• How do people with knee osteoarthritis use osteoarthritis pain medications and does this change over time? Data from the Osteoarthritis Initiative

      Kingsbury, Sarah R; Hensor, Elizabeth MA; Walsh, Ceara AE; Hochberg, Marc C; Conaghan, Philip G (2013-09-04)
      Abstract Introduction The aim of this analysis was to describe comprehensively the cross-sectional and longitudinal patterns of analgesic and nutraceutical medication use for knee osteoarthritis (OA) in a contemporary US cohort and to investigate associated demographic and clinical factors. Methods Baseline, 12, 24 and 36 month data were obtained retrospectively from the National Institutes of Health Osteoarthritis Initiative. Participants had symptomatic radiographic knee OA. Multiple binary logistic regression models identified characteristics independently associated with the use of analgesics or nutraceuticals. Results We included 987 subjects (55.9% female, mean age 61.5 years, 71.0% white). At baseline, 68.2% reported frequent use of a conventional analgesic or nutraceutical for joint pain (for more than half of the previous month). Non-prescription non-steroidal anti-inflammatory drugs (NSAIDs) were the most frequently reported medications (26.8%), even in those more than 75-years old. Multiple conventional analgesics were used by 11.9%. Frequent analgesic use was more likely in women (odds ratio (OR) 1.8 (95% confidence interval (CI) 1.3 to 2.3)) and people with more pain (moderate 1.7 (1.2 to 2.4); severe 3.1 (2.1 to 4.7)); nutraceutical use was less likely in non-whites (0.4 (0.3 to 0.6)), those more than 74-years old (0.6 (0.3 to 0.9)) and those with comorbidities (0.6 (0.5 to 0.9)) and more likely in people with Kellgren-Lawrence (KL) grade 4 (2.2 (1.5 to 3.3)). Overall there was no change in the proportion of participants frequently using prescription or over the counter (OTC) analgesics at 36 months, although most people had changed medication type; of those using a traditional analgesic at baseline approximately one third were still using the same type at 36 months (ranging from 26.2% of baseline prescription NSAID users to 40.6% of baseline acetaminophen users). All participants reporting baseline analgesic use also reported 36 month analgesic use. Female participants (OR 95% CI 1.2 to 3.2, P = 0.009), those with high body mass index (1.2 to 4.8, P = 0.010) and those with moderate (1.6 to 2.6, P = 0.090) or severe (1.8 to 12.0, P = 0.002) baseline pain were more likely to use pain medication during the 36 month follow-up period; participants more than 75-years old were less likely (0.2 to 1.0, P = 0.053). Conclusions Most people with knee OA used pharmacological therapies frequently, and use appeared to be according to American College of Rheumatology recommendations. Change in medication type used was common. Persistent non-prescription NSAID use in older people is an area of concern.
    • How many steps/day are enough? For children and adolescents

      Tudor-Locke, Catrine; Craig, Cora L; Beets, Michael W; Belton, Sarahjane; Cardon, Greet M; Duncan, Scott; Hatano, Yoshiro; Lubans, David R; Olds, Timothy S; Raustorp, Anders; et al. (2011-07-28)
      Abstract Worldwide, public health physical activity guidelines include special emphasis on populations of children (typically 6-11 years) and adolescents (typically 12-19 years). Existing guidelines are commonly expressed in terms of frequency, time, and intensity of behaviour. However, the simple step output from both accelerometers and pedometers is gaining increased credibility in research and practice as a reasonable approximation of daily ambulatory physical activity volume. Therefore, the purpose of this article is to review existing child and adolescent objectively monitored step-defined physical activity literature to provide researchers, practitioners, and lay people who use accelerometers and pedometers with evidence-based translations of these public health guidelines in terms of steps/day. In terms of normative data (i.e., expected values), the updated international literature indicates that we can expect 1) among children, boys to average 12,000 to 16,000 steps/day and girls to average 10,000 to 13,000 steps/day; and, 2) adolescents to steadily decrease steps/day until approximately 8,000-9,000 steps/day are observed in 18-year olds. Controlled studies of cadence show that continuous MVPA walking produces 3,300-3,500 steps in 30 minutes or 6,600-7,000 steps in 60 minutes in 10-15 year olds. Limited evidence suggests that a total daily physical activity volume of 10,000-14,000 steps/day is associated with 60-100 minutes of MVPA in preschool children (approximately 4-6 years of age). Across studies, 60 minutes of MVPA in primary/elementary school children appears to be achieved, on average, within a total volume of 13,000 to 15,000 steps/day in boys and 11,000 to 12,000 steps/day in girls. For adolescents (both boys and girls), 10,000 to 11,700 may be associated with 60 minutes of MVPA. Translations of time- and intensity-based guidelines may be higher than existing normative data (e.g., in adolescents) and therefore will be more difficult to achieve (but not impossible nor contraindicated). Recommendations are preliminary and further research is needed to confirm and extend values for measured cadences, associated speeds, and MET values in young people; continue to accumulate normative data (expected values) for both steps/day and MVPA across ages and populations; and, conduct longitudinal and intervention studies in children and adolescents required to inform the shape of step-defined physical activity dose-response curves associated with various health parameters.
    • How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex

      Setty, Yaki; Chen, Chih-Chun; Secrier, Maria; Skoblov, Nikita; Kalamatianos, Dimitrios; Emmott, Stephen (2011-09-30)
      Abstract Background Neuronal migration, the process by which neurons migrate from their place of origin to their final position in the brain, is a central process for normal brain development and function. Advances in experimental techniques have revealed much about many of the molecular components involved in this process. Notwithstanding these advances, how the molecular machinery works together to govern the migration process has yet to be fully understood. Here we present a computational model of neuronal migration, in which four key molecular entities, Lis1, DCX, Reelin and GABA, form a molecular program that mediates the migration process. Results The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1) the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2) we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1) under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2) under enhanced DCX expression in mice we predict a normal or a higher bipolar migration. Conclusions We present here a system-wide computational model of neuronal migration that integrates theory and data within a precise, testable framework. Our model accounts for a range of observable behaviors and affords a computational framework to study aspects of neuronal migration as a complex process that is driven by a relatively simple molecular program. Analysis of the model generated new hypotheses and yet unobserved phenomena that may guide future experimental studies. This paper thus reports a first step toward a comprehensive in-silico model of neuronal migration.
    • How valid are the rates of Down syndrome internationally? Findings from the International Clearinghouse for Birth Defects Surveillance and Research

      Leoncini, Emanuele; Botto, Lorenzo D.; Cocchi, Guido; Annerén, Goran; Bower, Carol; Halliday, Jane; Amar, Emmanuelle; Bakker, Marian K.; Bianca, Sebastiano; Canessa Tapia, Maria Aurora; et al. (2010-07)
    • How well are European Society of Cardiology (ESC) guidelines adhered to in patients with syncope?

      O'Dwyer, C; Hade, D; Fan, C W; Cunningham, C; Kenny, R A; Falls & Blackout Unit, St James's Hospital, James's St, Dublin 8. odwyercl@tcd.ie (2010-01)
      The ESC guidelines on syncope were published in 2001 and updated in 2004. Adherence to the recommendations enables early stratification of low and high risk patients and prevents unnecessary investigations and admissions. Vasovagal syncope (VVS) is the commonest cause of syncope in all age groups and a low risk condition. The study objective was to determine whether the ESC guidelines were adhered to prior to referral to a syncope unit; 100 consecutive patients with unexplained syncope (52 +/- 23 (15-91) years); 53 female. Sixty-six patients had VVS. Forty nine (75%) of patients with VVS had undergone unnecessary investigations prior to diagnosis and 31 (47%) were admitted to hospital for investigation. Research from other countries confirms that adherence to the ESC guidelines expediates accurate diagnosis, improves resource utilization and reduces health care cost. Greater awareness amongst Irish practitioners of guidelines may improve syncope management and reduce costs.
    • How well do performance indicators perform?

      Murphy, JFA (Irish Medical Journal, 2014-11)
    • HSP72 protects cells from ER stress-induced apoptosis via enhancement of IRE1alpha-XBP1 signaling through a physical interaction.

      Gupta, Sanjeev; Deepti, Ayswaria; Deegan, Shane; Lisbona, Fernanda; Hetz, Claudio; Samali, Afshin; Apoptosis Research Centre, School of Natural Sciences, NUI Galway, Galway, Ireland. (2010)
      Endoplasmic reticulum (ER) stress is a feature of secretory cells and of many diseases including cancer, neurodegeneration, and diabetes. Adaptation to ER stress depends on the activation of a signal transduction pathway known as the unfolded protein response (UPR). Enhanced expression of Hsp72 has been shown to reduce tissue injury in response to stress stimuli and improve cell survival in experimental models of stroke, sepsis, renal failure, and myocardial ischemia. Hsp72 inhibits several features of the intrinsic apoptotic pathway. However, the molecular mechanisms by which Hsp72 expression inhibits ER stress-induced apoptosis are not clearly understood. Here we show that Hsp72 enhances cell survival under ER stress conditions. The UPR signals through the sensor IRE1alpha, which controls the splicing of the mRNA encoding the transcription factor XBP1. We show that Hsp72 enhances XBP1 mRNA splicing and expression of its target genes, associated with attenuated apoptosis under ER stress conditions. Inhibition of XBP1 mRNA splicing either by dominant negative IRE1alpha or by knocking down XBP1 specifically abrogated the inhibition of ER stress-induced apoptosis by Hsp72. Regulation of the UPR was associated with the formation of a stable protein complex between Hsp72 and the cytosolic domain of IRE1alpha. Finally, Hsp72 enhanced the RNase activity of recombinant IRE1alpha in vitro, suggesting a direct regulation. Our data show that binding of Hsp72 to IRE1alpha enhances IRE1alpha/XBP1 signaling at the ER and inhibits ER stress-induced apoptosis. These results provide a physical connection between cytosolic chaperones and the ER stress response.
    • The human mesenteric lymph node microbiome differentiates between Crohn’s disease and ulcerative colitis

      Kiernan, Miranda G.; Coffey, J. Calvin; McDermott, Kieran; Cotter, Paul D.; Cabrera-Rubio, Raul; Kiely, Patrick A.; Dunne, Colum P.; 1.Graduate Entry Medical School and Centre for Interventions in Infection, Inflammation & Immunity (4i), University of Limerick, Limerick, Ireland, (Journal of Crohn's and Colitis (JCC), 2018-09)
    • Human microbiome science: vision for the future, Bethesda, MD, July 24 to 26, 2013

      Ravel, Jacques; Blaser, Martin J; Braun, Jonathan; Brown, Eric; Bushman, Frederic D; Chang, Eugene B; Davies, Julian; Dewey, Kathryn G; Dinan, Timothy; Dominguez-Bello, Maria; et al. (2014-07-18)
      Abstract A conference entitled ‘Human microbiome science: Vision for the future’ was organized in Bethesda, MD from July 24 to 26, 2013. The event brought together experts in the field of human microbiome research and aimed at providing a comprehensive overview of the state of microbiome research, but more importantly to identify and discuss gaps, challenges and opportunities in this nascent field. This report summarizes the presentations but also describes what is needed for human microbiome research to move forward and deliver medical translational applications.
    • Hungry bone syndrome and normalisation of renal phosphorus threshold after total parathyroidectomy for tertiary hyperparathyroidism in X-linked hypophosphataemia: a case report

      Crowley, Rachel K; Kilbane, Mark; King, Thomas FJ; Morrin, Michelle; O’Keane, Myra; McKenna, Malachi J (2014-03-04)
      Abstract Introduction This is the first report of which the authors are aware to describe this c.2166delinsGG mutation in X-linked hypophosphataemia and to describe normalisation of renal threshold for phosphate excretion after parathyroidectomy for tertiary hyperparathyroidism in X-linked hypophosphataemia. Case presentation We present the case of a 34-year-old Caucasian woman with X-linked hypophosphataemia. She developed tertiary hyperparathyroidism with markedly high bone turnover requiring total parathyroidectomy and had prolonged requirement for intravenous calcium infusion after surgery. She had a novel mutation in her phosphate-regulating gene with homologies to endopeptidases on the X-chromosome and had an unusual degree of dependence on phosphate supplementation. Prior to operative intervention she had a trial of cinacalcet that improved bone turnover markers when used in isolation but which led to a paradoxical rise in parathyroid hormone levels when given with phosphate supplementation. After correction of hungry bone syndrome, the renal phosphorus threshold normalised as a manifestation of hypoparathyroid state despite marked elevation in level of fibroblast growth factor 23. Conclusions This case illustrates the risk of tertiary hyperparathyroidism as a complication of treatment for hypophosphataemia; it highlights the morbidity associated with hungry bone syndrome and provides novel insight into renal handling of phosphorus.
    • Hybrid management of a spontaneous ilio-iliac arteriovenous fistula: a case report

      O'Brien, Gavin C; Murphy, Colm; Martin, Zenia; Haider, Naseem; Colgan, Mary P; Moore, Dermot; Madhavan, Prakash; O'Neill, Sean M (2011-08-22)
      Abstract Introduction Spontaneous iliac arteriovenous fistulae are a rare clinical entity. Such localized fistulation is usually a result of penetrating traumatic or iatrogenic injury. Clinical presentation can vary greatly but commonly includes back pain, high-output congestive cardiac failure and the presence of an abdominal bruit. Diagnosis, therefore, is often incidental or delayed. Case presentation We report a case of a spontaneous ilio-iliac arteriovenous fistula in a 68-year-old Caucasian man detected following presentation with unilateral claudication and congestive cardiac failure. Following computed tomography evaluation, the fistula was successfully treated with a combined endovascular (aorto-uni-iliac device) and open (femoro-femoral crossover) approach. Conclusion Endovascular surgery has revolutionized the management of such fistulae and we report an interesting case of a high-output iliac arteriovenous fistulae successfully treated with a hybrid vascular approach.
    • Hydroxymethylglutaryl-CoA reductase inhibition with simvastatin in Acute lung injury to Reduce Pulmonary dysfunction (HARP-2) trial: study protocol for a randomized controlled trial

      McAuley, Daniel F; Laffey, John G; O’Kane, Cecilia M; Cross, Mark; Perkins, Gavin D; Murphy, Lynn; McNally, Christine; Crealey, Grainne; Stevenson, Michael; and the HARP-2 investigators on behalf of the Irish Critical Care Trials Group (2012-09-17)
      Abstract Background Acute lung injury (ALI) is a common devastating clinical syndrome characterized by life-threatening respiratory failure requiring mechanical ventilation and multiple organ failure. There are in vitro, animal studies and pre-clinical data suggesting that statins may be beneficial in ALI. The Hydroxymethylglutaryl-CoA reductase inhibition with simvastatin in Acute lung injury to Reduce Pulmonary dysfunction (HARP-2) trial is a multicenter, prospective, randomized, allocation concealed, double-blind, placebo-controlled clinical trial which aims to test the hypothesis that treatment with simvastatin will improve clinical outcomes in patients with ALI. Methods/Design Patients fulfilling the American-European Consensus Conference Definition of ALI will be randomized in a 1:1 ratio to receive enteral simvastatin 80 mg or placebo once daily for a maximum of 28 days. Allocation to randomized groups will be stratified with respect to hospital of recruitment and vasopressor requirement. Data will be recorded by participating ICUs until hospital discharge, and surviving patients will be followed up by post at 3, 6 and 12 months post randomization. The primary outcome is number of ventilator-free days to day 28. Secondary outcomes are: change in oxygenation index and sequential organ failure assessment score up to day 28, number of non pulmonary organ failure free days to day 28, critical care unit mortality; hospital mortality; 28 day post randomization mortality and 12 month post randomization mortality; health related quality of life at discharge, 3, 6 and 12 months post randomization; length of critical care unit and hospital stay; health service use up to 12 months post-randomization; and safety. A total of 540 patients will be recruited from approximately 35 ICUs in the UK and Ireland. An economic evaluation will be conducted alongside the trial. Plasma and urine samples will be taken up to day 28 to investigate potential mechanisms by which simvastatin might act to improve clinical outcomes. Trial registration Current Controlled Trials ISRCTN88244364.
    • Hypercholesterolaemia in the Irish Adult population: A Cross-Sectional Study

      Murphy, C; Shelley, E; O Halloran, A; Fahey, T; Kenny, R.A (School of Nursing and Human Sciences, Dublin City University & The Irish Longitudinal Study on Ageing (TILDA), T, 2018-01)
    • Hypersensitivity to mesalazine in a patient with inflammatory bowel disease: a case report

      Cronin, Kevin C; Colleran, Gabrielle C; Smyth, Andrew; Houlihan, Diarmuid D; O'Gorman, Thomas A (2009-08-25)
      Abstract A 32-year-old male presented with diarrhoea, mucus and bleeding per rectum. On the basis of sigmoidoscopy, rectal mesalazine was commenced uneventfully, and subsequently changed to oral mesalazine due to failure to improve. He re-presented 4 days later with frequent rigors, lethargy, palpitations and was generally unwell. His condition settled with conservative management and IV antibiotics. Oral mesalazine was withheld during the first 24 hours but was recommenced on day 2. After 2 doses he developed rigors, pyrexia, tachycardia and vomiting. Oral mesalazine was discontinued thereafter and his condition progressively improved. Mesalazine has not been re-introduced.
    • Hypertensive disorders of pregnancy and risk of neurodevelopmental disorders in the offspring: a systematic review and meta-analysis protocol.

      Maher, Gillian M; O'Keeffe, Gerard W; Kenny, Louise C; Kearney, Patricia M; Dinan, Ted G; Khashan, Ali S (BMJ open, 2017-10-05)
      Hypertensive disorders of pregnancy (HDPs), that is chronic hypertension, gestational hypertension, pre-eclampsia (de novo or superimposed on chronic hypertension) and white coat hypertension, affect approximately 5%-15% of pregnancies. HDP exposure has been linked to an increased risk of autism spectrum disorder, attention deficit/hyperactivity disorder and other neurodevelopmental disorders in children. However, findings are inconsistent, and a clear consensus on the impact of HDPs on the risk of neurodevelopmental disorders is needed. Therefore, we aim to synthesise the published literature on the relationship between HDPs and the risk of neurodevelopmental disorders in the form of a systematic review and meta-analysis.
    • Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

      Kennedy, Muiris T; Higgins, Brendan D; Costello, Joseph F; Curtin, William A; Laffey, John G (2008-07-08)
      Abstract Background Hypertonic saline (HTS) reduces the severity of lung injury in ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. However, the potential for HTS to modulate the resolution of lung injury is not known. We investigated the potential for hypertonic saline to modulate the evolution and resolution of oleic acid induced lung injury. Methods Adult male Sprague Dawley rats were used in all experiments. Series 1 examined the potential for HTS to reduce the severity of evolving oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 12) or hypertonic saline (HTS, n = 12), and the extent of lung injury assessed after 6 hours. Series 2 examined the potential for HTS to enhance the resolution of oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 6) or hypertonic saline (HTS, n = 6), and the extent of lung injury assessed after 6 hours. Results In Series I, HTS significantly reduced bronchoalveolar lavage (BAL) neutrophil count compared to Control [61.5 ± 9.08 versus 102.6 ± 11.89 × 103 cells.ml-1]. However, there were no between group differences with regard to: A-a O2 gradient [11.9 ± 0.5 vs. 12.0 ± 0.5 KPa]; arterial PO2; static lung compliance, or histologic injury. In contrast, in Series 2, hypertonic saline significantly reduced histologic injury and reduced BAL neutrophil count [24.5 ± 5.9 versus 46.8 ± 4.4 × 103 cells.ml-1], and interleukin-6 levels [681.9 ± 190.4 versus 1365.7 ± 246.8 pg.ml-1]. Conclusion These findings demonstrate, for the first time, the potential for HTS to reduce pulmonary inflammation and enhance the resolution of oleic acid induced lung injury.
    • Hypogalactosylation of serum N-glycans fails to predict clinical response to methotrexate and TNF inhibition in rheumatoid arthritis

      Ercan, Altan; Cui, Jing; Hazen, Melissa M; Batliwalla, Franak; Royle, Louise; Rudd, Pauline M; Coblyn, Jonathan S; Shadick, Nancy; Weinblatt, Michael E; Gregersen, Peter; et al. (2012-03-05)
      Abstract Introduction Rheumatoid arthritis (RA) is associated with hypogalactosylation of immunoglobulin G (IgG). We examined whether a proxy measure for galactosylation of IgG N-glycans could predict response to therapy or was differentially affected by methotrexate (MTX) or TNF blockade. Methods Using a previously defined normal phase high-performance liquid chromatography approach, we ascertained the galactosylation status of whole serum N-glycans in two well-defined RA clinical cohorts: the Autoimmune Biomarkers Collaborative Network (n = 98) and Nested I (n = 64). The ratio of agalactosylated to monogalactosylated N-glycans in serum (sG0/G1) was determined before and during therapy with MTX or TNF inhibition and correlated with anticitrullinated peptide antibody (ACPA) status and clinical response as assessed by 28-joint Disease Activity Score utilizing C-reactive peptide and European League Against Rheumatism response criteria. Results RA patients from both cohorts exhibited elevation of sG0/G1 at baseline. Improvement in clinical scores correlated with a reduction in sG0/G1 (Spearman's ρ = 0.31 to 0.37; P < 0.05 for each cohort). However, pretreatment sG0/G1 was not predictive of clinical response. Changes in sG0/G1 were similar in the MTX and TNF inhibitor groups. Corrected for disease activity, ACPA positivity correlated with higher sG0/G1. Conclusions Baseline serum N-glycan hypogalactosylation, an index previously correlated with hypogalactosylation of IgG N-glycans, did not distinguish patients with rheumatoid arthritis who were likely to experience a favorable clinical response to MTX or TNF blockade. Clinical improvement was associated with partial glycan normalization. ACPA-positive patients demonstrated enhanced N-glycan aberrancy compared with ACPA-negative patients.
    • Hypoxia increases the metastatic ability of breast cancer cells via upregulation of CXCR4

      Cronin, Patricia A; Wang, Jiang H; Redmond, H PAUL (2010-05-21)
      Abstract Background Chemokine SDF1α and its unique receptor CXCR4 have been implicated in organ-specific metastases of many cancers including breast cancer. Hypoxia is a common feature of solid tumors and is associated with their malignant phenotype. We hypothesized that hypoxia would upregulate CXCR4 expression and lead to increased chemotactic responsiveness to its specific ligand SDF1α. Methods Three breast cancer cell lines MDA-MB-231, MCF7 and 4T1 were subjected to 48 hrs of hypoxia or normoxia. Cell surface receptor expression was evaluated using flow cytometry. An extracellular matrix invasion assay and microporous migration assay was used to assess chemotactic response and metastatic ability. Results CXCR4 surface expression was significantly increased in the two human breast cancer cell lines, MDA-MB-231 and MCF7, following exposure to hypoxia. This upregulation of CXCR4 cell surface expression corresponded to a significant increase in migration and invasion in response to SDF1-α in vitro. The increase in metastatic potential of both the normoxic and the hypoxic treated breast cancer cell lines was attenuated by neutralization of CXCR4 with a CXCR4 neutralizing mAb, MAB172 or a CXCR4 antagonist, AMD3100, showing the relationship between CXCR4 overexpression and increased chemotactic responsiveness. Conclusions CXCR4 expression can be modulated by the tissue microenvironment such as hypoxia. Upregulation of CXCR4 is associated with increased migratory and invasive potential and this effect can be abrogated by CXCR4 inhibition. Chemokine receptor CXCR4 is a potential therapeutic target in the adjuvant treatment of breast cancer.
    • Hypoxia-induced DNA hypermethylation in human pulmonary fibroblasts is associated with Thy-1 promoter methylation and the development of a pro-fibrotic phenotype

      Robinson, Claire M; Neary, Roisin; Levendale, Ashleigh; Watson, Chris J; Baugh, John A (2012-08-31)
      Abstract Background Pulmonary fibrosis is a debilitating and lethal disease with no effective treatment options. Understanding the pathological processes at play will direct the application of novel therapeutic avenues. Hypoxia has been implicated in the pathogenesis of pulmonary fibrosis yet the precise mechanism by which it contributes to disease progression remains to be fully elucidated. It has been shown that chronic hypoxia can alter DNA methylation patterns in tumour-derived cell lines. This epigenetic alteration can induce changes in cellular phenotype with promoter methylation being associated with gene silencing. Of particular relevance to idiopathic pulmonary fibrosis (IPF) is the observation that Thy-1 promoter methylation is associated with a myofibroblast phenotype where loss of Thy-1 occurs alongside increased alpha smooth muscle actin (α-SMA) expression. The initial aim of this study was to determine whether hypoxia regulates DNA methylation in normal human lung fibroblasts (CCD19Lu). As it has been reported that hypoxia suppresses Thy-1 expression during lung development we also studied the effect of hypoxia on Thy-1 promoter methylation and gene expression. Methods CCD19Lu were grown for up to 8 days in hypoxia and assessed for global changes in DNA methylation using flow cytometry. Real-time PCR was used to quantify expression of Thy-1, α-SMA, collagen I and III. Genomic DNA was bisulphite treated and methylation specific PCR (MSPCR) was used to examine the methylation status of the Thy-1 promoter. Results Significant global hypermethylation was detected in hypoxic fibroblasts relative to normoxic controls and was accompanied by increased expression of myofibroblast markers. Thy-1 mRNA expression was suppressed in hypoxic cells, which was restored with the demethylating agent 5-aza-2′-deoxycytidine. MSPCR revealed that Thy-1 became methylated following fibroblast exposure to 1% O2. Conclusion These data suggest that global and gene-specific changes in DNA methylation may play an important role in fibroblast function in hypoxia.
    • Hypoxia-inducible factor (HIF) network: insights from mathematical models

      Cavadas, Miguel AS; Nguyen, Lan K; Cheong, Alex (2013-06-10)
      Abstract Oxygen is a crucial molecule for cellular function. When oxygen demand exceeds supply, the oxygen sensing pathway centred on the hypoxia inducible factor (HIF) is switched on and promotes adaptation to hypoxia by up-regulating genes involved in angiogenesis, erythropoiesis and glycolysis. The regulation of HIF is tightly modulated through intricate regulatory mechanisms. Notably, its protein stability is controlled by the oxygen sensing prolyl hydroxylase domain (PHD) enzymes and its transcriptional activity is controlled by the asparaginyl hydroxylase FIH (factor inhibiting HIF-1). To probe the complexity of hypoxia-induced HIF signalling, efforts in mathematical modelling of the pathway have been underway for around a decade. In this paper, we review the existing mathematical models developed to describe and explain specific behaviours of the HIF pathway and how they have contributed new insights into our understanding of the network. Topics for modelling included the switch-like response to decreased oxygen gradient, the role of micro environmental factors, the regulation by FIH and the temporal dynamics of the HIF response. We will also discuss the technical aspects, extent and limitations of these models. Recently, HIF pathway has been implicated in other disease contexts such as hypoxic inflammation and cancer through crosstalking with pathways like NFκB and mTOR. We will examine how future mathematical modelling and simulation of interlinked networks can aid in understanding HIF behaviour in complex pathophysiological situations. Ultimately this would allow the identification of new pharmacological targets in different disease settings.