167 research outputs found

    On the origin of the Trojan asteroids: Effects of Jupiter's mass accretion and radial migration

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    We present analytic and numerical results which illustrate the effects of Jupiter's accretion of nebular gas and the planet's radial migration on its Trojan companions. Initially, we approximate the system by the planar circular restricted three-body problem and assume small Trojan libration amplitudes. Employing an adiabatic invariant calculation, we show that Jupiter's thirty-fold growth from a 10M10 M_\oplus core to its present mass causes the libration amplitudes of Trojan asteroids to shrink by a factor of about 2.5 to 40\sim 40% of their original size. The calculation also shows that Jupiter's radial migration has comparatively little effect on the Trojans; inward migration from 6.2 to 5.2 AU causes an increase in Trojan libration amplitudes of 4\sim4%. In each case, the area enclosed by small tadpole orbits, if made dimensionless by using Jupiter's semimajor axis, is approximately conserved. Similar adiabatic invariant calculations for inclined and eccentric Trojans show that Jupiter's mass growth leaves the asteroid's eccentricities and inclinations essentially unchanged, while one AU of inward migration causes an increase in both of these quantities by 4\sim 4%. Numerical integrations confirm and extend these analytic results. We demonstrate that our predictions remain valid for Trojans with small libration amplitudes even when the asteroids have low, butComment: Submitted to Icarus - 13 Fig

    Narrowband ultraviolet B treatment for psoriasis is highly economical and causes significant savings in cost for topical treatments

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    Background: Narrowband ultraviolet B (NB-UVB) treatment for psoriasis is considered expensive. However, existing data are based on estimates and do not consider indirect cost savings. Objectives: To define the actual costs of NB-UVB incurred by the service provider, as well as treatment-associated cost savings. Methods: We performed data linkage of (i) comprehensive treatment records and (ii) prescribing data for all NB-UVB treatment episodes spanning 6 years in a population of 420 000. We minimized data fluctuation by compiling data from four independent treatment sites, and using drug prescriptions unrelated to psoriasis as a negative control. Results: National Health Service Tayside spent an average of £257 per NB-UVB treatment course (mean 257 ± 63, range 150–286, across four independent treatment sites), contrasting sharply with the estimate of £1882 used by the U.K. National Institute for Health and Care Excellence. The cost of topical treatments averaged £128 per patient in the 12 months prior to NB-UVB, accounting for 42% of the overall drug costs incurred by these patients. This was reduced by 40% to £53 per patient over the 12-month period following NB-UVB treatment, while psoriasis-unrelated drug prescription remained unchanged, suggesting disease-specific effects of NB-UVB. The data were not due to site-specific factors, as confirmed by highly similar results observed between treatment sites operated by distinct staff. Finally, we detail all staff hours directly and indirectly involved in treatment, allowing direct translation of cost into other healthcare systems. Conclusions: NB-UVB is a low-cost treatment; cost figures currently used in health technology appraisals are an overestimate based on the data presented here. Creating or extending access to NB-UVB is likely to offer additional savings by delaying or avoiding costly third-line treatments for many patients.PostprintPeer reviewe

    Can screening and brief intervention lead to population-level reductions in alcohol-related harm?

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    A distinction is made between the clinical and public health justifications for screening and brief intervention (SBI) against hazardous and harmful alcohol consumption. Early claims for a public health benefit of SBI derived from research on general medical practitioners' (GPs') advice on smoking cessation, but these claims have not been realized, mainly because GPs have not incorporated SBI into their routine practice. A recent modeling exercise estimated that, if all GPs in England screened every patient at their next consultation, 96% of the general population would be screened over 10 years, with 70-79% of excessive drinkers receiving brief interventions (BI); assuming a 10% success rate, this would probably amount to a population-level effect of SBI. Thus, a public health benefit for SBI presupposes widespread screening; but recent government policy in England favors targeted versus universal screening, and in Scotland screening is based on new registrations and clinical presentation. A recent proposal for a national screening program was rejected by the UK National Health Service's National Screening Committee because 1) there was no good evidence that SBI led to reductions in mortality or morbidity, and 2) a safe, simple, precise, and validated screening test was not available. Even in countries like Sweden and Finland, where expensive national programs to disseminate SBI have been implemented, only a minority of the population has been asked about drinking during health-care visits, and a minority of excessive drinkers has been advised to cut down. Although there has been research on the relationship between treatment for alcohol problems and population-level effects, there has been no such research for SBI, nor have there been experimental investigations of its relationship with population-level measures of alcohol-related harm. These are strongly recommended. In this article, conditions that would allow a population-level effect of SBI to occur are reviewed, including their political acceptability. It is tentatively concluded that widespread dissemination of SBI, without the implementation of alcohol control measures, might have indirect influences on levels of consumption and harm but would be unlikely on its own to result in public health benefits. However, if and when alcohol control measures were introduced, SBI would still have an important role in the battle against alcohol-related harm

    Cytokine Signaling and Hematopoietic Homeostasis Are Disrupted in Lnk-deficient Mice

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    The adaptor protein Lnk, and the closely related proteins APS and SH2B, form a subfamily of SH2 domain-containing proteins implicated in growth factor, cytokine, and immunoreceptor signaling. To elucidate the physiological function of Lnk, we derived Lnk-deficient mice. Lnk−/− mice are viable, but display marked changes in the hematopoietic compartment, including splenomegaly and abnormal lymphoid and myeloid homeostasis. The in vitro proliferative capacity and absolute numbers of hematopoietic progenitors from Lnk−/− mice are greatly increased, in part due to hypersensitivity to several cytokines. Moreover, an increased synergy between stem cell factor and either interleukin (IL)-3 or IL-7 was observed in Lnk−/− cells. Furthermore, Lnk inactivation causes abnormal modulation of IL-3 and stem cell factor–mediated signaling pathways. Consistent with these results, we also show that Lnk is highly expressed in multipotent cells and committed precursors in the erythroid, megakaryocyte, and myeloid lineages. These data implicate Lnk as playing an important role in hematopoiesis and in the regulation of growth factor and cytokine receptor–mediated signaling

    Narrowband UVB treatment is highly effective and causes a strong reduction in the use of steroid and other creams in psoriasis patients in clinical practice

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    Narrowband NB-UVB phototherapy (NB-UVB) is an effective treatment for psoriasis, as demonstrated by clinical trials. However, due to required infrastructure and need for treatment attendance opinions on the value of offering this treatment in routine practice vary. AIMS: To provide high quality large-scale and long-term data on the efficacy of NB-UVB for psoriasis under real-world conditions in order to assist in management decisions.The following resources were employed: (1) complete and prospectively recorded prescription drug records for a population of 420,000 marked by low demographic mobility, (2) prospectively recorded clinical treatment outcomes for all NB-UVB treatment episodes occurring in the local population; (3) complete dermatology electronic treatment records of all psoriasis patients, allowing cross-validation of diagnoses and treatment records. Using these data sets, we analysed all first-ever initial NB-UVB treatment episodes occurring over 79 months (n = 1749) for both clinical outcomes and the effect of NB-UVB on the use of topical treatments for psoriasis.Around 75% of patients both achieved a status of "clear/minimal disease" and used fewer topical treatments. NB-UVB treatment led to a strong reduction for both steroid creams (25%) and psoriasis-specific topicals, e.g. vitamin-D products (30%) during the 12-month period following NB-UVB treatment. The effects measured were specific as no effect of NB-UVB was noted on drug prescriptions unrelated to psoriasis. Results were independent of individuals administering and/or scoring treatment, as they were highly similar between four geographically separate locations.NB-UVB treatment is highly effective and leads to a remarkable reduction in the need for topical cream treatments for a period of at least 12 months

    Safety and efficacy of ganaxolone in patients with CDKL5 deficiency disorder: results from the double-blind phase of a randomised, placebo-controlled, phase 3 trial

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    BACKGROUND: CDKL5 deficiency disorder (CDD) is a rare, X-linked, developmental and epileptic encephalopathy characterised by severe global developmental impairment and seizures that can begin in the first few months after birth and are often treatment refractory. Ganaxolone, an investigational neuroactive steroid, reduced seizure frequency in an open-label, phase 2 trial that included patients with CDD. We aimed to further assess the efficacy and safety of ganaxolone in patients with CDD-associated refractory epilepsy. METHODS: In the double-blind phase of this randomised, placebo-controlled, phase 3 trial, done at 39 outpatient clinics in eight countries (Australia, France, Israel, Italy, Poland, Russia, the UK, and the USA), patients were eligible if they were aged 2-21 years with a pathogenic or probably pathogenic CDKL5 variant and at least 16 major motor seizures (defined as bilateral tonic, generalised tonic-clonic, bilateral clonic, atonic, or focal to bilateral tonic-clonic) per 28 days in each 4-week period of an 8-week historical period. After a 6-week prospective baseline period, patients were randomly assigned (1:1) via an interactive web response system to receive either enteral adjunctive ganaxolone or matching enteral adjunctive placebo (maximum dose 63 mg/kg per day for patients weighing ≤28 kg or 1800 mg/day for patients weighing >28 kg) for 17 weeks. Patients, caregivers, investigators (including those analysing data), trial staff, and the sponsor (other than the investigational product manager) were masked to treatment allocation. The primary efficacy endpoint was percentage change in median 28-day major motor seizure frequency from the baseline period to the 17-week double-blind phase and was analysed (using a Wilcoxon-rank sum test) in all patients who received at least one dose of trial treatment and for whom baseline data were available. Safety (compared descriptively across groups) was analysed in all patients who received at least one dose of trial treatment. This study is registered with ClinicalTrials.gov, NCT03572933, and the open-label extension phase is ongoing. FINDINGS: Between June 25, 2018, and July 2, 2020, 114 patients were screened for eligibility, of whom 101 (median age 6 years [IQR 3 to 10]) were randomly assigned to receive either ganaxolone (n=50) or placebo (n=51). All patients received at least one dose of a study drug, but seizure frequency for one patient in the ganaxolone group was not recorded at baseline and so the primary endpoint was analysed in a population of 100 patients. There was a median percentage change in 28-day major motor seizure frequency of -30·7% (IQR -49·5 to -1·9) in the ganaxolone group and of -6·9% (-24·1 to 39·7) in the placebo group (p=0·0036). The Hodges-Lehmann estimate of median difference in responses to ganaxolone versus placebo was -27·1% (95% CI -47·9 to - 9·6). Treatment-emergent adverse events occurred in 43 (86%) of 50 patients in the ganaxolone group and in 45 (88%) of 51 patients in the placebo group. Somnolence, pyrexia, and upper respiratory tract infections occurred in at least 10% of patients in the ganaxolone group and more frequently than in the placebo group. Serious adverse events occurred in six (12%) patients in the ganaxolone group and in five (10%) patients in the placebo group. Two (4%) patients in the ganaxolone group and four (8%) patients in the placebo group discontinued the trial. There were no deaths in the double-blind phase. INTERPRETATION: Ganaxolone significantly reduced the frequency of CDD-associated seizures compared with placebo and was generally well tolerated. Results from what is, to our knowledge, the first controlled trial in CDD suggest a potential treatment benefit for ganaxolone. Long-term treatment is being assessed in the ongoing open-label extension phase of this trial. FUNDING: Marinus Pharmaceuticals

    Statistical considerations for the HPTN 052 Study to evaluate the effectiveness of early versus delayed antiretroviral strategies to prevent the sexual transmission of HIV-1 in serodiscordant couples

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    The HIV Prevention Trial Network (HPTN) 052 Study is a Phase III, two-arm, controlled, open-labeled, randomized clinical trial designed to determine whether early antiretroviral therapy (ART) can prevent the sexual transmission of human immunodeficiency virus type 1 (HIV-1). A total of 1,763 couples in which one partner was HIV-1-positive and the other was HIV-1-negative were enrolled in four continents, nine countries and thirteen study sites. The HIV-1-positive partner was randomly assigned to either of the two arms: “immediate” (early) therapy with ART initiated upon enrollment plus HIV primary care, or “delayed” therapy with HIV primary care but ART initiated when the index case would have two consecutive measurements of a CD4+ cell count within or below the range of 200–250 cells/mm3, or develop an AIDS-defining illness. In this paper, we describe several key statistical considerations for the design of this landmark study. Despite that the observed event rates were lower than expected, which might have compromised the study power, an early release of the trial results in May 2011 showed an overwhelming 96% risk reduction for the immediate therapy in the prevention of genetically linked HIV-1 incident transmissions. Nevertheless, the durability of its long-term effectiveness is yet to be assessed. The HPTN 052 Study is still ongoing and will not complete till 2015
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