6 results on '"Vlok, M."'
Search Results
2. Protocol for unified metabolomics and proteomics analysis of formalin-fixed paraffin-embedded tissue.
- Author
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Isaiah AR, Luies L, Loots DT, Williams AA, Vlok M, Chegou NN, Tutu van Furth M, van der Kuip M, and Mason S
- Abstract
The use of archival formalin-fixed paraffin-embedded (FFPE) tissue samples for biochemical analyses is problematic because of the formation of a Schiff base, leading to low protein and metabolite yields during analytical extractions. Here, we overcome this issue using a unified protocol on FFPE tissue for metabolomics and proteomics analyses. Using 20 mg of wet mass tissue, this protocol consistently extracted more than 50 metabolites (across 11 classes of metabolites) and over 900 proteins., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
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3. High prevalence of adult and nonadult scurvy in an early agricultural transition site from Mainland Southeast Asia was associated with decreased survivorship.
- Author
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Vlok M, Oxenham M, Domett K, Trinh HH, Minh TT, Nguyen MH, Matsumura H, and Buckley H
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- Humans, Adult, Male, Prevalence, Middle Aged, Female, Vietnam epidemiology, Young Adult, History, Ancient, Adolescent, Child, Survivorship, Child, Preschool, Aged, Infant, Scurvy epidemiology
- Abstract
Objectives: The osteological paradox recognizes that the presence of lesions is not always directly related with increased mortality. When combined with the clinical, historical, and epidemiological literature on scurvy, survivorship analysis, a form of statistical analysis to assess the relationship between the presence of diseases in the archeological record and survival, helps determine the overall burden of the disease both in terms of morbidity and mortality. This article explores the relationship between scurvy and survivorship in 26 adults from Man Bac, a Neolithic site from northern Vietnam together with prepublished evidence of scurvy in the nonadult population (n = 44)., Methods: Diagnosis of scurvy included differential diagnosis combined with the Snoddy, A. M. E., Buckley, H. R., Elliott, G. E., Standen, V. G., Arriaza, B. T., & Halcrow, S. E. (2018). Macroscopic features of scurvy in human skeletal remains: A literature synthesis and diagnostic guide. American Journal of Physical Anthropology, 167(4), 876-895. https://doi.org/10.1002/ajpa.23699 threshold criteria and the Brickley, M. B., & Morgan, B. (2023). Assessing diagnostic certainty for scurvy and rickets in human skeletal remains. American Journal of Biological Anthropology, 181, 637-645 diagnostic certainty approaches. Kaplan-Meier survival curves were produced to assess the relationship between the presence of probable scurvy and age-at-death., Results: The prevalence of probable scurvy in adults (35%) was considerably lower than reported for the nonadults (80%). Almost all lesions observed in the adults were in a mixed stage of healing. Kaplan-Meier analysis demonstrated no difference in survivorship between infants and children (<15 years) with or without probable scurvy, whereas a meaningful difference was observed for the adults and adolescents (15+ years)., Conclusions: The findings demonstrate that scurvy considerably decreased survivorship to older age categories. The degree of lesion remodeling, however, indicates that scurvy was not necessarily the direct cause of death but contributed to an overall disease burden that was ultimately fatal., (© 2024 The Author(s). American Journal of Biological Anthropology published by Wiley Periodicals LLC.)
- Published
- 2024
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4. Identification of the proteolytic signature in CVB3-infected cells.
- Author
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Vlok M, Solis N, Sadasivan J, Mohamud Y, Warsaba R, Kizhakkedathu J, Luo H, Overall CM, and Jan E
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- Humans, Mice, Animals, HeLa Cells, Viral Proteins metabolism, Proteomics methods, Host-Pathogen Interactions, 3C Viral Proteases metabolism, Cell Line, Viral Proteases metabolism, Polyproteins metabolism, Enterovirus B, Human metabolism, Proteolysis, Coxsackievirus Infections virology, Coxsackievirus Infections metabolism
- Abstract
Coxsackievirus B3 (CVB3) encodes proteinases that are essential for processing of the translated viral polyprotein. Viral proteinases also target host proteins to manipulate cellular processes and evade innate antiviral responses to promote replication and infection. While some host protein substrates of the CVB3 3C and 2A cysteine proteinases have been identified, the full repertoire of targets is not known. Here, we utilize an unbiased quantitative proteomics-based approach termed terminal amine isotopic labeling of substrates (TAILS) to conduct a global analysis of CVB3 protease-generated N-terminal peptides in both human HeLa and mouse cardiomyocyte (HL-1) cell lines infected with CVB3. We identified >800 proteins that are cleaved in CVB3-infected HeLa and HL-1 cells including the viral polyprotein, known substrates of viral 3C proteinase such as PABP, DDX58, and HNRNPs M, K, and D and novel cellular proteins. Network and GO-term analysis showed an enrichment in biological processes including immune response and activation, RNA processing, and lipid metabolism. We validated a subset of candidate substrates that are cleaved under CVB3 infection and some are direct targets of 3C proteinase in vitro . Moreover, depletion of a subset of TAILS-identified target proteins decreased viral yield. Characterization of two target proteins showed that expression of 3C
pro -targeted cleaved fragments of emerin and aminoacyl-tRNA synthetase complex-interacting multifunctional protein 2 modulated autophagy and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, respectively. The comprehensive identification of host proteins targeted during virus infection provides insights into the cellular pathways manipulated to facilitate infection., Importance: RNA viruses encode proteases that are responsible for processing viral proteins into their mature form. Viral proteases also target and cleave host cellular proteins; however, the full catalog of these target proteins is incomplete. We use a technique called terminal amine isotopic labeling of substrates (TAILS), an N-terminomics to identify host proteins that are cleaved under virus infection. We identify hundreds of cellular proteins that are cleaved under infection, some of which are targeted directly by viral protease. Revealing these target proteins provides insights into the host cellular pathways and antiviral signaling factors that are modulated to promote virus infection and potentially leading to virus-induced pathogenesis., Competing Interests: The authors declare no conflict of interest.- Published
- 2024
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5. Data-independent LC-MS/MS analysis of ME/CFS plasma reveals a dysregulated coagulation system, endothelial dysfunction, downregulation of complement machinery.
- Author
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Nunes M, Vlok M, Proal A, Kell DB, and Pretorius E
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- Humans, Male, Female, Middle Aged, Adult, Chromatography, Liquid, Case-Control Studies, Proteomics, COVID-19 blood, Complement System Proteins metabolism, Endothelium, Vascular metabolism, Endothelium, Vascular physiopathology, Liquid Chromatography-Mass Spectrometry, Tandem Mass Spectrometry, Blood Coagulation, Biomarkers blood, Down-Regulation, Fatigue Syndrome, Chronic blood, Fatigue Syndrome, Chronic physiopathology, Fatigue Syndrome, Chronic immunology, Fatigue Syndrome, Chronic metabolism
- Abstract
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic condition that is characterized by unresolved fatigue, post-exertion symptom exacerbation (PESE), cognitive dysfunction, orthostatic intolerance, and other symptoms. ME/CFS lacks established clinical biomarkers and requires further elucidation of disease mechanisms. A growing number of studies demonstrate signs of hematological and cardiovascular pathology in ME/CFS cohorts, including hyperactivated platelets, endothelial dysfunction, vascular dysregulation, and anomalous clotting processes. To build on these findings, and to identify potential biomarkers that can be related to pathophysiology, we measured differences in protein expression in platelet-poor plasma (PPP) samples from 15 ME/CFS study participants and 10 controls not previously infected with SARS-CoV-2, using DIA LC-MS/MS. We identified 24 proteins that are significantly increased in the ME/CFS group compared to the controls, and 21 proteins that are significantly downregulated. Proteins related to clotting processes - thrombospondin-1 (important in platelet activation), platelet factor 4, and protein S - were differentially expressed in the ME/CFS group, suggestive of a dysregulated coagulation system and abnormal endothelial function. Complement machinery was also significantly downregulated, including C9 which forms part of the membrane attack complex. Additionally, we identified a significant upregulation of lactotransferrin, protein S100-A9, and an immunoglobulin variant. The findings from this experiment further implicate the coagulation and immune system in ME/CFS, and bring to attention the pathology of or imposed on the endothelium. This study highlights potential systems and proteins that require further research with regards to their contribution to the pathogenesis of ME/CFS, symptom manifestation, and biomarker potential, and also gives insight into the hematological and cardiovascular risk for ME/CFS individuals affected by diabetes mellitus., (© 2024. The Author(s).)
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- 2024
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6. Corrigendum to "Technical note: The use and misuse of threshold diagnostic criteria in paleopathology".
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Vlok M
- Published
- 2024
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