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Background: While the introduction of HIV Pre-Exposure Prophylaxis (PrEP) as an HIV prevention strategy has allowed women to exercise more control over the reduction of HIV transmission rates, adolescent girls and young women in Sub-Saharan Africa continue to experience higher rates of HIV infections and bear the greatest disease burden. Understanding progress in PrEP uptake among adolescent girls and young women would enhance risk reduction in this vulnerable population. The Determined, Resilient, AIDS-Free, Mentored and Safe women (DREAMS) Initiative plays a key role in this risk reduction strategy., Methods: We performed a qualitative study to explore facilitators and barriers to PrEP implementation and assess factors effecting initiation and persistence on PrEP among adolescent girls and young women enrolled in the DREAMS Initiative at Pamoja Community Based Organization in Kisumu, Kenya. We conducted key informant interviews (n = 15) with Pamoja Community Based Organization staff, health care providers and community leaders. Additionally, we conducted focus group discussions with young women receiving PrEP and peer mentors (n = 40). We performed a directed content analysis using the Consolidated Framework for Implementation Research to organize the identified facilitators and barriers., Results: We found that the use of the safe space model, decentralization of PrEP support and delivery, peer mentors, effective linkage to local health care facilities, the sensitization of parents and male sexual partners, disclosure of PrEP use by beneficiaries, active stakeholder involvement and community engagement were among some of the facilitators to PrEP uptake. Barriers to PrEP implementation, initiation and persistence included stigma associated with the use of anti-retroviral drugs, drug side effects, frequent relocation of beneficiaries, limited resources for routine screening and medication monitoring, and a limited number of qualified health care workers for PrEP distribution and administration., Conclusion: Overall, the community roll-out of PrEP within the DREAMS Initiative was successful due to a number of key facilitating factors, which ultimately led to successful PrEP implementation, increased PrEP initiation and enhanced persistence among adolescent girls and young women. The identified barriers should be addressed so that a larger scale-up of PrEP roll-out is possible in the future.

A new oleanane type triterpene characterized as 3α, 24-diacetoxy-12-oleanene (1) together with known compounds 2-10 , were isolated from Annona mucosa leaf extracts. Their structural elucidation was accomplished using physical and spectroscopic methods. The compounds showed weak to moderate insecticidal activities against stored maize insect pests Sitophilus zeamais and Prostephanus truncatus .[Formula: see text].

The distribution and sources of organochlorine pesticides (OCPs) in air and surface waters were monitored in Nairobi City using triolein-filled semipermeable membrane devices (SPMDs). The SPMDs were extracted by dialysis using n-hexane, followed by cleanup by adsorption chromatography on silica gel cartridges. Sample analysis was done by GC-ECD and confirmed by GC-MS. Separation of means was achieved by analysis of variance, followed by pair-wise comparison using the t-test (p≤ 0.05). The total OCPs ranged between 0.018 - 1.277 ng/m 3 in the air and 3 in surface waters. Based on the results, the means of Industrial Area, Dandora and Kibera were not significantly different (p≤ 0.05), but were higher (p≤ 0.05) than those of City square and Ngong' Forest. The results revealed non-significant (p≤ 0.05) contribution of long-range transport to OCP pollution in Nairobi City. This indicated possible presence of point sources of environmental OCPs in the city. The water-air fugacity ratios indicated that volatilization and deposition played an important role in the spatial distribution of OCPs in Nairobi City. This indicated that contaminated surface waters could be major sources of human exposure to OCPs, through volatilization. The incremental lifetime cancer risks (ILCR) determined from inhalation of atmospheric OCPs were 2.3745  ×  10 -13 - 1.6845  ×  10 -11 (adult) and 5.5404  ×  10 -13 - 3.9306  ×  10 -11 (child) in the order: Dandora > Kibera > Industrial Area > City Square > Ngong' Forest. However, these were lower than the USEPA acceptable risks, 10 -6 - 10 -4 . This study concluded that atmospheric OCPs did not pose significant cancer risks to the residents., (Copyright © 2020. Published by Elsevier B.V.)

Background: Vector-borne diseases are increasingly becoming a major health problem among communities living along the major rivers of Africa. Although larger water bodies such as lakes and dams have been extensively researched, rivers and their tributaries have largely been ignored. This study sought to establish the spatial distribution of mosquito species during the dry season and further characterize their habitats along the Mara River and its tributaries., Methods: In this cross-sectional survey, mosquito larvae were sampled along the Mara River, its two perennial tributaries (Amala and Nyangores), drying streams, and adjacent aquatic habitats (e.g. swamps, puddles that receive direct sunlight [open sunlit puddles], rock pools, hippo and livestock hoof prints, and vegetated pools). Each habitat was dipped 20 times using a standard dipper. Distance between breeding sites and human habitation was determined using global positioning system coordinates. The collected mosquito larvae were identified using standard taxonomic keys. Water physico-chemical parameters were measured in situ using a multiparameter meter. Mean mosquito larvae per habitat type were compared using analysis of variance and chi-square tests, while the relationship between mosquito larvae and physico-chemical parameters was evaluated using a generalized linear mixed model. The Cox-Stuart test was used to detect trends of mosquito larvae distribution. The test allowed for verification of monotonic tendency (rejection of null hypothesis of trend absence) and its variability., Results: A total of 4001 mosquito larvae were collected, of which 2712 (67.8%) were collected from river/stream edge habitats and 1289 (32.2%) were sampled from aquatic habitats located in the terrestrial ecosystem about 50 m away from the main river/streams. Anopheles gambiae s.s, An. arabiensis, and An. funestus group, the three most potent vectors of malaria in Sub-Saharan Africa, together with other anopheline mosquitoes, were the most dominant mosquito species (70.3%), followed by Culex quinquefasciatus and Cx. pipiens complex combined (29.5%). Drying streams accounted for the highest number of larvae captured compared to the other habitat types. A stronger relationship between mosquito larvae abundance and dissolved oxygen (Z = 7.37, P ≤ 0.001), temperature (Z = 7.65, P ≤ 0.001), turbidity (Z = -5.25, P ≤ 0.001), and distance to the nearest human habitation (Z = 4.57, P ≤ 0.001), was observed., Conclusions: Presence of malaria and non-malaria mosquito larvae within the Mara River basin calls for immediate action to curtail the insurgence of vector-borne diseases within the basin. A vector control program should be conducted during the dry period, targeting drying streams shown to produce the highest number of larval mosquitoes.

A new β-carboline alkaloid named sacleuximine A (1) together with known compounds palmatine (2), isotetrandrine (3), trans-N-feruloyltyramine (4), trans-N-caffeoyltyramine (5), yangambin (6), syringaresinol (7), sesamin (8), (+) epi-quercitol (9), 4-hydroxybenzaldehyde (10), β-sitosterol (11), quercetin 3-O-rutinoside (12) and myricetin 3-O-β-glucose (1→6) α-rhamnoside (13) have been isolated from methanol extract of Triclisia sacleuxii aerial parts. Compounds 1-10 were evaluated for their cytotoxicity against human adenocarcinoma (HeLa), human hepatocarcinoma (Hep3B) and human breast carcinoma (MCF-7) cells lines and also for antibacterial activities against both Gram-positive and Gram-negative bacteria. The cytotoxicity (IC 50 ) values ranged between 0.15 and 36.7 μM while the minimum inhibitory concentrations were found to be in the range of 3.9 and 125 μM, respectively. This is the first report of antibacterial compounds and the isolation of lignans together with a β-carboline alkaloid from T. sacleuxii.

Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest destruction followed by human settlement and agricultural activities. These anthropogenic activities may be contributing nutrients and heavy metals, ultimately polluting the river water and eventually Lake Victoria water hence damaging these aquatic ecosystems. This study sought to establish the effect of anthropogenic activities and season on the water quality of the Amala and Nyangores tributaries of the River Mara in Kenya. Pristine springs in the Mau Forest were used as reference sites. Water samples were analyzed for pH, temperature, conductivity, nutrients, selected heavy metals, and selenium. The mean range of the parameters measured from sites along the tributaries was pH 5.44-7.48 and that for conductivity was 20-99 μS/cm while the mean range of nutrient levels (μg/L) was 80-443 (NO3--N), 21.7-82.7 (NH4+-N), 11.9-65.0 (soluble reactive phosphorous), and 51-490 (total phosphorous). The mean range for heavy metals and selenium (in μg/L) from sites along the tributaries were 6.56-37.6 (Cu), 0.26-4.97 (Cd), 13.9-213 (Zn), 0.35-3.14 (Cr), 0.19-5.53 (Mn), 1.90-9.62 (Pb), and 0.21-4.50 (Se). The results indicated a significant difference (p≤0.05) between the reference sites and the different sampling sites, indicating that anthropogenic activities were impacting the quality of water in the two tributaries. Although most of the parameters were within the WHO (2004), USEPA (2014) and NEMA (2006) acceptable limits for surface waters, they were above the permissible levels for domestic use. Moreover, the levels of nutrients, heavy metals, and selenium were significantly higher in the wet season than in the dry season, further indicating that anthropogenic activities are causing a disturbance in the aquatic system. Therefore, further anthropogenic activities should be checked and limited so as to conserve the ecosystem.

Among all the malaria controlling measures, biological control of mosquito larvae may be the cheapest and easiest to implement. This study investigated baseline predation of immature mosquitoes by macroinvertebrate predators along the Mara River, determined the diversity of predators and mosquito larvae habitats and the range of their adaptive capacity to water physico-chemical parameters. Between July and August 2011, sampling sites (n=39) along the Mara River were selected and investigated for the presence of macroinvertebrate predators and mosquito larvae. The selected sampling sites were geocoded and each dipped 20 times using standard mosquito larvae dipper to sample mosquito larvae, while a D-frame dip net was used to capture the macroinvertebrate predators. Water physico-chemical parameters (dissolved oxygen, temperature, pH, conductivity, salinity and turbidity) were taken in situ at access points, while hardness and alkalinity were measured titrimetically. The influence of macroinvertebrate predator occurrence was correlated with mosquito larvae and water quality parameters using Generalized Linear Model (GLM). Predators (n=297) belonging to 3 orders of Hemiptera (54.2%), Odonata (22.9%) and Coleoptera (22.9%), and mosquito larvae (n=4001) belonging to 10 species, which included An.gambiae s.l (44.9%), Culex spp. (34.8%) and An. coustani complex (13.8%), An. maculipalpis (3.6%), An. phaorensis (1.2%), An. funestus group (0.5%), An. azaniae (0.4%), An. hamoni (0.3%), An. christyi (0.3%), An. ardensis (0.08%), An. faini (0.07%), An. sergentii (0.05%) and 0.05% of Aedes mosquito larvae which were not identified to species level, due to lack of an appropriate key, were captured from different habitats along the Mara river. It was established that invasion of habitats by the macroinvertebrate predators were partially driven by the presence of mosquito larvae (p < 0.001), and the prevailing water physico-chemical parameters (DO, temperature, and turbidity, p <0.001). Understanding abiotic and biotic factors which favour mosquitoes and macroinveterbrate co-occurrence may contribute to the control of malaria.

We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss - the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus - the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss - the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin.

A new ceramide, 2,3-dihydroxy-N-[(2S,3S,4R)-1,3,4-trihydroxyicosan-2-yl[tetracosanamide (1) along with four known compounds: 2-(4'-hydroxyphenyl)-ethyl lignocerate (2), docosyl-3,4-dihydroxy-trans-cinnamate (3), β-sitosterol (4) and β-sitosterol glycoside (5) were isolated from Tinospora oblongifolia (Menispermaceae). Their structures were determined on the basis of spectroscopic methods, mass spectrometry analysis as well as chemical transformation and by comparing their physical and spectral data with those reported in the literature. Compound 1 exhibited strong cytotoxic activity against KB cells with IC50 = 3.4 μM although less than that of camptothecin IC50 = 0.3 μM (positive control).

Enzyme linked immunosorbent assay (ELISA) kit is a versatile, cheap and relatively available tool that can be used in remote areas. In this study, performance of ELISA kit was evaluated in terms of accuracy, recovery, precision, sensitivity, cross reactivity and matrix interference for pesticide residue determination in water and sediment samples. This method was compared with high performance liquid chromatography (HPLC) which is not a commonly available analytical technique for chlorpyrifos ethyl residue analysis in developing countries. The ELISA kit had limits of detection (LOD) of 0.37 µg L(-1) and 0.42 µg Kg(-1) dry weight (dw), for chlorpyrifos ethyl in water and sediment samples, respectively using deionized water and a control sediment sample. Mean percentage recoveries and coefficients of variation (CV) for ELISA kit varied from 96.0±5.8% to 108.0±3.4% for water and sediment samples. Comparison between ELISA and HPLC analysis results using water and sediment samples from Lake Naivasha showed no significant difference in results (p≤0.05). Strong correlations (r2=0.9878 water samples and r1=0.9670, p<0.0001 for sediment samples, n=48) were reported between the methods for the two samples analyzed. Bland-Altman bias plot analysis showed that the two methods were in agreement within 95% confidence interval of limits -2.9 to 3.8 and -2.2 to 3.6 for water and sediment, respectively. Given the high sensitivity reported and the obtained acceptable limits of coefficient of variation and percentage recovery, ELISA appears to be a suitable rapid analytical tool in analysis of chlorpyrifos ethyl in water and sediment samples. Results demonstrate comparability to HPLC and could complement conventional tools in regular monitoring program particularly in developing countries. This will hasten results delivery for ecological risk assessment and timely execution of mitigation measures., (© 2013 Elsevier B.V. All rights reserved.)

A bioassay guided isolation of potential antimalarial molecules from the stem bark of Caesalpinia volkensii Harms (Fabaceae) achieved three new 11-oxocassane-type diterpenoids named voulkensin C (1), D (2) and E (3) together with one steroid glycoside named 3-O-[β-glucopyranosyl(1→2)-O-β-xylopyranosyl]-stigmasterol (4) and seven other known compounds including stigmasterol (5), β-sitosterol (6), oleanolic acid (7), 3-β-acetoxyolean-12-en-28-methyl ester (8), voucap-5-ol (9), caesadekarin C (10), deoxycaesaldekarin C (11). The structures of the new compounds were determined on the basis of extensive spectroscopic data (IR, MS, (1)H and (13)C NMR and 2D NMR) analyses. The polar extracts revealed moderate to good antiplasmodial activities against chloquine-sensitive (D6) and -resistant strains (W2) of Plasmodium falciparum. Whereas the pure isolates exhibited limited to moderate antiplasmodial activities with compound 4 showing the highest antiplasmodial activities (IC50 values of 4.44±0.88 and 2.74±1.10μM against D6 and W2 strains, respectively). These results suggest a possible contribution of phytochemicals from C. volkensii stem bark towards inhibition of plasmodial parasites' growth hence potential antimalarial., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

This study reports evidence of increased chlorpyrifos contamination in sediment and water in Lake Naivasha following its intensive application in the horticultural farms in the catchment area. Analytical results show that levels of chlorpyrifos residues were influenced by climate-induced rainfall pattern with higher levels reported during period of heavy precipitation with significant decrease during low rainfall. On average, the levels ranged between 14.8 and 32.8 ng g(-1) in sediment during rainy season compared to a range of 8.5-16.6 ng g(-1) in the dry season. Additionally, the mean concentration of chlorpyrifos in water ranged between 8.61 and 22.4 μg L(-1) during rainy season and below detection limit (bdl) -13.6 μg L(-1) in dry season as quantified by enzyme-linked immunosorbent assay. Meanwhile, independent t test analysis indicated that there was significant difference in concentration at p ≤ 0.05 between the seasons with respect to sediment and water samples. This demonstrated that climate-induced variations had considerable influence on contamination. While diazinon and carbofuran were equally applied intensively, their levels were below the detection limit in the all the samples analyzed. ELISA results were validated by the capillary-HPLC photodiode-array detector instrument analysis, and statistical comparison showed no significant difference between them. It was evident that chlorpyrifos residues determination in water and sediment by ELISA can be a useful strategy in environmental management and monitoring program, and a complimentary analytical tool to high performance liquid chromatography. Levels of chlorpyrifos detected in sediment and water were found to exceed recommended criteria for protection of aquatic life and preservation of water quality and may be hazardous if not regularly monitored.

With reference to the ethnopharmacological significance of Vitex doniana Sweet (Lamiaceae) leaves in the treatment of stomach and rheumatic pains as well as inflammatory disorders, biological studies on its stem bark extracts have also reported anti-inflammatory and analgesic activities, with no attempt to identify the active components. Chromatographic and spectroscopic procedures identified three new phytoecdysteroids: 21-hydroxyshidasterone (1), 11β-hydroxy-20-deoxyshidasterone (2), and 2,3-acetonide-24-hydroxyecdysone (3) from the stem bark methanol extracts along with known ecdysteroids shidasterone (4), ajugasterone C (5), 24-hydroxyecdysone (6), and 11β,24-hydroxyecdysone (7). The compounds (1-7) showed significant (p ≤ 0.05) inhibitory effect at 100 mg/kg dose on rat paw oedema development due to carrageenan-induced inflammation in Sprague Dawley rats. These results suggest a possible contribution of ecdysteroids to the anti-inflammatory effect of some V. doniana stem bark extracts., (Georg Thieme Verlag KG Stuttgart · New York.)

The chloroform and ethyl acetate extract (100mg/kg) of Caesalpinia volkensii H. exhibited significant (P ≤ 0.05) antinociceptive activities using hot plate and writhing tests in mice while the later showed antiplasmodial activity (IC(50) 0.23 ± 0.07 and 4.39 ± 2.49 μg/ml) against chloroquine sensitive (D6) and chloroquine-resistant (W2), respectively. Two new furanoditerpenes [rel. 1β,5α-dihydroxyvoucapane (1) and rel. 1β,6β-dihydroxyvoucapane; 19β-methyl ester (2)] together with seven known compounds [voucapane (3), voucapan-5-ol (4), deoxycaesaldekarin C (5), caesaldekarin C (6), 5-hydroxyvinhaticoic acid (7), triacontanyl-(E)-ferulate (8), triacontanyl-(E)-caffaete (9) and 30'-hydroxytriacontanyl-(E)-ferulate (10)] were isolated from the two extracts. The administration of 3, 4, 5 and 6 (100mg/kg i.p) caused a significant (P ≤ 0.05) reduction in the number of writhing episodes induced by acetic acid and (P ≤ 0.01) increased pain latency threshold in hot-plate test compared to control. However, the pure compounds indicated relatively (P ≤ 0.05) low antiplasmodial activity. The phytochemical constituents from the root bark of C. volkensii had better analgesic properties than antimalarial properties, justifying the use of the plant root bark as a remedy for pain., (Copyright © 2011 Elsevier B.V. All rights reserved.)