Differential skewing of donor-unrestricted and γδ T cell repertoires in tuberculosis-infected human lungs

Unconventional T cells that recognize mycobacterial antigens are of great interest as potential vaccine targets against tuberculosis (TB). This includes donor-unrestricted T cells (DURTs), such as mucosa-associated invariant T cells (MAITs), CD1-restricted T cells, and γδ T cells. We exploited the distinctive nature of DURTs and γδ T cell receptors (TCRs) to investigate the involvement of these T cells during TB in the human lung by global TCR sequencing. Making use of surgical lung resections, we investigated the distribution, frequency, and characteristics of TCRs in lung tissue and matched blood from individuals infected with TB. Despite depletion of MAITs and certain CD1-restricted T cells from the blood, we found that the DURT repertoire was well preserved in the lungs, irrespective of disease status or HIV coinfection. The TCRδ repertoire, in contrast, was highly skewed in the lungs, where it was dominated by Vδ1 and distinguished by highly localized clonal expansions, consistent with the nonrecirculating lung-resident γδ T cell population. These data show that repertoire sequencing is a powerful tool for tracking T cell subsets during disease

Validation of xMAP SARS-CoV-2 Multi-Antigen IgG assay in Nigeria

Objective: There is a need for reliable serological assays to determine accurate estimates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence. Most single target antigen assays have shown some limitations in Africa. To assess the performance of a multi-antigen assay, we evaluated a commercially available SARS-CoV-2 Multi-Antigen IgG assay for human coronavirus disease 2019 (COVID-19) in Nigeria. / Methods: Validation of the xMAP SARS-CoV-2 Multi-Antigen IgG assay was carried out using well-characterized SARS-CoV-2 reverse transcription polymerase chain reactive positive (97) and pre-COVID-19 pandemic (86) plasma panels. Cross-reactivity was assessed using pre-COVID-19 pandemic plasma specimens (213) from the 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS). / Results: The overall sensitivity of the xMAP SARS-CoV-2 Multi-Antigen IgG assay was 75.3% [95% CI: 65.8%– 82.8%] and specificity was 99.0% [95% CI: 96.8%– 99.7%]. The sensitivity estimate increased to 83.3% [95% CI: 70.4%– 91.3%] for specimens >14 days post-confirmation of diagnosis. However, using the NAIIS pre-pandemic specimens, the false positivity rate was 1.4% (3/213). / Conclusions: Our results showed overall lower sensitivity and a comparable specificity with the manufacturer’s validation. There appears to be less cross-reactivity with NAIIS pre-pandemic COVID-19 specimens using the xMAP SARS-CoV-2 Multi-Antigen IgG assay. In-country SARS-CoV-2 serology assay validation can help guide the best choice of assays in Africa

Tuning the energetics and tailoring the optical properties of silver clusters confined in zeolites

The integration of metal atoms and clusters in well-defined dielectric cavities is a powerful strategy to impart new properties to them that depend on the size and geometry of the confined space as well as on metal-host electrostatic interactions. Here, we unravel the dependence of the electronic properties of metal clusters on space confinement by studying the ionization potential of silver clusters embedded in four different zeolite environments over a range of silver concentrations. Extensive characterization reveals a strong influence of silver loading and host environment on the cluster ionization potential, which is also correlated to the cluster's optical and structural properties. Through fine-tuning of the zeolite host environment, we demonstrate photoluminescence quantum yields approaching unity. This work extends our understanding of structure property relationships of small metal clusters and applies this understanding to develop highly photoluminescent materials with potential applications in optoelectronics and bioimaging

Anticandidal Effect of Extracts of Wild Polypore, Trametes elegans, on Candida Species Isolated from Pregnant Women in Selected Hospitals in Southwest Nigeria

Aim: Considering the significance of candidiasis among pregnant women, the study was designed to investigate the anticandidal effect of extracts of Trametes elegans (Spreng: Fr.) Fr. (fam.: Polyporaceae) against Candida species isolated from pregnant women and to screen for the phytochemical constituents of the crude extract of T. elegans. Place and Duration of Study: Candida species were isolated from 132 high vaginal swabs (HVS) collected from pregnant women attending ten selected hospitals in Ondo, Osun and Oyo States, Nigeria. Methods: Extracts of Trametes elegans was prepared with methanol, acetone and n-hexane. Phytochemical screening of the macrofungus extracts were thereafter performed qualitatively and quantitatively. The isolated Candida species were subjected to antifungal assay to determine the anticandidal efficacy of the macrofungus extracts. Results: A total of 67 Candida isolates were obtained from the patients. The prevalent organisms were C. albicans (49/67, 73.13%), C. glabrata (9/67, 13.43%), C. krusei (6/67, 8.96%) and C. tropicalis (3/67, 4.48%). Methanol gave the highest yield (3.4 mg/g), while n-hexane gave the least (0.7 mg/g). All the extracts contained saponin, tannin, steroid, terpenoid and cardiac glycosides, while flavonoid was only found in acetone extracts. Saponin was highest (31.77 mg/g) while flavonoid content was least (1.65 mg/g). Zones of inhibition ranging from 5.00 to 30.00 mm, 4.00 to 15.67 mm and 4.33 to 17.67 mm were produced by methanol, acetone and n-hexane extracts respectively. Methanol extract of T. elegans produced the highest anticandidal activity with an inhibition zone of 30.00 mm against isolate A3 (C. albicans.) The least inhibition zone (4.00 mm) was recorded with acetone extract of T. elegans against isolate A2. Conclusion: The high anticandidal activity exhibited by mushroom extracts suggests that bioactive compounds from these mushrooms could be developed into antifungal agents for the treatment of candidiasis

Evaluation of Antimicrobial Potency and Phytochemical Screening of Persea americana Leaf Extracts against Selected Bacterial and Fungal Isolates of Clinical Importance

Aim: The quest for novel bioactive from natural sources informed the evaluation of the antimicrobial alongside the phytochemical composition of leaf extracts of Persea americana obtained from Akure, Ondo State, Nigeria. Study Design: This study assessed the prospective antimicrobial efficacy of Persia americana against selected clinically relevant bacteria and fungi. Place and Duration of Study: The study was conducted between April and September, 2015 at the Microbiology Laboratory of the Federal University of Technology, Akure, Ondo State, Nigeria. Methodology: Clinical isolates (Bacillus cereus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, Shigella flexneri, Escherichia coli, Candida albicans) and typed cultures (Escherichia coli ATCC 35218, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 43300, Salmonella typhi ATCC 33489) were obtained from the Pathology and Clinical Laboratory of the Lagos State University Teaching Hospital, Lagos State, Nigeria while Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus were obtained from the culture collection center of the Department of Microbiology, FUTA. The authenticity of the bacterial and fungal isolates were confirmed using standard procedures. Persea americana leaves were collected from a building opposite BTO hall Ilesha garage, Akure, Ondo State and identified at the Department of Crop, Soil and Pest Management, Federal University of Technology, Akure. Antimicrobial activities of the leaves extract were assessed on clinical and typed microbial cultures using standard microbiological procedures. Results: The extracts displayed varying antimicrobial activities against all the test organisms with zones of inhibition ranging from 10.27 mm to 34.20 mm. The leaves extracts were effective against all the organisms; with the methanolic P. americana extract having the highest antibacterial activity (34.20 mm) while the acetone extract had the highest antifungal activity (12.60 mm). The phytochemical analysis revealed the presence of tannins, flavonoids, terpenoids, alkaloids and saponins. Conclusion: This study supports the claims that P. americana leaves could be promising in the development of drugs to combat human diseases especially those of fungal and bacterial origin

Growth and Productivity Assessment of Short-Duration Rice (Oryza sativa L. and Upland NERICA) Genotypes in Semiarid North-Central Namibia

In semiarid regions, drought is the major threat to crop production, but climate change and variability often bring floods to the regions, forming seasonal wetlands causing damage to local, drought-adapted staple grains and, hence, low yields and food deficit. Introduction of the semiaquatic crop rice (Oryza spp.) to these semiarid wetlands could complement the dryland crop low yields and overcome the food shortage problem. A field experiment was carried out at the University of Namibia-Ogongo Campus during the 2016/2017 and 2017/2018 cropping seasons to assess the growth and yield of rice genotypes. Twelve short-duration rice genotypes, nine from the International Rice Research Institute (IRRI) and three locally grown upland NERICA genotypes, were used. Parametric analysis of variance was performed to test their effects on crop growth and yield characters. The results showed significant genotype by year interaction for days to heading, plant height, the number of tillers per m2, shoot biomass, the number of panicles per m2, 1000-grain weight, harvest index, and grain yield. The IRRI genotypes produced a higher number of tillers, shoot biomass, and grain yield than the NERICA ones, which were early maturing, were taller, and had higher 1000-grain weight across the years. Generally, most of the genotypes had lower grain yield and higher shoot biomass in the first year, due to the prevailing cool, rainy, and seemingly cloudy weather conditions associated with lower temperature and lower solar radiation. Grain yield was positively correlated with most characters but negatively correlated with the 1000-grain weight. These results demonstrate the yield superiority of IRRI genotypes over their early-maturing NERICA counterparts. However, further studies on morphological characters and drought tolerance of the IRRI genotypes are warranted to ascertain production sustainability under semiarid environments

Verrucomicrobial methanotrophs grow on diverse C3 compounds and use a homolog of particulate methane monooxygenase to oxidize acetone

Short-chain alkanes (SCA; C2-C4) emitted from geological sources contribute to photochemical pollution and ozone production in the atmosphere. Microorganisms that oxidize SCA and thereby mitigate their release from geothermal environments have rarely been studied. In this study, propane-oxidizing cultures could not be grown from acidic geothermal samples by enrichment on propane alone, but instead required methane addition, indicating that propane was co-oxidized by methanotrophs. “Methylacidiphilum” isolates from these enrichments did not grow on propane as a sole energy source but unexpectedly did grow on C3 compounds such as 2-propanol, acetone, and acetol. A gene cluster encoding the pathway of 2-propanol oxidation to pyruvate via acetol was upregulated during growth on 2-propanol. Surprisingly, this cluster included one of three genomic operons (pmoCAB3) encoding particulate methane monooxygenase (PMO), and several physiological tests indicated that the encoded PMO3 enzyme mediates the oxidation of acetone to acetol. Acetone-grown resting cells oxidized acetone and butanone but not methane or propane, implicating a strict substrate specificity of PMO3 to ketones instead of alkanes. Another PMO-encoding operon, pmoCAB2, was induced only in methane-grown cells, and the encoded PMO2 could be responsible for co-metabolic oxidation of propane to 2-propanol. In nature, propane probably serves primarily as a supplemental growth substrate for these bacteria when growing on methane

Photonic Materials for Holographic Sensing

International audienc

Photonic Materials for Holographic Sensing

International audienc