Activation of the unfolded protein response is associated with favorable prognosis in acute myeloid leukemia

PURPOSE: The unfolded protein response is triggered by the accumulation of misfolded proteins within the endoplasmic reticulum. Previous studies suggest that the unfolded protein response is activated in some cancer cell lines and involved in tumor development. The role of the unfolded protein response during leukemogenesis is unknown thus far. EXPERIMENTAL DESIGN: Here, we assessed the induction of key effectors of the unfolded protein response in leukemic cells at diagnosis of 105 acute myeloid leukemia (AML) patients comprising all subtypes. We determined the formation of the spliced variant of the X-box-binding protein 1 (XBP1) mRNA, as well as expression levels of calreticulin, GRP78, and CHOP mRNA. RESULTS: The formation of the spliced variant of XBP1s was detectable in 16.2% (17 of 105) of AML patients. Consistent with activated unfolded protein response, this group also had significantly increased expression of calreticulin, GRP78, and CHOP. AML patients with activated unfolded protein response had lower WBC counts, lactate dehydrogenase levels, and more frequently, secondary AML. The incidence of fms-related tyrosine kinase 3 (FLT3) mutations was significantly lower in patients with activated unfolded protein response. In addition, an association was observed between activated unfolded protein response and deletion of chromosome 7. Finally, the clinical course of AML patients with activated unfolded protein response was more favorable with lower relapse rate (P = 0.0182) and better overall (P = 0.041) and disease-free survival (P = 0.022). CONCLUSIONS: These results suggest that the unfolded protein response is activated in a considerable subset of AML patients. AML patients with activated unfolded protein response present specific clinical characteristics and a more favorable course of the disease.

Dasatinib inhibits the growth of molecularly heterogeneous myeloid leukemias.

PURPOSE: Dasatinib is a dual Src/Abl inhibitor recently approved for Bcr-Abl+ leukemias with resistance or intolerance to prior therapy. Because Src kinases contribute to multiple blood cell functions by triggering a variety of signaling pathways, we hypothesized that their molecular targeting might lead to growth inhibition in acute myeloid leukemia (AML). EXPERIMENTAL DESIGN: We studied growth factor-dependent and growth factor-independent leukemic cell lines, including three cell lines expressing mutants of receptor tyrosine kinases (Flt3 or c-Kit) as well as primary AML blasts for responsiveness to dasatinib. RESULTS: Dasatinib resulted in the inhibition of Src family kinases in all cell lines and blast cells at approximately 1 x 10(-9) mol/L. It also inhibited mutant Flt3 or Kit tyrosine phosphorylation at approximately 1 x 10(-6) mol/L. Mo7e cells expressing the activating mutation (codon 816) of c-Kit were most sensitive to growth inhibition with a GI(50) of 5 x 10(-9) mol/L. Primary AML blast cells exhibited a growth inhibition of <1 x>10(-6) mol/L. Cell lines that showed growth inhibition at approximately 1 x 10(-6) mol/L showed a G(1) cell cycle arrest and correlated with accumulation of p21 and p27 protein. The addition of rapamycin or cytotoxic agents enhanced growth inhibition. Dasatinib also caused the apoptosis of Mo7e cells expressing oncogenic Kit. CONCLUSIONS: Although all of the precise targets for dasatinib are not known, this multikinase inhibitor causes either growth arrest or apoptosis in molecularly heterogeneous AML. The addition of cytotoxic or targeted agents can enhance its effects.

Influences of porcine circo-, arteriviruses and cathelicidins in plasmacytoid dendritic cell-derived interferon-alpha responses

Type I interferons (IFNs), mainly IFN-α/β play a crucial role in innate defense against viruses. In addition to their direct antiviral activity, type I IFNs have antitumoral and immunomodulatory effects. Although all cells are virtually able to induce IFN-α, the plasmacytoid dendritic cell (pDC) subset represents the ultimate producers of IFN-α as well as other proinflammatory cytokines. Due to the specific expression of TLR7 and TLR9 recognizing single-stranded (ss) RNA and unmethylated CpG motifs respectively, pDCs can secrete up to 1000 times more IFN-α than any cellular types. Additionally, it is well known that several cytokines including type I and II IFNs, Flt3-L, IL-4 and GM-CSF favor pDC-derived IFN-α responses to unmethylated CpG motifs. In a first step, we aimed to characterize and clarify the interactions of two porcine viruses with pDCs. The double-stranded DNA replicative forms of porcine circovirus type 2 (PCV2) were demonstrated to inhibit CpG-induced IFN- α by pDCs. Our study showed that none of the cytokines known to enhance pDC responsiveness can counter-regulate the PCV2-mediated inhibition of IFN-α induced by CpG, albeit IFN-γ significantly reduced the level of inhibition. Interestingly, the presence of IFN-γ enabled pDCs to induce IFN-α to low doses of PCV2. We also noted that after DNase treatment, PCV2 preparations were still able to stimulate pDCs. These data suggest that encapsulated viral ssDNA promotes the induction of IFN-α in pDCs treated with IFN-γ whereas free DNA, presumably as double-stranded forms, was responsible for inhibiting pDC responses. Regarding PRRSV, it has been reported that North American isolates did not induce and even inhibited IFN-α response in pDCs. However, PRRSV infection was also shown to lead to an induction of IFN-α in the serum and in the lungs suggesting that certain cells are responsive to the virus. Contrasting to previous reports we found that numerous PRRSV isolates directly induced IFN-α in pDCs. This response was still observed after UV-inactivation of viruses and required TLR7 signaling. The inhibition of CpG-induced IFN-α was weak and strain dependent, again contrasting with a previous report. We also observed that IFN-γ and IL-4 enhanced IFN-α response to two prototype strains, VR-2332 and LVP23. In summary, we demonstrated that both PCV2 and PRRSV promote IFN-α secretion in pDCs in vitro suggesting that IFN-α detected in PCV2- or PRRSV-infected animal might originate from pDCs. On the other hand, PRRSV replication is restricted to the macrophage (MΦ) lineage. These innate immune cells represent a heterogeneous population which can be induce to “classical” (M1) and “alternative” (M2) activated MΦ acquiring inflammatory or “wound-healing” functional properties, respectively. Nonetheless, little is known about the effect of polarization into M1 or M2 and the susceptibility of these cells to PRRSV. Thus, we examined the impact of cytokine on MΦ polarization into M1 or M2. Infections of these cells by several PRRSV isolates enabled the discrimination of PRRSV isolate in a genotype- and irulencedependent manner in M1 and IFN-β-activated MΦ. In contrast, the expression of PRRSV nucleocapsid in M2 or inactivated MΦ was indistinguishable among the PRRSV isolates tested. In the last part of my Thesis, we investigated the influence of three synthetic porcine cathelicidin peptides for their ability to deliver nucleic acid to pDCs. We reported that all cathelicidins tested can complex and quickly deliver nucleic acids resulting in IFN-α induction. Moreover, we show that the typical α- helical amphipathic conformation is required to mediate killing of bacteria but not for inducing IFN-α secretion by pDCs. Furthermore, we found that E.coli treated with one of these cathelicidins is able to induce significantly higher levels of IFN-α compared to a non-sense version of the peptide. These data suggest that cathelicidins could influence the immune response in a two-step process. First, these peptides target bacteria leading to cell lysis. In turn, cathelicidins form complexes and deliver extracellular microbial nucleic acids released into pDCs. These pDC-derived IFN-α responses could be of particular relevance in driving the adaptive immune responses against microbial infections.

Delayed Haematological recovery after autologous stem cell transplantation is associated with favourable outcome in acute myeloid leukaemia.

Autologous stem cell transplantation (ASCT) is applied to consolidate first remission in patients with acute myeloid leukaemia (AML). However, outcome after ASCT widely varies among AML patients. We analyzed the prognostic significance of haematological recovery for neutrophils [absolute neutrophil count (ANC) >1·0 × 10(9) /l] and platelets (platelet count >20·0 × 10(9) /l), stratifying at day 20 after ASCT in 88 consecutive and homogeneously treated AML patients in first remission. We observed that patients with delayed recovery had better overall survival (OS; ANC: P < 0·0001 and platelets: P = 0·0062) and time to progression (TTP; ANC: P = 0·0003 and platelets: P = 0·0125). Delayed recovery was an independent marker for better OS and TTP in a multivariate analysis including age, gender, number of transfused CD34+ cells, cytogenetics, FLT3-internal tandem duplication and NPM1 mutation. Our results suggest that delayed neutrophil and platelet recovery is associated with longer OS and TTP in AML patients consolidated with ASCT in first remission.

Tecnología de registro y reproducción sonora para entornos de realidad virtual

Este proyecto de fin de carrera tiene como objetivo obtener una visión detallada de los sistemas y tecnologías de grabación y reproducción utilizadas para aplicaciones de audio 3D y entornos de realidad virtual, analizando las diferentes alternativas existentes, su funcionamiento, características, detalles técnicos y sus ámbitos de aplicación. Como punto de partida se estudiará la teoría psicoacústica y la localización de fuentes sonoras en el espacio, base para el estudio de los sistemas de audio 3D. Se estudiará tanto la espacialización sonora en un espacio real y la espacialización virtual (simulación mediante procesado de información de la localización de fuentes sonoras), en los que intervienen algunos fenómenos acústicos y psicoacústicos como ITD, o diferencia de tiempo que existe entre una señal acústica que llega a los pabellones auditivos, la ILD, o diferencia de intensidad o amplitud que hay entre la señal que llega a los pabellones auditivos y la localización espacial mediante otra serie de mecanismos biaurales. Tras una visión general de la teoría psicoacústica y la espacialización sonora, se analizarán con detalle los elementos de grabación y reproducción existentes para audio 3D. Concretamente, a lo largo del proyecto se profundizará en el funcionamiento del sistema estéreo, caracterizado por el posicionamiento sonoro mediante la utilización de dos canales; del sistema biaural, caracterizado por reconstruir campos sonoros mediante el uso de las HRTF; de los sistemas multicanal, detallando gran parte de las alternativas y configuraciones existentes; del sistema Ambiophonics, caracterizado por implementar filtros de cruce; del sistema Ambisonics, y sus diferentes formatos y técnicas de codificación y decodificación; y del sistema Wavefield Synthesis, caracterizado por recrear ambientes sonoros en grandes espacios. ABSTRACT This project aims to get a detailed view of recording and reproducing systems and technologies used to 3D audio applications and virtual reality environments, analyzing the different alternatives available, their functioning, features, technical details and their different scopes of applications. As a starting point, will be studied the psychoacoustic theory and the localization of sound sources in space, basis for the 3D audio study. Will be studied both the spacialization of sound sources in real space as virtual spatialization of sound sources (simulation by information processing of localization of sound sources), in which involves some acoustic and psychoacoustic phenomena like ITD (or the Interaural time difference), the ILD, (or the Interaural Level Difference) and spatial localization by another set of binaural mechanisms. After a general overview of the psychoacoustics theory and the sound spatialization, will be analyzed in detail existing methods of recording and reproducing for 3D audio. Specifically, during the project will analyze the characteristics of the stereo systems, characterized by sound positioning using two channels; the binaural systems, characterized by reconstructing sound fields by using the HRTF; the multichannel systems, detailing many of the existing alternatives and configurations; the Ambiophonics system, which is characterized by implementing crosstalk elimination techniques; the Ambiosonics system, and its various formats and encoding and decoding techniques; and the Wavefield Synthesis system, characterized by recreate soundscapes in large spaces.

Public Private Partnerships in the Humanitarian Aid

This master thesis is intended to perform an exploratory approach for the potential to Public-Private Partnerships as a tool for advanced collaboration between businesses and the cooperation system in the specific context of humanitarian action. It intends to conduct a case study analysis of representative interactions between the public and private actors in the humanitarian aid, and in conjunction with a profound revision of the existing literature, creates a set of conclusions and recommendations that can serve as a prototype for possible inclusion guide the private sector in humanitarian action through new paradigms that go beyond the classical donor-recipient model.

Diseño de una interfaz de representación gráfica de la base de datos de HRTF

El actual proyecto consiste en la creación de una interfaz gráfica de usuario (GUI) en entorno de MATLAB que realice una representación gráfica de la base de datos de HRTF (Head-Related Transfer Function). La función de transferencia de la cabeza es una herramienta muy útil en el estudio de la capacidad del ser humano para percibir su entorno sonoro, además de la habilidad de éste en la localización de fuentes sonoras en el espacio que le rodea. La HRTF biaural (terminología para referirse al conjunto de HRTF del oído izquierdo y del oído derecho) en sí misma, posee información de especial interés ya que las diferencias entre las HRTF de cada oído, conceden la información que nuestro sistema de audición utiliza en la percepción del campo sonoro. Por ello, la funcionalidad de la interfaz gráfica creada presenta gran provecho dentro del estudio de este campo. Las diferencias interaurales se caracterizan en amplitud y en tiempo, variando en función de la frecuencia. Mediante la transformada inversa de Fourier de la señal HRTF, se obtiene la repuesta al impulso de la cabeza, es decir, la HRIR (Head-Related Impulse Response). La cual, además de tener una gran utilidad en la creación de software o dispositivos de generación de sonido envolvente, se utiliza para obtener las diferencias ITD (Interaural Time Difference) e ILD (Interaural Time Difference), comúnmente denominados “parámetros de localización espacial”. La base de datos de HRTF contiene la información biaural de diferentes puntos de ubicación de la fuente sonora, formando una red de coordenadas esféricas que envuelve la cabeza del sujeto. Dicha red, según las medidas realizadas en la cámara anecoica de la EUITT (Escuela Universitaria de Ingeniería Técnica de Telecomunicación), presenta una precisión en elevación de 10º y en azimut de 5º. Los receptores son dos micrófonos alojados en el maniquí acústico llamado HATS (Hats and Torso Simulator) modelo 4100D de Brüel&Kjaer. Éste posee las características físicas que influyen en la percepción del entorno como son las formas del pabellón auditivo (pinna), de la cabeza, del cuello y del torso humano. Será necesario realizar los cálculos de interpolación para todos aquellos puntos no contenidos en la base de datos HRTF, este proceso es sumamente importante no solo para potenciar la capacidad de la misma sino por su utilidad para la comparación entre otras bases de datos existentes en el estudio de este ámbito. La interfaz gráfica de usuario está concebida para un manejo sencillo, claro y predecible, a la vez que interactivo. Desde el primer boceto del programa se ha tenido clara su filosofía, impuesta por las necesidades de un usuario que busca una herramienta práctica y de manejo intuitivo. Su diseño de una sola ventana reúne tanto los componentes de obtención de datos como los que hacen posible la representación gráfica de las HRTF, las HRIR y los parámetros de localización espacial, ITD e ILD. El usuario podrá ir alternando las representaciones gráficas a la vez que introduce las coordenadas de los puntos que desea visualizar, definidas por phi (elevación) y theta (azimut). Esta faceta de la interfaz es la que le otorga una gran facilidad de acceso y lectura de la información representada en ella. Además, el usuario puede introducir valores incluidos en la base de datos o valores intermedios a estos, de esta manera, se indica a la interfaz la necesidad de realizar la interpolación de los mismos. El método de interpolación escogido es el de la ponderación de la distancia inversa entre puntos. Dependiendo de los valores introducidos por el usuario se realizará una interpolación de dos o cuatro puntos, siendo éstos limítrofes al valor introducido, ya sea de phi o theta. Para añadir versatilidad a la interfaz gráfica de usuario, se ha añadido la opción de generar archivos de salida en forma de imagen de las gráficas representadas, de tal forma que el usuario pueda extraer los datos que le interese para cualquier valor de phi y theta. Se completa el presente proyecto fin de carrera con un trabajo de investigación y estudio comparativo de la función y la aplicación de las bases de datos de HRTF dentro del marco científico y de investigación. Esto ha hecho posible concentrar información relacionada a través de revistas científicas de investigación como la JAES (Journal of the Audio Engineering Society) o la ASA (Acoustical Society of America), además, del IEEE ( Institute of Electrical and Electronics Engineers) o la “Web of knowledge” entre otras. Además de realizar la búsqueda en estas fuentes, se ha optado por vías de información más comunes como Google Académico o el portal de acceso “Ingenio” a los todos los recursos electrónicos contenidos en la base de datos de la universidad. El estudio genera una ampliación en el conocimiento de la labor práctica de las HRTF. La mayoría de los estudios enfocan sus esfuerzos en mejorar la percepción del evento sonoro mediante su simulación en la escucha estéreo o multicanal. A partir de las HRTF, esto es posible mediante el análisis y el cálculo de datos como pueden ser las regresiones, siendo éstas muy útiles en la predicción de una medida basándose en la información de la actual. Otro campo de especial interés es el de la generación de sonido 3D. Mediante la base de datos HRTF es posible la simulación de una señal biaural. Se han diseñado algoritmos que son implementados en dispositivos DSP, de tal manera que por medio de retardos interaurales y de diferencias espectrales es posible llegar a un resultado óptimo de sonido envolvente, sin olvidar la importancia de los efectos de reverberación para conseguir un efecto creíble de sonido envolvente. Debido a la complejidad computacional que esto requiere, gran parte de los estudios coinciden en desarrollar sistemas más eficientes, llegando a objetivos tales como la generación de sonido 3D en tiempo real. ABSTRACT. This project involves the creation of a Graphic User Interface (GUI) in the Matlab environment which creates a graphic representation of the HRTF (Head-Related Transfer Function) database. The head transfer function is a very useful tool in the study of the capacity of human beings to perceive their sound environment, as well as their ability to localise sound sources in the area surrounding them. The binaural HRTF (terminology which refers to the HRTF group of the left and right ear) in itself possesses information of special interest seeing that the differences between the HRTF of each ear admits the information that our system of hearing uses in the perception of each sound field. For this reason, the functionality of the graphic interface created presents great benefits within the study of this field. The interaural differences are characterised in space and in time, varying depending on the frequency. By means of Fourier's transformed inverse of the HRTF signal, the response to the head impulse is obtained, in other words, the HRIR (Head-Related Impulse Response). This, as well as having a great use in the creation of software or surround sound generating devices, is used to obtain ITD differences (Interaural Time Difference) and ILD (Interaural Time Difference), commonly named “spatial localisation parameters”. The HRTF database contains the binaural information of different points of sound source location, forming a network of spherical coordinates which surround the subject's head. This network, according to the measures carried out in the anechoic chamber at the EUITT (School of Telecommunications Engineering) gives a precision in elevation of 10º and in azimuth of 5º. The receivers are two microphones placed on the acoustic mannequin called HATS (Hats and Torso Simulator) Brüel&Kjaer model 4100D. This has the physical characteristics which affect the perception of the surroundings which are the forms of the auricle (pinna), the head, neck and human torso. It will be necessary to make interpolation calculations for all those points which are not contained the HRTF database. This process is extremely important not only to strengthen the database's capacity but also for its usefulness in making comparisons with other databases that exist in the study of this field. The graphic user interface is conceived for a simple, clear and predictable use which is also interactive. Since the first outline of the program, its philosophy has been clear, based on the needs of a user who requires a practical tool with an intuitive use. Its design with only one window unites not only the components which obtain data but also those which make the graphic representation of the HRTFs possible, the hrir and the ITD and ILD spatial location parameters. The user will be able to alternate the graphic representations at the same time as entering the point coordinates that they wish to display, defined by phi (elevation) and theta (azimuth). The facet of the interface is what provides the great ease of access and reading of the information displayed on it. In addition, the user can enter values included in the database or values which are intermediate to these. It is, likewise, indicated to the interface the need to carry out the interpolation of these values. The interpolation method is the deliberation of the inverse distance between points. Depending on the values entered by the user, an interpolation of two or four points will be carried out, with these being adjacent to the entered value, whether that is phi or theta. To add versatility to the graphic user interface, the option of generating output files in the form of an image of the graphics displayed has been added. This is so that the user may extract the information that interests them for any phi and theta value. This final project is completed with a research and comparative study essay on the function and application of HRTF databases within the scientific and research framework. It has been possible to collate related information by means of scientific research magazines such as the JAES (Journal of the Audio Engineering Society), the ASA (Acoustical Society of America) as well as the IEEE (Institute of Electrical and Electronics Engineers) and the “Web of knowledge” amongst others. In addition to carrying out research with these sources, I also opted to use more common sources of information such as Academic Google and the “Ingenio” point of entry to all the electronic resources contained on the university databases. The study generates an expansion in the knowledge of the practical work of the HRTF. The majority of studies focus their efforts on improving the perception of the sound event by means of its simulation in stereo or multichannel listening. With the HRTFs, this is possible by means of analysis and calculation of data as can be the regressions. These are very useful in the prediction of a measure being based on the current information. Another field of special interest is that of the generation of 3D sound. Through HRTF databases it is possible to simulate the binaural signal. Algorithms have been designed which are implemented in DSP devices, in such a way that by means of interaural delays and wavelength differences it is possible to achieve an excellent result of surround sound, without forgetting the importance of the effects of reverberation to achieve a believable effect of surround sound. Due to the computational complexity that this requires, a great many studies agree on the development of more efficient systems which achieve objectives such as the generation of 3D sound in real time.

Estrategias de apoyo a la innovación social. El itdUPM como espacio para la innovación social de base tecnológica.

El contexto actual de crisis financiera, ambiental y social parece estar reflejando una crisis del sistema vigente. La revolución tecnológica, los movimientos sociales que reaccionan frente a la persistencia de desigualdades, la explotación de recursos naturales hasta sus límites ecológicos o los cambios políticos son signos de que el modelo de vida contemporáneo provoca visiones y prácticas no sostenibles. En este escenario, la innovación social está emergiendo como potencial motor de generación de alternativas que responden de una forma más eficiente a las demandas sociales. Nuevos modelos de provisión de servicios básicos a poblaciones vulnerables, uso y aplicación de los últimos avances científicos y tecnológicos, o emprendimientos sociales inspiradores son sólo algunos ejemplos de estas respuestas innovadoras. Diversas organizaciones están realizando esfuerzos para apoyar y promocionar este tipo de iniciativas innovadoras que, en muchos de los casos, emergen desde la ciudadanía y están expresando alternativas interesantes al modelo de producción y consumo globalizado. El gran reto que supone el necesario cambio social y estructural está en dilucidar cómo avanzar hacia un modelo de desarrollo más sostenible, que reduzca las desigualdades, respete los límites ecológicos del planeta y promueva avances científicos y tecnológicos que amplíen las capacidades de la sociedad.

Comparison of Airborne Laser Scanning Methods for Estimating Forest Structure Indicators Based on Lorenz Curves

The purpose of this study was to compare a number of state-of-the-art methods in airborne laser scan- ning (ALS) remote sensing with regards to their capacity to describe tree size inequality and other indi- cators related to forest structure. The indicators chosen were based on the analysis of the Lorenz curve: Gini coefficient ( GC ), Lorenz asymmetry ( LA ), the proportions of basal area ( BALM ) and stem density ( NSLM ) stocked above the mean quadratic diameter. Each method belonged to one of these estimation strategies: (A) estimating indicators directly; (B) estimating the whole Lorenz curve; or (C) estimating a complete tree list. Across these strategies, the most popular statistical methods for area-based approach (ABA) were used: regression, random forest (RF), and nearest neighbour imputation. The latter included distance metrics based on either RF (NN–RF) or most similar neighbour (MSN). In the case of tree list esti- mation, methods based on individual tree detection (ITD) and semi-ITD, both combined with MSN impu- tation, were also studied. The most accurate method was direct estimation by best subset regression, which obtained the lowest cross-validated coefficients of variation of their root mean squared error CV(RMSE) for most indicators: GC (16.80%), LA (8.76%), BALM (8.80%) and NSLM (14.60%). Similar figures [CV(RMSE) 16.09%, 10.49%, 10.93% and 14.07%, respectively] were obtained by MSN imputation of tree lists by ABA, a method that also showed a number of additional advantages, such as better distributing the residual variance along the predictive range. In light of our results, ITD approaches may be clearly inferior to ABA with regards to describing the structural properties related to tree size inequality in for- ested areas.

Mature monocytic cells enter tissues and engraft

The goal of this study was to identify the circulating cell that is the immediate precursor of tissue macrophages. ROSA 26 marrow mononuclear cells (containing the β-geo transgene that encodes β-galactosidase and neomycin resistance activities) were cultured in the presence of macrophage colony-stimulating factor and flt3 Ligand for 6 days to generate monocytic cells at all stages of maturation. Expanded monocyte cells (EMC), the immature (ER-MP12+) and more mature (ER-MP20+) subpopulations, were transplanted into irradiated B6/129 F2 mice. β-gal staining of tissue sections from animals 15 min after transplantation demonstrated that the donor cells landed randomly. By 3 h, donor cells in lung and liver were more frequent in animals transplanted with ER-MP20+ (more mature) EMC than in animals transplanted with unseparated EMC or fresh marrow mononuclear cells, a pattern that persisted at 3 and 7 days. At 3 days, donor cells were found in spleen, liver, lung, and brain (rarely) as clusters as well as individual cells. By 7 and 14 days, the clusters had increased in size, and the cells expressed the macrophage antigen F4/80, suggesting that further replication and differentiation had occurred. PCR for the neogene was used to quantitate the amount of donor DNA in tissues from transplanted animals and confirmed that ER-MP20+ EMC preferentially engrafted. These data demonstrate that a mature monocytic cell gives rise to tissue macrophages. Because these cells can be expanded and manipulated in vitro, they may be a suitable target population for gene therapy of lysosomal storage diseases.

How do owls localize interaurally phase-ambiguous signals?

Owls and other animals, including humans, use the difference in arrival time of sounds between the ears to determine the direction of a sound source in the horizontal plane. When an interaural time difference (ITD) is conveyed by a narrowband signal such as a tone, human beings may fail to derive the direction represented by that ITD. This is because they cannot distinguish the true ITD contained in the signal from its phase equivalents that are ITD ± nT, where T is the period of the stimulus tone and n is an integer. This uncertainty is called phase-ambiguity. All ITD-sensitive neurons in birds and mammals respond to an ITD and its phase equivalents when the ITD is contained in narrowband signals. It is not known, however, if these animals show phase-ambiguity in the localization of narrowband signals. The present work shows that barn owls (Tyto alba) experience phase-ambiguity in the localization of tones delivered by earphones. We used sound-induced head-turning responses to measure the sound-source directions perceived by two owls. In both owls, head-turning angles varied as a sinusoidal function of ITD. One owl always pointed to the direction represented by the smaller of the two ITDs, whereas a second owl always chose the direction represented by the larger ITD (i.e., ITD − T).

How the owl resolves auditory coding ambiguity

The barn owl (Tyto alba) uses interaural time difference (ITD) cues to localize sounds in the horizontal plane. Low-order binaural auditory neurons with sharp frequency tuning act as narrow-band coincidence detectors; such neurons respond equally well to sounds with a particular ITD and its phase equivalents and are said to be phase ambiguous. Higher-order neurons with broad frequency tuning are unambiguously selective for single ITDs in response to broad-band sounds and show little or no response to phase equivalents. Selectivity for single ITDs is thought to arise from the convergence of parallel, narrow-band frequency channels that originate in the cochlea. ITD tuning to variable bandwidth stimuli was measured in higher-order neurons of the owl’s inferior colliculus to examine the rules that govern the relationship between frequency channel convergence and the resolution of phase ambiguity. Ambiguity decreased as stimulus bandwidth increased, reaching a minimum at 2–3 kHz. Two independent mechanisms appear to contribute to the elimination of ambiguity: one suppressive and one facilitative. The integration of information carried by parallel, distributed processing channels is a common theme of sensory processing that spans both modality and species boundaries. The principles underlying the resolution of phase ambiguity and frequency channel convergence in the owl may have implications for other sensory systems, such as electrolocation in electric fish and the computation of binocular disparity in the avian and mammalian visual systems.

Expansion in vitro of adult murine hematopoietic stem cells with transplantable lympho-myeloid reconstituting ability

Elucidation of mechanisms that regulate hematopoietic stem cell self-renewal and differentiation would be facilitated by the identification of defined culture conditions that allow these cells to be amplified. We now demonstrate a significant net increase (3-fold, P < 0.001) in vitro of cells that are individually able to permanently and competitively reconstitute the lymphoid and myeloid systems of syngeneic recipient mice when Sca-1+lin− adult marrow cells are incubated for 10 days in serum-free medium with interleukin 11, flt3-ligand, and Steel factor. Moreover, the culture-derived repopulating cells continued to expand their numbers in the primary hosts at the same rate seen in recipients of noncultured stem cells. In the expansion cultures, long-term culture-initiating cells increased 7- ± 2-fold, myeloid colony-forming cells increased 140- ± 36-fold, and total nucleated cells increased 230- ± 62-fold. Twenty-seven of 100 cultures initiated with 15 Sca-1+lin− marrow cells were found to contain transplantable stem cells 10 days later. This frequency of positive cultures is the same as the frequency of transplantable stem cells in the original input suspension, suggesting that most had undergone at least one self-renewal division in vitro. No expansion of stem cells was seen when Sca-1+TER119− CD34+ day 14.5 fetal liver cells were cultured under the same conditions. These findings set the stage for further investigations of the mechanisms by which cytokine stimulation may elicit different outcomes in mitotically activated hematopoietic stem cells during ontogeny and in the adult.