Valoración Radiológica del Fracaso de las Prótesis Cervico-Cefálicas de Cadera en Fracturas de Cuello Femoral y Cirugía de Revisión

Lo s autore s analiza n los diferentes signos radiológicos que sugieren intolerancia de la s prótesis cérvico-cefálicas de cader a implantada s po r fractur a cervical que será n sometida s a Cirugí a de Revisión. Se estudian retrospectivamente 61 casos intervenidos entre los años 77 al 89, analizándos e la evolución de los diferentes modelos: Monk, Austin-Moore, Thompson, Mülle r y Robert-Mathys. Asimismo se estudia n la presencia de calcificaciones intr a y periarticulare s y la aparició n de complicaciones. Po r último, se pretende concretar la indicación de la Artroplasti a parcia l de cader a en paciente s anciano s con alto riesgo quirúrgico en oposición a un mejor resultad o de la Artroplasti a Total en el resto de pacientes.The author s analys e the different radiologica l feature s suggestin g intoleranc e o f the cervical-cephali c hi p prosthesis, implante d b y cervica l fractur e a n d submitte d t o revisio n surgery. Retrospectivel y 6 1 cases, whic h wer e carrie d ou t betwee n 197 7 an d 1989, ar e studied, an d the evolutio n o f the different pattern s i n analysed : Monk, Austin-Moore , Thompson , Mülle r an d Robert-Mathys. A t the sam e time , the presenc e o f intr a an d peri-articula r calcification s an d the appearanc e o f complication s ar e examined . Finally , they inten d t o summariz e th e indicatio n o f the hi p hemiarthroplast y i n ol d patien s wit h a hig h surgica l risk oppositio n t o a bette r result o f the tota l hi p arthroplast y in the rest o f th e patients

COLA II - Radio and Spectroscopic Diagnostics of Nuclear Activity in Galaxies

We present optical spectroscopic observations of 93 galaxies taken from the infra-red selected COLA (Compact Objects in Low Power AGN) sample. The sample spans the range of far-IR luminosities from normal galaxies to LIRGs. Of the galaxies observed, 78 (84%) exhibit emission lines. Using a theoretically-based optical emission-line scheme we classify 15% of the emission-line galaxies as Seyferts, 77% as starbursts, and the rest are either borderline AGN/starburst or show ambiguous characteristics. We find little evidence for an increase in the fraction of AGN in the sample as a function of far-IR luminosity but our sample covers only a small range in infrared luminosity and thus a weak trend may be masked. As a whole the Seyfert galaxies exhibit a small, but significant, radio excess on the radio-FIR correlation compared to the galaxies classified as starbursts. Compact (<0.05'') radio cores are detected in 55% of the Seyfert galaxies, and these galaxies exhibit a significantly larger radio excess than the Seyfert galaxies in which cores were not detected. Our results indicate that there may be two distinct populations of Seyferts, ``radio-excess'' Seyferts, which exhibit extended radio structures and compact radio cores, and ``radio-quiet'' Seyferts, in which the majority of the radio emission can be attributed to star-formation in the host galaxy. No significant difference is seen between the IR and optical spectroscopic properties of Seyferts with and without radio cores. (Abridged)Comment: 24 pages, 4 figures, 6 tables. Accepted for publication in ApJ, February 200

Inner Size of a Dust Torus in the Seyfert 1 Galaxy NGC 4151

The most intense monitoring observations yet made were carried out on the Seyfert 1 galaxy NGC 4151 in the optical and near-infrared wave-bands. A lag from the optical light curve to the near-infrared light curve was measured. The lag-time between the V and K light curves at the flux minimum in 2001 was precisely 48+2-3 days, as determined by a cross-correlation analysis. The correlation between the optical luminosity of an active galactic nucleus (AGN) and the lag-time between the UV/optical and the near-infrared light curves is presented for NGC 4151 in combination with previous lag-time measurements of NGC 4151 and other AGNs in the literature. This correlation is interpreted as thermal dust reverberation in an AGN, where the near-infrared emission from an AGN is expected to be the thermal re-radiation from hot dust surrounding the central engine at a radius where the temperature equals to that of the dust sublimation temperature. We find that the inner radius of the dust torus in NGC 4151 is $\sim$ 0.04 pc corresponding to the measured lag-time, well outside the broad line region (BLR) determined by other reverberation studies of the emission lines.Comment: Accepted for publication in ApJ Letters, 13 pages, 3 figures; Corrected typo

Neutrino production through hadronic cascades in AGN accretion disks

We consider the production of neutrinos in active galactic nuclei (AGN) through hadronic cascades. The initial, high energy nucleons are accelerated in a source above the accretion disk around the central black hole. From the source, the particles diffuse back to the disk and initiate hadronic cascades. The observable output from the cascade are electromagnetic radiation and neutrinos. We use the observed diffuse background X-ray luminosity, which presumably results {}from this process, to predict the diffuse neutrino flux close to existing limits from the Frejus experiment. The resulting neutrino spectrum is $E^{-2}$ down to the \GeV region. We discuss modifications of this scenario which reduce the predicted neutrino flux.Comment: 12 Pages, LaTeX, TK 92 0

Aislamiento y cultivo de células osteoblásticas: Interés para la investigación en cirugía ortopédica y traumatología

Describimos un método de aislamiento y caracterización de células osteoblásticas procedentes de la superficie de trabéculas óseas de explantes obtenidos de metafisis de fémures y tibias de conejo y de cabezas femorales humanas de pacientes sometidos a cirugía protésica de cadera. Después de eliminar las células de la médula ósea de los explantes, estos se despositaron sobre dos tipos de mallas, de 80 y 100 µm., obteniéndose un cultivo en monocarpa que se mostró confluente a partir de los 20 días. La población celular aislada presentó un fenotipo osteoblástico utilizando métodos colorimétricos para determinación de la actividad de fosfatasa alcalina (FA) y morfológicos por medio de la observación con microscopía electrónica de barrido. Las células cultivadas exhibieron una morfología diferente según el grado de confluencia de cultivo, siendo en todo momento positivas las sucesivas determinaciones colorimétricas de FA realizadas a lo largo de la experiencia. Consideramos el método de gran interés en investigación en ortopédica, pues permite el estudio de comportamiento de estas células cuando están sometidas a cualquier tipo de estímulo externo, así como cuando se enfrentan a nuevas generaciones de biomateriales, etc.We describe a method of isolation and characterization of osteoblastic cells taken from the surface of bone trabeculae of explants obtained from femur and tibia metaphysis in rabbits and human femoral head in patients undergoing orthopaedic surgery. Afther removing the cells from the bone marrow of explants, they were placed over two mesh, 80 and 100 µmn, obtaining then a culture in monolayer which showed to be confluent after 20 days. The isolated cell population showed an osteoblastic phenotype using colourmetric methods to determinate the alkaline phosphatase (AF) activity and morphologic methods by means of scanning. The cultivated cell showed a different morphology according to the degree of confluence of the culture, being always positive the sucesive colourmetric determinations of AF along the experiment. We consider the method of a great interest for orthopaedic investigations, since it allows the study of the behaviour of these cells when they are subjet to different types of external stimulus as well as meet they the new generations of biomaterials