| 1. |
- Mansoor, Rashid, et al.
(författare)
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Haematological consequences of acute uncomplicated falciparum malaria : a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data
- 2022
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Ingår i: BMC Medicine. - : Springer Nature. - 1741-7015. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundPlasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia.MethodsIndividual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall >= 25% at day 3 and day 7.ResultsA total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0-19.7 g/dL) in Africa, 11.6 g/dL (range 5.0-20.0 g/dL) in Asia and 12.3 g/dL (range 6.9-17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to >= 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39-3.05], p < 0.001).ConclusionsIn patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery.
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| 2. |
- Nkfusai, Ngwayu Claude, et al.
(författare)
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Assessment of the current state of knowledge and risk factors of cervical cancer among women in the Buea Health District, Cameroon
- 2019
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Ingår i: Pan African Medical Journal. - : Pan African Medical Journal. - 1937-8688. ; 33
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: cervical cancer is a malignant proliferation of the cells of the uterine cervix and can be treated if diagnosed earlier. It is the second most common gynecological malignancy worldwide and the leading cause of cancer associated mortality among women in Africa and Cameroon. This study sort to determine the current state of knowledge of cervical cancer and its risk factors in the Buea Health District of the South West Region of Cameroon. Methods: this was a cross-sectional community based survey. We recruited 433 eligible women, in four (4) Health Areas (Molyko, Bolifamba, Muea and Buea Town) of the Buea Health District and used validated and pre-tested questionnaires to collect data. Collected data were keyed into Epi info version 7.2 statistical software and exported to SPSS Version 25 for analysis. Level of significance was set at P-value < 0.05. Results: fifty eight percent (58%) of the participants had good knowledge of cervical cancer. 58.99% (95%CI = 54.30-63.52) had good knowledge on the risk factors of cervical cancer. 40% knew at least one of the following risk factors; cigarette smoking, many sexual partners, family history of cervical cancer, being HIV/AIDS positive and giving birth 5 or more times. There was a significant association, OR = 7.5; 95%CI = 2.14-26.33; P = 0.001; X2 = 11.4 between having heard of cervical cancer and having “good” knowledge of cervical cancer among women in Buea. Conclusion: most of the women had heard of cervical cancer but the knowledge of the risk factors of cervical cancer among women aged 18-68 years in the Buea Health District is low. We found no association between awareness and knowledge of risk factors among the women.
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| 3. |
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| 4. |
- Coincon, Mathieu, et al.
(författare)
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Crystal structures reveal the molecular basis of ion translocation in sodium/proton antiporters
- 2016
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Ingår i: Nature Structural & Molecular Biology. - : Springer Science and Business Media LLC. - 1545-9993 .- 1545-9985. ; 23:3, s. 248-255
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Tidskriftsartikel (refereegranskat)abstract
- To fully understand the transport mechanism of Na+/H+ exchangers, it is necessary to clearly establish the global rearrangements required to facilitate ion translocation. Currently, two different transport models have been proposed. Some reports have suggested that structural isomerization is achieved through large elevator-like rearrangements similar to those seen in the structurally unrelated sodium-coupled glutamate-transporter homolog Glt(ph). Others have proposed that only small domain movements are required for ion exchange, and a conventional rocking-bundle model has been proposed instead. Here, to resolve these differences, we report atomic-resolution structures of the same Na+/H+ antiporter (NapA from Thermus thermophilus) in both outward- and inward-facing conformations. These data combined with cross-linking, molecular dynamics simulations and isothermal calorimetry suggest that Na+/H+ antiporters provide alternating access to the ion-binding site by using elevator-like structural transitions.
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| 5. |
- Lee, Chiara, et al.
(författare)
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MemStar : A one-shot Escherichia coli-based approach for high-level bacterial membrane protein production
- 2014
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 588:20, s. 3761-3769
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Tidskriftsartikel (refereegranskat)abstract
- Optimising membrane protein production yields in Escherichia coli can be time- and resource-consuming. Here, we present a simple and effective Membrane protein Single shot amplification recipe: MemStar. This one-shot amplification recipe is based on the E. coli strain Lemo21(DE3), the PASM-5052 auto-induction medium and, contradictorily, an IPTG induction step. Using MemStar, production yields for most bacterial membrane proteins tested were improved to reach an average of 5 mg L-1 per OD600 unit, which is significantly higher than yields obtained with other common production strategies. With MemStar, we have been able to obtain new structural information for several transporters, including the sodium/proton antiporter NapA. (C) 2014 Federation of European Biochemical Societies.
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| 6. |
- Moure, Vivian R., et al.
(författare)
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The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense
- 2019
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 286:6, s. 1214-1229
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Tidskriftsartikel (refereegranskat)abstract
- The ammonium-dependent posttranslational regulation of nitrogenase activity in Azospirillum brasilense requires dinitrogenase reductase ADPribosyl transferase (DraT) and dinitrogenase reductase ADP-glycohydrolase (DraG). These enzymes are reciprocally regulated by interaction with the PII proteins, GlnB and GlnZ. In this study, purified ADP-ribosylated Fe-protein was used as substrate to study the mechanism involved in the regulation of A. brasilense DraG in vitro. The data show that DraG is partially inhibited by GlnZ and that DraG inhibition is further enhanced by the simultaneous presence of GlnZ and AmtB. These results are the first to demonstrate experimentally that DraG inactivation requires the formation of a ternary DraG-GlnZ-AmtB complex in vitro. Previous structural data have revealed that when the DraG-GlnZ complex associates with AmtB, the flexible T-loops of the trimeric GlnZ bind to AmtB and become rigid; these molecular events stabilize the DraG-GlnZ complex, resulting in DraG inactivation. To determine whether restraining the flexibility of the GlnZ T-loops is a limiting factor in DraG inhibition, we used a GlnZ variant that carries a partial deletion of the T-loop (GlnZD42-54). However, although the GlnZD42-54 variant was more effective in inhibiting DraG in vitro, it bound to DraG with a slightly lower affinity than does wild-type GlnZ and was not competent to completely inhibit DraG activity either in vitro or in vivo. We, therefore, conclude that the formation of a ternary complex between DraG-GlnZ-AmtB is necessary for the inactivation of DraG.
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| 7. |
- Nji, Emmanuel, et al.
(författare)
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An engineered thermal-shift screen reveals specific lipid preferences of eukaryotic and prokaryotic membrane proteins
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Membrane bilayers are made up of a myriad of different lipids that regulate the functional activity, stability, and oligomerization of many membrane proteins. Despite their importance, screening the structural and functional impact of lipid-protein interactions to identify specific lipid requirements remains a major challenge. Here, we use the FSEC-TS assay to show cardiolipin-dependent stabilization of the dimeric sodium/proton antiporter NhaA, demonstrating its ability to detect specific protein-lipid interactions. Based on the principle of FSECTS, we then engineer a simple thermal-shift assay (GFP-TS), which facilitates the highthroughput screening of lipid-and ligand-interactions with membrane proteins. By comparing the thermostability of medically relevant eukaryotic membrane proteins and a selection of bacterial counterparts, we reveal that eukaryotic proteins appear to have evolved to be more dependent to the presence of specific lipids.
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| 8. |
- Nji, Emmanuel, et al.
(författare)
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BioStruct-Africa : empowering Africa-based scientists through structural biology knowledge transfer and mentoring - recent advances and future perspectives
- 2019
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 26, s. 1843-1850
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Tidskriftsartikel (refereegranskat)abstract
- Being able to visualize biology at the molecular level is essential for our understanding of the world. A structural biology approach reveals the molecular basis of disease processes and can guide the design of new drugs as well as aid in the optimization of existing medicines. However, due to the lack of a synchrotron light source, adequate infrastructure, skilled persons and incentives for scientists in addition to limited financial support, the majority of countries across the African continent do not conduct structural biology research. Nevertheless, with technological advances such as robotic protein crystallization and remote data collection capabilities offered by many synchrotron light sources, X-ray crystallography is now potentially accessible to Africa-based scientists. This leap in technology led to the establishment in 2017 of BioStruct-Africa, a non-profit organization (Swedish corporate ID: 802509-6689) whose core aim is capacity building for African students and researchers in the field of structural biology with a focus on prevalent diseases in the African continent. The team is mainly composed of, but not limited to, a group of structural biologists from the African diaspora. The members of BioStruct-Africa have taken up the mantle to serve as a catalyst in order to facilitate the information and technology transfer to those with the greatest desire and need within Africa. BioStruct-Africa achieves this by organizing workshops onsite at our partner universities and institutions based in Africa, followed by post-hoc online mentoring of participants to ensure sustainable capacity building. The workshops provide a theoretical background on protein crystallography, hands-on practical experience in protein crystallization, crystal harvesting and cryo-cooling, live remote data collection on a synchrotron beamline, but most importantly the links to drive further collaboration through research. Capacity building for Africa-based researchers in structural biology is crucial to win the fight against the neglected tropical diseases, e.g. ascariasis, hookworm, trichuriasis, lymphatic filariasis, active trachoma, loiasis, yellow fever, leprosy, rabies, sleeping sickness, onchocerciasis, schistosomiasis, etc., that constitute significant health, social and economic burdens to the continent. BioStruct-Africa aims to build local and national expertise that will have direct benefits for healthcare within the continent.
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| 9. |
- Nji, Emmanuel, et al.
(författare)
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Structural basis for the delivery of activated sialic acid into Golgi for sialyation
- 2019
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Ingår i: Nature Structural & Molecular Biology. - : Springer Science and Business Media LLC. - 1545-9993 .- 1545-9985. ; 26:6, s. 415-423
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Tidskriftsartikel (refereegranskat)abstract
- The decoration of secretory glycoproteins and glycolipids with sialic acid is critical to many physiological and pathological processes. Sialyation is dependent on a continuous supply of sialic acid into Golgi organelles in the form of CMP-sialic acid. Translocation of CMP-sialic acid into Golgi is carried out by the CMP-sialic acid transporter (CST). Mutations in human CST are linked to glycosylation disorders, and CST is important for glycopathway engineering, as it is critical for sialyation efficiency of therapeutic glycoproteins. The mechanism of how CMP-sialic acid is recognized and translocated across Golgi membranes in exchange for CMP is poorly understood. Here we have determined the crystal structure of a Zea mays CST in complex with CMP. We conclude that the specificity of CST for CMP-sialic acid is established by the recognition of the nucleotide CMP to such an extent that they are mechanistically capable of both passive and coupled antiporter activity.
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