Isospin analysis of charmless B-meson decays Charles, J.; Deschamps, O.; Descotes-Genon, S. ...
The European physical journal. C, Particles and fields,
08/2017, Letnik:
77, Številka:
8
Journal Article
Recenzirano
Odprti dostop
We discuss the determination of the CKM angle
α
using the non-leptonic two-body decays
B
→
π
π
,
B
→
ρ
ρ
and
B
→
ρ
π
using the latest data available. We illustrate the methods used in each case and ...extract the corresponding value of
α
. Combining all these elements, we obtain the determination
α
dir
=
(
86.2
-
4.0
+
4.4
∪
178.4
-
5.1
+
3.9
)
∘
. We assess the uncertainties associated to the breakdown of the isospin hypothesis and the choice of the statistical framework in detail. We also determine the hadronic amplitudes (tree and penguin) describing the QCD dynamics involved in these decays, briefly comparing our results with theoretical expectations. For each observable of interest in the
B
→
π
π
,
B
→
ρ
ρ
and
B
→
ρ
π
systems, we perform an indirect determination based on the constraints from all the other observables available and we discuss the compatibility between indirect and direct determinations. Finally, we review the impact of future improved measurements on the determination of
α
.
Summary
Background
Acute exanthemas (AEs) are frequently seen; they can be caused by drugs or viruses but often the cause is unknown.
Objectives
To describe the clinical, virological and histological ...aspects of AEs and explore their cytokinic and metagenomic profiles.
Methods
This prospective study examined 98 patients with AE, from February to July 2014. Clinical data were recorded in a standardized chart. Virological investigation and skin biopsies were performed. In addition, blood and skin samples were analysed for cytokines and then by a shotgun metagenomic approach. We identified five groups of patients: those with maculopapular exanthemas (MPEs) that were virally induced (group 1); those with drug‐induced MPEs (group 2), those with MPEs that were both viral and drug induced (group 3), those with idiopathic MPEs (group 4) and those with pityriasis rosea (group 5).
Results
A virus was identified in 29 cases (human herpesvirus 6, 72%). Cytokinic analysis of the skin (n = 23 MPEs) showed higher levels of interferon‐γ and interleukin‐1 receptor‐α in viral MPEs, higher interleukin‐33 levels in idiopathic MPEs, and higher macrophage inflammatory protein 1α levels in drug‐induced MPEs. By metagenomics analysis (n = 10 MPEs), viruses identified with routine practice methods were not found in group 1 (n = 4 MPEs). However, Enterovirus A was detected in two cases, especially in a group 1 patient for whom metagenomic analysis rectified the diagnosis of the culprit agent.
Conclusions
Human herpesvirus 6 was the virus most frequently identified, and histology did not discriminate MPEs. In addition, the level of interleukin‐33 seen in idiopathic MPEs suggests that an environmental factor may be the trigger for these. The results bring into question the utility of routine polymerase chain reaction analysis and viral serology for determining cause in AE.
What's already known about this topic?
Acute exanthemas, especially maculopapular exanthemas, are a frequent reason for patients consulting emergency and dermatology departments.
It is difficult to evaluate the aetiology of acute exanthema based on the clinical aspects.
Few data are available on the investigations needed in routine practice, and no prospective series have been published.
What does this study add?
Our study provides a global and prospective description of acute exanthemas.
Cytokine analysis could help to investigate the pathophysiology of idiopathic eruptions.
Metagenomic analysis provides new insights about the value of routine practice virological investigations.
We show for the first time the feasibility of metagenomics analysis in the skin, which results question the interest of routine PCR and viral sérologies for the exploration of such acute exanthemas.
Linked Comment: Shearer et al. Br J Dermatol 2020; 182:268–269.
Plain language summary available online
Summary
Severe rashes, called acute exanthemas (AE), are frequently seen in hospital. The most common type is called maculopapular exanthema (MPE), and another type is pityriasis rosea.
The main ...causes of AEs, especially MPEs, are drugs (delayed hypersensitivity) and viruses (such as HIV, human herpesvirus 6 ‐ HHV6, and measles virus), but for some no cause is identified, which is known as ideopathic.
There are no guidelines for which tests (viral investigations) should be carried out. The researchers conducted this study to better describe AE, and to explore the value of investigations into the causes of AE, called cytokinic and metagenomic analysis.
98 patients being seen at the Henri Mondor hospital in France were included. Patients were examined by a medic, received tests for viruses, and skin biopsies (tissue samples) were taken.
Patients were classified into five groups: viral group (18 people), drug‐induced group (33), drug‐induced and viral (5), idiopathic (32) and pityriasis rosea (10).
HHV6 was the most common virus found (74%).
Analysis looking at levels of proteins called cytokines showed higher levels of a cytokine called interleukin‐33 in the idiopathic exanthemas (i.e. the ones with an unidentified cause). This could suggest an environmental factor as a trigger.
The study showed for the first time the feasibility of metagenomics analysis (studying the genetic material) in the skin, and the results question whether some of the routine virus tests used are always beneficial.
This summary relates to the study: Acute exanthemas: a prospective study of 98 adult patients with an emphasis on cytokinic and metagenomic investigation
Linked Article: Deschamps et al. Br J Dermatol 2020; 182:355–363
Hyper-reactive malarial splenomegaly Maazoun, F; Deschamps, O; Barros-Kogel, E ...
La revue de medecine interne,
11/2015, Letnik:
36, Številka:
11
Journal Article
Recenzirano
Hyper-reactive malarial splenomegaly is a rare and severe form of chronic malaria. This condition is a common cause of splenomegaly in endemic areas. The pathophysiology of hyper-reactive malarial ...splenomegaly involves an intense immune reaction (predominantly B cell-driven) to repeated/chronic infections with Plasmodium sp. The diagnosis may be difficult, due to a poorly specific clinical presentation (splenomegaly, fatigue, cytopenias), a long delay between residence in a malaria-endemic area and onset of symptoms, and a frequent absence of parasites on conventional thin and thick blood smears. A strongly contributive laboratory parameter is the presence of high levels of total immunoglobulin M. When the diagnostic of hyper-reactive malarial splenomegaly is considered, search for anti-Plasmodium antibodies and Plasmodium nucleic acids (genus and species) by PCR is useful. Diagnosis of hyper-reactive malarial splenomegaly relies on the simultaneous presence of epidemiological, clinical, biological and follow-up findings. Regression of both splenomegaly and hypersplenism following antimalarial therapy allows the differential diagnosis with splenic lymphoma, a common complication of hyper-reactive malarial splenomegaly. Although rare in Western countries, hyper-reactive malarial splenomegaly deserves increased medical awareness to reduce the incidence of incorrect diagnosis, to prevent progression to splenic lymphoma and to avoid splenectomy.
In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, |Vub| and |Vcb|, are governed by the coupling of the quarks to the Higgs boson. Using ...data from the LHCb experiment at the Large Hadron Collider, the probability for the Λb0 baryon to decay into the p final state relative to the final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of |Vcb|, the first |Vub| measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of |Vub| using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states.
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