Time and Charge-Sign Dependence of the Heliospheric Modulation of Cosmic Rays

Simultaneous and continuous observations of galactic cosmic-ray electrons and positrons from the PAMELA and AMS02 space experiments are most suitable for numerical modeling studies of the heliospheric modulation of these particles below 50 GeV. A well-established comprehensive three-dimensional modulation model is applied to compute full spectra for electrons and positrons with the purpose of reproducing the observed ratio positrons/electrons for a period which covers the previous long and unusual deep solar minimum activity and the recent maximum activity phase including the polarity reversal of the solar magnetic field. For this purpose the very local interstellar spectra for these particles were established first. Our study is focused on how the main modulation processes, including particle drifts, and other parameters such as the three major diffusion coefficients, had evolved, and how the corresponding charge-sign dependent modulation had occurred subsequently. The end result of our effort is the detailed reproduction of positron/electrons from 2006 to 2015, displaying both qualitative and quantitative agreement with the main observed features. Particularly, we determine how much particle drifts is needed to explain the time dependence exhibited by the observed positron/electron during each solar activity phase, especially during the polarity reversal phase when no well-defined magnetic polarity was found.Comment: 16 pages, 8 figures, Submitted to Astrophysical Journa

The performance of different case definitions for severe influenza surveillance among HIV-infected and HIV-uninfected children aged <5 years in South Africa, 2011–2015

In 2014, the World Health Organization (WHO) proposed a new severe influenza surveillance case definition, which has not been evaluated in a high human immunodeficiency virus (HIV) prevalence setting. Our study aimed to assess the performance of this proposed case definition in identifying influenza among HIV-uninfected and HIV-infected children aged <5 years in South Africa. We prospectively enrolled children aged <5 years hospitalised with physician-diagnosed lower respiratory tract infection (LRTI) at two surveillance sites from January 2011 to December 2015. Epidemiologic and clinical data were collected. We tested nasopharyngeal aspirates for influenza using reverse transcription polymerase chain reaction. We used logistic regression to assess factors associated with influenza positivity among HIV-infected and HIV-uninfected children. We calculated sensitivity and specificity for different signs and symptoms and combinations of these for laboratory-confirmed influenza. We enrolled 2,582 children <5 years of age with LRTI of whom 87% (2,257) had influenza and HIV results, of these 14% (318) were HIV-infected. The influenza detection rate was 5% (104/1,939) in HIV-uninfected and 5% (16/318) in HIV-infected children. Children with measured fever (≥38°C) were two times more likely to test positive for influenza than those without measured fever among the HIV-uninfected (OR 2.2, 95% Confidence Interval (CI) 1.5–3.4; p<0.001). No significant association was observed between fever and influenza infection among HIV-infected children. Cough alone had sensitivity of 95% (95% CI 89–98%) in HIV-uninfected and of 100% (95% CI 79–100%) in HIV-infected children but low specificity: 7% (95% CI 6–8%) and 6% (95% CI 3–9%) in HIV-uninfected and HIV-infected children, respectively. The WHO post-2014 case definition for severe acute respiratory illness (SARI—an acute respiratory infection with history of fever or measured fever of ≥ 38°C and cough; with onset within the last ten days and requires hospitalization), had a sensitivity of 66% (95% CI 56–76%) and specificity of 46% (95% CI 44–48%) among HIV-uninfected and a sensitivity of 63% (95% CI 35–84%) and a specificity of 42% (95% CI 36–48%) among HIV-infected children. The sensitivity and specificity of the WHO post-2014 case definition for SARI were similar among HIV-uninfected and HIV-infected children. Our findings support the adoption of the 2014 WHO case definition for children aged <5 years irrespective of HIV infection status.MassGenicshttps://journals.plos.org/plosonehj2020School of Health Systems and Public Health (SHSPH

SCREENING FOR ANTIPROLIFERATIVE ACTIVITY OF A CRUDE ACETONE EXTRACT OF SENNA SPP ON HL-60 AND WIL-2 NS CELL LINES

For many decades plants have provided mankind with herbal remedies against many infectious diseases. Cancer is one of the major public health problem in many developed countries. Senna species falls under the Fabaceae family and are well known for their therapeutic properties. They are being used as plant herbs in many countries including South Africa. The acetone crude extract prepared from the roots of Senna sp was investigated for its cytotoxic activity against two cell lines, HL-60 promyelocytes and WIL-2 NS lymphocytes cells. The changes in nuclear morphology brought by the extract on these cells were also investigated. To investigate the cytotoxicity of the extract, cells were treated with concentrations varying from 0-200 µg/ml for 72 hours and samples collected at 24 hours interval to evaluate cell proliferation and viability using the trypan blue dye exclusion method. The extract was shown to inhibit the proliferation of both HL-60 and WIL-2 NS; with WIL-2 NS being more sensitive to the treatment as compared to HL-60 cells. The nuclear morphological changes of the treated HL-60 and WIL-2 NS cells showed characteristics that are associated with apoptotic features. This could mean that the extract inhibited the proliferation of the cells through the programmed cell death pathway. Acknowledgements: University of Limpopo senate research fund, NR

Mycotoxin contamination of home-grown maize in rural northern South Africa (Limpopo and Mpumalanga Provinces)

The aim of this study was to assess mycotoxin contamination of crops grown by rural subsistence farmers over two seasons (2011 and 2012) in two districts, Vhembe District Municipality (VDM, Limpopo Province) and Gert Sibande District Municiality (GSDM, Mpumalanga Province), in northern South Africa and to evaluate its impact on farmers’ productivity and human and animal health. A total of 114 maize samples were collected from 39 households over the two seasons and were analysed using a validated liquid chromatography-tandem mass spectrometry mycotoxins method. Aflatoxin B1 (AFB1) occurrence ranged from 1 to 133 µg kg−1 in VDM while AFB1 levels in GSDM were less than 1.0 µg kg−1 in all maize samples. Fumonisin B1 levels ranged from 12 to 8514 µg kg−1 (VDM) and 11–18924 µg kg−1 (GSDM) in 92% and 47% positive samples, respectively, over both seasons. Natural occurrence and contamination with both fumonisins and aflatoxins in stored home-grown maize from VDM was significantly (p < 0.0001) higher than from GSDM over both seasons