Systems for characterizing Internet routing

2018 Spring.Includes bibliographical references.Today the Internet plays a critical role in our lives; we rely on it for communication, business, and more recently, smart home operations. Users expect high performance and availability of the Internet. To meet such high demands, all Internet components including routing must operate at peak efficiency. However, events that hamper the routing system over the Internet are very common, causing millions of dollars of financial loss, traffic exposed to attacks, or even loss of national connectivity. Moreover, there is sparse real-time detection and reporting of such events for the public. A key challenge in addressing such issues is lack of methodology to study, evaluate and characterize Internet connectivity. While many networks operating autonomously have made the Internet robust, the complexity in understanding how users interconnect, interact and retrieve content has also increased. Characterizing how data is routed, measuring dependency on external networks, and fast outage detection has become very necessary using public measurement infrastructures and data sources. From a regulatory standpoint, there is an immediate need for systems to detect and report routing events where a content provider's routing policies may run afoul of state policies. In this dissertation, we design, build and evaluate systems that leverage existing infrastructure and report routing events in near-real time. In particular, we focus on geographic routing anomalies i.e., detours, routing failure i.e., outages, and measuring structural changes in routing policies

Gold nanorod reshaping in vitro and in vivo using a continuous wave laser

Funding for this project was provided by ERC grant 242991 (D. Elson), and by Cancer Research UK via the CRUK Cancer Imaging Centre at the Institute of Cancer Research (ICR) to J. Bamber. We acknowledge an ERC starting grant (project number 257182) to A. Porter, and BRC funding (project number P46143) to A. Porter, D. Elson and P. Ruenraroengsak. We acknowledge NHS funding to the NIHR Biomedical Research Centre at The Royal Marsden (J. Bamber) and at Imperial College London, as well as support provided by the Cancer Research UK Imperial Centre.Gold nanorods (GNRs) are increasingly being investigated for cancer theranostics as they possess features which lend themselves in equal measures as contrast agents and catalysts for photothermal therapy. Their optical absorption spectral peak wavelength is determined by their size and shape. Photothermal therapy using GNRs is typically established using near infrared light as this allows sufficient penetration into the tumour matrix. Continuous wave (CW) lasers are the most commonly applied source of near infrared irradiation on GNRs for tumour photothermal therapy. It is perceived that large tumours may require fractionated or prolonged irradiation. However the true efficacy of repeated or protracted CW irradiation on tumour sites using the original sample of GNRs remains unclear. In this study spectroscopy and transmission electron microscopy are used to demonstrate that GNRs reshape both in vitro and in vivo after CW irradiation, which reduces their absorption efficiency. These changes were sustained throughout and beyond the initial period of irradiation, resulting from a spectral blue-shift and a considerable diminution in the absorption peak of GNRs. Solid subcutaneous tumours in immunodeficient BALB/c mice were subjected to GNRs and analysed with electron microscopy pre- and post-CW laser irradiation. This phenomenon of thermally induced GNR reshaping can occur at relatively low bulk temperatures, well below the bulk melting point of gold. Photoacoustic monitoring of GNR reshaping is also evaluated as a potential clinical aid to determine GNR absorption and reshaping during photothermal therapy. Aggregation of particles was coincidentally observed following CW irradiation, which would further diminish the subsequent optical absorption capacity of irradiated GNRs. It is thus established that sequential or prolonged applications of CW laser will not confer any additional photothermal effect on tumours due to significant attenuations in the peak optical absorption properties of GNRs following primary laser irradiation.Publisher PDFPeer reviewe

Near-infrared photoimmunotherapy targeting EGFR-Shedding new light on glioblastoma treatment

Glioblastomas (GBMs) are high-grade brain tumors, differentially driven by alterations (amplification, deletion or missense mutations) in the epidermal growth factor receptor (EGFR), that carry a poor prognosis of just 12–15 months following standard therapy. A combination of interventions targeting tumor-specific cell surface regulators along with convergent downstream signaling pathways may enhance treatment efficacy. Against this background, we investigated a novel photoimmunotherapy approach combining the cytotoxicity of photodynamic therapy with the specificity of immunotherapy. An EGFR-specific affibody (ZEGFR:03115) was conjugated to the phthalocyanine dye, IR700DX, which when excited with near-infrared light produces a cytotoxic response. ZEGFR:03115–IR700DX EGFR-specific binding was confirmed by flow cytometry and confocal microscopy. The conjugate showed effective targeting of EGFR positive GBM cells in the brain. The therapeutic potential of the conjugate was assessed both in vitro, in GBM cell lines and spheroids by the CellTiter-Glo® assay, and in vivo using subcutaneous U87-MGvIII xenografts. In addition, mice were imaged pre- and post-PIT using the IVIS/Spectrum/CT to monitor treatment response. Binding of the conjugate correlated to the level of EGFR expression in GBM cell lines. The cell proliferation assay revealed a receptor-dependent response between the tested cell lines. Inhibition of EGFRvIII+ve tumor growth was observed following administration of the immunoconjugate and irradiation. Importantly, this response was not seen in control tumors. In conclusion, the ZEGFR:03115–IR700DX showed specific uptake in vitro and enabled imaging of EGFR expression in the orthotopic brain tumor model. Moreover, the proof-of-concept in vivo PIT study demonstrated therapeutic efficacy of the conjugate in subcutaneous glioma xenografts

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

REST/NRSF regulates genetic stability and cell fate in human embryonic stem cells

REST (RE1 silencing transcription factor), also known as NRSF (neuron-restrictive silencer factor), is well-known as a transcriptional repressor of neural genes in non-neural tissues. Dysregulation of REST activity is thought to play a role in diverse diseases including cardiac hypertrophy, Down Syndrome, Huntington's disease and cancer. Previous studies examining the pluripotency transcriptional network in mouse as well as human embryonic stem cells (hESCs) have revealed that REST is regulated by the pluripotency factors OCT4, NANOG and SOX2. The goal of the present study was to evaluate the role of REST in hESCs. An inducible REST knockdown system was used to examine growth and differentiation over short and long-term culture. Interestingly, altering REST levels in multiple hESC lines did not result in loss of self-renewal, but instead led to aneuploidy. During differentiation, reduced REST levels led to altered MAPK/ERK and WNT signaling, as well as upregulation of endoderm and mesoderm markers. Critical hurdles for the translation of the clinical potential of hESCs into practice are their tumorigenic capacity, and the inefficiency in tailoring lineage differentiation. Elucidating the role of REST in regulating cell fate and genetic stability of hESCs could enable development of robust methods to stably culture and tailor lineage differentiation of these cells for use in regenerative medicine applications

REST/NRSF regulates genetic stability and cell fate in human embryonic stem cells

REST (RE1 silencing transcription factor), also known as NRSF (neuron-restrictive silencer factor), is well-known as a transcriptional repressor of neural genes in non-neural tissues. Dysregulation of REST activity is thought to play a role in diverse diseases including cardiac hypertrophy, Down Syndrome, Huntington's disease and cancer. Previous studies examining the pluripotency transcriptional network in mouse as well as human embryonic stem cells (hESCs) have revealed that REST is regulated by the pluripotency factors OCT4, NANOG and SOX2. The goal of the present study was to evaluate the role of REST in hESCs. An inducible REST knockdown system was used to examine growth and differentiation over short and long-term culture. Interestingly, altering REST levels in multiple hESC lines did not result in loss of self-renewal, but instead led to aneuploidy. During differentiation, reduced REST levels led to altered MAPK/ERK and WNT signaling, as well as upregulation of endoderm and mesoderm markers. Critical hurdles for the translation of the clinical potential of hESCs into practice are their tumorigenic capacity, and the inefficiency in tailoring lineage differentiation. Elucidating the role of REST in regulating cell fate and genetic stability of hESCs could enable development of robust methods to stably culture and tailor lineage differentiation of these cells for use in regenerative medicine applications