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Resume Introduction La thrombopenie induite par le 177Lu-DOTATATE est un de ses effets indesirables frequents. Sa persistance impactant la prise en charge ulterieure des patients, notamment lors de la progression de la maladie, la prevenir est un enjeu capital. Devant la penurie de connaissances sur le sujet, nous avons cherche a determiner l’existence de facteurs predisposants a la toxicite plaquettaire dans le bilan de suivi standard. Materiel et methodes Cette etude retrospective monocentrique a inclus 20 patients atteints de tumeurs neuroendocrines gastroenteropancreatiques. Differents parametres ont ete analyses, parmi lesquels le bilan biologique, le facteur d’envahissement osteomedullaire, le volume de la rate et l’activite estimee dans la moelle osseuse et la rate 24 h post-injection. Resultats Quatre patients ont presente une thrombopenie de grade 2 persistante a un an. Une chute du taux de plaquettes superieure a 30 % des la premiere cure ainsi qu’un facteur d’envahissement osteomedullaire superieur a 30 % etaient des facteurs de risque de thrombopenie severe, odds-ratio = ∞ (p = 0,0379) et odds-ratio = ∞ (p = 0,003) respectivement. Le taux initial de plaquettes, la fleche splenique et l’activite dans la rate a 24 h etaient correles au nadir plaquettaire r = 0,5459 (p = 0,0128) ; r = − 0,8105 (p Conclusion Cette etude suggere que la profondeur de la chute des plaquettes a la premiere cure ainsi que l’importance de l’envahissement osteomedullaire seraient des facteurs de risque de thrombopenie et evoque un role de la rate dans la physiopathogenie de la severite de cette thrombopenie.

Quantum coherent transport of spin-polarized carriers is observed on a very unusual large scale within epitaxial nanowires of GaMnAs, a diluted ferromagnetic semiconductor. From the analysis of the amplitude of strong universal conductance fluctuations, an effective phase coherence length of about 100 nm is inferred at T = 100 mK, which is one order of magnitude larger than in a granular 3d-metal ferromagnets. Together with the temperature and bias dependence of these reproducible fluctuations, their wire-length dependence is studied in single-domain sub-micron long nanowires with a perprendicular anisotropy. In particular, variations for two equivalent probe configurations are shown when the length becomes comparable to the actual phase coherence length. This result forecasts the possible observation of non-local voltage drops in GaMnAs nanostructures smaller than about 200 nm. Generally speaking, this research contributes to pave the way towards the realization of quantum spintronics devices.

This work provides new developments of the field of spin dynamics in mesoscopic systems. We first discuss, by a few examples, how environmental degrees of freedom affect tunneling and subsequent slow quantum relaxation of large molecule spins (such as Mn 12− AC) or rare-earth (RE) spins (such as Ho diluted in YLiF 4 ) showing two different facets of the spin bath model. The case of low molecule spins (V 15 ) is also considered. Then we discuss AC-susceptibility experiments performed on YLiF 4 :Ho 3+ allowing to clarify the roles played by the phonon and the spin baths on single-ion and two-ion electro-nuclear tunneling. In the last part, we extend these quantum dynamical studies to the case of Er diluted in CaWO 4 where the spin and phonon baths are weak enough to allow fast and coherent quantum dynamics with the observation of Rabi oscillations. The angular momentum and magnetic moment of Er, J =15/2and 9 μ B, are comparable to those of large molecule spins, implying easy manipulations of potential RE solid-state qubits.

Tunneling of the total angular momentum of Ho 3+ in LiYF 4 (insulating matrix) is demonstrated. Due to strong hyperfine interactions, electronic angular momentum and nuclear spin tunnel simultaneously (two-body entanglement) and due to weak dipolar interactions, pairs of Ho 3+ ions also tunnel simultaneously (four-body entanglement). Similar results obtained with a metallic matrix (YRu 2 Si 2 ) prove the persistence of tunneling in the presence of free carriers.

We report our experience of 15 cases of gastroschisis which occured between 1981 and 1993. All but one were diagnosed antenatally by ultrasound between 16 and 32 weeks of pregnancy. We made a termination of the pregnancy in 3 cases, for multiple malformations in 2 cases and one case of very early premature rupture of the membranes (PROM). When checked (11 cases), the karyotype was normal. We made a cesarean section in 11 cases: the indication was a complication for 6 (fetal distress, PROM, polyhydramnios, large dilatation of the gut). We noted growth retardation in 7 newborns and prematurity in 5 12 (mean gestational age of 36.8 weeks). The preoperative study of the gut noted 5 cases with intestinal damage and one case of complete necrosis of the gut. The global prognosis is not as good as usual, with a perinatal mortality of 41.6% ( 5 12 ). We discuss this latter point and examine the literature.

We retrospectively studied the outcome of pregnancy in 62 cases of absent end diastolic flow (AEDF) of umbilical artery Doppler flow velocity waveform. The history of pregnancies revealed that nearly all were of high risk. Many cases presented cerebral (65%) or uterine (55.5%) Doppler flow abnormalities, or both (38%). We noted 10 fetal deaths and decided 7 pregnancy terminations. Malformation and chromosomal defect rate was 16%. We noted 44 (71%) live-births, a very high rate of cesarean section (86%), prematurity (75%), small for gestational age (39%). Forty-five percent of the neonates had a 1-min Apgar score under 7, which dropped to 27% at 5 min. Neonate mortality rate was 6.9% and the total mortality rate was 34% (21/62). Morbidity was significant (7 cases with severe morbidity, 2 cases with chromosomal abnormality of poor prognosis). We compared different sub-groups with a view to looking for some prenatal factors which predict poor neonatal outcome in case of AEDF.

Strong hyperfine coupling in a 0.2% Holmium doped LiYF_4 single crystal induces staircaselike hysteresis loops of the magnetization at very low temperatures. The field sweep rate dependence of hysteresis loops allows the study of two different regimes in the magnetic relaxation of these weakly coupled magnetic moments. At slow field sweep rates, quantum tunneling of the magnetization occurs at avoided level crossings in the low-energy scheme of a single ion Ho^3+. At faster sweep rates, nonequilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps., 4 figures, Conference proceeding: 1st Joint European Magnetic Symposia (JEMS01'), Grenoble (France), 28th August - 1st September, 2001

The properties of light particles emitted in 32 S induced reactions on 16 O, 27 A1, 28 Si and 40 Ca were studied. The bombarding energies varied between 135 and 225 MeV. The experiment employed two large-area, position-sensitive ionization chambers to measure the heavy reaction fragments, whereas the light particles were treated as the undetected deficit of the reaction. The charge deficit increases linearly with the c.m. bombarding energy; the corresponding linear-momentum deficits in the event plane indicate that the sequential evaporation from both intermediate fragments is the dominant source of light particles.