9 research outputs found
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Investigation of small molecule modulators of O-GlcNAc
No full textIn the central dogma of molecular biology, DNA is transcribed to RNA, which is spliced and then translated into proteins, which execute various biological functions and themselves are regulated by post-translational modifications. O-GlcNAc is an essential and ubiquitous monosaccharide post-translational modification involved in many major cellular processes. O-GlcNAc is installed and removed by a pair of enzymes, the writer O-GlcNAc transferase (OGT) and the eraser O-GlcNAcase (OGA). The cell tightly regulates these enzymes and thus O-GlcNAc homeostasis through a highly conserved post-transcriptional mechanism. Through this detained intron feedback mechanism, OGT and OGA levels are inversely adjusted to maintain O-GlcNAc levels. For example, if O-GlcNAc is elevated, the cell responds by downregulating OGT and upregulating OGA to diminish O-GlcNAc, and vice versa in the case that O-GlcNAc is lowered. Here, I present work detailing the development of assays to study O-GlcNAc and its cycling enzymes in vitro and in cells and the application of these assays to high-throughput screening, leading to the discovery of small molecule splicing modulators that can disrupt O-GlcNAc homeostasis.
In Chapter 1, I review the O-GlcNAc field, covering the multitude of protein biochemistry, medicinal chemistry, and chemical biology studies performed since the initial discovery of O-GlcNAc over four decades ago. This chapter also provides a timely update to clinical efforts to therapeutically modulate O-GlcNAc, primarily focused on OGA inhibition for the treatment of neurodegenerative diseases such as Alzheimer’s disease. In addition to highlighting the major fundamental discoveries within the O-GlcNAc field, I also emphasize opportunities for further research into the basic biology of O-GlcNAc and its cycling enzymes and the potential therapeutic application of these findings.
In Chapter 2, I discuss our assay development efforts towards discovery of OGT ligands. We adapted and developed protocols to purify OGT constructs and subsequent assays to characterize protein—ligand binding interactions including fluorescence polarization (FP), time-resolved Förster resonance energy transfer (TR-FRET), and differential scanning fluorimetry (DSF). We additionally discuss efforts to use DSF as a high-throughput screening assay to discover OGT binders from a bioactive compound library and a screening informer set and subsequent validation of these hits. While ultimately no hits were discovered to be selective OGT binders from these screens, the protocols developed here will be valuable for future efforts to discover OGT ligands through similar assays.
In Chapter 3, I describe three parallel screening campaigns employing the Broad Institute Drug Repurposing Hub. Specifically, we screened this library using in vitro enzymatic assays against OGT and OGA and using a cellular reporter of OGT splicing in a high-content microscopy format to understand how clinically relevant compounds and pathways may intersect with O-GlcNAc homeostasis. We describe the optimization and miniaturization of these assays and the subsequent validation of hits from these screening efforts. I report that the dopamine receptor agonist piribedil and the AKT inhibitor GSK690693 have previously unannotated OGA inhibitor activity, and that GSK690693 and the ROCK inhibitor Y-33075 are able to disrupt O-GlcNAc homeostasis in cells, downregulating both OGT and OGA.
In Chapter 4, I detail mechanistic investigations of how GSK690693 and Y-33075 disrupt O-GlcNAc homeostasis. I find that these compounds have unique effects on OGT and OGA transcripts compared to previously characterized O-GlcNAc perturbogens. We further demonstrate that these compounds act orthogonally to previously characterized cis-regulatory elements within OGT. After identifying an alternative 5’ splice site induced by Y-33075 within OGA, we conducted RNA sequencing and related alternative splicing analyses, finding that GSK690693 is a broad inhibitor of intron processing and that Y-33075 is a specific modulator of exon inclusion across the transcriptome. I conclude with a discussion of the implications of these findings for therapeutic targeting of O-GlcNAc and other targets by splicing modulators and understanding cross-talk between O-GlcNAc and splicing.Chemistry and Chemical Biolog
Y-Shaped Cutting for the Systematic Characterization of Cutting and Tearing
No full textThough they share the similarity of inducing material failure at a crack tip, the cutting and tearing energies of soft materials cannot be quantitatively related to one another. One of the reasons for this lack of understanding comes from additional complications that arise during standard cutting techniques. Decades ago, Lake and Yeoh [Int. J. of Fracture, 1978] described a natural rubber cutting method that uses a 'Y-shaped' sample geometry to mitigate several of these challenges, including minimizing friction and controlling the strain energy available to drive fracture. The latter, understood via a fracture mechanics framework, enables relative tuning between a tearing contribution to the cutting energy and a cutting contribution. In this manuscript, we extend Lake and Yeoh's largely unreplicated results to softer, more highly deformable polydimethylsiloxane (PDMS) materials. The range of applicability of this technique to variations in material response, sample geometry, boundary conditions, and cutting rate is large. We utilize this flexibility to describe factors leading to the onset of a material-dependent, stick-slip cutting response, which occurs at low cutting rates and high tearing contributions. Furthermore, variation in cutting blade radius reveals a minimum cutting energy threshold even for blades with radii on the order of a few tens of nanometers. For blunter blades, cutting energy reflects the effects of material strain-stiffening. These results establish the Y-shaped cutting geometry as a useful tool in the study of soft fracture.Open Restriction set for Item 110090 on 2019-02-26T17:36:25Z with date null by [email protected] by Shelby Hutchens ([email protected]) on 2019-02-26T17:42:15Z
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Previous issue date: 2019-02NSF grant no. 1562766Ope
New England BK consortium: Regional survey of BK screening and management protocols in comparison to published consensus guidelines.
No full textINTRODUCTION: BK polyomavirus (BKPyV) continues to impact renal transplant recipients (RTR). The New England BK Consortium aims to jointly optimize screening and management of BKPyV.
METHODS: Our first project was to survey centers\u27 BKPyV screening protocols and compare them to consensus guidelines.
RESULTS: Thirteen of 15 centers (86.7%) returned the survey. Only two center reported using monitoring parameters that were in line with consensus guidelines for BKPyV screening, while the majority of centers reported less intensive methods and shorter duration. One center reported performing renal biopsies in all patients with plasma viral loads \u3e10 000 copies/mL, while all other centers only perform for-cause biopsies. For presumptive nephropathy, 11 centers recommend a biopsy for confirmation. For management of documented BKPyV-associated nephropathy, 12 centers propose further immunosuppression reduction. Nine centers report CNI dose reduction as their primary treatment. More than half of centers surveyed reported use of leflunomide, cidofovir or intravenous immunoglobulin.
CONCLUSIONS: There was a large variance in BKPyV screening and management strategies among centers. Due to these results, all participating centers agreed to implement uniform screening and aim to optimize management protocols
Framing sociology in Taiwan, Hong Kong and Singapore : geopolitics, states and practitioners
No full textThis project maps and compares how sociology as an institutionalised discipline
of teaching and research has been introduced, developed and practiced in Taiwan,
Hong Kong and Singapore. It sets out to interpret the observed trajectories in
light of social-historical contexts. The three cases presented share some
similarities in their colonial pasts, Chinese-populated demography, and
development trajectories as "Asian tigers". However, they demonstrate a sharp
contrast in post-war geopolitics, political context, and identity.
Three levels of analytical categories are involved in the analysis: geopolitical,
state-institutional, and (collective) practitioner-level. On the one hand, this
project attempts to look beyond the national container to introduce various
trans-border factors (e.g. scholarly migration, foreign funding and knowledge
flow) into the analytical scope under the conceptual framework of a "world
system of knowledge network." On the other hand, the explanation sought is to
be grounded on a sympathetic understanding of the actors and their
psychological perspective.
The data analysed includes literature and archive material, bibliographic and
demographic datasets, interviews with 56 sociologists stratified by
bibliographical factors and a few informative talks, and some ethnographic
observation in the field study.
How sociology was introduced and institutionalized in three locations along the
post-war geopolitical structure will be traced. The "domestic disciplinary identity"
will be explored based on a systematic bibliographic review. A survey of the
various modes of public engagement of sociologists is interpreted and the thesis
relates some observed patterns to contextual factors. It further assesses the
impact of recent higher education reform under managerialism and academic
globalism on sociology
The weakness of a democratic system and its interplay with external political economic development － in case study of Taiwan after 1949
No full textAbstract
The major work of this research is to understand the characteristics and uniqueness of Taiwan’s democratic development. The weaknesses and problems of this democratic system are believed to be influential to its external political economic development especially when the Cross-Strait economic interaction is getting closer and become the most significant issue for the island’s further economic development.
In order to prove this argument, the research focuses on two major theories in the fields of democratic development and international political economy (IPE). The democratic development theories include the discussion of democratization (modernization, transition and social structural approach), democratic institutions (institutional choice and its political consequence), civil society and political culture. The IPE theories include the discussion of functional work of international economic organizations, type of trade, capital flow, and role of Multinational Corporations (MNCs). After reviewing the literatures about these two major theories, the researcher tries to apply these theoretical discussions into the case of Taiwan and createS a four-level analytical framework (democratic values, institutions choice and design and civil society) to examine and explain the interrelation between the weakness of Taiwan’s democratic system and its effects on the Cross-Strait economic interaction.
There are two parts of empirical research in this dissertation to enhance the idea mentioned above. The first part is the historical discussion in the chapters 5 and 6 which focus the sixty-one-year process (1949-2008) of the island’s gradually established democratic system under various periods of international political economy environment. The second part is the investigation on the current political situation of the island after the second party alternation and reconciliation of cross strait relations with a series of political talks and economic cooperation after 2008. In Chapter 7, the research focuses on Kuomintang (KMT) and its mainland policy; In Chapter 8, the discussion changes the focuses on the role of Democratic Progressive Party (DPP) and its different perspectives on the development of further Cross-Strait interaction.
The major finding of this research is the fundamental weakness of Taiwan’s democratic system due to the long-existing Blue-Green Conflicts. The uniqueness had created the difficulties (dispute over One China Principle) for the nascent democracy to establish an efficient democratic system which is very influential to make useful economic policies especially the appropriate trade relations and commercial cooperation with China (including how to support Taishang). Nevertheless, the research of this dissertation also finds that the closer cross strait interaction after 2008 did not produce a direct, manifest and complete influence on the island’s internal social economic development, as well as the change of the democratic system
DataSheet_1_Preoperative hydronephrosis is an independent protective factor of renal function decline after nephroureterectomy for upper tract urothelial carcinoma.pdf
No full textObjectivesTo evaluate the predictive role of pre-nephroureterectomy (NU) hydronephrosis on post-NU renal function (RF) change and preserved eligibility rate for adjuvant therapy in patients with upper tract urothelial carcinoma (UTUC).Patients and methodsThis retrospective study collected data of 1018 patients from the Taiwan UTUC Collaboration Group registry of 26 institutions. The patients were divided into two groups based on the absence or presence of pre-NU hydronephrosis. Estimated glomerular filtration rate (eGFR) was calculated pre- and post-NU respectively. The one month post-NU RF change, chronic kidney disease (CKD) progression, and the preserved eligibility rate for adjuvant therapy were compared for each CKD stage.Results404 (39.2%) patients without and 614 (60.8%) patients with pre-NU hydronephrosis were enrolled. The median post-NU change in the eGFR was significantly lower in the hydronephrosis group (-3.84 versus -12.88, pConclusionPre-NU hydronephrosis is an independent protective predictor for post-NU RF decline, CKD progression, and eligibility for adjuvant therapy. With cautious selection for those unfavorably prognostic, non-metastatic UTUC patients with preoperative hydronephrosis, adjuvant rather than neoadjuvant therapy could be considered due to higher chance of preserving eligibility.</p
Segmental ureterectomy outcome of upper tract urothelial carcinoma in a high endemic area: A Taiwan nationwide collaborative study
No full textPurpose:. According to the National Comprehensive Cancer Network guidelines, segmental ureterectomy (SU) of upper tract urothelial carcinoma (UTUC) is a considerable option for selected mid- and distal ureteral urothelial carcinoma (UC). As a UTUC endemic area, Taiwan lacks treatment outcome analysis of SU.
Materials and methods:. This study retrospectively reviewed the treatment outcomes of SU for clinically localized UTUCs. Patients with biopsy or washing cytology-confirmed UTUCs who underwent open, laparoscopic, or robot-assisted management with curative intent were retrospectively reviewed for the eligibility of analysis. Cox regression was applied for univariable and multivariable analyses.
Results:. A total of 161 patients who underwent SU were reviewed and analyzed. The median follow-up period was 44.5 (interquartile range, 21.6–84.9) months. After SU, 56/161 (34.8%) patients were free of UTUCs after the follow-up, 25/161 (15.5%) patients had local recurrence, and 35/161 (21.7%) had lymph node or distant metastasis. Surgical margin involvement was a risk factor associated with worse cancer-specific survival. Higher bladder recurrence and local recurrence rates were observed with concurrent bladder UC. Lymphovascular invasion and previous radical nephroureterectomy (RNU) for UC were related to higher local recurrence rates. Patients with pathological T3/T4 stage and end-stage renal disease tended to have higher metastasis rates. For the management of local recurrence, 19 patients received salvage RNU and 25 patients had adjuvant chemotherapy. However, 26/161 (16.1%) patients died of UTUCs and 2/161 (1.2%) patients died of surgery-related complications.
Conclusion:. SU provides acceptable oncological outcomes if the surgeons select candidates carefully. SU is not recommended if the patient has T3 or higher stage or comorbidity of end-stage renal disease. Concurrent bladder UC is a risk factor for worse bladder recurrence-free survival and local recurrence-free survival. Lymphovascular invasion and previous RNU for UC were related to higher local recurrence rates. After SU, periodic follow-up is mandatory because the local recurrence rate is higher than radical surgery
Effect of colchicine on perioperative atrial fibrillation and myocardial injury after non-cardiac surgery in patients undergoing major thoracic surgery (COP-AF): an international randomised trial
No full textBackground: Higher levels of inflammatory biomarkers are associated with an increased risk of perioperative atrial fibrillation and myocardial injury after non-cardiac surgery (MINS). Colchicine is an anti-inflammatory drug that might reduce the incidence of these complications. Methods: COP-AF was a randomised trial conducted at 45 sites in 11 countries. Patients aged 55 years or older and undergoing major non-cardiac thoracic surgery were randomly assigned (1:1) to receive oral colchicine 0·5 mg twice daily or matching placebo, starting within 4 h before surgery and continuing for 10 days. Randomisation was done with use of a computerised, web-based system, and was stratified by centre. Health-care providers, patients, data collectors, and adjudicators were masked to treatment assignment. The coprimary outcomes were clinically important perioperative atrial fibrillation and MINS during 14 days of follow-up. The main safety outcomes were a composite of sepsis or infection, and non-infectious diarrhoea. The intention-to-treat principle was used for all analyses. This trial is registered with ClinicalTrials.gov, NCT03310125. Findings: Between Feb 14, 2018, and June 27, 2023, we enrolled 3209 patients (mean age 68 years [SD 7], 1656 [51·6%] male). Clinically important atrial fibrillation occurred in 103 (6·4%) of 1608 patients assigned to colchicine, and 120 (7·5%) of 1601 patients assigned to placebo (hazard ratio [HR] 0·85, 95% CI 0·65 to 1·10; absolute risk reduction [ARR] 1·1%, 95% CI –0·7 to 2·8; p=0·22). MINS occurred in 295 (18·3%) patients assigned to colchicine and 325 (20·3%) patients assigned to placebo (HR 0·89, 0·76 to 1·05; ARR 2·0%, –0·8 to 4·7; p=0·16). The composite outcome of sepsis or infection occurred in 103 (6·4%) patients in the colchicine group and 83 (5·2%) patients in the placebo group (HR 1·24, 0·93–1·66). Non-infectious diarrhoea was more common in the colchicine group (134 [8·3%] events) than the placebo group (38 [2·4%]; HR 3·64, 2·54–5·22). Interpretation: In patients undergoing major non-cardiac thoracic surgery, administration of colchicine did not significantly reduce the incidence of clinically important atrial fibrillation or MINS but increased the risk of mostly benign non-infectious diarrhoea. Funding: Canadian Institutes of Health Research, Accelerating Clinical Trials Consortium, Innovation Fund of the Alternative Funding Plan for the Academic Health Sciences Centres of Ontario, Population Health Research Institute, Hamilton Health Sciences, Division of Cardiology at McMaster University, Canada; Hanela Foundation, Switzerland; and General Research Fund, Research Grants Council, Hong Kong
