375 research outputs found

    Hierarchical Self-Assembly of Supramolecular Helical Fibres from Amphiphilic C3-Symmetrical Functional Tris(tetrathiafulvalenes)

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    The preparation and self-assembly of the enantiomers of a series of C3-symmetric compounds incorporating three tetrathiafulvalene (TTF) residues is reported. The chiral citronellyl and dihydrocitronellyl alkyl chains lead to helical one dimensional stacks in solution. Molecular mechanics and dynamics simulations combined with experimental and theoretical circular dichroism support the observed helicity in solution. These stacks self-assemble to give fibres that have morphologies that depend on the nature of the chiral alkyl group and the medium in which the compounds aggregate. An inversion of macroscopic helical morphology of the citronellyl compound is observed when compared to analogous 2-methylbutyl chains, which is presumably a result of the stereogenic centre being further away from the core of the molecule. This composition still allows both morphologies to be observed, whereas an achiral compound shows no helicity. The morphology of the fibres also depends on the flexibility at the chain ends of the amphiphilic components, as there is not such an apparently persistent helical morphology for the dihydrocitronellyl derivative as for that prepared from citronellyl chains

    Twists and turns in the hierarchical self-assembly pathways of a non-amphiphilic chiral supramolecular material

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    The formation of helical self-assembled fibres by a C-3 symmetric molecule incorporating three tetrathiafulvalene units is shown to be influenced dramatically by the processing conditions, leading to a variety of different chiral forms, including unprecedented croissants

    Topological properties of punctual Hilbert schemes of almost-complex fourfolds (I)

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    In this article, we study topological properties of Voisin's punctual Hilbert schemes of an almost-complex fourfold XX. In this setting, we compute their Betti numbers and construct Nakajima operators. We also define tautological bundles associated with any complex bundle on XX, which are shown to be canonical in KK-theory

    Recurrence of hepatocellular carcinoma

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    Clinica I Chirurgie, Spitalul “Sf.Spiridon”, Departamentul de Chirurgie, Universitatea de Medicină și Farmacie “Gr.T.Popa”, Iași, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Rezecția hepatică rămâne “standardul de aur” în tratamentul cancerului hepatocelular (CHC). Alegerea variantei de rezecție hepatică depinde de mai mulți factori: localizarea tumorii, dimensiunile tumorii, starea parenchimului hepatic nontumoral, scorul Child-Pugh. Problema recurenței locoregionale în funcție de tipul de rezecție rămâne controversată. Scopul studiului: Ne-am propus să comparăm rata recurenței loco-regionale a CHC în funcție de tipul de rezecție hepatică (anatomică versus non-anatomică). Material și metode: Am analizat 64 de pacienți cu CHC, care au beneficiat de rezecție hepatică curativă în perioada 2005- 2013. Pacienții au fost împărțiți în două loturi: lotul A – 26 de pacienți la care s-a practicat o rezecție hepatică anatomică și lotul B – 38 de pacienți la care s-a practicat o rezecție hepatică non-anatomică. Rezultate: Pe o perioadă de urmărire postoperatorie cuprinsă între 12 și 60 de luni, rata recurenței CHC în cele două loturi a fost de 32% în grupul A și 31,4% în grupul B (P=0,963). Durata medie de apariție a recurenței a fost de 15,63±7,46 luni (între 5 și 25 luni) în lotul A și 16,91±9,35 luni (între 5 și 33 luni) în lotul B (P=0,753). Concluzii: Tipul de rezecție hepatică (anatomică sau non-anatomică) nu influențează apariția recurenței CHC, dacă se respectă limitele oncologice de rezecție.Introduction: Liver resection remains the gold standard in the treatment of hepatocellular cancer (HCC). Choosing liver resection depends on several factors: tumor location, tumor size, condition nontumoral liver parenchyma, Child-Pugh score. The locoregional recurrence problem depending on the type of resection remains controversial. The purpose of the study: We aimed to compare loco-regional recurrence rate of HCC according to the type of hepatic resection (anatomic versus non-anatomical). Material and methods: We analyzed 64 patients with HCC who received curative liver resection during the period 2005-2013. Patients were divided into two groups: group A – 26 patients who underwent hepatic anatomical resection and group B – 38 patients who underwent non-anatomical hepatic resection. Results: On a postoperative follow-up period between 12 and 60 months, HCC recurrence rate in the two groups was 32% in group A and 31.4% in group B (P=0.963). The average length of developing appellant was 15.63±7.46 months (between 5 and 25 months) in group A and 16.91±9.35 months (between 5 and 33 months) in group B (P=0.753). Conclusions: The type of liver resection (anatomical or non-anatomical) does not influence the occurrence of HCC recurrence, if we respect the oncologic limits resection

    Simulation-based power and sample size calculation for designing interrupted time series analyses of count outcomes in evaluation of health policy interventions

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    Objective: The purpose of this study was to present the design, model, and data analysis of an interrupted time series (ITS) model applied to evaluate the impact of health policy, systems, or environmental interventions using count outcomes. Simulation methods were used to conduct power and sample size calculations for these studies. Methods: We proposed the models and analyses of ITS designs for count outcomes using the Strengthening Translational Research in Diverse Enrollment (STRIDE) study as an example. The models we used were observation-driven models, which bundle a lagged term on the conditional mean of the outcome for a time series of count outcomes. Results: A simulation-based approach with ready-to-use computer programs was developed to calculate the sample size and power of two types of ITS models, Poisson and negative binomial, for count outcomes. Simulations were conducted to estimate the power of segmented autoregressive (AR) error models when autocorrelation ranged from -0.9 to 0.9, with various effect sizes. The power to detect the same magnitude of parameters varied largely, depending on the testing level change, the trend change, or both. The relationships between power and sample size and the values of the parameters were different between the two models. Conclusion: This article provides a convenient tool to allow investigators to generate sample sizes that will ensure sufficient statistical power when the ITS study design of count outcomes is implemented

    Temporal Trends and Factors Associated with Bisphosphonate Discontinuation and Restart

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    Adverse events related to long-term use of bisphosphonates have raised interest in temporary drug discontinuation. Trends in bisphosphonate discontinuation and restart, as well factors associated with these decisions, are not fully understood at a population level. We investigated temporal trends of bisphosphonate discontinuation from 2010 to 2015 and identified factors associated with discontinuation and restart of osteoporosis therapy. Our cohort consisted of long-term bisphosphonate users identified from 2010 to 2015 Medicare data. We defined discontinuation as 6512\u2009months without bisphosphonate prescription claims. We used conditional logistic regression to compare factors associated with alendronate discontinuation or osteoporosis therapy restart in the 120-day period preceding discontinuation or restart referent to the 120-day preceding control periods. Among 73,800 long-term bisphosphonate users, 59,251 (80.3%) used alendronate, 6806 (9.2%) risedronate, and 7743 (10.5%) zoledronic acid, exclusively. Overall, 26,281 (35.6%) discontinued bisphosphonates for at least 12\u2009months. Discontinuation of bisphosphonates increased from 1.7% in 2010, reaching a peak of 14% in 2012 with levels plateauing through 2015. The factors most strongly associated with discontinuation of alendronate were: benzodiazepine prescription (adjusted odds ratio [aOR] = 2.5; 95% confidence interval [CI] 2.1, 3.0), having a dual-energy X-ray absorptiometry (DXA) scan (aOR = 1.8; 95% CI 1.7, 2.0), and skilled nursing facility care utilization (aOR = 1.8; 95% CI 1.6, 2.1). The factors most strongly associated with restart of osteoporosis therapy were: having a DXA scan (aOR = 9.9; 95% CI 7.7, 12.6), sustaining a fragility fracture (aOR = 2.8; 95% CI 1.8, 4.5), and an osteoporosis or osteopenia diagnosis (aOR = 2.5; 95% CI 2.0, 3.1). Our national evaluation of bisphosphonate discontinuation showed that an increasing proportion of patients on long-term bisphosphonate therapy discontinue medications. The factors associated with discontinuation of alendronate were primarily related to worsening of overall health status, whereas traditional factors associated with worsening bone health were associated with restarting osteoporosis medication. \ua9 2019 American Society for Bone and Mineral Research

    Experience with telemedicine among rheumatology clinicians during the COVID-19 pandemic: an international survey

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    Objective: The aim was to assess rheumatology clinicians' perceptions of telemedicine and their experiences before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: We conducted a cross-sectional online survey and collected responses from rheumatology clinicians worldwide, between November 2020 and February 2021, regarding use and perceptions of telemedicine in rheumatology. We summarized data with descriptive statistics and qualitative analysis for free-text responses. Results: The survey was completed by 349 rheumatology clinicians from 49 countries; 59% were female and about two-thirds were in the 30-50 years age group. Academic affiliations were held by 55% of participants, and 44% were from North America. Before the pandemic, 24% of participants had experience with telemedicine, whereas about three-quarters used telemedicine for the first time during the pandemic. Overall, 56% thought they provided less adequate care with telemedicine. More than half of clinicians felt that telemedicine was adequate for evaluating crystalline arthritis, inflammatory arthritis and lupus flares. Telemedicine was felt to be inadequate for flares of myositis, vasculitis and scleroderma. Technical problems were reported in 29% of telemedicine encounters and were most commonly related to patient-encountered difficulties. Conclusion: Most rheumatology clinicians used telemedicine for the first time during the pandemic. The quality of care provided was thought to be inferior to that provided in person for specific clinical situations. Additional efforts are needed to address barriers to effective telemedicine, such as patient-related technology issues, challenges with building rapport and performing a physical examination, and to define the appropriate scope of clinical scenarios conducive to telemedicine

    Niraparib in patients with metastatic castration-resistant prostate cancer and DNA repair gene defects (GALAHAD):a multicentre, open-label, phase 2 trial

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    Background: Metastatic castration-resistant prostate cancers are enriched for DNA repair gene defects (DRDs) that can be susceptible to synthetic lethality through inhibition of PARP proteins. We evaluated the anti-tumour activity and safety of the PARP inhibitor niraparib in patients with metastatic castration-resistant prostate cancers and DRDs who progressed on previous treatment with an androgen signalling inhibitor and a taxane. Methods: In this multicentre, open-label, single-arm, phase 2 study, patients aged at least 18 years with histologically confirmed metastatic castration-resistant prostate cancer (mixed histology accepted, with the exception of the small cell pure phenotype) and DRDs (assessed in blood, tumour tissue, or saliva), with progression on a previous next-generation androgen signalling inhibitor and a taxane per Response Evaluation Criteria in Solid Tumors 1.1 or Prostate Cancer Working Group 3 criteria and an Eastern Cooperative Oncology Group performance status of 0–2, were eligible. Enrolled patients received niraparib 300 mg orally once daily until treatment discontinuation, death, or study termination. For the final study analysis, all patients who received at least one dose of study drug were included in the safety analysis population; patients with germline pathogenic or somatic biallelic pathogenic alterations in BRCA1 or BRCA2 (BRCA cohort) or biallelic alterations in other prespecified DRDs (non-BRCA cohort) were included in the efficacy analysis population. The primary endpoint was objective response rate in patients with BRCA alterations and measurable disease (measurable BRCA cohort). This study is registered with ClinicalTrials.gov, NCT02854436. Findings: Between Sept 28, 2016, and June 26, 2020, 289 patients were enrolled, of whom 182 (63%) had received three or more systemic therapies for prostate cancer. 223 (77%) of 289 patients were included in the overall efficacy analysis population, which included BRCA (n=142) and non-BRCA (n=81) cohorts. At final analysis, with a median follow-up of 10·0 months (IQR 6·6–13·3), the objective response rate in the measurable BRCA cohort (n=76) was 34·2% (95% CI 23·7–46·0). In the safety analysis population, the most common treatment-emergent adverse events of any grade were nausea (169 [58%] of 289), anaemia (156 [54%]), and vomiting (111 [38%]); the most common grade 3 or worse events were haematological (anaemia in 95 [33%] of 289; thrombocytopenia in 47 [16%]; and neutropenia in 28 [10%]). Of 134 (46%) of 289 patients with at least one serious treatment-emergent adverse event, the most common were also haematological (thrombocytopenia in 17 [6%] and anaemia in 13 [4%]). Two adverse events with fatal outcome (one patient with urosepsis in the BRCA cohort and one patient with sepsis in the non-BRCA cohort) were deemed possibly related to niraparib treatment. Interpretation: Niraparib is tolerable and shows anti-tumour activity in heavily pretreated patients with metastatic castration-resistant prostate cancer and DRDs, particularly in those with BRCA alterations. Funding: Janssen Research & Development
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