Publications by authors named "Sunday Makama"

5 Publications

  • Page 1 of 1

Metabolic Implications of Oxidative Stress and Inflammatory Process in SARS-CoV-2 Pathogenesis: Therapeutic Potential of Natural Antioxidants.

Front Cell Infect Microbiol 2021 26;11:654813. Epub 2021 May 26.

Regional Laboratory for Avian Influenza and Other Transboundary Animal Diseases, National Veterinary Research Institute, Vom, Nigeria.

COVID-19 is a zoonotic disease with devastating economic and public health impacts globally. Being a novel disease, current research is focused on a clearer understanding of the mechanisms involved in its pathogenesis and viable therapeutic strategies. Oxidative stress and inflammation are intertwined processes that play roles in disease progression and response to therapy interference with multiple signaling pathways. The redox status of a host cell is an important factor in viral entry due to the unique conditions required for the conformational changes that ensure the binding and entry of a virus into the host cell. Upon entry into the airways, viral replication occurs and the innate immune system responds by activating macrophage and dendritic cells which contribute to inflammation. This review examines available literature and proposes mechanisms by which oxidative stress and inflammation could contribute to COVID-19 pathogenesis. Further, certain antioxidants currently undergoing some form of trial in COVID-19 patients and the corresponding required research gaps are highlighted to show how targeting oxidative stress and inflammation could ameliorate COVID-19 severity.
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http://dx.doi.org/10.3389/fcimb.2021.654813DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8188981PMC
June 2021

Effects of Systematic Variation in Size and Surface Coating of Silver Nanoparticles on Their In Vitro Toxicity to Macrophage RAW 264.7 Cells.

Toxicol Sci 2018 03;162(1):79-88

Division of Toxicology, Wageningen University, WE 6708 Wageningen, The Netherlands.

In literature, varying and sometimes conflicting effects of physicochemical properties of nanoparticles (NPs) are reported on their uptake and effects in organisms. To address this, small- and medium-sized (20 and 50 nm) silver nanoparticles (AgNPs) with specified different surface coating/charges were synthesized and used to systematically assess effects of NP-properties on their uptake and effects in vitro. Silver nanoparticles were fully characterized for charge and size distribution in both water and test media. Macrophage cells (RAW 264.7) were exposed to these AgNPs at different concentrations (0-200 µg/ml). Uptake dynamics, cell viability, induction of tumor necrosis factor (TNF)-α, ATP production, and reactive oxygen species (ROS) generation were assessed. Microscopic imaging of living exposed cells showed rapid uptake and subcellular cytoplasmic accumulation of AgNPs. Exposure to the tested AgNPs resulted in reduced overall viability. Influence of both size and surface coating (charge) was demonstrated, with the 20-nm-sized AgNPs and bovine serum albumin (BSA)-coated (negatively charged) AgNPs being slightly more toxic. On specific mechanisms of toxicity (TNF-α and ROS production) however, the AgNPs differed to a larger extent. The highest induction of TNF-α was found in cells exposed to the negatively charged AgNP_BSA, both sizes (80× higher than control). Reactive oxygen species induction was only significant with the 20 nm positively charged AgNP_Chit.
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http://dx.doi.org/10.1093/toxsci/kfx228DOI Listing
March 2018

Properties of silver nanoparticles influencing their uptake in and toxicity to the earthworm Lumbricus rubellus following exposure in soil.

Environ Pollut 2016 Nov 11;218:870-878. Epub 2016 Aug 11.

Division of Toxicology, Wageningen University and Research Centre, Tuinlaan 5, 6703 HE, Wageningen, The Netherlands. Electronic address:

Physicochemical properties of nanoparticles influence their environmental fate and toxicity, and studies investigating this are vital for a holistic approach towards a comprehensive and adequate environmental risk assessment. In this study, we investigated the effects of size, surface coating (charge) of silver nanoparticles (AgNPs) - a most commonly-used nanoparticle-type, on the bioaccumulation in, and toxicity (survival, growth, cocoon production) to the earthworm Lumbricus rubellus. AgNPs were synthesized in three sizes: 20, 35 and 50 nm. Surface-coating with bovine serum albumin (AgNP_BSA), chitosan (AgNP_Chit), or polyvinylpyrrolidone (AgNP_PVP) produced negative, positive and neutral particles respectively. In a 28-day sub-chronic reproduction toxicity test, earthworms were exposed to these AgNPs in soil (0-250 mg Ag/kg soil DW). Earthworms were also exposed to AgNO at concentrations below known EC. Total Ag tissue concentration indicated uptake by earthworms was generally highest for the AgNP_BSA especially at the lower exposure concentration ranges, and seems to reach a plateau level between 50 and 100 mg Ag/kg soil DW. Reproduction was impaired at high concentrations of all AgNPs tested, with AgNP_BSA particles being the most toxic. The EC for the 20 nm AgNP_BSA was 66.8 mg Ag/kg soil, with exposure to <60 mg Ag/kg soil already showing a decrease in the cocoon production. Thus, based on reproductive toxicity, the particles ranked: AgNP_BSA (negative) > AgNP_PVP (neutral) > Chitosan (positive). Size had an influence on uptake and toxicity of the AgNP_PVP, but not for AgNP_BSA nor AgNP_Chit. This study provides essential information on the role of physicochemical properties of AgNPs in influencing uptake by a terrestrial organism L. rubellus under environmentally relevant conditions. It also provides evidence of the influence of surface coating (charge) and the limited effect of size in the range of 20-50 nm, in driving uptake and toxicity of the AgNPs tested.
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http://dx.doi.org/10.1016/j.envpol.2016.08.016DOI Listing
November 2016

Ethnobotanical survey of medicinal plants used in the treatment of animal diarrhoea in Plateau State, Nigeria.

BMC Vet Res 2011 Jul 11;7:36. Epub 2011 Jul 11.

National Veterinary Research Institute, P.M.B. 01. Vom, Plateau State, Nigeria.

Background: The use of medicinal plants in the treatment of diseases has generated renewed interest in recent times, as herbal preparations are increasingly being used in both human and animal healthcare systems. Diarrhoea is one of the common clinical signs of gastrointestinal disorders caused by both infectious and non-infectious agents and an important livestock debilitating condition. Plateau State is rich in savannah and forest vegetations and home to a vast collection of plants upheld in folklore as having useful medicinal applications. There is however scarcity of documented information on the medicinal plants used in the treatment of animal diarrhoea in the state, thus the need for this survey. Ten (10) out of 17 Local Government Areas (LGAs), spread across the three senatorial zones were selected. Farmers were interviewed using well structured, open-ended questionnaire and guided dialogue techniques between October and December 2010. Medicinal plants reported to be effective in diarrhoea management were collected using the guided field-walk method for identification and authentication.

Results: A total of 248 questionnaires were completed, out of which 207 respondents (83.47%) acknowledged the use of herbs in diarrhoea management, while 41 (16.53%) do not use herbs or apply other traditional methods in the treatment of diarrhoea in their animals. Medicinal plants cited as beneficial in the treatment of animal diarrhoea numbered 132, from which 57(43.18%) were scientifically identified and classified into 25 plant families with the families Fabaceae (21%) and Combretaceae (14.04%) having the highest occurrence. The plant parts mostly used in antidiarrhoeal herbal preparations are the leaves (43.86%) followed by the stem bark (29.82%). The herbal preparations are usually administered orally.

Conclusion: Rural communities in Plateau State are a rich source of information on medicinal plants as revealed in this survey. There is need to scientifically ascertain the authenticity of the claimed antidiarrhoeal properties of these plants and perhaps develop more readily available alternatives in the treatment of diarrhoea.
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http://dx.doi.org/10.1186/1746-6148-7-36DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3162497PMC
July 2011

Characterization of translocation of silver nanoparticles and effects on whole-genome gene expression using an in vitro intestinal epithelium coculture model.

ACS Nano 2011 May 20;5(5):4091-103. Epub 2011 Apr 20.

RIKILT, Institute of Food Safety, Wageningen University and Research Center, Akkermaalsbos 2, P.O. Box 230, 6700 AE Wageningen, The Netherlands.

Applications of nanoparticles in the food sector are eminent. Silver nanoparticles are among the most frequently used, making consumer exposure to silver nanoparticles inevitable. Information about uptake through the intestines and possible toxic effects of silver nanoparticles is therefore very important but still lacking. In the present study, we used an in vitro model for the human intestinal epithelium consisting of Caco-2 and M-cells to study the passage of silver nanoparticles and their ionic equivalents and to assess their effects on whole-genome mRNA expression. This in vitro intestine model was exposed to four sizes of silver nanoparticles for 4 h. Exposure to silver ions was included as a control since 6-17% of the silver nanoparticles were found to be dissociated into silver ions. The amount of silver ions that passed the Caco-2 cell barrier was equal for the silver ion and nanoparticle exposures. The nanoparticles induced clear changes in gene expression in a range of stress responses including oxidative stress, endoplasmatic stress response, and apoptosis. The gene expression response to silver nanoparticles, however, was very similar to that of AgNO(3). Therefore, the observed effects of the silver nanoparticles are likely exerted by the silver ions that are released from the nanoparticles.
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http://dx.doi.org/10.1021/nn2007145DOI Listing
May 2011
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