29 research outputs found
LANGUAGE ARRANGEMENT AND GLOBALIZATION OF WORLD LANGUAGES WITH A SPECIAL EMPHASIS ON NIGERIA (Ref No 556)
Motivation: This millennium constitutes an important context for any analysis or any intervention in policies of language at the level of states and regions and globally worldwide. Objectives:The objectives of this work were to examine the concepts of expansion or limitation of language planning and language policy and the scope of such concepts in specific linguistic situations such as in Nigeria with international languages. Methodology:It describes the hierarchy and functioning of languages in the world and in Nigeria in particular. It also focuses on the two strongest trends characterizing the current dynamic: the displacement of minority languages as the case in Nigeria and the expansion of English, French and Chinese as the sole world languages. In addition, this article studies the main strategies employed by various actors to oppose these trends, including in particular the representatives of the major national languages such as Igbo, Yoruba, Hausa in Nigeria as an example, whose presence is threatened in several strategic geographical areas. Findings: The reinforcement of local languages weakens national languages that are obstacle for the expansion of English. The reverse is observed in Nigeria where minority languages are not revitalized and where only major languages are thought in schools therefore neglecting minority languages and as a consequence reinforcing the expansion of English. This tendency can only be reversed if anything like a major language is wiped out, therefore giving a chance to every language to prosper and this will also help to stop other languages to disappear. Research Outcomes: This study highlights the role of stakeholders and emphasizes the importance of an expanded concept of language planning that takes into account all the competing forces so as to ensure the success of language policies. Future Scope: It is clear that States, families and enterprises learn languages of higher statuses in the hierarchy and this explains the progress and the expansion of the English circle but also of other super central languages such as Spanish but more importantly the new attractive pole which is Mandarin but also Nigerian languages
In vivo antimalarial effect of Ananas comosus (L) Merr (Bromeliaceae) fruit peel, and gas chromatography-mass spectroscopy profiling: A possible role for polyunsaturated fatty acid
Purpose: To evaluate the antimalarial effect of Ananas comosus extract and fractions and also to identify the likely bioactive compounds.Method: The fruit peel of the plant was extracted with methanol, and the extract successively fractionated with n-hexane, dichloromethane, ethyl acetate, methanol and water. The n-hexane fraction was further subjected to vacuum liquid chromatography to afford four sub-fractions, one of which was also analyzed using gas chromatography-mass spectroscopy (GC-MS). Plasmodium berghei-infected mice were treated orally with three doses (100, 200 and 400 mg/kg) of the plant extract and a single dose (200 mg/kg) of each of the fractions and sub-fractions in a curative antimalarial model using artemisinin combination therapy (ACT) as the reference drug.Results: The extract exhibited significant (p < 0.001) non-dose dependent parasitemia inhibitory activity in the range of 44.84 to 76.09 %. All fractions displayed inhibitory effect (p < 0.001) in the range of 46.44 to 87.58 % with the dichloromethane fraction displaying the highest effect (87.58 %). The subfractions exhibited significant inhibitory effect (p < 0.001) in the range of 84.14 to 92.54 %. The ACT produced significant (p < 0.001) inhibitory effect of 83.92 %. GC-MS analysis revealed the presence of 17 bioactive compounds, the most abundant of which were linoleic acid and palmitic acid.Conclusion: A. comosus displays strong antimalarial activity which supports the folkloric use of the plant for malarial treatment. A polyunsaturated fatty acid (linoleic acid) was the most abundant phytoconstituent identified.
Keywords: Ananas comosus, Antimalarial, Malaria, Pineapple, Plasmodium beighe
Steroid Alkaloids from Holarrhena africana with Strong Activity against Trypanosoma brucei rhodesiense
In our continued search for natural compounds with activity against Trypanosoma brucei, causative agent of human African trypanosomiasis (HAT, "sleeping sickness"), we have investigated extracts from the leaves and bark of the West African Holarrhenaafricana (syn. Holarrhena floribunda; Apocynaceae). The extracts and their alkaloid-enriched fractions displayed promising in vitro activity against bloodstream forms of T. brucei rhodesiense (Tbr; East African HAT). Bioactivity-guided chromatographic fractionation of the alkaloid-rich fractions resulted in the isolation of 17 steroid alkaloids, one nitrogen-free steroid and one alkaloid-like non-steroid. Impressive activities (IC50 in µM) against Tbr were recorded for 3β-holaphyllamine (0.40 ± 0.28), 3α-holaphyllamine (0.37 ± 0.16), 3β-dihydroholaphyllamine (0.67 ± 0.03), N-methylholaphyllamine (0.08 ± 0.01), conessimine (0.17 ± 0.08), conessine (0.42 ± 0.09), isoconessimine (0.17 ± 0.11) and holarrhesine (0.12 ± 0.08) with selectivity indices ranging from 13 to 302. Based on comparison of the structures of this congeneric series of steroid alkaloids and their activities, structure-activity relationships (SARs) could be established. It was found that a basic amino group at position C-3 of the pregnane or pregn-5-ene steroid nucleus is required for a significant anti-trypanosomal activity. The mono-methylated amino group at C-3 represents an optimum for activity. ∆(5,6) unsaturation slightly increased the activity while hydrolysis of C-12β ester derivatives led to a loss of activity. An additional amino group at C-20 engaged in a pyrrolidine ring closed towards C-18 significantly increased the selectivity index of the compounds. Our findings provide useful empirical data for further development of steroid alkaloids as a novel class of anti-trypanosomal compounds which represent a promising starting point towards new drugs to combat human African trypanosomiasis
Bioactivity guided fractionation of Icacina trichantha Oliv. (Icacinaceae) tuber for antimalarial activity against Plasmodium berghei infected mice and GC-MS profile of bioactive fraction
Aqueous methanol extract of the tuber of Icacina trichantha was prepared using cold maceration and dried in vacuo at 40°C. The extract was purified using solvent-solvent partitioning with n-hexane, dichloromethane, ethyl acetate, n-butanol. n-Hexane fraction was purified using Vacuum Liquid Chromatography, eluting with a gradient of dichloromethane in methanol (9:1, 7:3, 5:5, 0:10, each 500 mL) to obtain four sub-fractions. Acute toxicity study was done using Lorke’s method while in vivo anti-malarial study was carried out using suppressive model. Phytochemical analysis was carried out using standard procedure and most active sub-fraction was subjected to gas chromatography-mass spectroscopy. The extract at doses of 100, 200 and 400 mg/kg caused a significant (p<0.001) increase in percentage suppression of Plasmodium: 91.54 %, 94.48 % and 94.58% respectively. Phytochemical analysis of the extract revealed the presence of alkaloids, tannins, flavonoids saponin, glycoside, terpenoids, phenols, steroids, carbohydrates, reducing sugars. The GC-MS analysis showed the presence of eighteen compounds, the most abundant compound includes 9- octadecenoic acid (Z)-, methyl ester (oleic acid, 15.30%), 9, 12-octadecadienoic acid (Z, Z), methyl ester (linoleic acid, 14.34%). These findings suggest scientific evidence in support to the use of I. trichantha tuber for the management of malaria
Chemical constituents of Combretum dolichopetalum: Characterization, antitrypanosomal activities and molecular docking studies
Purpose: To evaluate the in vitro activities of a gallic acid ester and two apigenin flavone glucoside constituents of Combretum dolichopetalum against Trypanosoma brucei brucei s427 (Tbs427) and Trypanosoma congolense IL3000 (Tc-IL3000), and their interactions with a lysosomal papain-like cysteine protease (CP) enzyme in silico.Methods: Anti-trypanosomal activity-guided separation of ethyl acetate fraction using column chromatographic (CC) technique and purification of the CC sub-fractions with semi-preparative HPLC yielded three (1-3) compounds. The structures were characterized based on nuclear magnetic resonance (NMR) spectroscopic analyses and tested for activities against Tbs427 and Tc-IL3000. All the compounds were subjected to molecular docking studies for the inhibition of trypanosomal cathepsin B (TbCatB) CP.Results: An ester (1), a butyl gallate, and two positional isomeric apigenin flavone glucosides (2, 3) were identified. The compounds 2 (vitexin) and 3 (isovitexin) showed low in vitro IC50 against the tested parasites. However, 2 (IC50, 25 μM) was more potent than 3 (IC50, 68 μM) against Tbs427 while both were equipotent (IC50 = 2, 11.5 μM and 3, 10.8 μM) against Tc-IL3000. Compound 1 (butyl gallate) showed higher activity against Tc-IL3000 (IC50 = 0.80 μM) than to Tbs427 (IC50, 2.72 μM). The molecular docking study showed that all the compounds had minimum binding energies with a higher affinity towards the active pocket of TbCatB compared to the controls and native inhibitor (CA074).Conclusion: The relatively high in vitro activities and their strong affinity for TbCatB support the need for further optimization of the compounds towards lead identification against animal trypanosomiasis
Potent antitrypanosomal activities of 3-aminosteroids against African trypanosomes: investigation of cellular effects and of cross-resistance with existing drugs. Molecules
Treatment of animal African trypanosomiasis (AAT) requires urgent need for safe, potent and affordable drugs and this has necessitated this study. We investigated the trypanocidal activities and mode of action of selected 3-aminosteroids against Trypanosoma brucei brucei. The in vitro activity of selected compounds of this series against T. congolense (Savannah-type, IL3000), T. b. brucei (bloodstream trypomastigote, Lister strain 427 wild-type (427WT)) and various multi-drug resistant cell lines was assessed using a resazurin-based cell viability assay. Studies on mode of antitrypanosomal activity of some selected 3-aminosteroids against Tbb 427WT were also carried out. The tested compounds mostly showed moderate-to-low in vitro activities and low selectivity to mammalian cells. Interestingly, a certain aminosteroid, holarrhetine (10, IC50 = 0.045 ± 0.03 µM), was 2 times more potent against T. congolense than the standard veterinary drug, diminazene aceturate, and 10 times more potent than the control trypanocide, pentamidine, and displayed an excellent in vitro selectivity index of 2130 over L6 myoblasts. All multi-drug resistant strains of T. b. brucei tested were not significantly cross-resistant with the purified compounds. The growth pattern of Tbb 427WT on long and limited exposure time revealed gradual but irrecoverable growth arrest at ≥ IC50 concentrations of 3-aminosteroids. Trypanocidal action was not associated with membrane permeabilization of trypanosome cells but instead with mitochondrial membrane depolarization, reduced adenosine triphosphate (ATP) levels and G2/M cell cycle arrest which appear to be the result of mitochondrial accumulation of the aminosteroids. These findings provided insights for further development of this new and promising class of trypanocide against African trypanosomes
Ecological footprint, urbanization, and energy consumption in South Africa: including the excluded
The study explores the relationship between ecological footprint, urbanization, and energy consumption by applying the ARDL estimation technique on data spanning 1965–2014 for South Africa. After applying the unit root test that accounts for a break in the data, the Bayer and Hanck (J Time Ser Anal 34:83–95, 2013) combined cointegration test affirms cointegrating relationship
among the variables. Findings further reveal that economic growth and financial development exact a deteriorating impact on the environment in the short run. However, the same was not true for both energy use and urbanization. While urbanization and energy use promote environmental quality in the long run, financial development and economic growth degrade it further. The
long-run findings of our study are confirmed to be robust as reported by the fully modified OLS (FMOLS), dynamic OLS (DOLS), and the canonical cointegrating regression (CCR) estimates. The direction of causality supports the energy-led growth hypothesis for South Africa. Policy outcomes and directions, and the possibility of promoting sustainable growth without degrading the environment are discussed
Pediatric Bacterial Meningitis Surveillance in Nigeria From 2010 to 2016, Prior to and During the Phased Introduction of the 10-Valent Pneumococcal Conjugate Vaccine.
BACKGROUND: Historically, Nigeria has experienced large bacterial meningitis outbreaks with high mortality in children. Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae are major causes of this invasive disease. In collaboration with the World Health Organization, we conducted longitudinal surveillance in sentinel hospitals within Nigeria to establish the burden of pediatric bacterial meningitis (PBM). METHODS: From 2010 to 2016, cerebrospinal fluid was collected from children <5 years of age, admitted to 5 sentinel hospitals in 5 Nigerian states. Microbiological and latex agglutination techniques were performed to detect the presence of pneumococcus, meningococcus, and H. influenzae. Species-specific polymerase chain reaction and serotyping/grouping were conducted to determine specific causative agents of PBM. RESULTS: A total of 5134 children with suspected meningitis were enrolled at the participating hospitals; of these 153 (2.9%) were confirmed PBM cases. The mortality rate for those infected was 15.0% (23/153). The dominant pathogen was pneumococcus (46.4%: 71/153) followed by meningococcus (34.6%: 53/153) and H. influenzae (19.0%: 29/153). Nearly half the pneumococcal meningitis cases successfully serotyped (46.4%: 13/28) were caused by serotypes that are included in the 10-valent pneumococcal conjugate vaccine. The most prevalent meningococcal and H. influenzae strains were serogroup W and serotype b, respectively. CONCLUSIONS: Vaccine-type bacterial meningitis continues to be common among children <5 years in Nigeria. Challenges with vaccine introduction and coverage may explain some of these finding. Continued surveillance is needed to determine the distribution of serotypes/groups of meningeal pathogens across Nigeria and help inform and sustain vaccination policies in the country