Browsing by Author "Phillips, Richard O."

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    Simple, Rapid Mycobacterium ulcerans Disease Diagnosis from Clinical Samples by Fluorescence of Mycolactone on Thin Layer Chromatography
    (PLOS Neglected Tropical Diseases, 2015-11-19) Wadagni, Anita; Frimpong, Michael; Phanzu, Delphin Mavinga; Phillips, Richard O.; Ablordey, Anthony
    Mycobacterium ulcerans infection, known as Buruli ulcer, is a disease of the skin and subcutaneous tissues which is an important but neglected tropical disease with its major impact in rural parts of West and Central Africa where facilities for diagnosis and management are poorly developed. We evaluated fluorescent thin layer chromatography (f-TLC) for detection of mycolactone in the laboratory using samples from patients with Buruli ulcer and patients with similar lesions that gave a negative result on PCR for the IS2404 repeat sequence of M. ulcerans Methodology/Principal findings Mycolactone and DNA extracts from fine needle aspiration (FNA), swabs and biopsy specimen were used to determine the sensitivity and specificity of f-TLC when compared with PCR for the IS2404. For 71 IS2404 PCR positive and 28 PCR negative samples the sensitivity was 73.2% and specificity of 85.7%for f-TLC. The sensitivity was similar for swabs (73%), FNAs (75%) and biopsies (70%).
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    Two-Hit in vitro T-Cell Stimulation Detects Mycobacterium tuberculosis Infection in QuantiFERON Negative Tuberculosis Patients and Healthy Contacts From Ghana
    (Frontiers in Immunology, 2019-07-03) Phillips, Richard O.; Adankwah, Ernest; Lundtoft, Christian; Güler, Alptekin; L. M. C, Kees; et. al
    IFN-g release assays [e.g., QuantiFERON (QFT)] are widely used for diagnosis of Mycobacterium tuberculosis (Mtb) infection. T-cell responses against QFT antigens ESAT6 and CFP10 are highly Mtb specific but previous studies indicated suboptimal assay sensitivity. Especially for potentially infected healthy contacts (HCs) of tuberculosis patients, alternative antigen usage and more sensitive tests may contribute to improved detection of latent Mtb infection. In a pilot case-control study of tuberculosis patients (n = 22) and HCs (n = 20) from Ghana, we performed multifaceted in vitro assays to identify optimal assay conditions. This included a two-hit stimulation assay, which is based on initial and second re-stimulation with the same antigen on d6 and intracellular IFN-g analysis, to compare T-cell responses against ESAT6/CFP10 (E6/C10) and selected latency antigens (i.e. Rv2628, Rv1733, Rv2031, Rv3407) of Mtb. Considerable subgroups of tuberculosis patients (64%) and HCs (75%) had negative or indeterminate QFT results partially accompanied by moderate PHA induced responses and high IFN-g background values. Intracellular IFN-g analysis of E6/C10 specific CD4+ T-cell subpopulations and evaluation of responder frequencies had only moderate effects on assay sensitivity. However, two-hit in vitro stimulation significantly enhanced E6/C10 specific IFN-g positive T-cell proportions especially in QFT non-responders, and in both study groups. Mtb latency antigen-specific T cells against Rv1733 and Rv2628 were especially detected in HCs after two-hit stimulation and T-cell responses against Rv2628 were highly capable to discriminate tuberculosis patients and HCs. Two-hit in vitro stimulation may improve moderate sensitivity of short term IFN-g based assays, like QFT, to detect Mtb infection. Latency stage-specific antigens added significantly to detection of Mtb infection in HCs and tuberculosis patients with negative QFT test results.
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    Type-1 diabetes onset age and sex differences between Ghanaian and German urban populations
    (Journal of Diabetes, 2019) Phillips, Richard O.; Seyfarth, Julia; Sarfo-Kantanka, Osei; Rosenbauer, Joachim; Jacobsen, Marc
    Type 1 diabetes onset age in Kumasi/Ghana has a peak at around 17 to 20 years, whereas the peak is at 11 to 12 years in North Rhine-Westphalia, Germany. Higher proportions of females were found in the type 1 diabetes cohort from Ghana, and males were more frequent in the German cohort.