Prevalence and clinical significance of solitary pulmonary sub-segmental microembolism

BACKGROUND: Solitary pulmonary microembolism is rarely discussed as a distinct diagnostic entity. The purpose of this investigation was to determine the prevalence and clinical significance of embolism limited to subsegmental branches in a group of patients discharged from hospital on anticoagulants with a diagnosis of pulmonary embolism based on ventilation-perfusion imaging followed by selective angiography. MATERIAL AND METHODS: Of 29 consecutive patients with classic signs of pulmonary embolism at angiography, we identified a subgroup of 5 patients with sub-segmental embolism, which was solitary in all cases. RESULTS: Clinical presentation included chest pain (2/5), shortness of breath (2/5, or hypoxemia (1/5). Chest X-rays were normal (2/5), or showed pulmonary oedema (1/5) or atelectasis with (1/5), or without (1/5) pleural effusion. VQ imaging patterns included small subsegmental mismatch (1/5), one segment mismatch (1/5), single (1/5) or triple (2/5) match. The site and size of the microemboli found at angiography were incompatible with the location and severity of symptoms in 4/5 (80%) patients, and with location and extent of Chest X-ray findings and with VQ patterns in all patients. VQ abnormalities were either either disproportionably larger or were non congruent with the vascular territory compromised by the subsegmental embolus. CONCLUSIONS: Sub-segmental pulmonary micro-emboli were always solitary, and not uncommon, comprising 17% of all patients with pulmonary embolism. The location and size of the emboli were inconsistent with clinical, Chest X-ray and scintigraphic findings, suggesting that isolated microemboli are a serendipitous finding, of no clinical significance

Vilna Francine Bashi, Survival of the Knitted. Immigrant Social Networks in a Stratified World

L’ouvrage traite des réseaux sociaux des immigrés en montrant comment ils peuvent être un outil de mobilité sociale. L’auteure étudie le cas d’immigrants résidant dans les zones métropolitaines de Londres et de New York et de leurs familles et amis restés dans leurs îles d’origine de la Caraïbe-Est, anglophone. Elle entend montrer que le réseau joue un rôle essentiel dans la mesure où il permet à l’immigrant de tisser et d’entretenir des liens pour mieux vivre dans un milieu étranger, voire h..

Les migrants, acteurs transnationaux du développement : les associations haïtiennes en France et jamaïcaines au Royaume-Uni

Cette thèse porte sur l’analyse de la dynamique transnationale des pratiques associatives de migrants et de leur contribution au développement local de deux pays d’origine (Haïti et la Jamaïque). Elle a permis d’établir des parallèles entre des expériences de migrants situées dans des cadres socio-institutionnels et culturels à la fois convergents et différents (France, Royaume-Uni, etc.). Les associations de migrants ont constitué le socle de notre étude et ont été le point central d’un trav..

Age-related Changes in Auditory Cortex Without Detectable Peripheral Alterations: A Multi-level Study in Sprague–Dawley Rats

International audienceAging is often considered to affect both the peripheral (i.e. the cochlea) and central (brainstem and thalamus-cortex) auditory systems. We investigated the effects of aging on the cochlea, brainstem and cortex of female Sprague-Dawley rats. The auditory nerve threshold remained stable between the ages of nine and 21 months, as did distortion product otoa-coustic emissions and the number of ribbon synapses between inner hair cells and nerve fibers. The first clear signs of aging appeared in the brainstem, in which response amplitude decreased, with thresholds remaining stable until the age of 15 months, and increasing slightly thereafter. The responses of primary auditory cortex neurons revealed specific effects of aging: at 21 months, receptive fields were spectrally narrower and the temporal reliability of responses to communication sounds was lower. However, aging had a null or even positive effect on neuronal responses in the presence of background noise, responses to amplitude-modulated sounds, and responses in gap-detection protocols. Overall, inter-animal variability remained high relative to the variability across groups of different ages, for all parameters tested. Beha-vioral performance for the modulation depth of amplitude modulation noise was worse in 21-month old animals than in other animals. Age-related alterations of cortical and behavioral responses were thus observed in animals displaying no signs of aging at the peripheral level. These results suggest that intrinsic, central aging effects can affect the perception of acoustic stimuli independently of the effects of aging on peripheral receptors

Structure and Function of the Hair Cell Ribbon Synapse

Faithful information transfer at the hair cell afferent synapse requires synaptic transmission to be both reliable and temporally precise. The release of neurotransmitter must exhibit both rapid on and off kinetics to accurately follow acoustic stimuli with a periodicity of 1 ms or less. To ensure such remarkable temporal fidelity, the cochlear hair cell afferent synapse undoubtedly relies on unique cellular and molecular specializations. While the electron microscopy hallmark of the hair cell afferent synapse — the electron-dense synaptic ribbon or synaptic body — has been recognized for decades, dissection of the synapse’s molecular make-up has only just begun. Recent cell physiology studies have added important insights into the synaptic mechanisms underlying fidelity and reliability of sound coding. The presence of the synaptic ribbon links afferent synapses of cochlear and vestibular hair cells to photoreceptors and bipolar neurons of the retina. This review focuses on major advances in understanding the hair cell afferent synapse molecular anatomy and function that have been achieved during the past years

Auditory Cortex Basal Activity Modulates Cochlear Responses in Chinchillas

Background: The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory nerve fibers. The functional role of the cortico-olivocochlear efferent system remains debated. We hypothesized that auditory cortex basal activity modulates cochlear and auditory-nerve afferent responses through the efferent system. Methodology/Principal Findings: Cochlear microphonics (CM), auditory-nerve compound action potentials (CAP) and auditory cortex evoked potentials (ACEP) were recorded in twenty anesthetized chinchillas, before, during and after auditory cortex deactivation by two methods: lidocaine microinjections or cortical cooling with cryoloops. Auditory cortex deactivation induced a transient reduction in ACEP amplitudes in fifteen animals (deactivation experiments) and a permanent reduction in five chinchillas (lesion experiments). We found significant changes in the amplitude of CM in both types of experiments, being the most common effect a CM decrease found in fifteen animals. Concomitantly to CM amplitude changes, we found CAP increases in seven chinchillas and CAP reductions in thirteen animals. Although ACE

Disruption of Lateral Efferent Pathways: Functional Changes in Auditory Evoked Responses

The functional consequences of selectively lesioning the lateral olivocochlear efferent system in guinea pigs were studied. The lateral superior olive (LSO) contains the cell bodies of lateral olivocochlear neurons. Melittin, a cytotoxic chemical, was injected into the brain stem using stereotaxic coordinates and near-field evoked potentials to target the LSO. Brain stem histology revealed discrete damage to the LSO following the injections. Functional consequences of this damage were reflected in depressed amplitude of the compound action potential of the eighth nerve (CAP) following the lesion. Threshold sensitivity and N1 latencies were relatively unchanged. Onset adaptation of the cubic distortion product otoacoustic emission (DPOAE) was evident, suggesting a reasonably intact medial efferent system. The present results provide the first report of functional changes induced by isolated manipulation of the lateral efferent pathway. They also confirm the suggestion that changes in single-unit auditory nerve activity after cutting the olivocochlear bundle are probably a consequence of disrupting the more lateral of the two olivocochlear efferent pathways.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41379/1/10162_2002_Article_3018.pd

Les substances neuroactives des systemes efferents de la cochlee

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Migrants as Transnational Actors of Development : Haitian Associations in France and Jamaican Associations in the United Kingdom

Dans un contexte où l'importance croissante de la mondialisation des flux migratoires en provenance de la région caraïbéenne s'intensifie et se diversifie, une prise en compte plus détaillée de l'évolution des stratégies de migrants au sein des sociétés d'accueil et de leur impact socioéconomique et politique sur les sociétés de départ s'impose. Notre thèse déclinée en trois parties s'inscrit précisément dans une réflexion sur l'engagement associatif à distance du migrant-acteur haïtien et jamaïcain, dans un cadre institutionnel français pour l'un et britannique pour l'autre. Au cœur d'un dispositif qui lie responsables locaux du pays d'origine et élus de la société d'accueil mettant en interaction différentes formes d'intervention de l'État d'origine, comment donc ce dernier peut-il alors agir et avoir un rôle incitatif en favorisant la participation de cette communauté transnationale ou encore en coordonnant des actions des associations de migrants ? En quoi le cadre associatif transnational est-il favorable au développement dans le contexte haïtien / jamaïcain ? En considérant l'émergence puis l'évolution du tissu associatif haïtien en terre française, et celles du tissu associatif jamaïcain en terre britannique, nous avons voulu chercher à comprendre les motivations derrière l'engagement de porter des projets de développement dans le pays d'origine. Notre travail de terrain, ainsi que notre dispositif méthodologique dans une approche de terrain multi-situé, nous a permis de mieux saisir les mécanismes de solidarité collective et de mise en commun de ressources. Partant d'un fait observé, une dynamique associative, qui s'est amplifiée au lendemain du séisme en HaïtiIn a context where the growing importance of the globalization of migratory flows from the Caribbean region is intensifying and diversifying, a detailed attention on the evolution of migrants' strategies within host societies as well as their socioeconomic and political impact on the origin societies is required. Our thesis in three parts inscribes itself in a reflection on long-distance associative engagement of the Haitian and Jamaican migrant-actor, in a French institutional framework as well as a British one. At the heart of a model between local officials of the country of origin and elected officials of the host society, how can it act in an incentive capacity to foster or to better coordinate the actions taken by migrants' associations? How can a transnational associative framework be beneficiary to the development in the Haitian/Jamaican context? In considering the emergence and evolution of the Haitian associative landscape (France) and Jamaican (the United Kingdom), we wanted to understand the motivations behind the long-distance commitment to bring about development projects in the country of origin. Our fieldwork as well as our methodological approach in a multi-sited terrain helped us better grasp some of the mechanisms of bounded solidarity and of shared resources.Starting from an observed fact, an associative dynamic, which grew significantly in the aftermath of the earthquake in Haiti in January 2010, our study highlights three key elements: the relevance of the sense of belonging of migrants associations, the paramount importance of the relationship between the origin State and the its citizens abroad, and the growing, diverse and complex evolutio