Seasonality and trends of drivers of mesoscale convective systems in southern West Africa

Mesoscale convective systems (MCSs) are the major source of extreme rainfall over land in the tropics and are expected to intensify with global warming. In the Sahel, changes in surface temperature gradients and associated changes in wind shear have been found to be important for MCS intensification in recent decades. Here we extend that analysis to southern West Africa (SWA) by combining 34 years of cloud-top temperatures with rainfall and reanalysis data. We identify clear trends in intense MCSs since 1983 and their associated atmospheric drivers. We also find a marked annual cycle in the drivers, linked to changes in the convective regime during the progression of the West African monsoon. Before the peak of the first rainy season, we identify a shear regime where increased temperature gradients play a crucial role for MCS intensity trends. From June onward, SWA moves into a less unstable, moist regime during which MCS trends are mainly linked to frequency increase and may be more influenced by total column water vapor. However, during both seasons we find that MCSs with the most intense convection occur in an environment with stronger wind shear, increased low-level humidity, and drier midlevels. Comparing the sensitivity of MCS intensity and peak rainfall to low-level moisture and wind shear conditions preceding events, we find a dominant role for wind shear. We conclude that MCS trends are directly linked to a strengthening of two distinct convective regimes that cause the seasonal change of SWA MCS characteristics. However, the convective environment that ultimately produces the most intense MCSs remains the same

Serum Soluble Transferrin Receptor and Transferrin Levels among Regular Blood Donors

Background: The study evaluated the effects of regular blood donation on serum transferrin and soluble transferrin receptor levels at Wenchi Methodist Hospital. Methods: This was a hospital-based cross-sectional study conducted at the Medical Laboratory Department of the Wenchi Methodist Hospital in the Bono Region of Ghana. A total of eighty-nine (89) venous blood samples from apparently healthy blood donors were analyzed. Complete blood count parameters were analyzed using an automated haematology analyzer and serum transferrin and transferrin receptor using ELISA. The data were analyzed using SPSS version 22.0. Results: Haemoglobin (p<0.001) and HCT (p=0.004) were significantly lower among the regular blood donors compared with the first-time donors. Regular blood donors had relatively higher serum transferrin (p<0.001) and soluble transferrin receptor levels (p<0.001). A negative correlation was observed between Hb and serum transferrin (r=-0.552, p<0.001), as well as Hb and serum soluble transferrin receptor (r=-0.552, p<0.001). Remunerated donors had lower Hb (p=0.001) and HCT% (p=0.001) but a higher transferrin receptor (p=0.041) than non-remunerated donors. Conclusion: Regular blood donors had relatively lower erythrocyte parameters but higher serum transferrin and soluble transferrin receptors, indicating a possible reduction in serum iron and iron stores. Moderate negative correlations exist between Hb and both transferrin and soluble transferrin receptors. Again, remunerated donors had lower erythrocyte parameters but higher transferrin and soluble transferrin receptors than non-remunerated donors. Periodic assessment of iron parameters among regular blood donors is recommended. A future longitudinal study to assess the entire iron profile of regular blood donors is recommended.   Doi: 10.28991/SciMedJ-2022-04-03-01 Full Text: PD

Antibacterial Activity of GV-1 Chemical Derivatives in the Presence of Human Serum

Despite advancements in many areas of human medicine, infectious disease continues to be a major cause of mortality worldwide. Improper and excessive use of antibacterial compounds has led to the rise of resistant species of bacteria like Methicillin Resistant Staphylococcus aureus (MRSA). We have discovered a new class of antibiotics that inhibit the growth of Gram-positive bacteria. Upon discovery of inhibition against S. aureus and other Gram-positive bacteria, MRSA, VRE, and other resistant strains were tested. Inhibition by the newly developed compounds on the resistant strains was identical to their inhibition levels against non-resistant strains of these species. We have continued to synthesize and test chemical derivatives of our lead compound in an effort to increase their effectiveness. Overall, these results demonstrate that our carboxylic amide compounds are a novel, non-penicillin based antibiotic that could be used to treat MRSA and other Gram-positive infections

Potential Impact of 1.5oC and 2oC global warming on consecutive dry and wet days over West Africa

We examine the impact of +1.5 ◦C and +2 ◦C global warming levels above pre-industrial levels on consecutive dry days (CDD) and consecutive wet days (CWD), two key indicators for extreme precipitation and seasonal drought. This is done using climate projections from a multi-model ensemble of 25 regional climate model (RCM) simulations. The RCMs take boundary conditions from ten global climate models (GCMs) under the RCP8.5 scenario.We define CDD as the maximum number of consecutive days with rainfall amount less than 1mm and CWD as the maximum number of consecutive days with rainfall amount more than 1 mm. The differences in model representations of the change in CDD and CWD, at 1.5 ◦C and 2◦C global warming, and based on the control period 1971−2000 are reported. The models agree on a noticeable response to both 1.5 ◦C and 2◦C warming for each index. Enhanced warming results in a reduction in mean rainfall across the region.More than 80% of ensemble members agree that CDD will increase over the Guinea Coast, in tandem with a projected decrease in CWD at both 1.5 ◦C and 2◦C global warming levels. These projected changes may influence already fragile ecosystems and agriculture in the region, both of which are strongly affected by mean rainfall and the length of wet and dry periods.JRC.E.1-Disaster Risk Managemen

High-throughput sequencing of the B-cell receptor in African Burkitt lymphoma reveals clues to pathogenesis

Burkitt lymphoma (BL), themost common pediatric cancer in sub-Saharan Africa, is a malignancy of antigen-experienced B lymphocytes. High-throughput sequencing (HTS) of the immunoglobulin heavy (IGH) and light chain (IGK/IGL) loci was performed on genomic DNA from 51 primary BL tumors: 19 from Uganda and 32 from Ghana. Reverse transcription polymerase chain reaction analysis and tumor RNA sequencing (RNAseq) was performed on the Ugandan tumors to confirm and extend the findings from the HTS of tumor DNA. Clonal IGH and IGK/IGL rearrangements were identified in 41 and 46 tumors, respectively. Evidence for rearrangement of the second IGH allele was observed in only 6 of 41 tumor samples with a clonal IGH rearrangement, suggesting that the normal process of biallelic IGHD to IGHJ diversity-joining (DJ) rearrangement is often disrupted in BL progenitor cells. Most tumors, including those with a sole dominant, nonexpressed DJ rearrangement, contained many IGH and IGK/IGL sequences that differed from the dominant rearrangement by, 10 nucleotides, suggesting that the target of ongoing mutagenesis of these loci in BL tumor cells is not limited to expressed alleles. IGHV usage in both BL tumor cohorts revealed enrichment for IGHV genes that are infrequently used in memory B cells from healthy subjects. Analysis of publicly available DNA sequencing and RNAseq data revealed that these same IGHV genes were overrepresented in dominant tumor-associated IGH rearrangements in several independent BL tumor cohorts. These data suggest that BL derives from an abnormal B-cell progenitor and that aberrant mutational processes are active on the immunoglobulin loci in BL cells