provision and uptake of preventive care in a primary care setting in the United Kingdom is comparable between the survivors of three common cancers and those who have not had cancer. However, long-term breast cancer survivors in this cohort were less likely to receive a mammogra

    Diarrhea incidence in low- and middle-income countries in 1990 and 2010: a systematic review

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    <p>Abstract</p> <p>Background</p> <p>Diarrhea is recognized as a leading cause of morbidity and mortality among children under 5 years of age in low- and middle-income countries yet updated estimates of diarrhea incidence by age for these countries are greatly needed. We conducted a systematic literature review to identify cohort studies that sought to quantify diarrhea incidence among any age group of children 0-59 mo of age.</p> <p>Methods</p> <p>We used the Expectation-Maximization algorithm as a part of a two-stage regression model to handle diverse age data and overall incidence rate variation by study to generate country specific incidence rates for low- and middle-income countries for 1990 and 2010. We then calculated regional incidence rates and uncertainty ranges using the bootstrap method, and estimated the total number of episodes for children 0-59 mo of age in 1990 and 2010.</p> <p>Results</p> <p>We estimate that incidence has declined from 3.4 episodes/child year in 1990 to 2.9 episodes/child year in 2010. As was the case previously, incidence rates are highest among infants 6-11 mo of age; 4.5 episodes/child year in 2010. Among these 139 countries there were nearly 1.9 billion episodes of childhood diarrhea in 1990 and nearly 1.7 billion episodes in 2010.</p> <p>Conclusions</p> <p>Although our results indicate that diarrhea incidence rates may be declining slightly, the total burden on the health of each child due to multiple episodes per year is tremendous and additional funds are needed to improve both prevention and treatment practices in low- and middle-income countries.</p

    Isothermal Microcalorimetry, a New Tool to Monitor Drug Action against Trypanosoma brucei and Plasmodium falciparum

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    Isothermal microcalorimetry is an established tool to measure heat flow of physical, chemical or biological processes. The metabolism of viable cells produces heat, and if sufficient cells are present, their heat production can be assessed by this method. In this study, we investigated the heat flow of two medically important protozoans, Trypanosoma brucei rhodesiense and Plasmodium falciparum. Heat flow signals obtained for these pathogens allowed us to monitor parasite growth on a real-time basis as the signals correlated with the number of viable cells. To showcase the potential of microcalorimetry for measuring drug action on pathogenic organisms, we tested the method with three antitrypanosomal drugs, melarsoprol, suramin and pentamidine and three antiplasmodial drugs, chloroquine, artemether and dihydroartemisinin, each at two concentrations on the respective parasite. With the real time measurement, inhibition was observed immediately by a reduced heat flow compared to that in untreated control samples. The onset of drug action, the degree of inhibition and the time to death of the parasite culture could conveniently be monitored over several days. Microcalorimetry is a valuable element to be added to the toolbox for drug discovery for protozoal diseases such as human African trypanosomiasis and malaria. The method could probably be adapted to other protozoan parasites, especially those growing extracellularly
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