Browsing by Subject "Mass spectrometry"

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    Open Access
    The prevalence of liquid chromatography-tandem mass spectrometry confirmed paediatric poisoning at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa
    (2021-01-18) Washaya, Norbertta; Evans, Alicia; Muloiwa, Rudzani; Smith, Peter; Buys, Heloise
    Background Paediatric poisoning is a common presentation to emergency departments worldwide. There is a paucity of data on the role of liquid chromatography-tandem mass spectrometry (LC-MS/MS), in the management of paediatric poisoning in low-and middle-income countries (LMICs). In high-income countries, most studies are retrospective, and few include children. Objective The study describes the prevalence of liquid chromatography-tandem mass spectrometry confirmed paediatric poisoning at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa. Methods Children admitted with suspected poisoning between 1 January 2017 and 31 December 2017, were recruited. All patients had a urine and/or blood sample sent for LC-MS/MS toxicology. Data collected included demographic data, clinical features, investigations, management, outcome and social interventions. Results One hundred fifty-two children, with median age of 39 (IQR 25–61) months were enrolled of which 128 (84%) were poisoning cases. Of the 128 poisoning cases, 88 (69%) presented with a history of ingesting a known substance, 16 (12%) an unknown substance and 24 (19%) were cases of occult poisoning. LC-MS/MS was able to identify a substance in 92% of the cases of occult poisoning. In those who had presented with a seemingly known substance, LC-MS/MS found a different substance in 15 cases. LC-MS/MS was also able to detect multiple drugs in 40 patients. Of the poisoning cases, six (5%) cases were attempted homicide cases and 5 (4%) cases were attempted suicide cases. No children died. Individualized social interventions were instituted in poisoning cases. Emergency placement safety reasons was required in 6 children. Conclusion When the limitations are known, LC-MS/MS is useful in identifying cases of occult poisoning, identifying patients who have ingested multiple substances and/or an unknown substance and when targeted towards child protection. As LC-MS/MS is an expensive test, it should be used judiciously in LMICs.
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    Open Access
    Proteogenomic analysis of mycobacterium smegmatis using high resolution mass spectrometry
    (Frontiers Media, 2016) Potgieter, M G; Nakedi K C; Ambler, J M; Nel, A J; Garnett, S; Soares, N C; Mulder, N; Blackburn, J M
    Biochemical evidence is vital for accurate genome annotation. The integration of experimental data collected at the proteome level using high resolution mass spectrometry allows for improvements in genome annotation by providing evidence for novel gene models, while validating or modifying others. Here, we report the results of a proteogenomic analysis of a reference strain of Mycobacterium smegmatis (mc2155), a fast growing model organism for the pathogenic Mycobacterium tuberculosis—the causative agent for Tuberculosis. By integrating high throughput LC/MS/MS proteomic data with genomic six frame translation and ab initio gene prediction databases, a total of 2887 ORFs were identified, including 2810 ORFs annotated to a Reference protein, and 63 ORFs not previously annotated to a Reference protein. Further, the translational start site (TSS) was validated for 558 Reference proteome gene models, while upstream translational evidence was identified for 81. In addition, N-terminus derived peptide identifications allowed for downstream TSS modification of a further 24 gene models. We validated the existence of six previously described interrupted coding sequences at the peptide level, and provide evidence for four novel frameshift positions. Analysis of peptide posterior error probability (PEP) scores indicates high-confidence novel peptide identifications and shows that the genome of M. smegmatis mc2155 is not yet fully annotated. Data are available via ProteomeXchange with identifier PXD003500.
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    The South African and Namibian to populations of the resurrection plant Myrothamnus flabellifolius are genetically distinct and display variation in their galloylquinic acid composition
    (Springer Verlag, 2005) Moore, John P; Farrant, Jill M; Lindsey, George G; Brandt, Wolf F
    The polyphenol contents and compositions in desiccated leaves of Myrothamnus flabellifolius plants collected in various locations in Namibia and South Africa were analyzed using UV spectroscopy and high-performance liquid chromatography–mass spectrometry. A study of the genetic relatedness of these populations was also performed by determination of the DNA sequence of the intergenic spacer region between the psbA and the trnH genes in the chloroplast genome. Namibian M. flabellifolius plants contained signi- ficantly more polyphenols than South African plants. Namibian plants essentially contained a single polyphenol, 3,4,5-tri-O-galloylquinic acid, whereas South African plants contained a variety of galloylquinic acids including 3,4,5-tri-O-galloylquinic acid together with higher molecular weight galloylquinic acids. Sequence analysis revealed a 1.4% divergence between Namibian and South African plants corresponding to the separation of these populations of approximately 4 106 years. The significance of the polyphenol content and composition to the desiccation tolerance of the two populations is discussed.