561 research outputs found
Comment on: “Investigating Earth’s Formation History Through Copper & Sulfur Metal–Silicate Partitioning During Core-Mantle Differentiation” by Mahan et al. (2018)
The physical and chemical conditions of terrestrial core formation play a key role in the distribution of elements between the Earth’s silicate mantle and metallic core. To explore this, Mahan et al. (2018a) present experimentally-derived partitioning data, showing how Cu distributes itself between metal and silicate at lower-mantle PT conditions with implications for planetary accretion and core formation. Eight experiments were performed in a diamond anvil cell (DAC) and each sample was welded to a copper grid for analysis. An offset in partitioning behaviour was subsequently noted between the high-P experiments and the lower-P dataset. However, when analysing the DAC experiments by electron probe microanalysis, the authors did not account for the secondary fluorescence of Cu that arises from the sample holder. Using Monte Carlo simulations of X-ray and electron transport, we show that the fluorescence of the Cu grid, originating from high energy continuum X-rays emitted from the sample, makes a significant contribution to the reported measurement of Cu in both the silicate and metallic phases. This is in good agreement with previous measurements made on Cu-free analogues. On average, around 70% of the published Cu concentrations are attributable to X-rays that originate externally to the sample. The reported offset in KDmet-sil at high pressures may reflect the different experimental and analytical protocol used, rather than a true pressure effect. Although adequate post-hoc corrections can be made, uncertainties around the exact sample and detector geometries make it difficult to refine simulations and derive accurate correction factors for each experiment
Secondary fluorescence in WDS:the role of spectrometer positioning
Secondary fluorescence, typically a minor error in routine electron probe microanalysis (EPMA), may not be negligible when performing high precision trace element analyses in multiphase samples. Other factors, notably wavelength dispersive spectrometer defocusing, may introduce analytical artefacts.
To explore these issues, we measured EPMA transects across two material couples chosen for their high fluorescence yield. We measured transects away from the fluorescent phase, and at various orientations with respect to the spectrometer focal line. Compared to calculations using both the Monte Carlo simulation code PENEPMA and the semi-analytical model FANAL, both codes estimate the magnitude of SF, but accurate correction requires knowledge of the position of the spectrometer with respect to the couple interface. Positioned over the fluorescent phase or otherwise here results in a factor of 1.2-1.8 of apparent change in SF yield.
SF and spectrometer defocusing may introduce systematic errors into trace element analyses, both may be adequately accounted for by modelling. Of the two, however, SF is the dominant error, resulting in 0.1 wt% Zn apparently present in Al at 100 m away from the Zn boundary in an Al/Zn couple. Of this, around 200 ppm Zn can be attributed to spectrometer defocusing.</p
Cost-effectiveness of adjuvant therapy for hepatocellular carcinoma during the waiting list for liver transplantation.
Background: Survival after liver transplantation for early hepatocellular carcinoma (HCC) is worsened by the increasing dropout rate while waiting for a donor.
Aims: To assess the cost effectiveness of adjuvant therapy while waiting for liver transplantation in HCC patients.
Method: Using a Markov model, a hypothetical cohort of cirrhotic patients with early HCC was considered for: (1) adjuvant treatment—resection was limited to Child-Pugh's A patients with single tumours, and percutaneous treatment was considered for Child-Pugh's A and B patients with single tumours unsuitable for resection or with up to three nodules < 3 cm; and (2) standard management. Length of waiting time ranged from six to 24 months.
Results: Surgical resection increased the transplantation rate (>10%) and provided gains in life expectancy of 4.8–6.1 months with an acceptable cost (74 000/life of year gained) for shorter waiting times or high dropout rate scenarios. Percutaneous treatment increased life expectancy by 5.2–6.7 months with a marginal cost of approximately $20 000/year of life gained in all cases, remaining cost effective for all waiting times.
Conclusions: Adjuvant therapies for HCC while waiting for liver transplantation provide moderate gains in life expectancy and are cost effective for waiting lists of one year or more. For shorter waiting times, only percutaneous treatment confers a relevant survival advantage
Predicting the response to sorafenib in hepatocellular carcinoma: where is the evidence for phosphorylated extracellular signaling-regulated kinase (pERK)?
The approval of sorafenib and active development of many other molecularly targeted agents in hepatocellular carcinoma (HCC) have presented a challenge to understand the mechanism of action of sorafenib and identify predictive biomarkers to select patients more likely to benefit from sorafenib. The preclinical study by Zhang and celleagues published this month in BMC Medicine provides preliminary evidence that baseline phosphorylated extracellular signaling-regulated kinase (pERK) may be a relevant marker to reflect the level of constitutive activation of the RAF/mitogen-activated protein kinase kinase (MEK)/ERK signaling pathway and has the potential value in predicting response to sorafenib. The clinical data from the initial single arm phase II study and preliminary report from the randomized phase III study also suggest the correlation of baseline archived tumor pERK levels and time to tumor progression in HCC patients. Whether baseline pERK will prove to be a useful predictive biomarker of response and clinical benefits for sorafenib in HCC will need to be validated in future large prospective studies
Pattern of progression in advanced hepatocellular carcinoma treated with ramucirumab
Background & aims: Radiological progression patterns to first-line sorafenib have been associated with post-progression and overall survival in advanced hepatocellular carcinoma, but these associations remain unknown for therapies in second- and later-line settings. This post hoc analysis of REACH and REACH-2 examined outcomes by radiological progression patterns in the second-line setting of patients with advanced hepatocellular carcinoma treated with ramucirumab or placebo.Methods: Patients with advanced hepatocellular carcinoma, Child-Pugh A and Eastern Cooperative Oncology Group Performance Status 0 or 1 with prior sorafenib were randomized to receive ramucirumab 8mg/kg or placebo every 2 weeks. Among 625 patients with ≥1 progression pattern (new extrahepatic lesion [including new macrovascular invasion], new intrahepatic lesion, extrahepatic growth or intrahepatic growth), data were analysed by trial and for pooled individual patient data for REACH-2 and REACH (alpha-fetoprotein ≥400 ng/mL). Cox models evaluated prognostic implications of progression patterns on overall and post-progression survival. Results: Post-progression survival was worse among those with new extrahepatic lesions in REACH (HR 2.33, 95% CI 1.51-3.60), REACH-2 (HR 1.49, 95% CI 0.72-3.08) and the pooled population (HR 1.75, 95% CI 1.12-2.74) compared to other progression patterns. Overall survival was also significantly reduced in those with new extrahepatic lesions across studies. Ramucirumab provided an overall survival benefit across progression patterns, including patients with new extrahepatic lesions (HR 0.56, 95% CI 0.39-0.80) in the pooled population. Conclusions: The emergence of new extrahepatic lesions in the second-line setting is a poor prognostic factor for post-progression survival. The benefit of ramucirumab for overall survival was consistent across progression patterns
Petrology, metallogeny and U-Pb geochronology of the paleoproterozoic mafic-ultramafic Hamutenha intrusion, Angolan Shield
The Hamutenha intrusion (Huíla province, SW Angola) is a 3-km-long elongated magmatic body defined by a set of two intrusive units. The northern unit is formed by alternating bands of dunites and olivine gabbros, while the southern unit is composed of amphibole diorites. The Hamutenha body is hosted by the Paleoproterozoic Epupa Complex in the Angolan Shield, SW margin of the Congo Craton. A mineralogical, petrological and geochemical study of the Hamutenha intrusion has been performed. The constrained compositional features of the parental melt suggest interaction of tholeiitic magmas with a significant enrichment in Fe and Ti. Although disseminated Fe–Ni–Cu-(Co) secondary sulphides are observed, both the crustal contamination parameters and generally low bulk-rock metals contents indicate that these elements were most likely previously extracted from the parental melt. U–Pb zircon dating of amphibole diorite samples from the southern unit yields a date of 1844 ± 14 Ma. These data suggest that the emplacement of these rocks was previous to the KC emplacement and it was probably related to the Paleoproterozoic Epupa Complex magmatism.This work has been supported by the project CGL2009-13758 of the Spanish Government and the projects SGR-444 and SGR-589 of the Catalan Governmen
Search: A phase III, randomized, double-blind, placebo-controlled trial of sorafenib plus erlotinib in patients with advanced hepatocellular carcinoma
PURPOSE: To compare the clinical outcomes of sorafenib plus either erlotinib or placebo in patients with advanced hepatocellular carcinoma (HCC) in a multicenter, multinational, randomized, phase III trial. PATIENTS AND METHODS: Patients with advanced HCC and underlying Child-Pugh class A cirrhosis, who were naive to systemic treatment (N = 720), were randomly assigned to sorafenib plus either erlotinib (n = 362) or placebo (n = 358). The primary end point was overall survival (OS). RESULTS: Median OS was similar in the sorafenib plus erlotinib and sorafenib plus placebo groups (9.5 v 8.5 months, respectively; hazard ratio [HR], 0.929; P = .408), as was median time to progression (3.2 v 4.0 months, respectively; HR, 1.135; P = .18). In the sorafenib/erlotinib arm versus the sorafenib/placebo arm, the overall response rate trended higher (6.6% v 3.9%, respectively; P = .102), whereas the disease control rate was significantly lower (43.9% v 52.5%, respectively; P = .021). The median durations of treatment with sorafenib were 86 days in the sorafenib/erlotinib arm and 123 days in the sorafenib/placebo arm. In the sorafenib/erlotinib and sorafenib/placebo arms, the rates of treatment-emergent serious AEs (58.0% v 54.6%, respectively) and drug-related serious AEs (21.0% v 22.8%, respectively) were similar. AEs matched the known safety profiles of both agents, but rates of rash/desquamation, anorexia, and diarrhea were higher in the sorafenib/erlotinib arm, whereas rates of alopecia and hand-foot skin reaction were higher in the sorafenib/placebo arm. Withdrawal rates for AEs during cycles 1 to 3 were higher in the sorafenib/erlotinib arm. CONCLUSION: Adding erlotinib to sorafenib did not improve survival in patients with advanced HCC
Ramucirumab in the second-line for patients with hepatocellular carcinoma and elevated alpha-fetoprotein: patient-reported outcomes across two randomised clinical trials
Background: Symptoms of advanced hepatocellular carcinoma (HCC) represent a substantial burden for the patient and are important endpoints to assess when evaluating treatment. Patient-reported outcomes were evaluated in subjects with advanced HCC and baseline alpha-fetoprotein (AFP) ≥400 ng/mL treated with second-line ramucirumab. Patients and methods: Patients with AFP≥400 ng/mL enrolled in the REACH or REACH-2 phase 3 studies were used in this analysis. Eligible patients had advanced HCC, Child-Pugh A, Eastern Cooperative Oncology Group performance status 0/1 and prior sorafenib. Patients received ramucirumab 8 mg/kg or placebo once every 2 weeks. Disease-related symptoms and health-related quality of life (HRQoL) were assessed with the Functional Assessment of Cancer Therapy Hepatobiliary Symptom Index (FHSI)-8 and EuroQoL-5-Dimensions (EQ-5D) instruments, respectively. Time to deterioration (TTD) (≥3-point decrease in FHSI-8 total score;≥0.06-point decrease in EQ-5D score, from randomisation to first date of deterioration) was determined using Kaplan-Meier estimation and the Cox proportional hazards model. Both separate and pooled analyses for REACH AFP≥400 ng/mL and REACH-2 patients were conducted. Results: In the pooled population with AFP ≥400 ng/mL (n=542; ramucirumab, n=316; placebo, n=226), median TTD in FHSI-8 total score was prolonged with ramucirumab relative to placebo (3.3 vs 1.9 months; HR 0.725; (95% CI 0.559 to 0.941); p=0.0152), including significant differences in back pain (0.668; (0.497 to 0.899); p=0.0044), weight loss (0.699; (0.505 to 0.969); p=0.0231) and pain (0.769; (0.588 to 1.005); p=0.0248) symptoms. TTD in EQ-5D score was not significantly different between ramucirumab and placebo groups (median 2.9 vs 1.9 months). Results in the individual trials were consistent with these findings. Conclusions: Ramucirumab in second-line treatment of advanced HCC demonstrates consistent benefit in the delay of deterioration in disease-related symptoms with no worsening of HRQoL. Taken with previously demonstrated ramucirumab-driven survival benefits in this setting, these data may inform patient-clinician discussions about the benefit-risk profile of this therapy
Randomised double-blind trial of megestrol acetate vs placebo in treatment-naive advanced hepatocellular carcinoma
10.1038/bjc.2011.333British Journal of Cancer1057945-952BJCA
Phase Ib Study of Lenvatinib Plus Pembrolizumab in Patients With Unresectable Hepatocellular Carcinoma
PURPOSE The immunomodulatory effect of lenvatinib (a multikinase inhibitor) on tumor microenvironments may contribute to antitumor activity when combined with programmed death receptor-1 (PD-1) signaling inhibitors in hepatocellular carcinoma (HCC). We report results from a phase Ib study of lenvatinib plus pembrolizumab (an anti-PD-1 antibody) in unresectable HCC (uHCC). PATIENTS AND METHODS In this open-label multicenter study, patients with uHCC received lenvatinib (bodyweight 3 treatment-related adverse events occurred in 67% (grade 5, 3%) of patients. No new safety signals were identified. CONCLUSION Lenvatinib plus pembrolizumab has promising antitumor activity in uHCC. Toxicities were manageable, with no unexpected safety signals
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