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Search Results: 1 - 10 of 212271 matches for " Roger L Leandri "
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Zona pellucida from fertilised human oocytes induces a voltage-dependent calcium influx and the acrosome reaction in spermatozoa, but cannot be penetrated by sperm
Catherine Patrat, Jana Auer, Patricia Fauque, Roger L Leandri, Pierre Jouannet, Catherine Serres
BMC Developmental Biology , 2006, DOI: 10.1186/1471-213x-6-59
Abstract: The hZP of fertilised oocytes retained their ability to bind sperm (albeit less strongly than that from unfertilised oocytes), to induce an intraspermatic calcium influx through voltage-dependent channels similar to that observed with hZP from unfertilised oocytes and to promote the acrosome reaction at a rate similar to that induced by the ZP of unfertilised oocytes (61.6 ± 6.2% vs60.7 ± 9.1% respectively). Conversely, the rate of hZP penetrated by sperm was much lower for fertilised than for unfertilised oocytes (19% vs 57% respectively, p < 0.01). We investigated the status of ZP2 in the oocytes used in the functional tests, and demonstrated that sperm binding and acrosome reaction induction, but not ZP penetration, occurred whether or not ZP2 was cleaved.The change in ZP function induced by fertilisation could be different in human and mouse species. Our results suggest a zona blocking to polyspermy based at the sperm penetration level in humans.Sperm interaction with the extracellular matrix surrounding the oocyte, the zona pellucida (ZP), is a key step in mammalian fertilisation. The structure and function of the ZP were first studied in mice in the 1980s [1-3]. Mouse ZP contains three glycoproteins: ZP1, ZP2 and ZP3. ZP3 binds to primary receptors on capacitated spermatozoa, inducing a cascade of intraspermatic events including the biphasic calcium influx leading to the acrosome reaction (AR). Following the AR, spermatozoa remain bound to the ZP via ZP2; they then penetrate the ZP and fuse with the egg plasma membrane [4]. The fertilisation is followed by the fusion of peripheral cortical granules with the vitelline membrane, resulting in the discharge of the contents of these granules into the perivitelline space. This exocytosis modifies the ZP matrix such that sperm no longer bind to or penetrate ZP, preventing polyspermy.Our understanding at a molecular level of gamete interaction in humans is much more restricted than for mice and other mammalian species
Pseudoparkinsonism: A review of a common nonparkinsonian hypokinetic movement disorder  [PDF]
Roger Kurlan, Marcie L. Rabin
Advances in Parkinson's Disease (APD) , 2013, DOI: 10.4236/apd.2013.24020
Abstract: This article reviews the syndrome pseudoparkinsonism, a movement disorder described in the literature that resembles parkinsonism but differs qualitatively. Patients with this disorder have apraxic slowness, paratonic rigidity, frontal gait disorder and elements of akinesia that, taken together, may be mistaken for true parkinsonism. Pseudoparkinsonism appears to be common and is most often due to Alzheimer’s disease or vascular dementia. It seems that patients with even mild cognitive deficits can present with pseudoparkinsonism and that the primary dementing disorder may be overlooked. The authors emphasize the importance of pseudoparkinsonism and implications for clinical diagnosis, treatment and research.
Internacionalidad, Higiene y Cuestión Social en Buenos Aires (1850-1910). Tres momentos históricos
González Leandri, Ricardo
Revista de Indias , 2013,
Abstract: By looking at three historic moments, this article analyzes aspects about the international circulation of experts, knowledge and institutional models that linked Hygiene to the Social Question in Argentina in the 19th century. In this regard, the great mobility as well as the early and permanent eclecticism through which networks were formed and knowledge became integrated are worth noting. A través de tres momentos históricos este artículo analiza aspectos de la circulación internacional de expertos, conocimientos y modelos institucionales que vincularon a la Higiene con la Cuestión Social en Argentina en el siglo XIX y principios del XX. Resalta la gran movilidad a la vez que el eclecticismo temprano y permanente con los que se formaron redes y se incorporaron conocimientos.
Miradas médicas sobre la cuestión social. Buenos aires a fines del siglo XIX y principios del XX
González Leandri, Ricardo
Revista de Indias , 2000,
Abstract: This article shows the role played by the medical professionalization process in the emergence and development of the Social Issue ( Cuestión Social ) in Argentina at end-19th and beginning- 20th Centuries. Attention is given to the complex and tight institutional, corporative and intellectual scheme between medical doctors and the State. El presente artículo destaca el papel jugado por el proceso de profesionalización médico en el surgimiento y desarrollo de la Cuestión Social en Argentina a fines del siglo XIX y principios del XX. Con tal objetivo presta especial atención a la compleja y estrecha trama institucional, corporativa e intelectual establecida para esas fechas entre los médicos y el Estado.
La elite profesional docente como fracción intelectual subordinada. Argentina: 1852-1900
González Leandri, Ricardo
Anuario de Estudios Americanos , 2001,
Abstract: La centralización y el impulso a la “educación patriótica”, dise ados para lograr una rápida homogeneidad cultural entre la población fueron las características clave del sistema público de educación elemental que se consolidó en Argentina en la segunda mitad del siglo XIX. Ellas auparon hacia su cúspide a un sector de funcionarios “normalistas” que tendieron a considerarse como una elite intelectual más apegada a los destinos del Estado que a los de la profesión de la que formaban parte. Sin embargo, en contra de sus expectativas, no pudieron dejar de ser un grupo intelectual subordinado. Los motivos deben buscarse en el monopolio que los “doctores”, pertenecientes en general a los sectores sociales más encumbrados, ejercieron sobre los espacios en los que se definían las abstracciones académicas y las políticas educativas y en las estrategias de distinción que los propios “normalistas” aplicaron sobre los demás docentes, que los debilitó como sector profesional.
III Jornadas Americanistas de Oto o. Escuela de Estudios Hispanoamericanos-CSIC
González Leandri, Ricardo
Anuario de Estudios Americanos , 2005,
Abstract:
El Consejo Nacional de Higiene y la consolidación de una elite profesional al servicio del Estado. Argentina, 1880-1900
González Leandri, Ricardo
Anuario de Estudios Americanos , 2004,
Abstract: This article analyzes aspects of the process of consolidation of a medical intelligentsia in Argentina during the last twenty years of the 19th century. It deals particularly with its link with the State through the Council of Hygiene, an institution charged with fixing health policy at the time. Thanks to the growing influence of these doctors, paradoxically closer to the Government but also more autonomous, the Council acquired during the period examined a set of new attributions at the national level, while at the same time it managed to give more attention to so-called internal health. Este artículo analiza aspectos del proceso de consolidación de una intelligentzia médica en Argentina en los últimos veinte a os del siglo XIX. Trata, sobre todo, de su vínculo con el Estado a través del Consejo de Higiene, institución encargada de fijar la política sanitaria del periodo. Gracias a la creciente influencia de estos médicos, paradójicamente más cercanos al gobierno a la vez que más autónomos, el Consejo adquirió durante el periodo rese ado un conjunto de nuevas atribuciones a nivel nacional, a la vez que consiguió prestar mayor atención a la llamada sanidad interna.
Asociacionismo y representación de intereses médicos en Buenos Aires, 1852-1880
González Leandri, Ricardo
Asclepio : Revista de Historia de la Medicina y de la Ciencia , 1998,
Abstract: This paper discusses the first medical associations in Buenos Aires, between 1852 and 1880. The main characteristic of the very first association, the Asociación Médica Bonaerense, was its ambivalent attitude in regards to doctor's and professor's elitism. Following the decline of this association, due to the creation of the Academia de Medicina de Buenos Aires, its more pugnacious facet was retaken by the Círculo Médico Argentino, who attempted to unite both students and young teacher's interests aims. El presente artículo analiza el surgimiento de las primeras asociaciones médicas de Buenos Aires entre 1852 y 1880. La primera, la Asociación Médica Bonaerense, se caracterizó por su ambivalencia frente al elitismo de los catedráticos de la Facultad de Medicina. Tras su declive, consecuencia de la creación de la Academia de Medicina de Buenos Aires, el impulso asociativo fue retomado por el Círculo Médico Argentino, que recuperó su faceta más impugnadora e intentó aunar los intereses de estudiantes y profesores jóvenes.
Magnetic and thermal properties of 4f-3d ladder-type molecular compounds
M. Evangelisti,M. L. Kahn,J. Bartolome,L. J. de Jongh,C. Meyers,J. Leandri,Y. Leroyer,C. Mathoniere
Physics , 2003, DOI: 10.1103/PhysRevB.68.184405
Abstract: We report on the low-temperature magnetic susceptibilities and specific heats of the isostructural spin-ladder molecular complexes L$_{2}$[M(opba)]$_{3\cdot x$DMSO$\cdot y$H$_{2}$O, hereafter abbreviated with L$_{2}$M$_{3}$ (where L = La, Gd, Tb, Dy, Ho and M = Cu, Zn). The results show that the Cu containing complexes (with the exception of La$_{2}$Cu$_{3}$) undergo long range magnetic order at temperatures below 2 K, and that for Gd$_{2}$Cu$_{3}$ this ordering is ferromagnetic, whereas for Tb$_{2}$Cu$_{3}$ and Dy$_{2}$Cu$_{3}$ it is probably antiferromagnetic. The susceptibilities and specific heats of Tb$_{2}$Cu$_{3}$ and Dy$_{2}$Cu$_{3}$ above $T_{C}$ have been explained by means of a model taking into account nearest as well as next-nearest neighbor magnetic interactions. We show that the intraladder L--Cu interaction is the predominant one and that it is ferromagnetic for L = Gd, Tb and Dy. For the cases of Tb, Dy and Ho containing complexes, strong crystal field effects on the magnetic and thermal properties have to be taken into account. The magnetic coupling between the (ferromagnetic) ladders is found to be very weak and is probably of dipolar origin.
The Heart Failure Epidemic
Véronique L. Roger
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7041807
Abstract: Heart failure has been singled out as an emerging epidemic, which could be the result of increased incidence and/or increased survival leading to increased prevalence. Knowledge of the responsibility of each factor in the genesis of the epidemic is crucial for prevention. Population-based studies have shown that, over time, the incidence of heart failure remained overall stable, while survival improved. Therefore, the heart failure epidemic is chiefly one of hospitalizations. Data on temporal trends in the incidence and prevalence of heart failure according to ejection fraction and how it may have changed over time are needed while interventions should focus on reducing the burden of hospitalizations in hear failure.
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