Assessing hydrological controls on the lithium isotope weathering tracer

To investigate the impact of riverine discharge and weathering intensity on lithium isotopes (δ7Li) in a mono-lithological terrain, this study examines the dissolved load and leached suspended load (exchangeable, oxide, and clay fractions) from Icelandic rivers spanning a wide range of discharge, weathering rates, and weathering intensity. The δ7Lidissolved co-varies inversely with the discharge, confirming that water-rock interaction time is a primary control on the secondary mineral formation that fractionates Li isotopes. The “boomerang” shape observed in global rivers between the weathering intensity (i.e. W/D = weathering rate/denudation rate) and δ7Lidissolved also exists for these basaltic rivers at low to medium W/D. However, these rivers do not extend to such low δ7Lidissolved values as seen in the global compilation at low W/D, indicating that there is a lithological control on this relationship arising from the type of the lithology-specific secondary minerals forming and their precipitation rates. In addition, the Δ7Lix-dissolved between each leached solid phase and the dissolved load also co-varies with discharge. At low discharge (long water-rock interaction times), Δ7Lix-dissolved values agree with experimentally-determined equilibrium values, whereas less fractionated values are observed at higher discharge (shorter water-rock interaction times). As a result, there is a different relationship between W/D and Δ7Liclay-source in this basaltic terrain than previously reported from global multi-lithological river sediment samples, with clay leachates from Iceland more closely mimicking the boomerang shape of the dissolved load. However, the relationship between δ7Li and weathering processes is complicated because the fractionation between the clay fraction and the dissolved load is not constant but varies with both W/D and discharge. Overall, this study confirms the utility of Li isotopes as a tracer of modern and palaeo-weathering processes, and also has important implications for the specific interpretations of detrital δ7Li values, which may be more sensitive to weathering parameters than previously thought

Assessing hydrological controls on the lithium isotope weathering tracer

To investigate the impact of riverine discharge and weathering intensity on lithium isotopes (δ7Li) in a mono-lithological terrain, this study examines the dissolved load and leached suspended load (exchangeable, oxide, and clay fractions) from Icelandic rivers spanning a wide range of discharge, weathering rates, and weathering intensity. The δ7Lidissolved co-varies inversely with the discharge, confirming that water-rock interaction time is a primary control on the secondary mineral formation that fractionates Li isotopes. The “boomerang” shape observed in global rivers between the weathering intensity (i.e. W/D = weathering rate/denudation rate) and δ7Lidissolved also exists for these basaltic rivers at low to medium W/D. However, these rivers do not extend to such low δ7Lidissolved values as seen in the global compilation at low W/D, indicating that there is a lithological control on this relationship arising from the type of the lithology-specific secondary minerals forming and their precipitation rates. In addition, the Δ7Lix-dissolved between each leached solid phase and the dissolved load also co-varies with discharge. At low discharge (long water-rock interaction times), Δ7Lix-dissolved values agree with experimentally-determined equilibrium values, whereas less fractionated values are observed at higher discharge (shorter water-rock interaction times). As a result, there is a different relationship between W/D and Δ7Liclay-source in this basaltic terrain than previously reported from global multi-lithological river sediment samples, with clay leachates from Iceland more closely mimicking the boomerang shape of the dissolved load. However, the relationship between δ7Li and weathering processes is complicated because the fractionation between the clay fraction and the dissolved load is not constant but varies with both W/D and discharge. Overall, this study confirms the utility of Li isotopes as a tracer of modern and palaeo-weathering processes, and also has important implications for the specific interpretations of detrital δ7Li values, which may be more sensitive to weathering parameters than previously thought

New Insights into the Structure of (1→3,1→6)-β-D-Glucan Side Chains in the Candida glabrata Cell Wall

β-glucan is a (1→3)-β-linked glucose polymer with (1→6)-β-linked side chains and a major component of fungal cell walls. β-glucans provide structural integrity to the fungal cell wall. The nature of the (1–6)-β-linked side chain structure of fungal (1→3,1→6)-β-D-glucans has been very difficult to elucidate. Herein, we report the first detailed structural characterization of the (1→6)-β-linked side chains of Candida glabrata using high-field NMR. The (1→6)-β-linked side chains have an average length of 4 to 5 repeat units spaced every 21 repeat units along the (1→3)-linked polymer backbone. Computer modeling suggests that the side chains have a bent curve structure that allows for a flexible interconnection with parallel (1→3)-β-D-glucan polymers, and/or as a point of attachment for proteins. Based on these observations we propose new approaches to how (1→6)-β-linked side chains interconnect with neighboring glucan polymers in a manner that maximizes fungal cell wall strength, while also allowing for flexibility, or plasticity

Impact of an Interactive On-line Tool on Therapeutic Decision-Making for Patients with Advanced Non-Small-Cell Lung Cancer

Background:Treatment guidelines provide recommendations but cannot account for the wide variability in patient-tumor characteristics in individual patients. We developed an on-line interactive decision tool to provide expert recommendations for specific patient scenarios in the first-line and maintenance settings for advanced non–small-cell lung cancer. We sought to determine how providing expert feedback would influence clinical decision-making.Method:Five lung cancer experts selected treatment for 96 different patient cases based on patient and/or tumor-specific features. These data were used to develop an on-line decision tool. Participant physicians entered variables for their patient scenario with treatment choices, and then received expert treatment recommendations for that scenario. To determine the impact on decision-making, users were asked whether the expert feedback impacted their original plan.Results:A total of 442 individual physicians, of which 88% were from outside the United States, entered 653 cases, with report on impact in 389 cases. Expert feedback affected treatment choice in 73% of cases (23% changed and 50% confirmed decisions). For cases with epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) fusion, all experts selected targeted therapy whereas 51% and 58% of participants did not. Greater variability was seen between experts and participants for cases involving EGFR or ALK wild-type tumors. Participants were 2.5-fold more likely to change to expert recommended therapy for ALK fusions than for EGFR mutations (p = 0.017).Conclusion:This online tool for treatment decision-making resulted in a positive influence on clinician's decisions. This approach offers opportunities for improving quality of care and meets an educational need in application of new therapeutic paradigms

Evaluation of Current Methods to Detect Cellular Leucine-Rich Repeat Kinase 2 (LRRK2) Kinase Activity

Background: Coding variation in the Leucine rich repeat kinase 2 gene linked to Parkinson’s disease (PD) promotes enhanced activity of the encoded LRRK2 kinase, particularly with respect to autophosphorylation at S1292 and/or phosphorylation of the heterologous substrate RAB10. Objective: To determine the inter-laboratory reliability of measurements of cellular LRRK2 kinase activity in the context of wildtype or mutant LRRK2 expression using published protocols. Methods: Benchmark western blot assessments of phospho-LRRK2 and phospho-RAB10 were performed in parallel with in situ immunological approaches in HEK293T, mouse embryonic fibroblasts, and lymphoblastoid cell lines. Rat brain tissue, with or without adenovirus-mediated LRRK2 expression, and human brain tissues from subjects with or without PD, were also evaluated for LRRK2 kinase activity markers. Results: Western blots were able to detect extracted LRRK2 activity in cells and tissue with pS1292-LRRK2 or pT73-RAB10 antibodies. However, while LRRK2 kinase signal could be detected at the cellular level with over-expressed mutant LRRK2 in cell lines, we were unable to demonstrate specific detection of endogenous cellular LRRK2 activity in cell culture models or tissues that we evaluated. Conclusion: Further development of reliable methods that can be deployed in multiple laboratories to measure endogenous LRRK2 activities are likely required, especially at cellular resolution

Polymorphisms in DNA-repair genes in a cohort of prostate cancer patients from different areas in Spain: heterogeneity between populations as a confounding factor in association studies

Background: Differences in the distribution of genotypes between individuals of the same ethnicity are an important confounder factor commonly undervalued in typical association studies conducted in radiogenomics. Objective: To evaluate the genotypic distribution of SNPs in a wide set of Spanish prostate cancer patients for determine the homogeneity of the population and to disclose potential bias. Design, Setting, and Participants: A total of 601 prostate cancer patients from Andalusia, Basque Country, Canary and Catalonia were genotyped for 10 SNPs located in 6 different genes associated to DNA repair: XRCC1 (rs25487, rs25489, rs1799782), ERCC2 (rs13181), ERCC1 (rs11615), LIG4 (rs1805388, rs1805386), ATM (rs17503908, rs1800057) and P53 (rs1042522). The SNP genotyping was made in a Biotrove OpenArrayH NT Cycler. Outcome Measurements and Statistical Analysis: Comparisons of genotypic and allelic frequencies among populations, as well as haplotype analyses were determined using the web-based environment SNPator. Principal component analysis was made using the SnpMatrix and XSnpMatrix classes and methods implemented as an R package. Non-supervised hierarchical cluster of SNP was made using MultiExperiment Viewer. Results and Limitations: We observed that genotype distribution of 4 out 10 SNPs was statistically different among the studied populations, showing the greatest differences between Andalusia and Catalonia. These observations were confirmed in cluster analysis, principal component analysis and in the differential distribution of haplotypes among the populations. Because tumor characteristics have not been taken into account, it is possible that some polymorphisms may influence tumor characteristics in the same way that it may pose a risk factor for other disease characteristics. Conclusion: Differences in distribution of genotypes within different populations of the same ethnicity could be an important confounding factor responsible for the lack of validation of SNPs associated with radiation-induced toxicity, especially when extensive meta-analysis with subjects from different countries are carried out

Characteristics and outcomes of patients with advanced non-small-cell lung cancer who declined to participate in randomised clinical chemotherapy trials

There are inadequate data on the outcomes of patients who declined to participate in randomised clinical trials as compared with those of participants. We retrospectively reviewed the patient characteristics and treatment outcomes of both participants and non-participants in the two randomised trials for chemotherapy-naive advanced non-small-cell lung cancer. Trial 1 compared four platinum-based combination regimens. Trial 2 compared two sequences of carboplatin plus paclitaxel and gefitinib therapies. Nineteen of 119 (16%) and 153 (37%) patients declined to participate in Trials 1 and 2, respectively. Among the background patient characteristics, the only variable associated with trial participation or declining was the patients' attending physicians (P<0.001). Important differences were not observed in the clinical outcomes between participants and non-participants, for whom the response rates were 30.6 vs 34.2% and the median survival times were 489 vs 461 days, respectively. The hazard ratio for overall survival, adjusted for other confounding variables, was 0.965 (95% confidence interval: 0.73–1.28). In conclusion, there was no evidence to suggest any difference in the characteristics and clinical outcomes between participants and non-participants. Trial designs and the doctor–patient relationship may have an impact on the patient accrual to randomised trials

A comparison of psoriasis severity in pediatric patients treated with methotrexate vs biologic agents

This cohort study compares the use of methotrexate vs biologic agents in children with moderate to severe psoriasis. Question What is the association between use of methotrexate vs biologics and psoriasis severity and drug survival (rate and duration of adherence to a specific drug regimen) in pediatric patients with moderate to severe psoriasis? Findings In this cohort study including 234 pediatric patients with moderate to severe psoriasis, those receiving biologics were more likely than those treated with methotrexate to achieve a Physician Global Assessment status of clear/almost clear and 75% or more improvement of the Psoriasis Area and Severity Index rating at 6 months. In addition, biologics were associated with better drug survival rates at 1, 3, and 5 years, with comparable discontinuation rates owing to lack of response. Meaning In pediatric patients with psoriasis, treatment with biologics may be associated with a significantly greater reduction in psoriasis severity than methotrexate; nevertheless, with 35.6% of the patients achieving clear/almost clear and 40.0% reaching 75% or more improvement on the Psoriasis Area and Severity Index, methotrexate remains an effective treatment for pediatric psoriasis. Importance Few studies have compared the use of methotrexate and biologics, the most commonly used systemic medications for treatment of moderate to severe psoriasis in children. Objective To assess the real-world, 6-month reduction in psoriasis severity and long-term drug survival (rate and duration of adherence to a specific drug) of methotrexate vs biologics in plaque psoriasis in children. Design, Setting, and Participants A retrospective medical records review was conducted at 20 European and North American centers. Treatment response was based on site-reported Psoriasis Area and Severity Index (PASI) and/or Physician Global Assessment (PGA) scores at baseline and within the first 6 months of treatment. Participants included all 234 consecutively seen children with moderate to severe psoriasis who received at least 3 months of methotrexate or biologics from December 1, 1990, to September 16, 2014, with sufficient data for analysis. Data analysis was performed from December 14, 2015, to September 1, 2016. Main Outcomes and Measures PASI, with a range from 0 to 72 (highest score indicating severe psoriasis), and/or PGA, with a scale of 0 (clear), 1 (minimal), 2 (mild), 3 (moderate), 4 (severe), and 5 (very severe). Results Of 234 pediatric patients (103 boys [44.0%]; 131 girls [56.0%]) treated with methotrexate and/or biologics, 163 patients (69.7%) exclusively received methotrexate, 47 patients (20.1%) exclusively received biologics, and 24 children (10.2%) received methotrexate and biologics sequentially. Of the latter cohort, 23 children were treated initially with methotrexate. Mean (SD) age at initiation was 11.6 (3.7) years for methotrexate and 13.3 (2.9) years for biologics (73.2% for etanercept) (P = .002). Among patients evaluated by a scoring method at 6-month follow-up, 75% or greater improvement in PASI (PASI75) was achieved in 12 of 30 patients (40.0%) receiving methotrexate and 20 of 28 patients (71.4%) receiving biologics, and PGA was clear/almost clear (PGA 0/1) in 41 of 115 patients (35.6%) receiving methotrexate and 18 of 37 patients (48.6%) receiving biologics. Achieving PASI75 and/or PGA 0/1 between baseline and 6 months was more likely with biologics than methotrexate (PASI75: odds ratio [OR], 4.56; 95% CI, 2.02-10.27; P < .001; and PGA 0/1: OR, 2.00; 95% CI, 0.98-4.00; P = .06). Decreased mean PASI and PGA scores were associated with biologics more than with methotrexate (PASI effect, -3.13; 95% CI, -4.33 to -1.94; P < .001; and PGA effect, -0.31; 95% CI, -0.56 to -0.06; P = .02). After 1, 3, and 5 years of use, overall drug survival rates for methotrexate were 77.5%, 50.3%, and 35.9%, and for biologics, the rates were 83.4%, 64.3%, and 57.1%, respectively. Biologics were associated with a better confounder-corrected drug survival than methotrexate (hazard ratio [HR], 2.23; 95% CI, 1.21-4.10; P = .01). Discontinuation owing to lack of response was comparable (HR, 1.64; 95% CI, 0.80-3.36; P = .18). Conclusions and Relevance Methotrexate and biologics appear to be associated with improvement in pediatric psoriasis, although biologics seem to be associated with greater reduction in psoriasis severity scores and higher drug survival rates than methotrexate in the real-world setting. Additional studies directly comparing these medications should be performed for confirmation

Molecular subtypes of breast cancer in relation to paclitaxel response and outcomes in women with metastatic disease: results from CALGB 9342

INTRODUCTION: The response to paclitaxel varies widely in metastatic breast cancer. We analyzed data from CALGB 9342, which tested three doses of paclitaxel in women with advanced disease, to determine whether response and outcomes differed according to HER2, hormone receptor, and p53 status. METHODS: Among 474 women randomly assigned to paclitaxel at a dose of 175, 210, or 250 mg/m(2), adequate primary tumor tissue was available from 175. Immunohistochemistry with two antibodies and fluorescence in situ hybridization were performed to evaluate HER2 status; p53 status was determined by immunohistochemistry and sequencing. Hormone receptor status was obtained from pathology reports. RESULTS: Objective response rate was not associated with HER2 or p53 status. There was a trend toward a shorter median time to treatment failure among women with HER2-positive tumors (2.3 versus 4.2 months; P = 0.067). HER2 status was not related to overall survival (OS). Hormone receptor expression was not associated with differences in response but was associated with longer OS (P = 0.003). In contrast, women with p53 over-expression had significantly shorter OS than those without p53 over-expression (11.5 versus 14.4 months; P = 0.002). In addition, triple negative tumors were more frequent in African-American than in Caucasian patients, and were associated with a significant reduction in OS (8.7 versus 12.9 months; P = 0.008). CONCLUSION: None of the biomarkers was predictive of treatment response in women with metastatic breast cancer; however, survival differed according to hormone receptor and p53 status. Triple negative tumors were more frequent in African-American patients and were associated with a shorter survival