Neutron skin of (208)pb from coherent pion photoproduction.

Information on the size and shape of the neutron skin on (208)Pb is extracted from coherent pion photoproduction cross sections measured using the Crystal Ball detector together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections, the half-height radius and diffuseness of the neutron distribution are found to be c(n)=6.70±0.03(stat.) fm and a(n)=0.55±0.01(stat.)(-0.03)(+0.02)(sys.) fm, respectively, corresponding to a neutron skin thickness Δr(np)=0.15±0.03(stat.)(-0.03)(+0.01)(sys.) fm. The results give the first successful extraction of a neutron skin thickness with an electromagnetic probe and indicate that the skin of (208)Pb has a halo character. The measurement provides valuable new constraints on both the structure of nuclei and the equation of state for neutron-rich matter.

Photoproduction of π0 mesons off neutrons in the nucleon resonance region.

Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.

Measurement of the 1H(γ, p)π0 reaction using a novel nucleon spin polarimeter.

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.4

Accurate test of chiral dynamics in the γp→π0p reaction.

A precision measurement of the differential cross sections dσ/dΩ and the linearly polarized photon asymmetry Σ≡(dσ⊥-dσ∥)/(dσ⊥+dσ∥) for the γp→π0p reaction in the near-threshold region has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The Glasgow-Mainz photon tagging facility along with the Crystal Ball/TAPS multiphoton detector system and a cryogenic liquid hydrogen target were used. These data allowed for a precise determination of the energy dependence of the real parts of the S- and all three P-wave amplitudes for the first time and provide the most stringent test to date of the predictions of chiral perturbation theory and its energy region of agreement with experiment.

Narrow structure in the excitation function of η photoproduction off the neutron.

The photoproduction of η mesons off nucleons bound in 2H and 3He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the η→2γ and η→3π0 decays and the recoil nucleons were detected with an almost 4π electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of γn→nη. The results from the two measurements are consistent, taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are W=(1670±5) MeV and Γ=(30±15) MeV. For the first time precise results for the angular dependence of this structure have been extracted.

[Reactive perforating collagenosis]. / Collagénose perforante réactionnelle.

BACKGROUND: Reactive perforating collagenosis (RPC) belongs to the group of perforating dermatoses, which comprises elastosis perforans serpiginosa, RPC, perforating folliculitis and Kyrle's disease. RPC was initially described as a distinctive form of transepithelial elimination of altered collagen related to superficial trauma. Two types are distinguished: a hereditary type (MIM 216700), which is rare and begins during early childhood, and a second type, called acquired RPC, which is more frequent, appears in adults and is associated with other diseases, diabetes mellitus, renal insufficiency, solid tumors, lymphomas and AIDS. We report the case of a young man whose illness began during infancy, militating in favor of a diagnosis of a hereditary form of RPC. The description of similar lesions in the patient's brother confirmed our diagnosis. PATIENTS AND METHODS: A 26-year-old man, the child of consanguinous parents, presented crusted papular lesions on his hands. The cutaneous lesions, located on the external side of the limbs, had been present since childhood, with flares during winter. Histologic analysis showed a cup-shaped depression in the epidermis containing keratinous material with extruded degenerated collagen towards the cutaneous surface. Treatment with topic retinoids did not result in any real resolution of the disease. The patient reported the presence of similar lesions in his brother, which was consistent with our diagnosis. DISCUSSION: The pathogenesis of hereditary RPC is still unknown, even if superficial trauma is suspected as the cause of RPC. In contrast, in diabetes, acquired RPC pathogenesis has recently been related to advanced glycation end-products of collagen.

Beam-helicity asymmetries in double-pion photoproduction off the proton.

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels gamma[over -->]p-->pi(+)pi(0)n, gamma[over -->]p-->pi(0)pi(0)p, and gamma[over -->]p-->pi(+)pi(-)p. The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of pi(0) mesons were detected in a 4pi electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. The precisely measured asymmetries are very sensitive to details of the production processes and are thus key observables in the modeling of the reaction dynamics.

Incoherent neutral pion photoproduction on 12C.

We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the Delta in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a Delta-hole model.

[Lymphocytic infiltrate of the dermis preceding typical Sweet's syndrome]. / Infiltration lymphocytaire dermique précédant un syndrome de Sweet.

BACKGROUND: The histologic criteria for Sweet's syndrome consist in prominent oedema of the dermis and a diffuse infiltrate of numerous neutrophils with leukocytoclasis without vasculitis in the superficial and the deep dermis. Several comorbidities have been observed in patients with Sweet's syndrome, particularly hemo-proliferative diseases. PATIENTS: We report the cases of two men aged 60 and 75 years with Sweet's syndrome associated in one case with myelodysplasia and in the other with chronic lymphocytic leukemia. These two patients had typical edematous plaques highly evocative of Sweet's syndrome. However, histological examination revealed superficial and deep perivascular lymphocytic infiltrate in the dermis on 5 occasions before the typical neutrophilic dermatosis of Sweet's could be diagnosed after respectively 2 and 4 years of progression. DISCUSSION: Histological findings in Sweet's syndrome are characteristic and constitute a major diagnostic factor. However, these two cases show that a lymphocytic infiltrate can occur months or even years before the appearance of typical neutrophilic infiltrate in patients with Sweet's syndrome.

[Epidermodysplasia verruciformis: clinicaland epidemiological features of 45 cases in the Department of Dermatology at the University Hospital Center of Yalgado Ouedraogo, Ouagadougou]. / Epidermodysplasie verruciforme: aspects epidémiologiques et cliniques de 45 cas dans le service de Dermatologie du Centre Hospitalier Universitaire Yalgado Ouédraogo, Ouagadougou.

INTRODUCTION: The epidermodysplasia verruciformis is a rare, autosomic, recessive, genodermatose characterized by a chronic, disseminated, cutaneous infection with human papillomavirus. The majority of these patients have a genetic or acquired immunodeficiency. PATIENTS AND METHODS: This retrospective study was conducted on the records of all patients who presented in our dermatology department with an epidermodysplasia verruciformis in a 13 years and 6 months period, from January 1st, 1992 to June 30th, 2005. RESULTS: We have collected 45 cases of epidermodysplasia verruciformis. They were aged from 3 to 57 years, with a mean of 24.6 years. The most concerned age bracket was that from zero to 9 years. They were 29 women (64.4%) and 16 men (35.6%). The eruption presented as papules of 2 to 3 mm size, associated with hypochromic, finely squamous macules with the same size. We noted three cases of itching. We found 37.7% of family cases. We observed 14 cases of HIV positive patients and one case of cancer. CONCLUSION: This study confirmed that the epidermodysplasia verruciformis was rare. Genetic factors or immunodeficiency would support the appearance of the disease.

Measurement of the Gerasimov-Drell-Hearn Integrand for 2H from 200 to 800 MeV.

A measurement of the helicity dependence of the total inclusive photoabsorption cross section on the deuteron was carried out at MAMI (Mainz) in the energy range 200

Measurement of helicity-dependent photoabsorption cross sections on the neutron from 815 to 1825 MeV.

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

The combination of complement deficiency and cigarette smoking as risk factor for cutaneous lupus erythematosus in men; a focus on combined C2/C4 deficiency.

BACKGROUND: Although deficiencies in the early components of the complement system were among the first identified genetic risk factors for systemic lupus erythematosus (SLE), only a few studies addressed their significance in patients with cutaneous LE (CLE). Among environmental factors, it was postulated that cigarette smoking might intervene in the pathogenesis of LE. OBJECTIVES: To describe the clinical and biological features of patients with CLE and a complement deficiency. A secondary objective was to assess cigarette smoking in patients with CLE. PATIENTS AND METHODS: A retrospective study including all patients diagnosed as having LE between 1995 and 2003 in the Dermatology Department of Strasbourg University Hospital. Patient charts were reviewed and those patients in whom a C4 and/or C2 deficiency was diagnosed were included. Two patients with a combined C2/C4 deficiency were analysed in detail. RESULTS: There were 48 females and 37 males (F/M ratio = 1.3), with a mean age of 41 years at diagnosis; 73% of the patients had chronic LE and 27% subacute CLE. Among 32 screened patients, 24 patients with a mean age of 36 years had a complement deficiency; 17 had a C4A deficiency, five a C4B deficiency and two a combined C4A/C2 deficiency. A high proportion (58%) of these patients was male; 82% of the patients were smokers. This was especially true in males: 94% were smokers compared with 69% of females. CONCLUSIONS: Partial deficiency of C4, C2 or C4 and C2 is a common finding in patients with CLE. Most male patients with CLE are smokers. It is thus suggested that the combination of cigarette smoking and complement deficiency could be a risk factor for LE in men.

Experimental check of the Gerasimov-Drell-Hearn sum rule for 1H.

For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.

[Primary cutaneous non T non B CD4+ CD56+ leukemia (2 cases): an original anatomoclinical syndrome]. / Leucémie aleucémique non T non B CD4+ CD56+ (2 cas). Une entité anatomoclinique originale.

INTRODUCTION: Non T non B CD4+ CD56+ leukemia is often revealed by cutaneous lesions. We report 2 patients with this disorder who had characteristic anatomoclinical findings. CASE REPORTS: An 81 year-old female and a 75 year-old man presented with erythematous macules which increased in number and progressed to infiltrated plaques and nodules. The lesions became ecchymotic, but the patients remained in good general condition and blood count as well as bone marrow examination were unremarkable. A cutaneous biopsy revealed a lymphomatous mononuclear cell infiltrate. The cells expressed CD4 and CD56, but not CD3. The cutaneous lesions preceded for 10 and 9 months respectively the appearance of overt leukemia and medullar involvement. At this stage, the patients deceased rapidly from their leukemia. DISCUSSION: This is an original anatomoclinical syndrome. The histopathologist must pay attention to the unusual CD4+ and CD3- immunophenotype and search for CD56 expression. The malignant cell responsible for this type of leukemia is now individualized and corresponds to a type II dendritic cell precursor.

[Acquired lymphangiectasias or mammary dermolytic blisters with spontaneous resolution]. / Lymphangiectasies acquises ou bulles dermolytiques mammaires spontanément résolutives.

INTRODUCTION: Spontaneous occurrence of hemorrhagic blisters on the lower side of the breasts is an unusual clinical presentation of acquired lymphangiectasia. CASE REPORT: A 64 Year-old and a 85 Year-old woman had developed recurrent bleeding blisters in the sub-mammary region for several Months. Histological, immunohistochemical and electron microscopic examination revealed a subpapillary dermal bullous dehiscence, parallel to the epidermis, which was connected to lymphangiectasias of the superficial dermis. Their extreme dilatation and rupture were probably responsible for the clinical inflammatory and bleeding aspect of the lesions, which have not recurred after 1 and 3 Years, respectively. DISCUSSION: The presence of subpapillary inflammatory lymphangiectasias might be responsible for recurrent dermal blister formation. The reason for the presence of these hemorrhagic lymphangiectasias, restricted to the sub-mammary location and their spontaneous regression after several flare-ups, remain unclear. The unusual clinical presentation of the lesions observed in these two women constitutes a differential diagnosis of acquired dermolytic blisters.

[Porphyria cutanea tarda in a hemodialysed patient with hepatitis C virus infection: efficacy treatment by small repeated phlebotomies]. / Porphyrie cutanée tardive chez un hémodialysé ayant une hépatite virale C: efficacité du traitement par petites phlébotomies.

INTRODUCTION: Porphyria cutanea tarda (PCT) is a disorder of heme biosynthesis resulting from deficiency in the enzyme uroporphyrinogen decarboxylase. In the sporadic form of PCT, there are many agents that trigger the clinical manifestations. EXEGESIS: We report a case of PCT in an hemodialysed patient with hepatitis C virus infection (HVC). He was treated with small repeated phlebotomies of 50 ml every week with photoprotection, eviction of traumatismes and inducing drugs. A clinical remission was induced after five months of treatment. CONCLUSION: A proper diagnosis of PCT in non uremic hemodialysed patients requires fractionation of serum and fecal porphyrin changes. Management of this patients is difficult. Small repeated phlebotomies (50-100 ml) could be an interesting therapy.

[Generalized granuloma annulare and drug-induced immunodeficiency]. / Granulomes annulaires disséminés et immunodépression iatrogène.

BACKGROUND: Granuloma have already been described in the context of immunosuppression. We report six cases of widespread granuloma annulare occurring in patients with drug-induced immunosuppression. CASE REPORTS: There were four women and two men, with mean age of 61 years (35-76). Three patients were treated with chemotherapy for breast (2 cases) and liver cancer. One woman was given chemotherapy for Hodgkin's disease. One had undergone liver transplantation and was given cyclosporine, another was treated with systemic steroids for polyarthritis. All had generalized non-photoexposed granuloma annulare, composed of multiple erythematous papules, sometimes with annular pattern. The lesions were localized on the trunk, legs and arms. Histopathology revealed granuloma annulare in each patient. DISCUSSION: These six cases suggest a relationship between drug-induced immunodeficiency and generalized granuloma annulare. The immune dysregulation induced by the drugs may have been responsible for the formation of granuloma annulare.

First Measurement of the Gerasimov-Drell-Hearn Sum Rule for 1H from 0.7 to 1.8 GeV at ELSA.

To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.