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1.
Cureus ; 16(3): e56252, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38623128

RESUMO

Aim The study aims to determine the incidence of malignancy at presentation and subsequent risk of malignancy (at 12 months follow-up) in a cohort of patients with double duct sign (DDS) on cross-sectional imaging but no visible stigmata of jaundice. The study also correlates malignancy with liver enzyme dysfunction and estimates the resource burden incurred during the investigation of these patients. Methods A search for the key term "double duct sign" was undertaken in the radiological database of a tertiary hepatopancreatobiliary (HPB) centre between March 2017 and March 2022. Radiological reports, clinic letters, blood results, and multidisciplinary team meeting (MDT) outcomes were reviewed during this period and at one year. The national tariff payment system was reviewed to identify tariffs for different investigations required for the cohort and to calculate the total cost incurred. Results Ninety-seven patients with DDS were identified. Sixty-four patients (66%) had a normal bilirubin (0-21 µmol/L) at presentation and were included in the analysis. Seven patients (10.9%) were diagnosed with malignant peri-ampullary tumours, and 21 (32.8%) were diagnosed with benign diseases. In 34 patients (53%) with DDS, the underlying cause remained uncharacterised. Most patients had mild abnormalities of liver enzymes, but two patients (4.3%) were diagnosed with malignant peri-ampullary tumours despite having normal serological values. Patients who had a benign diagnosis and/or who had cancer excluded without a definitive diagnosis did not go on to develop a malignancy at 12 months follow-up. However, in those patients where the underlying aetiology could not be characterised, extended surveillance was required with a total of 80 MDT discussions and multiple surveillance scans (103 CT and 65 MRI scans). Twenty-six patients underwent endoscopic ultrasound (EUS) with three patients requiring more than one EUS examination (29 investigations in total). The cost of these investigations was £38,926.89. Conclusion This study confirms that DDS even in patients without clinical jaundice or with normal liver enzymes requires careful investigation to exclude malignancy despite the resource burden this entails. This supports previously reported results in the literature, and despite the increased use of cross-sectional imaging, DDS remains a clinically significant finding. Large cohort risk stratification studies would be useful to determine clinical urgency and allow the appropriate allocation of resources.

2.
Cureus ; 15(2): e34804, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36915839

RESUMO

Ex-vivo perfusion describes the extra-corporeal delivery of fluid to an organ or tissue. Although it has been widely studied in the context of organ preservation and transplantation, it has also proven to be an invaluable tool in the development of novel models for translational pre-clinical research. Here, we review the literature reporting ex-vivo human liver perfusion experiments to further understand current perfusion techniques and protocols together with their applications. A computerised search was made of Ovid, MEDLINE, and Embase using the search words "ex-vivo liver or hepatic perfusion". All relevant studies in English describing experiments using ex-vivo perfusion of human livers between 2016 and 2021, inclusive, were included. Of 21 reviewed studies, 19 used ex-vivo human liver perfusion in the context of allogeneic liver transplantation. The quality and size of the studies varied considerably. Human liver perfusion was almost exclusively limited to whole organs and "split" livers, although one study did describe the successful perfusion of tissue sections following a partial hepatectomy. This review of recent literature involving ex-vivo human liver perfusion demonstrates that the technique is not limited to whole liver perfusion. Split-liver perfusion is extremely valuable allowing one lobe to act as a control and increasing the number available for research. This review also highlights the present lack of any reports of segmental liver perfusion. The discarded donor liver is a scarce resource, and the successful use of segmental perfusion has the potential to expand the available experimental models to facilitate pre-clinical experimentation.

3.
Diabetologia ; 66(4): 657-673, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36690836

RESUMO

AIMS/HYPOTHESIS: The aim of this study was to describe the long-term trends in cancer mortality rates in people with type 2 diabetes based on subgroups defined by sociodemographic characteristics and risk factors. METHODS: We defined a cohort of individuals aged ≥35 years who had newly diagnosed type 2 diabetes in the Clinical Practice Research Datalink between 1 January 1998 and 30 November 2018. We assessed trends in all-cause, all-cancer and cancer-specific mortality rates by age, gender, ethnicity, socioeconomic status, obesity and smoking status. We used Poisson regression to calculate age- and calendar year-specific mortality rates and Joinpoint regression to assess trends for each outcome. We estimated standardised mortality ratios comparing mortality rates in people with type 2 diabetes with those in the general population. RESULTS: Among 137,804 individuals, during a median follow-up of 8.4 years, all-cause mortality rates decreased at all ages between 1998 and 2018; cancer mortality rates also decreased for 55- and 65-year-olds but increased for 75- and 85-year-olds, with average annual percentage changes (AAPCs) of -1.4% (95% CI -1.5, -1.3), -0.2% (-0.3, -0.1), 1.2% (0.8, 1.6) and 1.6% (1.5, 1.7), respectively. Higher AAPCs were observed in women than men (1.5% vs 0.5%), in the least deprived than the most deprived (1.5% vs 1.0%) and in people with morbid obesity than those with normal body weight (5.8% vs 0.7%), although all these stratified subgroups showed upward trends in cancer mortality rates. Increasing cancer mortality rates were also observed in people of White ethnicity and former/current smokers, but downward trends were observed in other ethnic groups and non-smokers. These results have led to persistent inequalities by gender and deprivation but widening disparities by smoking status. Constant upward trends in mortality rates were also observed for pancreatic, liver and lung cancer at all ages, colorectal cancer at most ages, breast cancer at younger ages, and prostate and endometrial cancer at older ages. Compared with the general population, people with type 2 diabetes had a more than 1.5-fold increased risk of colorectal, pancreatic, liver and endometrial cancer mortality during the whole study period. CONCLUSIONS/INTERPRETATION: In contrast to the declines in all-cause mortality rates at all ages, the cancer burden has increased in older people with type 2 diabetes, especially for colorectal, pancreatic, liver and endometrial cancer. Tailored cancer prevention and early detection strategies are needed to address persistent inequalities in the older population, the most deprived and smokers.


Assuntos
Neoplasias Colorretais , Diabetes Mellitus Tipo 2 , Neoplasias do Endométrio , Masculino , Humanos , Feminino , Idoso , Inglaterra/epidemiologia , Classe Social , Mortalidade
4.
ANZ J Surg ; 92(9): 2094-2101, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36097430

RESUMO

BACKGROUND: Superior patient outcomes rely on surgical training being optimized. Accordingly, we conducted an international, prospective, cross-sectional study determining relative impacts of COVID-19, gender, race, specialty and seniority on mental health of surgical trainees. METHOD: Trainees across Australia, New Zealand and UK enrolled in surgical training accredited by the Royal Australasian College of Surgeons or Royal College of Surgeons were included. Outcomes included the short version of the Perceived Stress Scale, Oxford Happiness Questionnaire short scale, Patient Health Questionnaire-2 and the effect on individual stress levels of training experiences affected by COVID-19. Predictors included trainee characteristics and local COVID-19 prevalence. Multivariable linear regression analyses were conducted to assess association between outcomes and predictors. RESULTS: Two hundred and five surgical trainees were included. Increased stress was associated with number of COVID-19 patients treated (P = 0.0127), female gender (P = 0.0293), minority race (P = 0.0012), less seniority (P = 0.001), and greater COVID-19 prevalence (P = 0.0122). Lower happiness was associated with training country (P = 0.0026), minority race (P = 0.0258) and more seniority (P < 0.0001). Greater depression was associated with more seniority (P < 0.0001). Greater COVID-19 prevalence was associated with greater reported loss of training opportunities (P = 0.0038), poor working conditions (P = 0.0079), personal protective equipment availability (P = 0.0008), relocation to areas of little experience (P < 0.0001), difficulties with career progression (P = 0.0172), loss of supervision (P = 0.0211), difficulties with pay (P = 0.0034), and difficulties with leave (P = 0.0002). CONCLUSION: This is the first study to specifically describe the relative impacts of COVID-19 community prevalence, gender, race, surgical specialty and level of seniority on stress, happiness and depression of surgical trainees on an international scale.


Assuntos
COVID-19 , Especialidades Cirúrgicas , COVID-19/epidemiologia , Estudos Transversais , Feminino , Humanos , Saúde Mental , Estudos Prospectivos , Especialidades Cirúrgicas/educação
5.
Ann Transl Med ; 9(2): 98, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33569400

RESUMO

BACKGROUND: The initial response to islet transplantation and the subsequent acute inflammation is responsible for significant attrition of islets following both autologous and allogenic procedures. This multicentre study compares this inflammatory response using cytokine profiles and complement activation. METHODS: Inflammatory cytokine and complement pathway activity were examined in two cohorts of patients undergoing total pancreatectomy followed either by autologous (n=11) or allogenic (n=6) islet transplantation. Two patients who underwent total pancreatectomy alone (n=2) served as controls. RESULTS: The peak of cytokine production occurred immediately following induction of anaesthesia and during surgery. There was found to be a greater elevation of the following cytokines: TNF-alpha (P<0.01), MCP-1 (P=0.0013), MIP-1α (P=0.001), MIP-1ß (P=0.00020), IP-10 (P=0.001), IL-8 (P=0.004), IL-1α (P=0.001), IL-1ra (0.0018), IL-10 (P=0.001), GM-CSF (P=0.001), G-CSF (P=0.0198), and Eotaxin (P=0.01) in the allogenic group compared to autografts and controls. Complement activation and consumption was observed in all three pathways, and there were no significant differences in between the groups although following allogenic transplantation ∆IL-10 and ∆VEGF levels were significantly elevated those patients who became insulin-independent compared with those who were insulin-dependent. CONCLUSIONS: The cytokine profiles following islet transplantation suggests a significantly greater acute inflammatory response following allogenic islet transplantation compared with auto-transplantation although a significant, non-specific inflammatory response occurs following both forms of islet transplantation.

6.
Nutr Metab Cardiovasc Dis ; 31(1): 14-22, 2021 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-33223399

RESUMO

AIM: Whether the relative risk of cancer incidence and mortality associated with diabetes has changed over time is unknown. DATA SYNTHESIS: On August 12th, 2020, we electronically searched for observational studies reporting on the association between diabetes and cancer. We estimated temporal trends in the relative risk of cancer incidence or mortality associated with diabetes and calculated the ratio of relative risk (RRR) comparing different periods. As many as 193 eligible articles, reporting data on 203 cohorts (56,852,381 participants; 3,735,564 incident cancer cases; 185,404 cancer deaths) and covering the period 1951-2013, were included. The relative risk of all-site cancer incidence increased between 1980 and 2000 [RRR 1990 vs.1980: (1.24; 95% CI: 1.16, 1.34); 2000 vs.1990: (1.23; 1.15, 1.31)] and stabilised thereafter at a relative risk of 1.2; the relative risk of all-site cancer mortality was constant at about 1.2 from 1980 to 2010. Both magnitudes and trends in relative risk varied across cancer sites: the relative risk of colorectal, female breast, and endometrial cancer incidence and pancreatic cancer mortality was constant during the observed years; it increased for bladder, stomach, kidney, and pancreatic cancer incidence until 2000; and decreased for liver while increased for prostate, colon and gallbladder cancer incidence after 2000. CONCLUSIONS: Alongside the increasing prevalence of diabetes, the temporal patterns of the relative risk of cancer associated with diabetes may have contributed to the current burden of cancer in people with diabetes.


Assuntos
Diabetes Mellitus/mortalidade , Neoplasias/mortalidade , Causas de Morte/tendências , Diabetes Mellitus/diagnóstico , Humanos , Incidência , Neoplasias/diagnóstico , Estudos Observacionais como Assunto , Prevalência , Medição de Risco , Fatores de Risco , Fatores de Tempo
7.
J Surg Case Rep ; 2020(10): rjaa377, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33101639

RESUMO

A 28-year-old male with infra-cardiac totally anomalous pulmonary venous connection (TAPVC) repaired as new-born presented in adulthood with right heart strain and very large left atrium to portal vein vessel. Residual connections from pulmonary veins to systemic circulation are believed to represent persistent 'vertical veins' (VV) not ligated at the time of the initial surgery. In our patient, since endovascular occlusion was not judged suitable, the anomalous vessel was surgically ligated and resected. A review of the literature failed to find such a procedure reported in an adult patient and analyzed the intra-operative ligation of VV during repair of TAPVC.

8.
BMJ Open ; 10(9): e036471, 2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32978187

RESUMO

OBJECTIVE: To estimate the effect of empathy interventions in health education and training from randomised controlled trials (RCTs). METHODS: MEDLINE, PsycINFO, EMBASE, CINAHL and Cochrane databases were searched from inception to June 2019 for RCTs investigating the effect of empathy-enhancing interventions in medical and healthcare students and professionals. Studies measuring any aspect of 'clinical empathy' as a primary or secondary outcome were included. Two reviewers extracted data and assessed the risk of bias of eligible studies using the Cochrane Risk of Bias Tool. Random effects meta-analyses of the impact of empathy training on participants' empathy levels were performed. RESULTS: Twenty-six trials were included, with 22 providing adequate data for meta-analysis. An overall moderate effect on participant empathy postintervention (standardised mean difference 0.52, 95% CI 0.36 to 0.67) was found. Heterogeneity across trial results was substantial (I2=63%). Data on sustainability of effect was provided by 11 trials and found a moderate effect size for improved empathy up until 12 weeks (0.69, 95% CI 0.23 to 1.15), and a small but statistically significant effect size for sustainability at 12 weeks and beyond (standardised mean difference 0.34, 95% CI 0.11 to 0.57). In total, 15 studies were considered to be either unclear or high risk of bias. The quality of evidence of included studies was low. CONCLUSION: Findings suggest that empathy-enhancing interventions can be effective at cultivating and sustaining empathy with intervention specifics contributing to effectiveness. This review focuses on an important, growing area of medical education and provides guidance to those looking to develop effective interventions to enhance empathy in the healthcare setting. Further high-quality trials are needed that include patient-led outcome assessments and further evaluate the long-term sustainability of empathy training. PROTOCOL REGISTRATION NUMBER: PROSPERO (CRD42019126843).


Assuntos
Empatia , Educação em Saúde , Ingestão de Alimentos , Humanos
9.
Diabetes Care ; 43(9): 2313-2322, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32910779

RESUMO

BACKGROUND AND PURPOSE: Whether the association between type 2 diabetes (T2D) and cancer is causal remains controversial. The goal of this work is to assess the robustness of the observational associations between T2D and cancer to unmeasured confounding. DATA SOURCES AND STUDY SELECTION: PubMed, Web of Science, and the Cochrane library were systematically searched on 10 January 2019 for observational studies investigating associations between T2D and cancer incidence or mortality. DATA EXTRACTION AND DATA SYNTHESIS: Cohort-level relative risk (RR) was extracted. RRs were combined in random-effects meta-analyses and pooled estimates used in bias analyses. A total of 151 cohorts (over 32 million people, 1.1 million cancer cases, and 150,000 cancer deaths) were included. In meta-analyses, T2D was associated with incidence of several cancers, from prostate (RR 0.83; 95% CI 0.79, 0.88) to liver (2.23; 1.99, 2.49), and with mortality from pancreatic cancer (1.67; 1.30, 2.14). In bias analyses, assuming an unmeasured confounding associated with both T2D and cancer with a RR of 1.5, the proportion of studies with a true effect size larger than a RR of 1.1 (i.e., 10% increased risk in individuals with T2D) was nearly 100% for liver, pancreatic, and endometrial, 86% for gallbladder, 67% for kidney, 64% for colon, 62% for colorectal, and <50% for other cancer incidences, and 92% for pancreatic cancer mortality. LIMITATIONS: Biases other than unmeasured confounding were not analytically assessed. CONCLUSIONS: Our findings strongly suggest a causal association between T2D and liver, pancreatic, and endometrial cancer incidence, and pancreatic cancer mortality. Conversely, associations with other cancers were less robust to unmeasured confounding.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Neoplasias/epidemiologia , Adolescente , Adulto , Idoso , Criança , Estudos de Coortes , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/mortalidade , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Mortalidade , Neoplasias/complicações , Neoplasias/mortalidade , Risco , Adulto Jovem
10.
Ann Transl Med ; 8(5): 170, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32309317

RESUMO

BACKGROUND: Numerous factors influence pancreatic islet survival following auto-transplantation. Of these, the host immune response in the early peri-operative period is one of the most important. In this study we investigated the role of the mannose-binding lectin (MBL)-dependent pathway in a group of total pancreatectomy (TP) islet auto-transplantation (TPIAT) patients and classified them as competent or deficient in MBL activity. Complement pathway activities, MBL protein and inflammatory cytokine concentrations were evaluated from eleven pancreatic islet auto-transplant patients from two institutions. METHODS: Eleven patients from two institutions were prospectively recruited. Serum was screened at different time points for 29 different cytokines and compared according to their MBL deficient or competent status. Twelve patients from previous TPIAT patients also underwent screening of MBL pathway activity. RESULTS: A total nine of twenty three patients (39%) were MBL pathway deficient. MCP-1, IL-7 and IL-1a concentrations were significantly lower in the MBL deficient cohort compared to the normal MBL group (P=0.0237, 0.0001 and 0.0051 respectively). IL-6 and IL-8 concentrations were significantly raised in the normal MBL group. MBL functional activity was lower in insulin-independent group compared to the insulin-dependent group. CONCLUSIONS: Complement activation is an important, possibly damaging response during intra-portal islet infusion. MBL pathway deficiency appears common in this population and the cytokine response was attenuated in MBL pathway deficient patients. Therapeutic MBL pathway blockade during and following islet auto-transplantation (IAT) may improve islet survival and function and thereby clinical outcome.

11.
Clin Nutr ; 39(9): 2686-2694, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-31959476

RESUMO

BACKGROUND: Acute pancreatitis (AP) is marked by a strong pro-inflammatory response, which may cause a systemic inflammatory response syndrome (SIRS), organ failure, and death. Early administration of omega-3 fatty acids (FA) may reduce the pro-inflammatory response and improve outcome in AP. A systematic review focusing on the safety and efficacy of omega-3 FA in AP is lacking. AIM: Evaluate the safety and efficacy of an intervention with omega-3 FA in acute pancreatitis and additionally in sepsis. METHODS: A systematic review and meta-analysis was performed using the PubMed, Embase, and Cochrane databases including only randomized controlled trials in AP and, for safety endpoints, in sepsis investigating intervention including omega-3 FA without other active components (e.g. addition of glutamine to the intervention). The primary outcome was mortality. RESULTS: After screening 1186 studies, five randomized trials (n = 229) with omega-3 FA in AP were included. In AP patients treated with omega-3 FA within 48 h after hospitalization, a non-significant reduction of mortality was seen (OR 0∙50, 95%CI 0∙13-1∙99, p = 0∙33), compared to controls. In two studies (n = 85), omega-3 FA reduced the risk of new onset of organ failure (OR 0∙33, 95%CI 0∙12-0∙93, p = 0∙04). Nine randomized trials with 312 patients suffering from sepsis (not pancreatitis related) demonstrated a reduced mortality (OR 0∙52, 95%CI 0∙28-0∙97, p = 0·04). None of these 14 randomized trials reported safety concerns. CONCLUSIONS: Administration of omega-3 FA could reduce the risk of new-organ failure in patients with AP. There were no safety issues reported of the early administration of omega-3 FA in any of the included studies. To show the real clinical benefit of omega-3 FA in AP, a large and pragmatic randomized controlled trial is needed.


Assuntos
Ácidos Graxos Ômega-3/uso terapêutico , Pancreatite/tratamento farmacológico , Sepse/tratamento farmacológico , Doença Aguda , Anti-Inflamatórios , Síndrome da Liberação de Citocina/prevenção & controle , Ácidos Graxos Ômega-3/efeitos adversos , Humanos , Inflamação/prevenção & controle , Pancreatite/mortalidade , Sepse/mortalidade
12.
Br J Cancer ; 121(1): 65-75, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31123345

RESUMO

BACKGROUND: S100 proteins have been implicated in various aspects of cancer, including epithelial-mesenchymal transitions (EMT), invasion and metastasis, and also in inflammatory disorders. Here we examined the impact of individual members of this family on the invasion of pancreatic ductal adenocarcinoma (PDAC) cells, and their regulation by EMT and inflammation. METHODS: Invasion of PDAC cells was analysed in zebrafish embryo xenografts and in transwell invasion assays. Expression and regulation of S100 proteins was studied in vitro by immunoblotting, quantitative PCR and immunofluorescence, and in pancreatic lesions by immunohistochemistry. RESULTS: Whereas the expression of most S100 proteins is characteristic for epithelial PDAC cell lines, S100A4 and S100A6 are strongly expressed in mesenchymal cells and upregulated by ZEB1. S100A4/A6 and epithelial protein S100A14 respectively promote and represses cell invasion. IL-6/11-STAT3 pathway stimulates expression of most S100 proteins. ZEB1 synergises with IL-6/11-STAT3 to upregulate S100A4/A6, but nullifies the effect of inflammation on S100A14 expression. CONCLUSION: EMT/ZEB1 and IL-6/11-STAT3 signalling act independently and congregate to establish the expression pattern of S100 proteins, which drives invasion. Although ZEB1 regulates expression of S100 family members, these effects are masked by IL-6/11-STAT3 signalling, and S100 proteins cannot be considered as bona fide EMT markers in PDAC.


Assuntos
Interleucina-11/fisiologia , Interleucina-6/fisiologia , Neoplasias Pancreáticas/patologia , Proteínas S100/genética , Fator de Transcrição STAT3/fisiologia , Homeobox 1 de Ligação a E-box em Dedo de Zinco/fisiologia , Animais , Linhagem Celular Tumoral , Transição Epitelial-Mesenquimal , Regulação Neoplásica da Expressão Gênica , Humanos , Invasividade Neoplásica , Transdução de Sinais/fisiologia , Peixe-Zebra
13.
Mol Pharm ; 15(9): 3962-3968, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30036484

RESUMO

Angiopoietin-1 (Ang1) is a vascular protective ligand that acts through the receptor tyrosine kinase Tie2 to enhance endothelial survival and quiescence. In sepsis, diabetic retinopathy, and a range of other diseases, Ang2, an antagonist of Tie2, increases markedly. This antagonist suppresses Ang1 protective effects leading to vascular destabilization, inflammation, and endothelial death. Administration of recombinant Ang1 can counter Ang2 antagonism and restore vascular function. However, recombinant Ang1 is needed at sufficiently high concentrations to block Ang2, and the protein is difficult to produce, requires mammalian expression systems, and is prone to aggregation. Here we present an engineered synthetic Tie2 ligand that is not antagonized by Ang2 but is easy to produce and more robust than Ang1. Using a peptide phage display, we isolated a heptameric sequence that binds Tie2-ectodomain and fused this to the coiled:coil domain of cartilage oligomeric matrix protein. This pentameric protein is 60 kDa in size, expressed in E. coli, and facile to purify. The protein, designated TSL1, binds to Tie2-ectodomain in vitro and on the cell surface. TSL1 inhibits endothelial apoptosis. Crucially, TSL1 binds at a site on Tie2 distinct from the angiopoietin-binding site and is resistant to antagonism by Ang2. This engineered ligand has several advantages over recombinant Ang1 for potential therapeutic applications. The study also highlights the value of orthogonal ligands for regulating cellular receptors without being subject to antagonism or modulation by endogenous ligands.


Assuntos
Angiopoietina-2/metabolismo , Biblioteca de Peptídeos , Receptor TIE-2/metabolismo , Angiopoietina-2/genética , Apoptose/genética , Apoptose/fisiologia , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Citometria de Fluxo , Células Endoteliais da Veia Umbilical Humana , Humanos , Imunoprecipitação , Receptor TIE-2/genética
14.
Biochem Soc Trans ; 39(6): 1592-6, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22103492

RESUMO

The angiopoietins act through the endothelial receptor tyrosine kinase Tie2 to regulate vessel maturation in angiogenesis and control quiescence and stability of established vessels. The activating ligand, Ang1 (angiopoietin-1), is constitutively expressed by perivascular cells, and the ability of endothelial cells to respond to the ligand is controlled at the level of the Ang1 receptor. This receptor interacts with the related protein Tie1 on the cell surface, and Tie1 inhibits Ang1 signalling through Tie2. The responsiveness of endothelium to Ang1 is determined by the relative levels of Tie2 and the inhibitory co-receptor Tie1 in the cells. Tie1 undergoes regulated ectodomain cleavage which is stimulated by a range of factors including VEGF (vascular endothelial growth factor), inflammatory cytokines and changes in shear stress. Ectodomain cleavage of Tie1 relieves inhibition of Tie2 and enhances Ang1 signalling. This mechanism regulates Ang1 signalling without requiring changes in the level of the ligand and allows Ang1 signalling to be co-ordinated with other signals in the cellular environment. Regulation of signalling at the level of receptor responsiveness may be an important adaptation in systems in which an activating ligand is normally present in excess or where the ligand provides a constitutive maintenance signal.


Assuntos
Angiopoietinas/metabolismo , Transdução de Sinais , Animais , Humanos , Receptores de TIE/metabolismo
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