On rationality of the intersection points of a line with a plane quartic

We study the rationality of the intersection points of certain lines and smooth plane quartics C defined over F_q. For q \geq 127, we prove the existence of a line such that the intersection points with C are all rational. Using another approach, we further prove the existence of a tangent line with the same property as soon as the characteristic of F_q is different from 2 and q \geq 66^2+1. Finally, we study the probability of the existence of a rational flex on C and exhibit a curious behavior when the characteristic of F_q is equal to 3.Comment: 17 pages. Theorem 2 now includes the characteristic 2 case; Conjecture 1 from the previous version is proved wron

Comparison of plasma and CSF Neurofilament-light in an MS trial

OBJECTIVE: The main objective of this study was to evaluate the axonal component neurofilament light protein (NFL) in plasma and cerebrospinal fluid (CSF) as an outcome measure in a clinical trial on disease-modifying treatments in multiple sclerosis. MATERIALS & METHODS: Seventy-five patients with clinically stable relapsing-remitting multiple sclerosis (RRMS) participating in the clinical trial "Switch-To RItuXimab in MS" (STRIX-MS) were switched to rituximab from first-line injectable therapy and then followed for two years. Thirty patients from the extension trial (STRIX-MS extension), accepting repeated lumbar punctures, were followed for an additional three years. Plasma and CSF samples were collected yearly during the follow-up. NFL concentration in plasma was measured by an in-house NF-light assay on the Simoa platform with a Homebrew kit. NFL concentration in CSF was measured by sandwich ELISA. RESULTS: The mean levels of NFL, in both CSF and plasma, were low. The reduction of CSF-NFL was 25% during the first year of follow-up (from a mean of 471 (SD 393) to 354 (SD 174) pg/mL; p=0.006) and was statistically significant. The corresponding reduction in plasma-NFL was 18% (from 9.73 (SD 7.04) to 7.94 (SD 3.10) pg/mL; p=0.055) and did not reach statistical significance. CONCLUSION: This study indicates that NFL in plasma is less sensitive as an endpoint in group comparisons than NFL in CSF. Given that plasma NFL is far easier to access, it is a promising and awaited method but further studies are needed to optimise the use in clinical trials. This article is protected by copyright. All rights reserved

Methylation and copy number profiling : emerging tools to differentiate osteoblastoma from malignant mimics?

Rearrangements of the transcription factors FOS and FOSB have recently been identified as the genetic driver event underlying osteoid osteoma and osteoblastoma. Nuclear overexpression of FOS and FOSB have since then emerged as a reliable surrogate marker despite limitations in specificity and sensitivity. Indeed, osteosarcoma can infrequently show nuclear FOS expression and a small fraction of osteoblastomas seem to arise independent of FOS/FOSB rearrangements. Acid decalcification and tissue preservation are additional factors that can negatively influence immunohistochemical testing and make diagnostic decision-making challenging in individual cases. Particularly aggressive appearing osteoblastomas, also referred to as epithelioid osteoblastomas, and osteoblastoma-like osteosarcoma can be difficult to distinguish, underlining the need for additional markers to support the diagnosis. Methylation and copy number profiling, a technique well established for the classification of brain tumors, might fill this gap. Here, we set out to comprehensively characterize a series of 77 osteoblastomas by immunohistochemistry, fluorescence in-situ hybridization as well as copy number and methylation profiling and compared our findings to histologic mimics. Our results show that osteoblastomas are uniformly characterized by flat copy number profiles that can add certainty in reaching the correct diagnosis. The methylation cluster formed by osteoblastomas, however, so far lacks specificity and can be misleading in individual cases

Effectiveness of first generation disease-modifying therapy to prevent conversion to secondary progressive multiple sclerosis

Background: The use of disease-modifying therapies (DMTs) in multiple sclerosis (MS) has been associated with reduced relapse rates and accumulation of disability. However, studies examining impact of DMT on risk of transition to secondary progressive MS (SPMS) leveraging population-based nationwide data are still rare. Here, we determine the population incidence of conversion to SPMS using two consecutive nation-wide cohorts, one immediately before and one after the introduction of DMT in Sweden. Methods: We included two consecutive population cohorts of relapsing-remitting MS (RRMS) from the Swedish national MS register for the periods 1975–1994 (n = 2161), before DMT availability, and 1995–2011 (n = 3510), in which DMTs, mainly first generation DMT (injectables), became available and eventually were used by 70% of patients. We explored the risk of transition to SPMS as a calendar year function encompassing the two cohorts. In addition, we determined the incidence of transition to SPMS through age strata below and above 50 years in untreated and treated patient subgroups. Results: The risk of conversion to SPMS (adjusted for current age, current time since onset, calendar year and sex) was significantly lower in the second compared with the first population cohort (hazard ratio 0.58; CI 0.48, 0.70). The risk of SPMS conversion per calendar year decreased by 2.6% annually (p < 0.001) after 1995. The risk of SPMS conversion increased with age until age 50. Thereafter, it was unchanged or decreased among those with early MS onset age (<35 years), but continued to increase with onset at higher age, with similar trends in treated and untreated subgroups. Conclusion: The incidence of SPMS conversion significantly decreased at the population level after introduction of first generation DMTs by 1995. DMT efficiency was confirmed by a downward turn of the annual trajectory of the risk of SPMS conversion after 1995. An onset age determined pattern of variable SPMS incidence in higher age appeared in both treated and untreated strata. While first generation DMT delayed conversion to SPMS, their long-term effect was only moderate