Co-designing the computational model and the computing substrate

Given a proposed unconventional computing substrate, we can ask: Does it actually compute? If so, how well does it compute? Can it be made to compute better? Given a proposed unconventional computational model we can ask: How powerful is the model? Can it be implemented in a substrate? How faithfully or efficiently can it be implemented? Given complete freedom in the choice of model and substrate, we can ask: Can we co-design a model and substrate to work well together? Here I propose an approach to posing and answering these questions, building on an existing definition of physical computing and framework for characterising the computing properties of given substrates

pO polarography, contrast enhanced color duplex sonography (CDS), [18F] fluoromisonidazole and [18F] fluorodeoxyglucose positron emission tomography: validated methods for the evaluation of therapy-relevant tumor oxygenation or only bricks in the puzzle of tumor hypoxia?

<p>Abstract</p> <p>Background</p> <p>The present study was conducted to analyze the value of ([¹⁸F] fluoromisonidazole (FMISO) and [¹⁸F]-2-fluoro-2'-deoxyglucose (FDG) PET as well as color pixel density (CPD) and tumor perfusion (TP) assessed by color duplex sonography (CDS) for determination of therapeutic relevant hypoxia. As a standard for measuring tissue oxygenation in human tumors, the invasive, computerized polarographic needle electrode system (pO₂histography) was used for comparing the different non invasive measurements.</p> <p>Methods</p> <p>Until now a total of 38 Patients with malignancies of the head and neck were examined. Tumor tissue pO₂was measured using a pO₂-histograph. The needle electrode was placed CT-controlled in the tumor without general or local anesthesia. To assess the biological and clinical relevance of oxygenation measurement, the relative frequency of pO₂readings, with values ≤ 2.5, ≤ 5.0 and ≤ 10.0 mmHg, as well as mean and median pO₂were stated. FMISO PET consisted of one static scan of the relevant region, performed 120 min after intravenous administration. FMISO tumor to muscle ratios (FMISO_T/M) and tumor to blood ratios (FMISO_T/B) were calculated. FDG PET of the lymph node metastases was performed 71 ± 17 min after intravenous administration. To visualize as many vessels as possible by CDS, a contrast enhancer (Levovist^®, Schering Corp., Germany) was administered. Color pixel density (CPD) was defined as the ratio of colored to grey pixels in a region of interest. From CDS signals two parameters were extracted: color hue – defining velocity (v) and color area – defining perfused area (A). Signal intensity as a measure of tissue perfusion (TP) was quantified as follows: TP = v_mean× A_mean.</p> <p>Results</p> <p>In order to investigate the degree of linear association, we calculated the Pearson correlation coefficient. Slight (|r| > 0.4) to moderate (|r| > 0.6) correlation was found between the parameters of pO₂polarography (pO₂readings with values ≤ 2.5, ≤ 5.0 and ≤ 10.0 mmHg, as well as median pO₂), CPD and FMISO_T/M. Only a slight correlation between TP and the fraction of pO₂values ≤ 10.0 mmHg, median and mean pO₂could be detected. After exclusion of four outliers the absolute values of the Pearson correlation coefficients increased clearly. There was no relevant association between mean or maximum FDG uptake and the different polarographic- as well as the CDS parameters.</p> <p>Conclusion</p> <p>CDS and FMISO PET represent different approaches for estimation of therapy relevant tumor hypoxia. Each of these approaches is methodologically limited, making evaluation of clinical potential in prospective studies necessary.</p

Intensified therapies improve survival and identification of novel prognostic factors for placental-site and epithelioid trophoblastic tumours

BACKGROUND: Placental-site trophoblastic (PSTT) and epithelioid trophoblastic tumours (ETT) are the rarest malignant forms of gestational trophoblastic disease (GTD). Our prior work demonstrated that an interval of ≥48 months from the antecedent pregnancy was associated with 100% death rate, independent of the stage. Here, we assess whether modified treatments for these patients have increased survival and identify new prognostic factors. METHODS: The United Kingdom GTD database was screened to identify all PSTT/ETT cases diagnosed between 1973 and 2014. Data and survival outcomes from our prior patient cohort (1976–2006) were compared to our new modern cohort (2007–2014), when intensified treatments were introduced. RESULTS: Of 54,743 GTD patients, 125 (0.23%) were diagnosed with PSTT and/or ETT. Probability of survival at 5 and 10 years following treatment was 80% (95% CI 72.8–87.6%) and 75% (95% CI 66.3–84.3%), respectively. Univariate analysis identified five prognostic factors for reduced overall survival (age, FIGO stage, time since antecedent pregnancy, hCG level, mitotic index) of which stage IV disease (HR 6.18, 95% CI 1.61–23.81, p = 0.008) and interval ≥48 months since antecedent pregnancy (HR 14.57, 95% CI 4.17–50.96, p < 0.001) were most significant on multivariable analysis. No significant differences in prognostic factors were seen between the old and new patient cohort. However, the new cohort received significantly more cisplatin-based and high-dose chemotherapy, and patients with an interval ≥48 months demonstrated an improved median overall survival (8.3 years, 95% CI 1.53–15.1, versus 2.6 years, 95% CI 0.73–4.44, p = 0.·005). CONCLUSION: PSTT/ETT with advanced FIGO stage or an interval ≥48 months from their last known pregnancy have poorer outcomes. Platinum-based and high-dose chemotherapy may help to improve survival in poor-prognosis patients

Mental health burden for NHS healthcare staff during the COVID-19 pandemic: first results of a longitudinal survey

Background The current investigation aimed to assess the mental health burden on healthcare workers during the early stages of the COVID-19 pandemic. Methods A link to an online survey was sent to an estimate of 18,100 employees of Sheffield Teaching Hospitals NHS Foundation Trust (STH) who had access to email. The survey was completed between 2nd and June 12, 2020.1390 healthcare workers (medical, nursing, administrative and other professions) participated in the first survey. Data from a general population sample (n = 2025) was used for comparison. Severity of somatic symptoms was measured by the PHQ-15. Severity and probable diagnosis of depression, anxiety, and PTSD were measured by the PHQ-9, GAD-7, and ITQ. Linear and logistic regressions were performed to determine if population group predicted the severity of mental health outcomes, and probable diagnosis of depression, anxiety, and PTSD. Additionally, ANCOVAs were performed to compare mental health outcomes between occupational roles in HCWs. Analysis was performed using SPSS. Findings Healthcare workers are more likely to experience greater severity of somatic symptoms, as well as severity and probable diagnosis of depression and anxiety, compared to the general population, but not increased traumatic stress symptoms. Scientific and technical, nursing and admin staff were more likely to experience worse mental health outcomes, compared to medical staff. Interpretation The COVID-19 pandemic has led to increased mental health burden in some, but not all healthcare workers during the first acute phase of the pandemic. The findings from the current investigation provide valuable insights into which healthcare workers are particularly vulnerable to developing adverse mental health outcomes during and after a pandemic

A novel combretastatin A-4 derivative, AC7700, strongly stanches tumour blood flow and inhibits growth of tumours developing in various tissues and organs

In a previous study, we used subcutaneous LY80 tumours (a subline of Yoshida sarcoma), Sato lung carcinoma, and methylcholanthrene-induced primary tumours, to demonstrate that a novel water-soluble combretastatin A-4 derivative, AC7700, abruptly and irreversibly stopped tumour blood flow. As a result of this interrupted supply of nutrients, extensive necrosis was induced within the tumour. In the present study, we investigated whether AC7700 acts in the same way against solid tumours growing in the liver, stomach, kidney, muscle, and lymph nodes. Tumour blood flow and the change in tumour blood flow induced by AC7700 were measured by the hydrogen clearance method. In a model of cancer chemotherapy against metastases, LY80 cells (2×106) were injected into the lateral tail vein, and AC7700 at 10 mg kg−1 was injected i.v. five times at intervals of 2 days, starting on day 7 after tumour cell injection. The number and size of tumours were compared with those in the control group. The change in tumour blood flow and the therapeutic effect of AC7700 on microtumours were observed directly by using Sato lung carcinoma implanted in a rat transparent chamber. AC7700 caused a marked decrease in the tumour blood flow of all LY80 tumours developing in various tissues and organs and growth of all tumours including lymph node metastases and microtumours was inhibited. In every tumour, tumour blood flow began to decrease immediately after AC7700 administration and reached a minimum at approximately 30 min after injection. In many tumour capillaries, blood flow completely stopped within 3 min after AC7700 administration. These results demonstrate that AC7700 is effective for tumours growing in various tissues and organs and for metastases. We conclude that tumour blood flow stanching induced by AC7700 may become an effective therapeutic strategy for all cancers, including refractory cancers because the therapeutic effect is independent of tumour site and specific type of cancer

Sequence dependent antitumour efficacy of the vascular disrupting agent ZD6126 in combination with paclitaxel

The clinical success of small-molecule vascular disrupting agents (VDAs) depends on their combination with conventional therapies. Scheduling and sequencing remain key issues in the design of VDA–chemotherapy combination treatments. This study examined the antitumour activity of ZD6126, a microtubule destabilising VDA, in combination with paclitaxel (PTX), a microtubule-stabilising cytotoxic drug, and the influence of schedule and sequence on the efficacy of the combination. Nude mice bearing MDA-MB-435 xenografts received weekly cycles of ZD6126 (200 mg kg−1 i.p.) administered at different times before or after PTX (10, 20, and 40 mg kg−1 i.v.). ZD6126 given 2 or 24 h after PTX showed no significant benefit, a result that was attributed to a protective effect of PTX against ZD6126-induced vascular damage and tumour necrosis, a hallmark of VDA activity. Paclitaxel counteracting activity was reduced by distancing drug administrations, and ZD6126 given 72 h after PTX potentiated the VDA's antitumour activity. Schedules with ZD6126 given before PTX improved therapeutic activity, which was paralleled by a VDA-induced increase in cell proliferation in the viable tumour tissue. Paclitaxel given 72 h after ZD6126 yielded the best response (50% tumours regressing). A single treatment with ZD6126 followed by weekly administration of PTX was sufficient to achieve a similar response (57% remissions). These findings show that schedule, sequence and timing are crucial in determining the antitumour efficacy of PTX in combination with ZD6126. Induction of tumour necrosis and increased proliferation in the remaining viable tumour tissue could be exploited as readouts to optimise schedules and maximise therapeutic efficacy

Standing on the shoulders of tech giants: Media delivery, streaming television, and the rise of global suppliers

This article uses the case study of Internet Protocol (IP) delivery for streaming television to demonstrate how technology and globalization combine to change what media firms do, how they create value, and with whom. Media delivery - the sum of the value-adding tasks necessary to transfer content from source to audience - has become a mosaic of technologies that sustain a complex and fast-evolving video ecosystem. Broadcasters had been in charge of the full transmission process once, of tasks deemed core to their business. Today, media delivery is externalized to the market and devolved to a network of suppliers. These suppliers are no ordinary firms, but tech giants that have developed deep global capabilities. They gain further leverage by being cross-sectoral, serving clients across multiple industries. Who are these suppliers? What makes them unique? And what are the implications for the television industry

The Elusive Third Subunit IIa of the Bacterial B-Type Oxidases: The Enzyme from the Hyperthermophile Aquifex aeolicus

The reduction of molecular oxygen to water is catalyzed by complicated membrane-bound metallo-enzymes containing variable numbers of subunits, called cytochrome c oxidases or quinol oxidases. We previously described the cytochrome c oxidase II from the hyperthermophilic bacterium Aquifex aeolicus as a ba3-type two-subunit (subunits I and II) enzyme and showed that it is included in a supercomplex involved in the sulfide-oxygen respiration pathway. It belongs to the B-family of the heme-copper oxidases, enzymes that are far less studied than the ones from family A. Here, we describe the presence in this enzyme of an additional transmembrane helix “subunit IIa”, which is composed of 41 amino acid residues with a measured molecular mass of 5105 Da. Moreover, we show that subunit II, as expected, is in fact longer than the originally annotated protein (from the genome) and contains a transmembrane domain. Using Aquifex aeolicus genomic sequence analyses, N-terminal sequencing, peptide mass fingerprinting and mass spectrometry analysis on entire subunits, we conclude that the B-type enzyme from this bacterium is a three-subunit complex. It is composed of subunit I (encoded by coxA2) of 59000 Da, subunit II (encoded by coxB2) of 16700 Da and subunit IIa which contain 12, 1 and 1 transmembrane helices respectively. A structural model indicates that the structural organization of the complex strongly resembles that of the ba3 cytochrome c oxidase from the bacterium Thermus thermophilus, the IIa helical subunit being structurally the lacking N-terminal transmembrane helix of subunit II present in the A-type oxidases. Analysis of the genomic context of genes encoding oxidases indicates that this third subunit is present in many of the bacterial oxidases from B-family, enzymes that have been described as two-subunit complexes

The Myxococcus xanthus Two-Component System CorSR Regulates Expression of a Gene Cluster Involved in Maintaining Copper Tolerance during Growth and Development

Myxococcus xanthus is a soil-dwelling member of the δ–Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M. xanthus cells because several housekeeping enzymes use it as a cofactor, high copper concentrations are toxic. These opposing effects force cells to maintain a tight copper homeostasis. A plethora of paralogous genes involved in copper detoxification, all of which are differentially regulated, have been reported in M. xanthus. The use of in-frame deletion mutants and fusions with the reporter gene lacZ has allowed the identification of a two-component system, CorSR, that modulates the expression of an operon termed curA consisting of nine genes whose expression slowly increases after metal addition, reaching a plateau. Transcriptional regulation of this operon is complex because transcription can be initiated at different promoters and by different types of regulators. These genes confer copper tolerance during growth and development. Copper induces carotenoid production in a ΔcorSR mutant at lower concentrations than with the wild-type strain due to lack of expression of a gene product resembling subunit III of cbb3-type cytochrome c oxidase. This data may explain why copper induces carotenoid biosynthesis at suboptimal rather than optimal growth conditions in wild-type strains.This work has been funded by the Spanish Government (grants CSD2009-00006 and BFU2012-33248, 70% funded by FEDER). This work was also supported by the National Institute of General Medical Science of the National Institutes of Health under award number R01GM095826 to LJS, and by the National Science Foundation under award number MCB0742976 to LJS. JMD and JP received a fellowship from Junta de Andalucía to do some work at University of Georgia