Le syndrome des antiphospholipides (SAPL) est un syndrome clinicobiologique associant une atteinte vasculaire et la persistance d’anticorps antiphospholipides (aPL). Les patients avec des ...manifestations cliniques évocatrices de SAPL mais sans aPL sont considérés comme « SAPL séronégatif » (SNAPS). Le but de cette étude était d’évaluer l’intérêt de la recherche d’anticorps antiphosphatidyléthanolamine (aPE) chez les patients ayant une suspicion de SNAPS.
Il s’agit d’une étude rétrospective sur tous les patients ayant eu une suspicion de SNAPS. La recherche d’aPE a été réalisée par une méthode Elisa « maison ». Cette méthode a été comparée avec un Elisa de screening global d’aPL.
Au total, 228 patients ont été répertoriés pour une recherche de SNAPS. La recherche d’aPE a été effectuée dans 58,3 % des cas pour un événement thrombotique. Parmi ces patients, 23 avaient une recherche d’aPE positive et persistante dans le temps (10 %). Quinze patients avaient eu un accident thrombotique, 6 avaient eu une complication obstétricale et 2 un événement combiné. Le test de screening des aPL n’était positif que dans 11 de ces 23 patients (47,8 %).
Ces données sont en faveur de l’implication des aPE dans le SNAPS. Elles suggèrent qu’il semble intéressant de rechercher les aPL non conventionnels pour améliorer le diagnostic de SNAPS.
Antiphospholipid syndrome (APS) is a clinico-biological syndrome, which associates vascular injury and persisting antiphospholipid antibodies (aPL). Patients with clinical symptoms of APS but without aPL are defined as “seronegative APS” (SNAPS). The aim of this study was to evaluate antiphosphatidylethanolamine antibody (aPE) investigation in patients with SNAPS suspicion.
This retrospective study was conducted in patients with SNAPS suspicion. A homemade enzyme-linked immunosorbent assay (ELISA) was used to search for aPE. The results of this homemade method were compared with those from a global screening ELISA.
Two hundred twenty-eight patients with SNAPS suspicion were included. Among them, 58.3% had a thrombotic event. The homemade ELISA found positive persisting aPE in 23 patients (10%): 15 with a thrombotic event, 6 with obstetrical morbidity and 2 with a combined event. The global screening ELISA was positive in only 11 of these 23 patients (47.8%).
These results suggest the implication of aPE in SNAPS.
The nature of the primary particle giving rise to an atmospheric shower may be, to some extent, inferred from the observable properties: longitudinal profile (especially position of the maximum of ...the number of charged particles) or shape at ground level (lateral distribution, curvature and thickness of the shower front, muonic component). Distinguishing different nuclei cannot be performed unambiguously on a single shower, because of the random fluctuations in the first steps of the cascade; however, it is possible to study the composition of the incident flux on a statistical basis: showers from heavier nuclei have a faster development, and contain more muons. The uncertainties on the hadronic interactions at the highest energies limit the reliability of the identification. Other primaries, if they exist, could be easier to distinguish. Photons would give a slower development than protons, especially at highest energies, and a very reduced muonic component; neutrinos would be characterized by deep interactions in the atmosphere, or even within the Earth, giving almost horizontal showers with a large electromagnetic component, clearly different from the muonic tail of showers induced in the upper atmosphere by nuclei. Such ‘exotic’ primaries have not yet been observed.
To cite this article: P. Billoir, P. Sommers, C. R. Physique 5 (2004).
La nature de la particule primaire qui produit une gerbe atmosphérique peut être, dans une certaine mesure, déduite de ses propriétés observables : profil longitudinal (particulièrement position du maximum du nombre de particules chargées) ou forme au niveau du sol (distribution latérale, courbure et épaisseur du front de gerbe, composante muonique). Il est impossible de distinguer individuellement les différents noyaux, à cause des fluctuations aléatoires dans les premières étapes de la cascade ; toutefois on peut étudier statistiquement la composition du flux incident : les gerbes de noyaux lourds ont un développement plus rapide, et contiennent plus de muons. Les incertitudes sur les interactions hadroniques aux énergies les plus élevées limitent la fiabilité de l'identification. D'autres primaires, s'ils existent, pourraient être plus faciles à distinguer. Des photons donneraient un développement plus lent que les protons, en particulier aux énergies extrêmes, et une composante muonique très réduite ; des neutrinos seraient caractérisés par des interactions profondes dans l'atmosphère, ou même à l'intérieur de la Terre, donnant des gerbes presque horizontales avec une forte composante électromagnétique, clairement différentes des queues muoniques de gerbes induites dans la haute atmosphère par des noyaux. De tels primaires « exotiques » n'ont pas encore été observés.
Pour citer cet article : P. Billoir, P. Sommers, C. R. Physique 5 (2004).
Factor (F)XI deficiency is a rare bleeding disorder with a poor correlation between bleeding tendency and FXI level. Management of pregnant women with FXI deficiency is not clearly established, ...especially regarding neuraxial analgesia (NA).
A retrospective multicenter observational study was conducted in French hemostasis centers on pregnant women with FXI of <60 IU/dL.
Data to report were (i) FXI levels before pregnancy and at time of delivery, (ii) type of NA and delivery management modalities, and (iii) possible complications related to NA and bleeding complications.
Three hundred fourteen pregnancies in patients with FXI deficiency of <60 IU/dL were reported (from 20 centers); among them, 199 NA procedures have been completed (137 epidurals and 61 spinals, 1 had both). The period of childbirth was mostly from 2014 to 2020 (281/314; 89.5%). Congenital FXI deficiency was established with certainty by investigators in 32.8% patients (n = 103). Previous bleedings were described in 20.4% of the patients (64/314; 45.3% cutaneous, 31.3% gynecologic, and 15.6% postsurgical). Thirteen deliveries had an NA procedure with FXI of <30 IU/dL, 42 with FXI of 30-40 IU/dL, and 118 with FXI of 40-60 IU/dL. Median FXI levels at delivery in the epidural and spinal groups were not significantly different but were significantly lower in the group without NA by medical staff contraindications. There were no complications related to NA. A 17.5% postpartum hemorrhage or excessive postpartum bleeding incidence was reported, which is consistent with previous data.
Our data support the use of a 30 IU/dL FXI threshold for NA, as suggested by the French proposals published in August 2023.
•Factor (F)XI deficiency is a rare bleeding disorder with a poor correlation between bleeding tendency and FXI level. The management of FXI deficiency in pregnant women is not yet established, particularly with regard to neuraxial analgesia (NA).•We conducted an anonymous retrospective study from 2009 to 2020 of women with FXI activity level below 60 IU/dL before pregnancy and/or below 60 IU/dL at time of delivery in 20 French centers. Of the 314 reported pregnancies, 199 NA procedures were completed (137 epidurals and 61 spinals, 1 had both). There were no complications related to NA, and 173 NAs were allowed with known FXI levels at time of delivery ranging from 17 to 60 IU/dL with a mean FXI level at time of delivery of 44.2 ± 9.5 IU/dL.•Our results support the use of a 30 IU/dL threshold for NA (all types of NA in women with no bleeding history: spinal and epidural) at time of procedure or for catheter removal. However, we also reported a 17.5% incidence of postpartum hemorrhage or excessive postpartum bleeding, which is in accordance with previous studies. Our results now need to be confirmed by large prospective studies.
Abstract We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the ...spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the ...spectrum is observed, confirming the presence of the so-called
second-knee
feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Les héparines sont des anticoagulants utilisés dans la prévention des accidents thromboemboliques. Parmi les effets indésirables recensés pour cette classe médicamenteuse, on retrouve notamment des ...cas d’allergies. Celles-ci peuvent revêtir différentes formes et impliquent, quand elles se rencontrent chez un patient, une prise en charge adaptée. Nous rapportons le cas d’un patient opéré pour une reprise de prothèse totale de hanche (PTH) avec comme antécédent une allergie à l’héparine. Devant l’urgence de l’opération, aucune investigation clinique ou biologique n’a pu être faite afin de vérifier l’allergie. Le patient a donc été mis sous danaparoïde sodique en post-chirurgie et un relais par apixaban en prévention du risque thromboembolique a été réalisé, bien qu’il ne s’agisse pas du traitement de référence en cas d’antécédent d’allergie à l’héparine.
Heparins are anticoagulants used in the prevention of thromboembolic events. Adverse reactions identified for this drug class include allergies. These can take different forms and involve, when they occur in a patient, appropriate management. We report the case of a patient operated on for a revision of a total hip replacement with a history of allergy to heparin. Given the urgency of the operation, no clinical or biological investigation could be carried out to verify the allergy. The patient was therefore placed on danaparoid sodic and apixaban has been introduced to prevent thromboembolic risk, although this is not the standard treatment for patients with a history of allergy to heparin.
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10{sup 18} eV at the Pierre Auger Observatory is reported. For the first time, ...these large-scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments in this energy range. These upper limits provide constraints on the production of cosmic rays above 10{sup 18} eV, since they allow us to challenge an origin from stationary galactic sources densely distributed in the galactic disk and emitting predominantly light particles in all directions.
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