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15 result(s) for "Merkel, Stephen W."
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Sources of early Islamic silver: lead isotope analysis of dirhams
The expansion of the early Islamic state (c. AD 700–900) was underpinned by the minting of silver coins (dirhams) on an enormous scale. While the wider effects of this coinage have been studied extensively, the sources of silver have attracted less attention and research has relied on literary texts pointing to mines in Arabia and Central Asia. Here, the authors use lead isotope and trace element analyses of more than 100 precisely dated silver coins to provide a geochemical perspective on Islamic silver. The results identify multiple new sources, stretching from Morocco to the Tien Shen, and indicate an Abbasid-period mining boom. These source locations have implications for contemporary geopolitics including on the Islamic-Byzantine frontier.
Byzantine plate and Frankish mines: the provenance of silver in north-west European coinage during the Long Eighth Century (c. 660–820)
The late seventh-century introduction of silver coinage marked a transformation in the economy of north-west Europe, yet the source(s) of the silver bullion behind this change remains uncertain. Here, the authors use combined lead isotope and trace element analysis of 49 coins from England, Frisia and Francia to provide new insights into north-European silver sources during the ‘long eighth century’ (c. AD 660–820). The results indicate an early reliance on recycled Byzantine silver plate, followed by a shift c. AD 750 to newly mined metal from Francia. This change indicates the strong role of the Carolingian state in the control of metal sources and economic structures across the North Sea zone.
Mepolizumab or Placebo for Eosinophilic Granulomatosis with Polyangiitis
Among participants with eosinophilic granulomatosis with polyangiitis, 32% had remission at weeks 36 and 48 when treated with mepolizumab, an anti–interleukin-5 monoclonal antibody, as compared with 3% of the participants in the placebo group. Eosinophilic granulomatosis with polyangiitis (formerly known as the Churg–Strauss syndrome) is characterized by asthma, sinusitis, pulmonary infiltrates, neuropathy, and eosinophilic vasculitis of one or more end-organs. 1 – 4 Eosinophils are thought to induce pathogenic effects in patients with eosinophilic granulomatosis with polyangiitis by means of tissue and vascular infiltration and inflammation through a variety of mediators. 5 , 6 Although systemic glucocorticoids form the cornerstone of treatment for eosinophilic granulomatosis with polyangiitis, 7 – 9 most patients remain dependent on glucocorticoid therapy, and relapses are common. 10 – 13 Furthermore, some patients do not have a sufficient response to glucocorticoids. Because recurrent relapses place the patient at . . .
Using mechanobiological mimicry of red blood cells to extend circulation times of hydrogel microparticles
It has long been hypothesized that elastic modulus governs the biodistribution and circulation times of particles and cells in blood; however, this notion has never been rigorously tested. We synthesized hydrogel microparticles with tunable elasticity in the physiological range, which resemble red blood cells in size and shape, and tested their behavior in vivo. Decreasing the modulus of these particles altered their biodistribution properties, allowing them to bypass several organs, such as the lung, that entrapped their more rigid counterparts, resulting in increasingly longer circulation times well past those of conventional microparticles. An 8-fold decrease in hydrogel modulus correlated to a greater than 30-fold increase in the elimination phase half-life for these particles. These results demonstrate a critical design parameter for hydrogel microparticles.
Advances in the treatment of ANCA-associated vasculitis
Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) consists of a group of small-vessel vasculitides that often present with organ-threatening or life-threatening manifestations. Current immunosuppressive treatments have improved survival and rates of remission, but are not curative, have frequent toxicities, and do not effectively prevent relapse. Clinical trials have established the role of rituximab, an anti-CD20 B cell-depleting monoclonal antibody, in both the remission-induction and maintenance phases of the disease and demonstrated that glucocorticoid doses can be substantially reduced from historical dosing levels without affecting treatment efficacy. Therapies that have the potential to be more effective and safer have become available or are under investigation. Avacopan, an oral C5a receptor antagonist, was approved as an adjunctive treatment for AAV and use of this drug in combination with rituximab or cyclophosphamide and markedly reduced glucocorticoid dosing demonstrated superior efficacy and potentially greater kidney recovery than prior standard of care. Other agents under study for treatment of AAV include next-generation anti-CD20 monoclonal antibodies, anti-CD19 chimeric antigen receptor T cells, novel complement inhibitors and agents that can target fibrosis. Alongside traditional randomized controlled trials with clinical endpoints, experimental medicine studies are focusing on mechanistic endpoints and disease biomarkers. This Review discusses current treatments and the advances in the management of AAV. This Review discusses the advances and challenges of managing antineutrophil cytoplasmic antibody-associated vasculitis. The authors discuss current treatment options, emerging therapies and unmet needs in the management of this disease. Key points The main regimen of remission induction in antineutrophil cytoplasmic antibody-associated vasculitis is based on high-dose glucocorticoids combined with rituximab or cyclophosphamide. The initial approach to treatment induces remission of vasculitis in most patients but does not prevent relapse in a substantial number of people and has multiple toxicities. Clinical trial data show that reduced-dose regimens of glucocorticoids are non-inferior to standard-dose regimens and have a lower risk of serious infections; rituximab is superior to azathioprine in maintaining disease remission. B cell-targeting therapies under evaluation for antineutrophil cytoplasmic antibody-associated vasculitis treatment include anti-CD20 monoclonal antibodies with increased B cell depletion capacity compared with rituximab, chimeric antigen receptor T cells and B cell-inhibiting antibodies. Avacopan in combination with rituximab or cyclophosphamide and markedly reduced glucocorticoids has superior efficacy, kidney function recovery and improvement in quality of life to regimens based on standard glucocorticoid dose. Novel targets include pathways involved in antineutrophil cytoplasmic antibody-induced inflammation and fibrosis, which could be combined with immunosuppressive therapies. Strategies to reduce cardiovascular risk and improve response to vaccines are being tested.
MCL1 and BCL-xL Levels in Solid Tumors Are Predictive of Dinaciclib-Induced Apoptosis
Dinaciclib is a potent CDK1, 2, 5 and 9 inhibitor being developed for the treatment of cancer. Additional understanding of antitumor mechanisms and identification of predictive biomarkers are important for its clinical development. Here we demonstrate that while dinaciclib can effectively block cell cycle progression, in vitro and in vivo studies, coupled with mouse and human pharmacokinetics, support a model whereby induction of apoptosis is a main mechanism of dinaciclib's antitumor effect and relevant to the clinical duration of exposure. This was further underscored by kinetics of dinaciclib-induced downregulation of the antiapoptotic BCL2 family member MCL1 and correlation of sensitivity with the MCL1-to-BCL-xL mRNA ratio or MCL1 amplification in solid tumor models in vitro and in vivo. This MCL1-dependent apoptotic mechanism was additionally supported by synergy with the BCL2, BCL-xL and BCL-w inhibitor navitoclax (ABT-263). These results provide the rationale for investigating MCL1 and BCL-xL as predictive biomarkers for dinaciclib antitumor response and testing combinations with BCL2 family member inhibitors.
Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 — Part 1 liquid chromatography – tandem mass spectrometry (LC-MS/MS) assays — impact of 3-epi-25-hydroxyvitamin D3 on assay performance
An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of liquid chromatography – tandem mass spectrometry (LC-MS/MS) assays used for the determination of serum total 25-hydroxyvitamin D (25(OH)D), which is the sum of 25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3). A set of 50 single-donor samples was assigned target values for concentrations of 25(OH)D2, 25(OH)D3, 3-epi-25-hydroxyvitamin D3 (3-epi-25(OH)D3), and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) using isotope dilution liquid chromatography – tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 1 includes results from 14 laboratories using 14 custom LC-MS/MS assays. Assay performance was evaluated using mean % bias compared to the assigned target values and using linear regression analysis of the test assay mean results and the target values. Only 53% of the LC-MS/MS assays met the VDSP criterion of mean % bias ≤ |±5%|. For the LC-MS/MS assays not meeting the ≤ |±5%| criterion, four assays had mean % bias of between 12 and 21%. Based on multivariable regression analysis using the concentrations of the four individual vitamin D metabolites in the 50 single-donor samples, the performance of several LC-MS/MS assays was found to be influenced by the presence of 3-epi-25(OH)D3. The results of this interlaboratory study represent the most comprehensive comparison of LC-MS/MS assay performance for serum total 25(OH)D and document the significant impact of the lack of separation of 3-epi-25(OH)D3 and 25(OH)D3 on assay performance, particularly with regard to mean % bias.
Assessment of serum total 25-hydroxyvitamin D assay commutability of Standard Reference Materials and College of American Pathologists Accuracy-Based Vitamin D (ABVD) Scheme and Vitamin D External Quality Assessment Scheme (DEQAS) materials: Vitamin D Standardization Program (VDSP) Commutability Study 2
An interlaboratory study was conducted through the Vitamin D Standardization Program (VDSP) to assess commutability of Standard Reference Materials® (SRMs) and proficiency testing/external quality assessment (PT/EQA) samples for determination of serum total 25-hydroxyvitamin D [25(OH)D] using ligand binding assays and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A set of 50 single-donor serum samples were assigned target values for 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] using reference measurement procedures (RMPs). SRM and PT/EQA samples evaluated included SRM 972a (four levels), SRM 2973, six College of American Pathologists (CAP) Accuracy-Based Vitamin D (ABVD) samples, and nine Vitamin D External Quality Assessment Scheme (DEQAS) samples. Results were received from 28 different laboratories using 20 ligand binding assays and 14 LC-MS/MS methods. Using the test assay results for total serum 25(OH)D (i.e., the sum of 25(OH)D2 and 25(OH)D3) determined for the single-donor samples and the RMP target values, the linear regression and 95% prediction intervals (PIs) were calculated. Using a subset of 42 samples that had concentrations of 25(OH)D2 below 30 nmol/L, one or more of the SRM and PT/EQA samples with high concentrations of 25(OH)D2 were deemed non-commutable using 5 of 11 unique ligand binding assays. SRM 972a (level 4), which has high exogenous concentration of 3-epi-25(OH)D3, was deemed non-commutable for 50% of the LC-MS/MS assays.
Assessment of serum total 25-hydroxyvitamin D assays for Vitamin D External Quality Assessment Scheme (DEQAS) materials distributed at ambient and frozen conditions
The Vitamin D External Quality Assessment Scheme (DEQAS) distributes human serum samples four times per year to over 1000 participants worldwide for the determination of total serum 25-hydroxyvitamin D [25(OH)D)]. These samples are stored at −40 °C prior to distribution and the participants are instructed to store the samples frozen at −20 °C or lower after receipt; however, the samples are shipped to participants at ambient conditions (i.e., no temperature control). To address the question of whether shipment at ambient conditions is sufficient for reliable performance of various 25(OH)D assays, the equivalence of DEQAS human serum samples shipped under frozen and ambient conditions was assessed. As part of a Vitamin D Standardization Program (VDSP) commutability study, two sets of the same nine DEQAS samples were shipped to participants at ambient temperature and frozen on dry ice. Twenty-eight laboratories participated in this study and provided 34 sets of results for the measurement of 25(OH)D using 20 ligand binding assays and 14 liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods. Equivalence of the assay response for the frozen versus ambient DEQAS samples for each assay was evaluated using multi-level modeling, paired t-tests including a false discovery rate (FDR) approach, and ordinary least squares linear regression analysis of frozen versus ambient results. Using the paired t-test and confirmed by FDR testing, differences in the results for the ambient and frozen samples were found to be statistically significant at p < 0.05 for four assays (DiaSorin, DIAsource, Siemens, and SNIBE prototype). For all 14 LC–MS/MS assays, the differences in the results for the ambient- and frozen-shipped samples were not found to be significant at p < 0.05 indicating that these analytes were stable during shipment at ambient conditions. Even though assay results have been shown to vary considerably among different 25(OH)D assays in other studies, the results of this study also indicate that sample handling/transport conditions may influence 25(OH)D assay response for several assays.
Web-Based Mindfulness-Based Interventions for Well-being: Randomized Comparative Effectiveness Trial
Mindfulness can improve overall well-being by training individuals to focus on the present moment without judging their thoughts. However, it is unknown how much mindfulness practice and training are necessary to improve well-being. The primary aim of this study was to determine whether a standard 8-session web-based mindfulness-based cognitive therapy (MBCT) program, compared with a brief 3-session mindfulness intervention, improved overall participant well-being. In addition, we sought to explore whether the treatment effects differed based on the baseline characteristics of the participants (ie, moderators). Participants were recruited from 17 patient-powered research networks, web-based communities of stakeholders interested in a common research area. Participants were randomized to either a standard 8-session MBCT or a brief 3-session mindfulness training intervention accessed on the web. The participants were followed for 12 weeks. The primary outcome of the study was well-being, as measured by the World Health Organization-Five Well-Being Index. We hypothesized that MBCT would be superior to a brief mindfulness training. We randomized 4411 participants, 3873 (87.80%) of whom were White and 3547 (80.41%) of female sex assigned at birth. The mean baseline World Health Organization-Five Well-Being Index score was 50.3 (SD 20.7). The average self-reported well-being in each group increased over the intervention period (baseline to 8 weeks; model-based slope for the MBCT group: 0.78, 95% CI 0.63-0.93, and brief mindfulness group: 0.76, 95% CI 0.60-0.91) as well as the full study period (ie, intervention plus follow-up; baseline to 20 weeks; model-based slope for MBCT group: 0.41, 95% CI 0.34-0.48; and brief mindfulness group: 0.33, 95% CI 0.26-0.40). Changes in self-reported well-being were not significantly different between MBCT and brief mindfulness during the intervention period (model-based difference in slopes: -0.02, 95% CI -0.24 to 0.19; P=.80) or during the intervention period plus 12-week follow-up (-0.08, 95% CI -0.18 to 0.02; P=.10). During the intervention period, younger participants (P=.05) and participants who completed a higher percentage of intervention sessions (P=.005) experienced greater improvements in well-being across both interventions, with effects that were stronger for participants in the MBCT condition. Attrition was high (ie, 2142/4411, 48.56%), which is an important limitation of this study. Standard MBCT improved well-being but was not superior to a brief mindfulness intervention. This finding suggests that shorter mindfulness programs could yield important benefits across the general population of individuals with various medical conditions. Younger people and participants who completed more intervention sessions reported greater improvements in well-being, an effect that was more pronounced for participants in the MBCT condition. This finding suggests that standard MBCT may be a better choice for younger people as well as treatment-adherent individuals. ClinicalTrials.gov NCT03844321; https://clinicaltrials.gov/ct2/show/NCT03844321.