ORCID Profile
0000-0002-4223-9736
Current Organisations
University College London
,
Paulista University / University of Taubaté
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Publisher: Springer Science and Business Media LLC
Date: 07-06-2021
DOI: 10.1038/S41467-021-23641-8
Abstract: Barrett’s esophagus in gastrointestinal reflux patients constitutes a columnar epithelium with distal characteristics, prone to progress to esophageal adenocarcinoma. HOX genes are known mediators of position-dependent morphology. Here we show HOX collinearity in the adult gut while Barrett’s esophagus shows high HOXA13 expression in stem cells and their progeny. HOXA13 overexpression appears sufficient to explain both the phenotype (through downregulation of the epidermal differentiation complex) and the oncogenic potential of Barrett’s esophagus. Intriguingly, employing a mouse model that contains a reporter coupled to the HOXA13 promotor we identify single HOXA13-positive cells distally from the physiological esophagus, which is mirrored in human physiology, but increased in Barrett’s esophagus. Additionally, we observe that HOXA13 expression confers a competitive advantage to cells. We thus propose that Barrett’s esophagus and associated esophageal adenocarcinoma is the consequence of expansion of this gastro-esophageal HOXA13 -expressing compartment following epithelial injury.
Publisher: Wiley
Date: 10-06-2011
DOI: 10.1111/J.1365-2265.2011.04022.X
Abstract: UK national guidelines recommend the measurement of TSH receptor antibodies (TRAb) in certain clinical scenarios. A commercial third-generation TRAb autoantibody M22-biotin ELISA assay was introduced in May 2008 in our centre. To evaluate the diagnostic performance of a TRAb assay in a retrospective and subsequently a prospective cohort in a UK centre. A retrospective review of patients with thyroid disease followed by a prospective observational study in consecutive patients with newly found suppressed serum thyrotrophin (TSH). Medical records of 200 consecutive patients with thyroid disorders who had TRAb measured since the introduction of the assay. In a prospective study 44 patients with newly identified hyperthyroidism (TSH < 0·02 mIU/l) had sera assayed for TRAb prior to their clinic appointment at which a final diagnosis was sought. In the retrospective cohort, the manufacturer's cut-off point of TRAb ≥0·4 U/l resulted in a positive predictive value (PPV) of 95%, sensitivity 85%, specificity 94% and negative predictive value (NVP) 79% to diagnose Graves' disease using defined criteria. Receiver operating characteristic (ROC) analysis determined an optimal cut-off point of TRAb ≥3·5 U/l with a 100% specificity to exclude patients without Graves' disease at the cost though of a lower sensitivity (43%). In the prospective study, the sensitivity, PPV, specificity and NPV were all 96% using the ≥0·4 U/l cut-off. When combining hyperthyroid patients from both cohorts the assay sensitivity and specificity at ≥0·4 U/l cut-off were 95% and 92% respectively. A positive TRAb result increased the probability of Graves' disease for a particular patient by 25-35% and only six (2·5%) patients had a diagnosis of hyperthyroidism of uncertain aetiology after TRAb testing. The assay studied specifically identifies patients with Graves' disease. It is a reliable tool in the initial clinical assessment to determine the aetiology of hyperthyroidism and has the potential for cost-savings.
Publisher: Wiley
Date: 10-04-2014
Abstract: The active vitamin D metabolite 1α,25-dihydroxyvitamin D (1,25[OH]₂ D) potently inhibits DC priming of T-cell activation, suggesting that it mediates a homeostatic role in this context. Therefore, careful regulation of 1,25[OH]₂ D levels is necessary to avoid inappropriate inhibition of T-cell activation. Cell-autonomous control of vitamin D activity can be modulated by the action of the vitamin D-activating and -inactivating hydroxylases, CYP27B1, and CYP24A1, respectively. We show that in comparison to macrophages, human monocyte-derived DCs exhibit significantly less activation of 25-dihydroxyvitamin D to 1,25[OH]₂ D, and that DCs predominantly express a truncated CYP27B1 transcript that may contribute to the deficiency in activation of vitamin D. Furthermore, in response to stimulation with 1,25[OH]₂ D, upregulation of the inactivating enzyme CYP24A1 curtailed the functional effects of vitamin D in DCs, but not macrophages. Production of 1,25[OH]₂ D by macrophages was adequate to induce expression of vitamin D-responsive genes by DCs, inhibit DC maturation in response to innate immune stimulation and DC-dependent T-cell responses. Our data suggest that in comparison to macrophages, differential regulation of hydroxylases limits autocrine vitamin D activity in DCs, and that paracrine activation of vitamin D exerts a more potent mechanism for homeostatic control of DC function.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Bernard Khoo.