Imperial College London

DrTriciaTan

Faculty of MedicineDepartment of Metabolism, Digestion and Reproduction

Professor of Practice (Metabolic Medicine & Endocrinology)
 
 
 
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+44 (0)20 3313 8038t.tan

 
 
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6N6ECommonwealth BuildingHammersmith Campus

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Summary

 

Publications

Publication Type
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152 results found

Pickford P, Lucey M, Rujan R-M, McGlone ER, Bitsi S, Ashford FB, Corrêa IR, Hodson DJ, Tomas A, Deganutti G, Reynolds CA, Owen BM, Tan TM, Minnion J, Jones B, Bloom SRet al., 2021, Partial agonism improves the anti-hyperglycaemic efficacy of an oxyntomodulin-derived GLP-1R/GCGR co-agonist, Molecular Metabolism, Vol: 51, ISSN: 2212-8778

OBJECTIVE: Glucagon-like peptide-1 and glucagon receptor (GLP-1R/GCGR) co-agonism can maximise weight loss and improve glycaemic control in type 2 diabetes and obesity. In this study we investigated the cellular and metabolic effects of modulating the balance between G protein and β-arrestin-2 recruitment at GLP-1R and GCGR using oxyntomodulin (OXM)-derived co-agonists. This strategy has been previously shown to improve the duration of action of GLP-1R mono-agonists by reducing target desensitisation and downregulation. METHODS: Dipeptidyl dipeptidase-4 (DPP-4)-resistant OXM analogues were generated and assessed for a variety of cellular readouts. Molecular dynamic simulations were used to gain insights into the molecular interactions involved. In vivo studies were performed in mice to identify effects on glucose homeostasis and weight loss. RESULTS: Ligand-specific reductions in β-arrestin-2 recruitment were associated with slower GLP-1R internalisation and prolonged glucose-lowering action in vivo. The putative benefits of GCGR agonism were retained, with equivalent weight loss compared to the GLP-1R mono-agonist liraglutide in spite of a lesser degree of food intake suppression. The compounds tested showed only a minor degree of biased agonism between G protein and β-arrestin-2 recruitment at both receptors and were best classified as partial agonists for the two pathways measured. CONCLUSIONS: Diminishing β-arrestin-2 recruitment may be an effective way to increase the therapeutic efficacy of GLP-1R/GCGR co-agonists. These benefits can be achieved by partial rather than biased agonism.

Journal article

Marzook A, Chen S, Pickford P, Lucey M, Wang Y, Corrêa Jr IR, Broichhagen J, Hodson DJ, Salem V, Rutter GA, Tan TM, Bloom SR, Tomas A, Jones Bet al., 2021, Evaluation of efficacy- versus affinity-driven agonism with biased GLP-1R ligands P5 and exendin-F1, Biochemical Pharmacology, Vol: 190, Pages: 1-12, ISSN: 0006-2952

The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of glucose homeostasis and has been successfully targeted for the treatment of type 2 diabetes. Recently described biased GLP-1R agonists with selective reductions in β-arrestin versus G protein coupling show improved metabolic actions in vivo. However, two prototypical G protein-favouring GLP-1R agonists, P5 and exendin-F1, are reported to show divergent effects on insulin secretion. In this study we aimed to resolve this discrepancy by performing a side-by-side characterisation of these two ligands across a variety of in vitro and in vivo assays. Exendin-F1 showed reduced acute efficacy versus P5 for several readouts, including recruitment of mini-G proteins, G protein-coupled receptor kinases (GRKs) and β-arrestin-2. Maximal responses were also lower for both GLP-1R internalisation and the presence of active GLP-1R-mini-Gs complexes in early endosomes with exendin-F1 treatment. In contrast, prolonged insulin secretion in vitro and sustained anti-hyperglycaemic efficacy in mice were both greater with exendin-F1 than with P5. We conclude that the particularly low acute efficacy of exendin-F1 and associated reductions in GLP-1R downregulation appear to be more important than preservation of endosomal signalling to allow sustained insulin secretion responses. This has implications for the ongoing development of affinity- versus efficacy-driven biased GLP-1R agonists as treatments for metabolic disease.

Journal article

Salem V, Demetriou L, Behary P, Alexiadou K, Scholtz S, Tharakan G, Miras A, Purkayastha S, Ahmed A, Bloom S, Wall M, Dhillo W, Tan Tet al., 2021, Weight loss by low calorie diet versus gastric bypass surgery in people with diabetes results in divergent brain activation patterns: an functional MRI study, Diabetes Care, ISSN: 0149-5992

OBJECTIVE: Weight loss achieved with very-low-calorie diets (VLCDs) can produce remission of type 2 diabetes (T2D), but weight regain very often occurs with reintroduction of higher calorie intakes. In contrast, bariatric surgery produces clinically significant and durable weight loss, with diabetes remission that translates into reductions in mortality. We hypothesized that in patients living with obesity and prediabetes/T2D, longitudinal changes in brain activity in response to food cues as measured using functional MRI would explain this difference.RESEARCH DESIGN AND METHODS: Sixteen participants underwent gastric bypass surgery, and 19 matched participants undertook a VLCD (meal replacement) for 4 weeks. Brain responses to food cues and resting-state functional connectivity were assessed with functional MRI pre- and postintervention and compared across groups.RESULTS: We show that Roux-en-Y gastric bypass surgery (RYGB) results in three divergent brain responses compared with VLCD-induced weight loss: 1) VLCD resulted in increased brain reward center food cue responsiveness, whereas in RYGB, this was reduced; 2) VLCD resulted in higher neural activation of cognitive control regions in response to food cues associated with exercising increased cognitive restraint over eating, whereas RYGB did not; and 3) a homeostatic appetitive system (centered on the hypothalamus) is better engaged following RYGB-induced weight loss than VLCD.CONCLUSIONS: Taken together, these findings point to divergent brain responses to different methods of weight loss in patients with diabetes, which may explain weight regain after a short-term VLCD in contrast to enduring weight loss after RYGB.

Journal article

Phylactou M, Abbara A, Al-Memar M, Kyriacou C, Pei Chia E, Nadir R, Izzie-Engbeaya C, Clarke S, Mills E, Daniels E, Huo L, Pacuszka E, Yang L, Patel B, Tan T, Bech P, Comninos A, Fourie H, Kelsey T, Bourne T, Dhillo Wet al., 2021, Performance of plasma kisspeptin as a biomarker for miscarriage improves with gestation during the first trimester, Fertility and Sterility, ISSN: 0015-0282

ObjectiveTo compare the performance of kisspeptin and beta human chorionic gonadotropin (βhCG), both alone and in combination, as biomarkers for miscarriage throughout the first trimester.DesignProspective, nested case-control study.SettingTertiary Centre, Queen Charlotte Hospital, London, United Kingdom.Patient(s)Adult women who had miscarriages (n = 95, 173 samples) and women with healthy pregnancies (n = 265, 557 samples).Intervention(s)The participants underwent serial ultrasound scans and blood sampling for measurement of plasma kisspeptin and βhCG levels during the first trimester.Main Outcome Measure(s)The ability of plasma kisspeptin and βhCG levels to distinguish pregnancies complicated by miscarriage from healthy pregnancies unaffected by miscarriage.Result(s)Gestation-adjusted levels of circulating kisspeptin and βhCG were lower in samples from women with miscarriages than in women with healthy pregnancies by 79% and 70%, respectively. The area under the receiver-operating characteristic curve for identifying miscarriage during the first trimester was 0.874 (95% confidence interval [CI] 0.844–0.904) for kisspeptin, 0.859 (95% CI 0.820–0.899) for βhCG, and 0.916 (95% CI 0.886–0.946) for the sum of the two markers. The performance of kisspeptin in identifying miscarriage improved with increasing length of gestation, whereas that of βhCG worsened. A decision matrix incorporating kisspeptin, βhCG, and gestational age had 83% to 87% accuracy for the prediction of miscarriage.Conclusion(s)Plasma kisspeptin is a promising biomarker for miscarriage and provides additional value to βhCG alone, especially during later gestational weeks of the first trimester.

Journal article

Clarke S, Phylactou M, Patel B, Mills E, Muzi B, Izzi-Engbeaya C, Choudhury S, Khoo B, Meeran K, Comninos A, Abbara A, Tan T, Dhillo Wet al., 2021, Normal adrenal and thyroid function in patients who survive COVID-19 infection, Journal of Clinical Endocrinology and Metabolism, ISSN: 0021-972X

ContextThe COVID-19 pandemic continues to exert an immense burden on global health services. Moreover, up to 63% of patients experience persistent symptoms, including fatigue, after acute illness. Endocrine systems are vulnerable to the effects of COVID-19 as many glands express the ACE2 receptor, used by the SARS-CoV-2 virion for cellular access. However, the effects of COVID-19 on adrenal and thyroid gland function after acute COVID-19 remain unknown. ObjectivesOur objectives were to evaluate adrenal and thyroid gland function in COVID-19 survivors. DesignA prospective, observational study was undertaken. SettingClinical Research Facility, Imperial College NHS Healthcare Trust. ParticipantsSeventy patients ≥ 18 years at least 3 months after diagnosis of COVID-19 were included. InterventionParticipants attended a research study visit (08:00-09:30), during which a short Synacthen test (250 µg IV bolus), and thyroid function assessments were performed.ResultsAll patients had a peak cortisol ≥450 nmol/l after Synacthen, consistent with adequate adrenal reserve. Basal and peak serum cortisol did not differ according to disease severity or history of dexamethasone treatment during COVID-19. There was no difference in baseline or peak cortisol after Synacthen or in thyroid function tests, or thyroid status, in patients with fatigue (n=44) compared to those without (n=26).ConclusionsAdrenal and thyroid function ≥3 months after presentation with COVID-19 was preserved. Whilst a significant proportion of patients experienced persistent fatigue, their symptoms were not accounted for by alterations in adrenal or thyroid function. These findings have important implications for the clinical care of patients after COVID-19.

Journal article

Zaman S, Almazrouei R, Sam AH, DiMarco AN, Todd JF, Palazzo FF, Tan T, Dhillo WS, Meeran K, Wernig Fet al., 2021, Synacthen stimulation test following unilateral adrenalectomy needs to be interpreted with caution, Frontiers in Endocrinology, Vol: 12, Pages: 1-7, ISSN: 1664-2392

Background: Cortisol levels in response to stress are highly variable. Baseline and stimulated cortisol levels are commonly used to determine adrenal function following unilateral adrenalectomy. We report the results of synacthen stimulation testing following unilateral adrenalectomy in a tertiary referral center.Methods: Data were collected retrospectively for 36 patients who underwent synacthen stimulation testing one day post unilateral adrenalectomy. None of the patients had clinical signs of hypercortisolism preoperatively. No patient received pre- or intraoperative steroids. Patients with overt Cushing’s syndrome were excluded.Results: The median age was 58 (31-79) years. Preoperatively, 16 (44%) patients had a diagnosis of pheochromocytoma, 12 (33%) patients had primary aldosteronism and 8 (22%) patients had non-functioning adenomas with indeterminate/atypical imaging characteristics necessitating surgery. Preoperative overnight dexamethasone suppression test results revealed that 6 of 29 patients failed to suppress cortisol to <50 nmol/L. Twenty (56%) patients achieved a stimulated cortisol ≥450 nmol/L at 30 minutes and 28 (78%) at 60 minutes. None of the patients developed clinical adrenal insufficiency necessitating steroid replacement.Conclusions: Synacthen stimulation testing following unilateral adrenalectomy using standard stimulated cortisol cut-off values would wrongly label many patients adrenally insufficient and may lead to inappropriate prescriptions of steroids to patients who do not need them.

Journal article

Salem V, Demetriou L, Behary P, Alexiadou K, Miras A, Scoltz S, Purkayastha S, Ahmed S, Dhillo W, Tan Tet al., 2021, Weight loss by low-calorie diet versus gastric bypass surgery in people with diabetes results in divergent brain activation patterns which may explain differences in long-term outcomes: an FMRI study, The Diabetes UK Professional Conference 2021, Publisher: Wiley, Pages: 1-1, ISSN: 0742-3071

Objective: Clinically significant weight loss can produce remission of type 2 diabetes. Bariatric surgery (specifically, Roux-en-Y gastric bypass, RYGB) produces durable weight loss that translates into reductions in mortality. In contrast, weight regain is very common after very low-calorie diets (VLCD). No study has investigated longitudinal changes in brain activity using functional MRI in patients living with obesity and prediabetes/type 2 diabetes to explain this difference.Methods: Visual food cue responses and resting state connectivity was assessed with functional MRI pre- and post-intervention and compared between 16 participants who underwent gastric bypass surgery and 19 age, gender, and disease stage matched participants who undertook a VLCD for 4 weeks.Results: Brain responses to RYGB-induced weight loss diverge from those induced by VLCD in three domains: (i) dieting resulted in increased responsiveness to visual food cues in reward areas whereas after RYGB this was reduced; (ii) dieting therefore engaged greater activation of brain regions involved in cognitive control, associated with the need to exercise increased restraint over eating; and (iii) a homeostatic appetitive system (centred on the hypothalamus) was better engaged following RYGB-induced weight loss than dieting.Conclusion: This study provides a holistic view of multiple divergent brain responses to different methods of weight loss in patients with diabetes, which may explain weight regain after a short-term VLCD in contrast with the enduring weight loss after RYGB.

Conference paper

Ansari S, Abdel-Malek M, Kenkre J, Choudhury SM, Barnes S, Misra S, Tan T, Cegla Jet al., 2021, The use of whole blood capillary samples to measure 15 analytes for a home-collect biochemistry service during the SARS-CoV-2 pandemic: A proposed model from North West London Pathology, ANNALS OF CLINICAL BIOCHEMISTRY, ISSN: 0004-5632

Journal article

Tan TM-M, Minnion J, Khoo B, Ball L-J, Malviya R, Day E, Fiorentino F, Brindley C, Bush J, Bloom SRet al., 2021, Safety and efficacy of an extended-release peptide YY analogue for obesity: A randomized, placebo-controlled, phase 1 trial, DIABETES OBESITY & METABOLISM, Vol: 23, Pages: 1471-1483, ISSN: 1462-8902

Journal article

Miras AD, Kamocka A, Tan T, Pérez-Pevida B, Chahal H, Moorthy K, Purkayastha S, Patel A, Umpleby AM, Frost G, Bloom SR, Ahmed AR, Rubino Fet al., 2021, Long limb compared with standard limb Roux-en-Y gastric bypass for type 2 diabetes and obesity: the LONG LIMB RCT, Efficacy and Mechanism Evaluation, Vol: 8, ISSN: 2050-4365

BackgroundRoux-en-Y gastric bypass is recognised as a standard of care in the treatment of diabetes mellitus and obesity. However, the optimal length of the Roux-en-Y gastric bypass limbs remains controversial, with substantial variation in practice. Specifically, a longer biliopancreatic limb length of 150 cm (‘long limb’) has been hypothesised to be better for the treatment of diabetes mellitus because it increases the postprandial secretion of gut hormones, such as glucagon-like peptide 1, and increases insulin sensitivity, compared with the Roux-en-Y gastric bypass utilising a standard biliopancreatic limb length of 50 cm (‘standard limb’).ObjectiveTo evaluate the mechanisms, clinical efficacy and safety of long limb versus the standard limb Roux-en-Y gastric bypass in patients undergoing metabolic surgery for obesity and diabetes mellitus.DesignA double-blind, mechanistic randomised controlled trial was conducted to evaluate the mechanisms, clinical efficacy and safety of the two interventions.SettingImperial College London, King’s College London and their associated NHS trusts.ParticipantsPatients with obesity and type 2 diabetes mellitus who were eligible for metabolic surgery.InterventionsParticipants were randomly assigned (1 : 1) to 150-cm (long limb) or 50-cm (standard limb) biliopancreatic limb Roux-en-Y gastric bypass with a fixed alimentary limb of 100 cm. The participants underwent meal tolerance tests to measure glucose excursions, glucagon-like peptide 1 and insulin secretion, and hyperinsulinaemic–euglycaemic clamps with stable isotopes to measure insulin sensitivity preoperatively, at 2 weeks after the surgery and at matched 20% total body weight loss. Clinical follow-up continued up to 1 year.Main outcome measuresPrimary – postprandial peak of active glucagon-like peptide 1 concentration at 2 weeks after intervention. Secondary – fasting and postprandial glucose an

Journal article

Femminella GD, Livingston NR, Raza S, van der Doef T, Frangou E, Love S, Busza G, Calsolaro V, Carver S, Holmes C, Ritchie CW, Lawrence RM, McFarlane B, Tadros G, Ridha BH, Bannister C, Walker Z, Archer H, Coulthard E, Underwood B, Prasanna A, Koranteng P, Karim S, Junaid K, McGuinness B, Passmore AP, Nilforooshan R, Macharouthu A, Donaldson A, Thacker S, Russell G, Malik N, Mate V, Knight L, Kshemendran S, Tan T, Holscher C, Harrison J, Brooks DJ, Ballard C, Edison Pet al., 2021, Does insulin resistance influence neurodegeneration in non-diabetic Alzheimer's subjects?, ALZHEIMERS RESEARCH & THERAPY, Vol: 13

Journal article

Kenkre J, Ahmed A, Purkayastha S, Mallalah K, Bloom S, Blakemore A, Prevost A, Tan Tet al., 2021, Who will benefit from bariatric surgery for diabetes? A protocol for an observational cohort study, BMJ Open, Vol: 11, ISSN: 2044-6055

Introduction Type 2 diabetes mellitus (T2DM) and obesity are pandemic diseases that lead to a great deal of morbidity and mortality. The most effective treatment for obesity and T2DM is bariatric or metabolic surgery; it can lead to long-term diabetes remission with 4 in 10 of those undergoing surgery having normal blood glucose on no medication 1 year postoperatively. However, surgery carries risks and, additionally, due to resource limitations, there is a restricted number of patients who can access this treatment. Moreover, not all those who undertake surgery respond equally well metabolically. The objective of the current research is to prospectively investigate predictors of T2DM response following metabolic surgery, including those directly involved in its aetiopathogenesis such as fat distribution and genetic variants. This will inform development of a clinically applicable model to help prioritise this therapy to those predicted to have remission.Methods and analysis A prospective multicentre observational cohort study of adult patients with T2DM and obesity undergoing Roux-en-Y gastric bypass surgery. Patients will be comprehensively assessed before surgery to determine their clinical, metabolic, psychological, genetic and fat distribution profiles. A multivariate logistic regression model will be used to assess the value of the factors derived from the preoperative assessment in terms of prediction of diabetes remission.Ethics and dissemination Formal ethics review was undertaken with a favourable opinion (UK HRA RES reference number 18/LO/0931). The dissemination plan is to present the results at conferences, in peer-reviewed journals as well as to lay media and to patient organisations.Trial registration details ClinicalTrials.gov, Identifier: NCT03842475.

Journal article

Ilesanmi I, Tharakan G, Alexiadou K, Behary P, Alessimii H, Bovill-Taylor C, Kenkre J, Choudhury S, Doyle C, Purkayastha S, Miras A, Tsironis C, Chahal H, Bloom SR, Oliver NS, Ahmed AR, Khoo B, Tan TM-Met al., 2021, Roux-en-Y Gastric Bypass Increases Glycemic Variability and Time in Hypoglycemia in Patients With Obesity and Prediabetes or Type 2 Diabetes: A Prospective Cohort Study, DIABETES CARE, Vol: 44, Pages: 614-617, ISSN: 0149-5992

Journal article

Misra S, Khozoee B, Huang-Jiawei P, Mitsaki K, Reddy M, Salem V, Tan T, Tharakan G, Gable D, Bravis V, Valabhji Jet al., 2021, Comparison of diabetic ketoacidosis in adults, during the SARS-CoV-2 outbreak and over the same time period for the 3 preceding years, Diabetes Care, Vol: 44, Pages: e29-e31, ISSN: 0149-5992

Journal article

Miras A, Kamocka A, Pérez-Pevida B, Purkayastha S, Moorthy K, Patel A, Chahal H, Frost G, Bassett P, Castagnetto-Gissey L, Coppin L, Jackson N, Umpleby M, Bloom S, Tan T, Ahmed A, Rubino Fet al., 2021, The effect of standard versus longer intestinal bypass on GLP-1 regulation and glucose metabolism in patients with type 2 diabetes undergoing roux-en-Y gastric bypass. The long-limb study, Diabetes Care, Vol: 44, Pages: 1-9, ISSN: 0149-5992

ObjectiveRoux-en-Y gastric bypass (RYGB) characteristically enhances post-prandial levels of Glucagon-like peptide 1 (GLP-1), a mechanism that contributes to its profound glucose-lowering effects. This enhancement is thought to be triggered by bypass of food to the distal small intestine with higher densities of neuroendocrine L-cells. We hypothesised that if this is the predominant mechanism behind the enhanced secretion of GLP-1, a longer intestinal bypass would potentiate the post-prandial peak in GLP-1, translating into higher insulin secretion and thus additional improvements in glucose tolerance. To investigate this, we conducted a mechanistic study comparing two variants of RYGB that differ in the length of intestinal bypass.Research Design and MethodsFifty-three patients with type 2 diabetes and obesity were randomised to either ‘standard limb’ RYGB (50cm biliopancreatic limb) or ‘long limb’ RYGB (150cm biliopancreatic limb). They underwent measurements of GLP-1 and insulin secretion following a mixed meal and insulin sensitivity using euglycaemic hyperinsulinaemic clamps at baseline, 2 weeks and at 20% weight loss after surgery.ResultsBoth groups exhibited enhancement in post-prandial GLP-1 secretion and improvements in glycaemia compared to baseline. There were no significant differences in post-prandial peak concentrations of GLP-1, time to peak, insulin secretion, and insulin sensitivity. ConclusionThe findings of this study demonstrate that lengthening of the intestinal bypass in RYGB does not affect GLP-1 secretion. Thus, the characteristic enhancement of GLP-1 response after RYGB might not depend on delivery of nutrients to more distal intestinal segments.

Journal article

Khoo B, Tan T, Clarke S, Mills E, Patel B, Modi M, Phylactou M, Eng PC, Thurston L, Alexander E, Meeran K, Comninos A, Abbara A, Dhillo Wet al., 2021, Thyroid function before, during and after COVID-19, Journal of Clinical Endocrinology and Metabolism, Vol: 106, Pages: e803-e811, ISSN: 0021-972X

Context: The effects of COVID-19 on the thyroid axis remain uncertain. Recent evidence has been conflicting, with both thyrotoxicosis and suppression of thyroid function reported. Objective: We aimed to detail the acute effects of COVID-19 on thyroid function and determine if these effects persisted upon recovery from COVID-19. Design: Cohort observational study. Participants and setting: Adult patients admitted to Imperial College Healthcare National Health Service Trust, London, UK with suspected COVID-19 between March 9 to April 22, 2020 were included, excluding those with pre-existing thyroid disease and those missing either free thyroxine (FT4) or TSH measurements. Of 456 patients, 334 had COVID-19 and 122 did not.Main Outcome Measures: TSH and FT4 measurements at admission, and where available, those taken in 2019 and at COVID-19 follow-up. Results: Most patients (86·6%) presenting with COVID-19 were euthyroid, with none presenting with overt thyrotoxicosis. Patients with COVID-19 had a lower admission TSH and FT4 compared to those without COVID-19. In the COVID-19 patients with matching baseline thyroid function tests from 2019 (n=185 for TSH and 104 for FT4), both TSH and FT4 were reduced at admission compared to baseline. In a complete cases analysis of COVID-19 patients with TSH measurements at follow-up, admission and baseline (n=55), TSH was seen to recover to baseline at follow-up. Conclusions: Most patients with COVID-19 present with euthyroidism. We observed mild reductions in TSH and FT4 in keeping with a non-thyroidal illness syndrome. Furthermore, in survivors of COVID-19, thyroid function tests at follow-up returned to baseline.

Journal article

McGlone ER, Malallah K, Cuenco J, Wewer Albrechtsen NJ, Holst JJ, Vincent RP, Ling C, Khan OA, Verma S, Ahmed AR, Walters JR, Khoo B, Bloom SR, Tan TM-Met al., 2021, DIFFERENTIAL EFFECTS OF BILE ACIDS ON THE POST-PRANDIAL SECRETION OF GUT HORMONES: a randomised crossover study., Am J Physiol Endocrinol Metab

AIMS Bile acids (BA) regulate post-prandial metabolism directly and indirectly by affecting the secretion of gut hormones like glucagon-like peptide-1 (GLP-1). The post-prandial effects of BA on the secretion of other metabolically active hormones are not well understood. The objective of this study was to investigate the effect of oral ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) on post-prandial secretion of GLP-1, oxyntomodulin (OXM), peptide YY (PYY), glucose-dependent insulinotropic peptide (GIP), glucagon and ghrelin. METHODS Twelve healthy volunteers underwent a mixed meal test 60 minutes after ingestion of UDCA (12-16 mg/kg), CDCA (13-16 mg/kg) or no BA in a randomised cross-over study. Glucose, insulin, GLP-1, OXM, PYY, GIP, glucagon, ghrelin and fibroblast growth factor 19 were measured prior to BA administration at -60, 0 (just prior to mixed meal) and 15, 30, 60, 120, 180 and 240 minutes after the meal. RESULTS UDCA and CDCA provoked differential gut hormone responses: UDCA did not have any significant effects, but CDCA provoked significant increases in GLP-1 and OXM and a profound reduction in GIP. CDCA increased fasting GLP-1 and OXM secretion in parallel with an increase in insulin. On the other hand, CDCA reduced post-prandial secretion of GIP, with an associated reduction in post-prandial insulin secretion. CONCLUSIONS Exogenous CDCA can exert multiple salutary effects on the secretion of gut hormones; if these effects are confirmedin obesity and type 2 diabetes, CDCA may be a potential therapy for these conditions.

Journal article

Choudhury SM, Tan TMM, Lazarus K, Meeran Ket al., 2021, The use of prednisolone versus dual-release hydrocortisone in the treatment of hypoadrenalism, Endocrine Connections, Vol: 10, Pages: R66-R76, ISSN: 2049-3614

The introduction of adrenocortical extract in 1930 improved the life expectancy of hyhpoadrenal patients, with further increases seen after the introduction of cortisone acetate from 1948. Most patients are now treated with synthetic hydrocortisone, and incremental advances have been made with optimisation of daily dosing and the introduction of multidose regimens. There remains a significant mortality gap between individuals with treated hypoadrenalism and the general population. It is unclear whether this gap is a result of glucocorticoid over-replacement, under-replacement or loss of the circadian and ultradian rhythm of cortisol secretion, with the risk of detrimental excess glucocorticoid exposure at later times in the day. The way forwards will involve replacement of the diurnal cortisol rhythm with better glucocorticoid replacement regimens. The steroid profile produced by both prednisolone and dual-release hydrocortisone (Plenadren), provide a smoother glucocorticoid profile of cortisol than standard oral multidose regimens of hydrocortisone and cortisone acetate. The individualisation of prednisolone doses and lower bioavailability of Plenadren offer reductions in total steroid exposure. Although there is emerging evidence of both treatments offering better cardiometabolic outcomes than standard glucocorticoid replacement regimens, there is a paucity of evidence involving very low dose prednisolone (2–4 mg daily) compared to the larger doses (~7.5 mg) historically used. Data from upcoming clinical studies on prednisolone will therefore be of key importance in informing future practice.

Journal article

Izzi-Engbeaya C, Distaso W, Amin A, Kenkre J, Abdel-Malek M, Hope D, Oliver N, Misra S, Tan T, Hill N, Salem Vet al., 2021, Adverse outcomes in COVID-19 and diabetes – a retrospective cohort study from three London Teaching hospitals, BMJ Open Diabetes Research and Care, Vol: 9, Pages: 1-10, ISSN: 2052-4897

INTRODUCTION: Patients with diabetes mellitus admitted to hospital with COVID-19 have poorer outcomes. However, the drivers for this are not fully elucidated. We performed detailed characterisation of COVID-19 patients to determine clinical and biochemical factors that may be the drivers of poorer outcomes. RESEARCH DESIGN AND METHODS: Retrospective cohort study of 889 consecutive inpatients diagnosed with COVID-19 between 9th March 2020 and 22nd April 2020 in a large London NHS Trust. Unbiased multivariate logistic regression analysis was performed to determine variables that were independently and significantly associated with increased risk of death and/or ICU admission within 30 days of COVID-19 diagnosis. RESULTS: 62% of patients in our cohort were of non-White ethnic backgrounds and the diabetes prevalence was 38%. 323 (36%) patients met the primary outcome of death/admission to the intensive care unit (ICU) within 30 days of COVID-19 diagnosis. Male gender, lower platelet count, advancing age and higher Clinical Frailty Scale (CFS) score (but not diabetes) independently predicted poor outcomes on multivariate analysis. Antiplatelet medication was associated with a lower risk of death/ICU admission. Factors that were significantly and independently associated with poorer outcomes in patients with diabetes were co-existing ischaemic heart disease, increasing age and lower platelet count. CONCLUSIONS: In this large study of a diverse patient population, comorbidity (i.e. diabetes with ischaemic heart disease; increasing CFS score in older patients) were major determinants of poor outcomes with COVID-19. Antiplatelet medication should be evaluated in randomised clinical trials amongst high-risk patient groups.

Journal article

Jones B, McGlone ER, Fang Z, Pickford P, Corrêa IR, Oishi A, Jockers R, Inoue A, Kumar S, Görlitz F, Dunsby C, French PMW, Rutter GA, Tan TM, Tomas A, Bloom SRet al., 2021, Genetic and biased agonist-mediated reductions in β-arrestin recruitment prolong cAMP signalling at glucagon family receptors, Journal of Biological Chemistry, Vol: 296, Pages: 1-15, ISSN: 0021-9258

Receptors for the peptide hormones glucagon-like peptide-1 (GLP-1R), glucose-dependent insulinotropic polypeptide (GIPR) and glucagon (GCGR) are important regulators of insulin secretion and energy metabolism. GLP-1R agonists have been successfully deployed for the treatment of type 2 diabetes, but it has been suggested that their efficacy is limited by target receptor desensitisation and downregulation due to recruitment of β-arrestins. Indeed, recently described GLP-1R agonists with reduced β-arrestin-2 recruitment have delivered promising results in preclinical and clinical studies. We therefore aimed to determine if the same phenomenon could apply to the closely related GIPR and GCGR. In HEK293 cells depleted of both β-arrestin isoforms the duration of G protein-dependent cAMP/PKA signalling was increased in response to the endogenous ligand for each receptor. Moreover, in wild-type cells, “biased” GLP-1, GCG and GIP analogues with selective reductions in β-arrestin-2 recruitment led to reduced receptor endocytosis and increased insulin secretion over a prolonged stimulation period, although the latter effect was only seen at high agonist concentrations. Biased GCG analogues increased the duration of cAMP signalling, but this did not lead to increased glucose output from hepatocytes. Our study provides a rationale for development of GLP-1R, GIPR and GCGR agonists with reduced β-arrestin recruitment, but further work is needed to maximally exploit this strategy for therapeutic purposes.

Journal article

Jones B, Fang Z, Chen S, Manchanda Y, Bitsi S, Pickford P, David A, Shchepinova MM, Corrêa Jr IR, Hodson DJ, Broichhagen J, Tate EW, Reimann F, Salem V, Rutter GA, Tan T, Bloom SR, Tomas Aet al., 2020, Ligand-specific factors influencing GLP-1 receptor post-endocytic trafficking and degradation in pancreatic beta cells, International Journal of Molecular Sciences, Vol: 212, Pages: 1-24, ISSN: 1422-0067

The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, using biorthogonal labelling of GLP-1R to determine its localisation and degradation after treatment with GLP-1, exendin-4 and several further GLP-1R agonist peptides. We also characterised the effect of a rare GLP1R coding variant, T149M, and the role of endosomal peptidase endothelin-converting enzyme-1 (ECE-1), in GLP1R trafficking. Our data reveal how treatment with GLP-1 versus exendin-4 is associated with preferential GLP-1R targeting towards a recycling pathway. GLP-1, but not exendin-4, is a substrate for ECE-1, and the resultant propensity to intra-endosomal degradation, in conjunction with differences in binding affinity, contributes to alterations in GLP-1R trafficking behaviours and degradation. The T149M GLP-1R variant shows reduced signalling and internalisation responses, which is likely to be due to disruption of the cytoplasmic region that couples to intracellular effectors. These observations provide insights into how ligand- and genotype-specific factors can influence GLP-1R trafficking.

Journal article

Hameed S, Salem V, Alessimii H, Scholtz S, Dar O, Miras AD, Meeran K, Bloom SR, Ahmed AR, Purkayastha S, Chahal H, Tan Tet al., 2020, Imperial Satiety Protocol: A new non-surgical weight-loss programme, delivered in a health care setting, produces improved clinical outcomes for people with obesity, Diabetes, Obesity and Metabolism: a journal of pharmacology and therapeutics, Vol: 23, Pages: 270-275, ISSN: 1462-8902

‘Imperial Satiety Protocol’ (I-SatPro) is a new multifaceted approach to weight loss for people with obesity (PwO), encompassing dietary advice, time-restricted eating, physical activity and coaching to support behaviour change. Participants (n = 84) attended fortnightly I-SatPro group sessions for 30 weeks, with 70% of participants completing. On completion at 30 weeks, the mean weight loss was 15.2 ± 1.1 kg (13.2 ± 0.8% from baseline, P < .0001), which was maintained to 52 weeks (16.6 ± 1.5 kg, 14.1 ± 1.2%, P < .0001). Weight loss was not associated with reduced energy expenditure. In participants with type 2 diabetes and pre-diabetes (n = 16), glycated haemoglobin fell from 50 to 43 mmol/mol (P < .01). Systolic blood pressure fell by 12 mmHg (P < .0001). Triglycerides fell by 0.37 mmol/L (P < .01) and high-density lipoprotein rose by 0.08 mmol/L (P < .01). Short Form-36 (SF-36) functioning and wellbeing scores increased in all domains post I-SatPro intervention. For selected PwO, I-SatPro delivers clinically meaningful weight loss, and the potential for long-term health and wellbeing improvements.

Journal article

Tan T, Khoo B, Mills EG, Phylactou M, Patel B, Eng PC, Thurston L, Muzi B, Meeran K, Prevost AT, Comninos AN, Abbara A, Dhillo WSet al., 2020, Cortisol concentrations and mortality from COVID-19 - Authors' reply, The Lancet Diabetes and Endocrinology, Vol: 8, Pages: 809-810, ISSN: 2213-8595

Journal article

Chen Q, Alexiadou K, Jones B, Sands C, Lewis MR, Bloom SR, Tan T, Li Jet al., 2020, Low-calorie intake: a key mechanism contributing to the metabolic impacts of Roux-en-Y gastric bypass surgery, 56th Annual Meeting of the European-Association-for-the-Study-of-Diabetes (EASD), Publisher: SPRINGER, Pages: S263-S264, ISSN: 0012-186X

Conference paper

Khoo B, Tan TM-M, 2020, Combination gut hormones: prospects and questions for the future of obesity and diabetes therapy, Journal of Endocrinology, Vol: 246, Pages: R65-R74, ISSN: 0022-0795

Obesity represents an important public health challenge for the twenty-first century: globalised, highly prevalent and increasingly common with time, this condition is likely to reverse some of the hard-won gains in mortality accomplished in previous centuries. In the search for safe and effective therapies for obesity and its companion, type 2 diabetes mellitus (T2D), the gut hormone glucagon-like peptide-1 (GLP-1) has emerged as a forerunner and analogues thereof are now widely used in treatment of obesity and T2D, bringing proven benefits in improving glycaemia and weight loss and, notably, cardiovascular outcomes. However, GLP-1 alone is subject to limitations in terms of efficacy, and as a result, investigators are evaluating other gut hormones such as glucose-dependent insulinotropic peptide (GIP), glucagon and peptide YY (PYY) as possible partner hormones that may complement and enhance GLP-1's therapeutic effects. Such combination gut hormone therapies are in pharmaceutical development at present and are likely to make it to market within the next few years. This review examines the physiological basis for combination gut hormone therapy and presents the latest clinical results that underpin the excitement around these treatments. We also pose, however, some hard questions for the field which need to be answered before the full benefit of such treatments can be realised.

Journal article

Tan T, Khoo B, Mills EG, Phylactou M, Patel B, Eng PC, Thurston L, Muzi B, Meeran K, Prevost AT, Comninos AN, Abbara A, Dhillo WSet al., 2020, Association between high serum total cortisol concentrations and mortality from COVID-19, The Lancet Diabetes and Endocrinology, Vol: 8, Pages: 659-660, ISSN: 2213-8595

Journal article

Suba K, Patel YS, Alonso AM, Scott R, Minnion JS, Leclerc I, Owen B, Distaso W, Tan TM, Murphy K, Bloom S, Rutter GA, Salem Vet al., 2020, Chronic Administration of a Long-Acting Glucagon Analogue Results in Enhanced Insulin Secretory Activity in a Directly-Observed Murine Model, 80th Scientific Sessions of the American-Diabetes-Association (ADA), Publisher: AMER DIABETES ASSOC, ISSN: 0012-1797

Conference paper

Izzi-Engbeaya C, Mills E, Yang L, Minnion J, Tharakan G, Abbara A, Comninos A, Tan T, Dhillo Wet al., 2020, Acute effects of glucagon on reproductive hormone secretion in healthy men, Journal of Clinical Endocrinology and Metabolism, Vol: 105, ISSN: 0021-972X

ContextGlucagon increases energy expenditure; consequently, glucagon receptor agonists are in development for the treatment of obesity. Obesity negatively affects the reproductive axis, and hypogonadism itself can exacerbate weight gain. Therefore, knowledge of the effects of glucagon receptor agonism on reproductive hormones is important for developing therapeutics for obesity; but reports in the literature about the effects of glucagon receptor agonism on the reproductive axis are conflicting.ObjectiveThe objective of this work is to investigate the effect of glucagon administration on reproductive hormone secretion in healthy young men.DesignA single-blinded, randomized, placebo-controlled crossover study was conducted.SettingThe setting of this study was the Clinical Research Facility, Imperial College Healthcare NHS Trust.ParticipantsEighteen healthy eugonadal men (mean ± SEM: age 25.1 ± 1.0 years; body mass index 22.5 ± 0.4 kg/m2; testosterone 21.2 ± 1.2 nmol/L) participated in this study.InterventionAn 8-hour intravenous infusion of 2 pmol/kg/min glucagon or rate-matched vehicle infusion was administered.Main Outcome MeasuresLuteinizing hormone (LH) pulsatility; LH, follicle-stimulating hormone (FSH), and testosterone levels were measured.ResultsAlthough glucagon administration induced metabolic effects (insulin area under the curve: vehicle 1065 ± 292 min.µU/mL vs glucagon 2098 ± 358 min.µU/mL, P < .001), it did not affect LH pulsatility (number of LH pulses/500 min: vehicle 4.7 ± 0.4, glucagon 4.2 ± 0.4, P = .22). Additionally, there were no significant differences in circulating LH, FSH, or testosterone levels during glucagon administration compared with vehicle administration.ConclusionsAcute administration of a metabolically active dose of glucagon does not alter reproductive hormone secretion in healthy men. These data are important for the continued development of glucagon-based tre

Journal article

Alexiadou K, Tan TM-M, 2020, Gastrointestinal peptides as therapeutic targets to mitigate obesity and metabolic syndrome, Current Diabetes Reports, Vol: 20, Pages: 1-7, ISSN: 1534-4827

Purpose of ReviewObesity affects over than 600 million adults worldwide resulting in multi-organ complications and major socioeconomic impact. The purpose of this review is to summarise the physiological effects as well as the therapeutic implications of the gut hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin, peptide YY (PYY), and glucose-dependent insulinotropic peptide (GIP) in the treatment of obesity and type 2 diabetes.Recent FindingsClinical trials have proven that the widely used GLP-1 analogues have pleotropic effects beyond those on weight and glucose metabolism and appear to confer favourable cardiovascular and renal outcomes. However, GLP-1 analogues alone do not deliver sufficient efficacy for the treatment of obesity, being limited by their dose-dependent gastrointestinal side effects. Novel dual agonists for GLP-1/glucagon and GLP-1/GIP are being developed by the pharmaceutical industry and have demonstrated some promising results for weight loss and improvement in glycaemia over and above GLP-1 analogues. Triagonists (for example GLP-1/GIP/glucagon) are currently in pre-clinical or early clinical development.SummaryGastrointestinal hormones possess complementary effects on appetite, energy expenditure, and glucose metabolism. We highlight the idea that combinations of these hormones may represent the way forward in obesity and diabetes therapeutics.

Journal article

Kamocka A, McGlone ER, Pérez-Pevida B, Moorthy K, Hakky S, Tsironis C, Chahal H, Miras AD, Tan T, Purkayastha S, Ahmed ARet al., 2020, Candy cane revision after Roux-en-Y gastric bypass, Surgical Endoscopy, Vol: 34, Pages: 2076-2081, ISSN: 0930-2794

BACKGROUND: An excessively long-blind end of the alimentary limb following a Roux-en-Y gastric bypass (RYGB), known as a 'candy cane' (CC), may cause symptoms including abdominal pain, regurgitation and vomiting. Very few studies have examined the efficacy of surgical resection of the CC. OBJECTIVES: The aim of this study was to assess sensitivity of preoperative diagnostic tools for CC, as well as perioperative outcomes and symptom resolution after CC revision surgery. SETTING: High volume bariatric centre of excellence, United Kingdom. METHODS: Observational study of CC revisions from 2010 to 2017. RESULTS: Twenty-eight CC revision cases were identified (mean age 45 ± 9 years, female preponderance 9:1). Presenting symptoms were abdominal pain (86%), regurgitation/vomiting (43%), suboptimal weight loss (36%) and acid reflux (21%). Preoperative tests provided correct diagnosis in 63% of barium contrast swallows, 50% of upper gastrointestinal endoscopies and 29% computed tomographies. Patients presenting with pain had significantly higher CC size as compared with pain-free group (4.2 vs. 2 cm, p = 0.001). Perioperative complications occurred in 25% of cases. Complete or partial symptom resolution was documented in 73% of patients undergoing CC revision. Highest success rates were recorded in the regurgitation/vomiting group (67%). CONCLUSION: Surgical revision of CC is associated with good symptom resolution in the majority of patients, especially those presenting with regurgitation/vomiting. However, it carries certain risk of complications. CC diagnosis may frequently be missed; hence more than one diagnostic tool should be considered when investigating symptomatic patients after RYGB.

Journal article

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