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The purpose of this study is to provide new evidence on the relationship between trade openness and carbon dioxide (CO2) emissions in Africa. Based on recent data and an uncommon and more informative composite indicator of trade openness proposed by Squalli and Wilson, we use an augmented Stochastic Impact by Regression on Population, Affluence and Technology (STIRPAT) model. The empirical evidence using the Two-Stage Least Square estimation (2SLS) validates the "pollution haven" hypothesis and shows that trade openness increases CO2 emissions in Africa. However, the elasticity varies greatly depending on the different measures of trade openness used. Moreover, we find that trade openness is associated with an increase in CO2 emissions in North Africa, South Africa and West Africa, but rather has a negative effect on CO2 emissions in East Africa and in Central Africa. Furthermore, the quantile regression approach shows that the effect of trade openness is increasing on the 10th, 25th, 50th, and 75th quintiles, but decreasing at the 90th quintile, thus highlighting the "scale effect". The results obtained are robust even when using other indicators of environmental quality. The findings suggest that it is important to have a real measure of the level of trade openness of countries, which will allow African leaders in particular to take appropriate measures to strengthen barriers to the entry of technologies and polluting materials, and invest more in green technologies. [ABSTRACT FROM AUTHOR]

Although the relationship between urbanization, the informal economy, economic growth, and environmental degradation (CO2 emissions) have received considerable attention from multidisciplinary researchers, little work has been undertaken on how differences in the stages of development of different sub-regions of the countries studied may affect these relationships. This paper empirically explores the relationship between urbanization, the informal sector, economic growth, and CO2 emissions. A balanced dataset for a panel of 45 African countries subdivided into sub-regions was analyzed over the period 1991–2019. To achieve the objectives of the study, we used a vector autoregression panel (PVAR). The results demonstrated a bidirectional relationship between CO2 emissions and urbanization, CO2 emissions and economic growth, CO2 emissions and the informal sector, the informal sector and economic growth, and economic growth and urbanization. Furthermore, the empirical results of this study not only contribute in advancing the literature that addresses the relationship between human activity and the environment, but also warrant new insights into the importance of the stage of development in a sub-region in Africa for public policy decisions related to CO2 emissions reduction. [ABSTRACT FROM AUTHOR]

This study evaluates the predictive performance of the North American Multi-model Ensemble (NMME) over Central Africa (CA) using the historical rainfall data. The African Rainfall Climatology Version 2 (ARC2) is used as a substitute for reference observational data to examine the capability of 11 NMME and their NMME ensemble mean (MME) in simulating rainfall. Using the Kling- Gupta efficiency (KGE), Taylor skill score (TSS), and Heidke skill score, the predictive evaluation of the models is performed from lead 0 to lead 5 of each season. The results show that the NMME models satisfactorily reproduce the bimodal and unimodal structure of rainfall in CA at the lead 0 level of different seasons: December–February (DJF), March–May (MAM), June–August (JJA), and September–November (SON). The pattern correlation coefficient (PCC) shows values of NMME and MME greater than ~0.69 and TSS > 0.60 for all four seasons. The MME presents a maximum in DJF 0.~96 between 0 and 1 month lead time. With the same time scale, just over 85% of the NMME have a KGE between 0 and 0.42. It follows that as the forecast lead time increases, the PCC and TSS of each model become small, with PCC 0:~12 in JJA and DJF, TSS<0.21 in JJA at lead 5. The NMME models exhibit an important rainfall bias and the calculated scores show the quality of the forecast decreases with increasing lead time; this may justify a constraint on the models to keep the good quality of the long-term seasonal forecast in CA. [ABSTRACT FROM AUTHOR]

This study examines the seasonal forecast of the North American Multi-Model Ensemble (NMME) over Central Africa (CA), which encompasses a region of the world where the economies of the countries are highly dependent on agriculture and livestock breeding. Following many regional climate perspectives, we evaluated the seasonal forecast over the 4 seasons: December to February (DJF), March to May (MAM), June to August (JJA), September to November (SON) between 0 and 5 months lead time before the beginning of each season. Deterministic and categorical approaches which focus on the rainfall variable were used to assess NMME ensemble mean (MME). The observed and predicted rainfalls have been divided into three categories: below normal, normal, and above normal. The results show that for 0 to 2 months lead time, the MME reproduces well the peak rainfall of the Atlantic coast and in the East of Democratic Republic of Congo in MAM and SON between 9 and 10 mm/day. Again in the same lead time interval, values of correlation coefficients (R) between the MME and the Global Precipitation Climatology Center (GPCC) reference observation of all seasons are greater than 0.72. For 3 to 5 months lead time, lower values of R are observed. It follows that probabilities of detection (POD) are greater than 50% for all different normal seasons and less than 45% for below and above normal seasons. On the other hand, high false alarm (FAR) values and low Critical Success Index (CSI) values are observed for both below and above normal seasons. From our results, one can argue that the NMME seems to be an interesting tool during the first three forecasting lead times in CA capable of providing important seasonal characteristics before the start of each season, which will allow proper consideration of meteorological phenomena. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is an infectious disease caused by the Mycobacterium tuberculosis (M. tuberculosis) complex, resposible for health problems in developing countries. In Africa, various medicinal plants are traditionally used to treat TB. The aim of this study is to carry out the phytochemical screening, to evaluate the antimycobacterial activity of the crude extracts of three medicinal plants present in Cameroon (Zingiber officinale, Vitellaria paradoxa and Alstonia boonei) and the acute toxicity of hydroethanolic extract of Vitellaria paradoxa. The phytochemical screening was obtained by hydroethanolic extraction and decoction. Inhibitory parameters of antimycobacterial activities were determined using the microplate alamar blue assay against M. tuberculosis H37Rv (ATCC 27294) and on one M. tuberculosis clinical strain. The crude extract with the best antimycobacterial activity was used for the acute toxicity assessment according to the OECD protocol. The results of the phytochemical screening revealed the presence of triterpenes and steroids in all the extracts, whereas phenols were only present in the decoction of Alstonia boonei. All extracts tested showed antimycobacterial activities. The hydroethanolic extract of V. paradoxa presented the best antimycobacterial activity with MICs of 78.13 and 625 μg/mL and MBCs of 78.13 and 2500 μg/mL respectively on M. tuberculosis H37Rv and on M. tuberculosis clinical strain. The results of the acute toxicity evaluation of V. paradoxa showed a lethal dose 50 greater than 5000 mg/kg compared to control. The antimycobacterial activity of all the plant extracts used in this study justifies the traditional use of these medicinal plants on the treatment of TB. [ABSTRACT FROM AUTHOR]

Background: Human co-infection with malaria and helmimths is ubiquitous throughout Africa. Nevertheless, its public health significance on malaria severity remains poorly understood. Methodology/Principal Findings: To contribute to a better understanding of epidemiology and control of this co-infection in Cameroon, a cross-sectional study was carried out to assess the prevalence of concomitant intestinal geohelminthiasis and malaria, and to evaluate its association with malaria and anaemia in Nkassomo and Vian. Finger prick blood specimens from a total of 263 participants aged 1–95 years were collected for malaria microscopy, assessment of haemoglobin levels, and molecular identification of Plasmodium species by PCR. Fresh stool specimens were also collected for the identification and quantification of geohelminths by the Kato-Katz method. The prevalence of malaria, geohelminths, and co-infections were 77.2%, 28.6%, and 22.1%, respectively. Plasmodium falciparum was the only malaria parasite species identified with mean parasite density of 111 (40; 18,800) parasites/µl of blood. The geohelminths found were Ascaris lumbricoides (21.6%) and Trichuris trichiura (10.8%), with mean parasite densities of 243 (24; 3,552) and 36 (24; 96) eggs/gram of faeces, respectively. Co-infections of A. lumbricoides and P. falciparum were the most frequent and correlated positively. While no significant difference was observed on the prevalences of single and co-infections between the two localities, there was a significant difference in the density of A. lumbricoides infection between the two localities. The overall prevalence of anaemia was 42%, with individuals co-infected with T. trichiura and P. falciparum (60%) being the most at risk. While the prevalence of malaria and anaemia were inversely related to age, children aged 5–14 years were more susceptible to geohelminthiasis and their co-infections with malaria. Conclusion/Significance: Co-existence of geohelminths and malaria parasites in Nkassomo and Vian enhances the occurrence of co-infections, and consequently, increases the risk for anaemia. Author Summary: Co-infection of malaria and intestinal helminths causes significant and additive problems against the host. In order to contribute to a better understanding of the epidemiology and control of concomitant intestinal geohelminthiasis and malaria infections in Cameroon, a cross-sectional study to assess its prevalence and evaluate its influence on malaria and anaemia was carried out in two rural communities (Nkassomo and Vian) of the Mfou health district. Fresh stool and finger prick blood samples from 263 participants aged 1–95 years were analysed to identify and quantify the geohelminths and malaria parasites respectively. Anaemia was assessed by measuring the haemoglobin levels. Whereas Plasmodium falciparum (77.2%) was the only malaria parasite species found in the study population, Ascaris lumbricoides (21.6%) and Trichuris trichiura (10.8%) were the only geohelminths detected. The prevalence of malaria and geohelminth co-infections was 22.1% with co-infections of A. lumbricoides and P. falciparum being the most frequently encountered and associating positively. The prevalence of anaemia was 42%, with the most affected being those with co-infections of T. trichiura and P. falciparum. Schoolchildren had significantly higher risk of geohelminthiasis, and their co-infection is a cause for concern and should strategically be considered in the designing and implementation of their control. [ABSTRACT FROM AUTHOR]

Abstract: Ricinodendron heudelotii is a valuable multipurpose tree from Africa that is lacking an efficient and inexpensive vegetative propagation method. To improve multiplication, a series of nursery experiments were conducted to assess the effect of propagation media, plant growth regulators (NAA and IBA), accession source harvest timing, cutting type, and pre-treatment with honey. Maximum survival and rooting percentages of 90.2 and 93.7% respectively were achieved in all experiments. The maximum number of leaves and roots were respectively, 7.4 and 8.7; maximum root length was 15.6cm. Fine sand was superior to sawdust or fine sand:sawdust mixture. IBA, at 100μg/l was more effective than NAA for rooting and growth. Principal component analysis showed that, independent of the accession source, cuttings harvested from April to May were more suitable for propagation, giving the highest rates of rooting and growth. In contrast, variable results were achieved with apical cuttings (highest rooting), basal single-node leafy cuttings (highest number of leaves and length of root) and basal two-node leafy cuttings (highest number of roots). Cuttings were more successful when they were soaked in honey for 60min. After acclimatization, maximum survival rate of plants was 67.6%. This improved protocol can be incorporated into agro forestry system in which propagation of R. heudelotii is a component. [Copyright &y& Elsevier]

Background: The recent epidemic of diabetes mellitus (DM) in Africa, coupled with rampant poverty, is an indication of the urgent need to develop new efficacious, cheaper and more available drugs to face this growing public health challenge. A number of plants products among which the protein-rich Cucurbitaceae seeds are commonly used in traditional medicine with increasing acclaimed efficacy against DM. The aim of this study was to analyse and evaluate the hypoglycaemic activity of storage proteins of five species of Cucurbitaceae, which include Telfairia occidentalis, Citrullus lanatus, Lagenaria siceraria, Cucumeropsis mannii and Cucurbita moschata. Methods: The different families of storage proteins were extracted following differential solubility, and their contents were estimated using the Bradford method. The analysis of these proteins was done by electrophoresis in non-denaturing and denaturing conditions. The evaluation of hypoglycaemic properties of various globulins extracted was performed on male Wistar rats by the oral glucose tolerance test. Results: The results showed that among the proteins extracted, globulins constitute the most abundant class of storage proteins in all five species selected. Citrullus lanatus and Cucurbita moschata presented the highest levels of globulin (275.34 and 295.11 mg/g dry matter, respectively). The results of electrophoresis showed that all species possess acidic and neutrals albumins and globulins, with molecular weight of protein subunits ranging from 6.36-44.11 kDa for albumins, 6.5-173.86 kDa for globulins and 6.5-49.66 kDa for glutelins. The 6.36 kDa of albumin subunit protein and the 6.5 kDa of globulin subunit protein were present in all the species. The oral glucose tolerance test showed that the globulins of the seeds of all species except Cucumeropsis mannii caused significant drop in blood sugar (88 - 137.80%, compared to the controls, p<0.05). Conclusions: These findings showed that the selected Cucurbitaceae seeds contained globulins with significant anti-hyperglycaemic activity. It is therefore highly encouraged to pursue investigations towards development of peptide-drugs and/or phytomedicines from these bioactive proteins which could be used as affordable alternative therapy against DM. [ABSTRACT FROM AUTHOR]

Background: Entada abyssinica is a plant traditionally used against gastrointestinal bacterial infections. Eight compounds including three flavonoids, three terpenoids, a monoglyceride and a phenolic compound isolated from E. abyssinica were investigated for their cytotoxicity, antibacterial and antioxidant activity., Results: Compounds 7 and 2 had remarkable activity against Salmonella typhimurium with the lowest respective minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL. The antioxidant assay gave IC 50 values varied from 0.48 to 2.87 μg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, from 2.53 to 17.04 μg/mL in the 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay and from 1.43 to 103.98 µg/mL in the FRAP assay. Compounds had relatively low cytotoxicity (LC 50 values ranging from 22.42 to 80.55 µg/mL) towards Vero cells. Ursolic acid had the most potent cytotoxicity against THP-1 and RAW 264.7 cells with LC 50 values of 9.62 and 4.56 μg/mL respectively, and selectivity index values of 7.32 and 15.44 respectively., Conclusion: Our findings suggest that among the terpenoid and flavonoid compounds studied, entadanin (compound 7) possess tremendous antibacterial activity against S. typhimurium and could be developed for the treatment of bacterial diseases.