Gravitational waves provide a novel way to probe axions or axion-like particles coupled to a dark... more Gravitational waves provide a novel way to probe axions or axion-like particles coupled to a dark photon field, even in the absence of couplings to Standard Model particles. In the conventional misalignment mechanism, the generation of an observable stochastic gravitational wave background, however, requires large axion decay constants. We here investigate the gravitational wave signal generated within the kinetic misalignment scenario, where the axion is assumed to have a large initial velocity. Its kinetic energy then provides a sufficiently high energy budget to generate a detectable gravitational wave signal also at lower values of the decay constant. We obtain an analytic estimate as well as perform numerical simulations of the corresponding gravitational wave signal, and evaluate its detectability at current and future gravitational wave observatories. We further present the corresponding projected constraints on the parameter space of the model, along with the parameter regio...
O manejo de desfolha possui como um dos principais objetivos o rebrote vigoroso após o rebaixamen... more O manejo de desfolha possui como um dos principais objetivos o rebrote vigoroso após o rebaixamento, uma vez que a área foliar remanescente possui alta correlação com o potencial de rebrote dos pastos. Desta forma, o objetivo do presente trabalho foi avaliar o efeito de intervenções pontuais de alta severidade (70%) sobre características produtivas de pastos de azevém anual manejados sob desfolhações intermitentes. O experimento foi conduzido na área experimental da Universidade Tecnológica Federal do Paraná. Os tratamentos consistiram de quatro estratégias de desfolha a partir de uma única altura de entrada (20cm): severidade constante de 40%; severidade de 40% com intervenções pontuais de 70% no segundo corte; severidade de 40% com intervenções pontuais de 70% no quarto corte; e severidades de 40% e 70% intercaladas. Os tratamentos foram aplicados em delineamento inteiramente casualizado com três repetições, totalizando 12 unidades experimentais. Foram avaliadas as variáveis de in...
Emilie Flon s’interroge dans son ouvrage sur la mise en scene du patrimoine dans les musees, ques... more Emilie Flon s’interroge dans son ouvrage sur la mise en scene du patrimoine dans les musees, question importante pour elle, parce que les technologies de mediation (audioguides, graphisme, films, realite augmentee, etc.) permettent de produire aujourd’hui des effets de verite tout autant que des effets de fiction. Du point de vue des maitrises d’ouvrage et parfois des institutions museales elles-memes, les objectifs de frequentation invitent a favoriser la mediation fictionnelle et emotionnel...
Some recent papers have recommended moderate intensities of defoliation in order to maximize herb... more Some recent papers have recommended moderate intensities of defoliation in order to maximize herbage intake at different time-scales. Most of them, however, did not assess the grazing dynamics of individual tillers during the stocking period. Therefore, the objective of this work was to describe the defoliation dynamics of kikuyugrass (Pennisetum clandestinum Hochst ex. Chiov) pastures subjected to different intensities of defoliation (40, 50, 60, and 70% of the initial height). Twelve 1500 m2 plots were strip-grazed over 24 h, and the frequency and severity of defoliation of individual tillers were assessed in 40 tagged tillers per experimental unit. From these data (n = 1920), we calculated the grazed area in the upper, second, and third horizon, and the total grazed area. We found that the frequency of defoliation by leaf category (expanding, mature, and senescent) increased linearly with the intensity of defoliation, and that reductions in extended tillers could not be used as a...
The number of scholars working on transition concepts in the Global South is rapidly increasing. ... more The number of scholars working on transition concepts in the Global South is rapidly increasing. In this context, a substantial amount of research output particularly focusses on niches and how they affect transition towards sustainability in a wider framework of the multi-level-perspective. At the same time, there is a growing interest in digital technology and its effect on sustainability challenges. In this article, we combine the two fields, and by utilizing social media data, we create an innovative network science approach to analyze the production environment of digital innovations in Africa. We focus on three innovation hubs that we conceptualize as niches and innovation intermediaries that not only create communities to develop, test and implement new technology but also function as networks to discuss and form new ideas around innovations. Our key findings show how local communities are embedded in larger innovation structures. The connections between local stakeholders an...
ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pa... more ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (ma...
To better characterize human dendritic cells (DCs) that originate from lymphoid progenitors, the ... more To better characterize human dendritic cells (DCs) that originate from lymphoid progenitors, the authors examined the DC differentiation pathways from a novel CD7+CD45RA+ progenitor population found among cord blood CD34+ cells. Unlike CD7−CD45RA+ and CD7+CD45RA− progenitors, this population displayed high natural killer (NK) cell differentiation capacity when cultured with stem cell factor (SCF), interleukin (IL)-2, IL-7, and IL-15, attesting to its lymphoid potential. In cultures with SCF, Flt3 ligand (FL), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-α (standard condition), CD7+CD45RA+ progenitors expanded less (37- vs 155-fold) but yielded 2-fold higher CD1a+ DC percentages than CD7−CD45RA+ or CD7+CD45RA− progenitors. As reported for CD34+CD1a− thymocytes, cloning experiments demonstrated that CD7+CD45RA+ cells comprised bipotent NK/DC progenitors. DCs differentiated from CD7−CD45RA+ and CD7+CD45RA+ progenitors differed as to E-cadhe...
Laboratory mice are used in biomedical research as “models” for studying human disease. These mic... more Laboratory mice are used in biomedical research as “models” for studying human disease. These mice may be subject to significant levels of stress during transportation that can cause alterations that could negatively affect the results of the performed investigation. Here, we present the design and realization of a prototypical transportation container for laboratory mice, which may contribute to improved laboratory animal welfare. This prototype incorporates electric potential integrated circuit (EPIC) sensors, which have been shown to allow the recording of physiological parameters (heart rate and breathing rate) and other sensors for recording environmental parameters during mouse transportation. This allows for the estimation of the stress levels suffered by mice. First experimental results for capturing physiological and environmental parameters are shown and discussed.
It is well-known that as humans age they experience significant changes in gait including reducti... more It is well-known that as humans age they experience significant changes in gait including reduction in velocity and ground reaction forces and changes in leg mechanics. Progressive changes in gait can lead to disability and frailty, defined as an inability to carry out activities of daily living. This topic is relevant to basic understanding of the aging process and for clinical intervention. As such, studies of frailty can benefit from nonhuman animal models, yet little is known about gait frailty in nonhuman primates. This study examines a nonhuman primate model to evaluate its relevance to understanding human aging processes. To test the null hypothesis that age-related changes in joint function and gait do occur in primate models in a similar fashion to humans, a detailed gait analysis, including velocity, footfall timings, and vertical ground reaction forces, on bipedal locomotion was performed in Coquerel's sifaka (Propithecus coquereli), ranging in age from 5 years to 24 ...
American journal of physical anthropology, Jan 29, 2018
In this study, we explore whether ground reaction forces recorded during horizontal walking co-va... more In this study, we explore whether ground reaction forces recorded during horizontal walking co-vary with the shape of the long bones of the forelimb in strepsirrhines. To do so, we quantify (1) the shape of the shaft and articular surfaces of each long bone of the forelimb, (2) the peak vertical, mediolateral, and horizontal ground reaction forces applied by the forelimb during arboreal locomotion, and (3) the relationship between the shape of the forelimb and peak forces. Geometric morphometric approaches were used to quantify the shape of the bones. Kinetic data were collected during horizontal arboreal walking in eight species of strepsirrhines that show variation in habitual substrate use and morphology of the forelimb. These data were then used to explore the links between locomotor behavior, morphology, and mechanics using co-variation analyses in a phylogenetic framework. Our results show significant differences between slow quadrupedal climbers (lorises), vertical clinger an...
Angewandte Chemie (International ed. in English), Jan 13, 2018
The direct union of primary, secondary, and tertiary carboxylic acids with a chiral glyoxylate-de... more The direct union of primary, secondary, and tertiary carboxylic acids with a chiral glyoxylate-derived sulfinimine provides rapid access to a variety of enantiomerically-pure α-amino acids (>85 examples). Characterized by operational simplicity, this radical-based reaction enables the modular assembly of exotic α-amino acids, including both unprecedented structures and those of established industrial value. The described method performs well in high-throughput library synthesis, and has already been implemented in three distinct medicinal chemistry campaigns.
During quadrupedal walking in most animals, the forelimbs play a net braking role, whereas the hi... more During quadrupedal walking in most animals, the forelimbs play a net braking role, whereas the hindlimbs are net propulsive. However, the mechanism by which this differentiation occurs remains unclear. Here, we test two models to explain this pattern using primates and felines: (1) the horizontal strut effect (in which limbs are modeled as independent struts), and (2) the linked strut model (in which limbs are modeled as linked struts with a center of mass in between). Video recordings were used to determine point of contact, timing of mid-stance, and limb protraction/retraction duration. Single-limb forces were used to calculate contact time, impulses and the proportion of the stride at which the braking-to-propulsive transition (BP) occurred for each limb. We found no association between the occurrence of the BP and mid-stance, little influence of protraction and retraction duration on the braking-propulsive function of a limb, and a causative relationship between vertical force d...
Resumo O objetivo deste trabalho foi avaliar o acúmulo de forragem durante o período de ocupação ... more Resumo O objetivo deste trabalho foi avaliar o acúmulo de forragem durante o período de ocupação pelos animais em pastos de capim-quicuiu (Pennisetum clandestinum Hochst. Ex. Chiov.) manejados sob lotação intermitente. Os tratamentos consistiram de quatro proporções de desfolhação (remoção de 40, 50, 60 e 70% da altura inicial) partindo de uma mesma altura em pré-pastejo (20 cm). Foram avaliadas: taxas de alongamento foliar e colmos e senescência de folhas, índice de área foliar e taxa de acúmulo de forragem. Adicionalmente, dez perfilhos por faixa foram avaliados para as mesmas variáveis dentro de gaiolas de exclusão. Os efeitos linear, quadrático e cúbico da severidade de desfolhação foram avaliados por contrastes de polinômios ortogonais com 5% de nível de significância. Houve relação linear e inversa entre a porcentagem do índice de área foliar removido e o alongamento de lâminas foliares e o acúmulo de forragem. As taxas de alongamento de folhas em perfilhos bem como o acúmulo ...
Décrite à Berlin en 1868 par un jeune étudiant en médecine, Paul Langerhans, la cellule qui porte... more Décrite à Berlin en 1868 par un jeune étudiant en médecine, Paul Langerhans, la cellule qui porte son nom appartient à la famille des cellules dendritiques caractérisées par leur morphologie et leur capacité spécifique à initier une réponse immune primaire, c'est-à-dire sensibiliser des lymphocytes T naïfs. Ces cellules de Langerhans, modèle d'étude et cellule den dritique la mieux connue, sont présentes dans l'épi derme, dans l'épithélium bronchique et l'ensemble des muqueuses à l'exception de l'intestin. Après une stimulation antigénique, les cellules de Langerhans quittent les épithéliums de revêtement et migrent par la voie lymphatique vers les zones thymo-dépendants des ganglions proximaux où elles vont transmettre aux lymphocytes T naïfs l'information antigénique et stimuler ainsi la prolifération de clones spécifiques. Les cellules de Langerhans naissent dans la moelle osseuse et l'on connaît leurs précurseurs CD34+ dans le sang circulant ou le sang de cordon. Ces cellules sont responsables de réactions cutanées allergiques de contact et jouent un rôle essentiel dans l'atopie. Elles jouent un rôle sentinelle dans la défense anti cancer et représentent la première cible et le vecteur de diffusion dans l'infection muqueuse par le VIH. Depuis 1992, on sait produire in vitro des cellules de Langerhans, soit à partir des précurseurs hémato INSERM Unité 346, Dermatologie, Pavillon R, poïétiques CD34+ par culture en présence de GM-CSF et TNFa, soit à partir des monocytes circulants par culture en présence de GM-CSF, IL4 et TGFß. Une sous-population CDla+ circulante représente leur précurseur direct. La possibilité d'obtenir ainsi, en grand nombre, ces cellules dendritiques à partir d'éléments du sang a ouvert la voie à leur utilisation en thérapie cellulaire et, en particulier, en immuno thérapie anti-cancer. En dermatologie, c'est dans le mélanome que les essais cliniques sont les plus avan cés. Nestlé et al., en 1998, Schuler et al. en 1999 ont utilisé chez des patients porteurs de mélanome, des cellules dendritiques produites à partir des mono cytes sanguins, et chargées avec des antigènes tumo raux de mélanome. Injectées soit dans la peau, soit dans les ganglions, ces cellules ainsi chargées indui sent une forte réponse immune spécifique, une régres sion significative dans un nombre important de cas et, dans un petit nombre, une rémission complète des métastases. Ces résultats encourageants nécessitent des études complémentaires visant à mieux com prendre les mécanismes de la tolérance induite par les cellules tumorales et les mécanismes immuns induits chez les patients par vaccination au moyen des cel lules dendritiques.
Revue Française d'Allergologie et d'Immunologie Clinique, 1997
La peau est un organe tr6s riche en cellules immunitaires et en fibres nerveuses. Les neurom6diat... more La peau est un organe tr6s riche en cellules immunitaires et en fibres nerveuses. Les neurom6diateurs cutan6s semblent jouer un r61e important dans la physiologie cutan6e et l'inflammarion cutan6e. Au cours de dermatoses allergiques teltes que la dermatite atopique ou l'urticaire, de nombreuses modifications du systbme nerveux (densit6 des fibres nerveuses, concentration et r6partition des neurom6diateurs) ont 6t6 observ6es. L'implication des neurom6diateurs dans la patho-g6nie des phases vasculaire et cellulaire de l'inflammation permet de penser que de nouvelles possibilit6s th6rapeutiques vont bient6t 6merger dans les dermatoses allergiques. MOTS-CLt~S : Neurom6diateurs-Neuropeptides-Allergie-Dermatoses allergiques. SUMMARY Neurotransmitters and the skin. Perspectives for allergic dermatoses?-The skin has a high density of immune cells and nerve fibers. Cutaneous neurotransmitters are very important in skin physiology and cutaneous inflammation. In the course of allergic dermatoses, such as atopic delTmatitis or urticaria, the cutaneous nervous system is modified (density of nerve fibers, concentration and distribution of neuropeptides). Neurotransmitters are actively involved in the pathogenesis of the vascular and cellular phases of inflammation. These data suggest that agonists and antagonists of neurotransmitters may represent a new and very interesting alternative for the treatment of patients.
Gravitational waves provide a novel way to probe axions or axion-like particles coupled to a dark... more Gravitational waves provide a novel way to probe axions or axion-like particles coupled to a dark photon field, even in the absence of couplings to Standard Model particles. In the conventional misalignment mechanism, the generation of an observable stochastic gravitational wave background, however, requires large axion decay constants. We here investigate the gravitational wave signal generated within the kinetic misalignment scenario, where the axion is assumed to have a large initial velocity. Its kinetic energy then provides a sufficiently high energy budget to generate a detectable gravitational wave signal also at lower values of the decay constant. We obtain an analytic estimate as well as perform numerical simulations of the corresponding gravitational wave signal, and evaluate its detectability at current and future gravitational wave observatories. We further present the corresponding projected constraints on the parameter space of the model, along with the parameter regio...
O manejo de desfolha possui como um dos principais objetivos o rebrote vigoroso após o rebaixamen... more O manejo de desfolha possui como um dos principais objetivos o rebrote vigoroso após o rebaixamento, uma vez que a área foliar remanescente possui alta correlação com o potencial de rebrote dos pastos. Desta forma, o objetivo do presente trabalho foi avaliar o efeito de intervenções pontuais de alta severidade (70%) sobre características produtivas de pastos de azevém anual manejados sob desfolhações intermitentes. O experimento foi conduzido na área experimental da Universidade Tecnológica Federal do Paraná. Os tratamentos consistiram de quatro estratégias de desfolha a partir de uma única altura de entrada (20cm): severidade constante de 40%; severidade de 40% com intervenções pontuais de 70% no segundo corte; severidade de 40% com intervenções pontuais de 70% no quarto corte; e severidades de 40% e 70% intercaladas. Os tratamentos foram aplicados em delineamento inteiramente casualizado com três repetições, totalizando 12 unidades experimentais. Foram avaliadas as variáveis de in...
Emilie Flon s’interroge dans son ouvrage sur la mise en scene du patrimoine dans les musees, ques... more Emilie Flon s’interroge dans son ouvrage sur la mise en scene du patrimoine dans les musees, question importante pour elle, parce que les technologies de mediation (audioguides, graphisme, films, realite augmentee, etc.) permettent de produire aujourd’hui des effets de verite tout autant que des effets de fiction. Du point de vue des maitrises d’ouvrage et parfois des institutions museales elles-memes, les objectifs de frequentation invitent a favoriser la mediation fictionnelle et emotionnel...
Some recent papers have recommended moderate intensities of defoliation in order to maximize herb... more Some recent papers have recommended moderate intensities of defoliation in order to maximize herbage intake at different time-scales. Most of them, however, did not assess the grazing dynamics of individual tillers during the stocking period. Therefore, the objective of this work was to describe the defoliation dynamics of kikuyugrass (Pennisetum clandestinum Hochst ex. Chiov) pastures subjected to different intensities of defoliation (40, 50, 60, and 70% of the initial height). Twelve 1500 m2 plots were strip-grazed over 24 h, and the frequency and severity of defoliation of individual tillers were assessed in 40 tagged tillers per experimental unit. From these data (n = 1920), we calculated the grazed area in the upper, second, and third horizon, and the total grazed area. We found that the frequency of defoliation by leaf category (expanding, mature, and senescent) increased linearly with the intensity of defoliation, and that reductions in extended tillers could not be used as a...
The number of scholars working on transition concepts in the Global South is rapidly increasing. ... more The number of scholars working on transition concepts in the Global South is rapidly increasing. In this context, a substantial amount of research output particularly focusses on niches and how they affect transition towards sustainability in a wider framework of the multi-level-perspective. At the same time, there is a growing interest in digital technology and its effect on sustainability challenges. In this article, we combine the two fields, and by utilizing social media data, we create an innovative network science approach to analyze the production environment of digital innovations in Africa. We focus on three innovation hubs that we conceptualize as niches and innovation intermediaries that not only create communities to develop, test and implement new technology but also function as networks to discuss and form new ideas around innovations. Our key findings show how local communities are embedded in larger innovation structures. The connections between local stakeholders an...
ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pa... more ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (ma...
To better characterize human dendritic cells (DCs) that originate from lymphoid progenitors, the ... more To better characterize human dendritic cells (DCs) that originate from lymphoid progenitors, the authors examined the DC differentiation pathways from a novel CD7+CD45RA+ progenitor population found among cord blood CD34+ cells. Unlike CD7−CD45RA+ and CD7+CD45RA− progenitors, this population displayed high natural killer (NK) cell differentiation capacity when cultured with stem cell factor (SCF), interleukin (IL)-2, IL-7, and IL-15, attesting to its lymphoid potential. In cultures with SCF, Flt3 ligand (FL), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-α (standard condition), CD7+CD45RA+ progenitors expanded less (37- vs 155-fold) but yielded 2-fold higher CD1a+ DC percentages than CD7−CD45RA+ or CD7+CD45RA− progenitors. As reported for CD34+CD1a− thymocytes, cloning experiments demonstrated that CD7+CD45RA+ cells comprised bipotent NK/DC progenitors. DCs differentiated from CD7−CD45RA+ and CD7+CD45RA+ progenitors differed as to E-cadhe...
Laboratory mice are used in biomedical research as “models” for studying human disease. These mic... more Laboratory mice are used in biomedical research as “models” for studying human disease. These mice may be subject to significant levels of stress during transportation that can cause alterations that could negatively affect the results of the performed investigation. Here, we present the design and realization of a prototypical transportation container for laboratory mice, which may contribute to improved laboratory animal welfare. This prototype incorporates electric potential integrated circuit (EPIC) sensors, which have been shown to allow the recording of physiological parameters (heart rate and breathing rate) and other sensors for recording environmental parameters during mouse transportation. This allows for the estimation of the stress levels suffered by mice. First experimental results for capturing physiological and environmental parameters are shown and discussed.
It is well-known that as humans age they experience significant changes in gait including reducti... more It is well-known that as humans age they experience significant changes in gait including reduction in velocity and ground reaction forces and changes in leg mechanics. Progressive changes in gait can lead to disability and frailty, defined as an inability to carry out activities of daily living. This topic is relevant to basic understanding of the aging process and for clinical intervention. As such, studies of frailty can benefit from nonhuman animal models, yet little is known about gait frailty in nonhuman primates. This study examines a nonhuman primate model to evaluate its relevance to understanding human aging processes. To test the null hypothesis that age-related changes in joint function and gait do occur in primate models in a similar fashion to humans, a detailed gait analysis, including velocity, footfall timings, and vertical ground reaction forces, on bipedal locomotion was performed in Coquerel's sifaka (Propithecus coquereli), ranging in age from 5 years to 24 ...
American journal of physical anthropology, Jan 29, 2018
In this study, we explore whether ground reaction forces recorded during horizontal walking co-va... more In this study, we explore whether ground reaction forces recorded during horizontal walking co-vary with the shape of the long bones of the forelimb in strepsirrhines. To do so, we quantify (1) the shape of the shaft and articular surfaces of each long bone of the forelimb, (2) the peak vertical, mediolateral, and horizontal ground reaction forces applied by the forelimb during arboreal locomotion, and (3) the relationship between the shape of the forelimb and peak forces. Geometric morphometric approaches were used to quantify the shape of the bones. Kinetic data were collected during horizontal arboreal walking in eight species of strepsirrhines that show variation in habitual substrate use and morphology of the forelimb. These data were then used to explore the links between locomotor behavior, morphology, and mechanics using co-variation analyses in a phylogenetic framework. Our results show significant differences between slow quadrupedal climbers (lorises), vertical clinger an...
Angewandte Chemie (International ed. in English), Jan 13, 2018
The direct union of primary, secondary, and tertiary carboxylic acids with a chiral glyoxylate-de... more The direct union of primary, secondary, and tertiary carboxylic acids with a chiral glyoxylate-derived sulfinimine provides rapid access to a variety of enantiomerically-pure α-amino acids (>85 examples). Characterized by operational simplicity, this radical-based reaction enables the modular assembly of exotic α-amino acids, including both unprecedented structures and those of established industrial value. The described method performs well in high-throughput library synthesis, and has already been implemented in three distinct medicinal chemistry campaigns.
During quadrupedal walking in most animals, the forelimbs play a net braking role, whereas the hi... more During quadrupedal walking in most animals, the forelimbs play a net braking role, whereas the hindlimbs are net propulsive. However, the mechanism by which this differentiation occurs remains unclear. Here, we test two models to explain this pattern using primates and felines: (1) the horizontal strut effect (in which limbs are modeled as independent struts), and (2) the linked strut model (in which limbs are modeled as linked struts with a center of mass in between). Video recordings were used to determine point of contact, timing of mid-stance, and limb protraction/retraction duration. Single-limb forces were used to calculate contact time, impulses and the proportion of the stride at which the braking-to-propulsive transition (BP) occurred for each limb. We found no association between the occurrence of the BP and mid-stance, little influence of protraction and retraction duration on the braking-propulsive function of a limb, and a causative relationship between vertical force d...
Resumo O objetivo deste trabalho foi avaliar o acúmulo de forragem durante o período de ocupação ... more Resumo O objetivo deste trabalho foi avaliar o acúmulo de forragem durante o período de ocupação pelos animais em pastos de capim-quicuiu (Pennisetum clandestinum Hochst. Ex. Chiov.) manejados sob lotação intermitente. Os tratamentos consistiram de quatro proporções de desfolhação (remoção de 40, 50, 60 e 70% da altura inicial) partindo de uma mesma altura em pré-pastejo (20 cm). Foram avaliadas: taxas de alongamento foliar e colmos e senescência de folhas, índice de área foliar e taxa de acúmulo de forragem. Adicionalmente, dez perfilhos por faixa foram avaliados para as mesmas variáveis dentro de gaiolas de exclusão. Os efeitos linear, quadrático e cúbico da severidade de desfolhação foram avaliados por contrastes de polinômios ortogonais com 5% de nível de significância. Houve relação linear e inversa entre a porcentagem do índice de área foliar removido e o alongamento de lâminas foliares e o acúmulo de forragem. As taxas de alongamento de folhas em perfilhos bem como o acúmulo ...
Décrite à Berlin en 1868 par un jeune étudiant en médecine, Paul Langerhans, la cellule qui porte... more Décrite à Berlin en 1868 par un jeune étudiant en médecine, Paul Langerhans, la cellule qui porte son nom appartient à la famille des cellules dendritiques caractérisées par leur morphologie et leur capacité spécifique à initier une réponse immune primaire, c'est-à-dire sensibiliser des lymphocytes T naïfs. Ces cellules de Langerhans, modèle d'étude et cellule den dritique la mieux connue, sont présentes dans l'épi derme, dans l'épithélium bronchique et l'ensemble des muqueuses à l'exception de l'intestin. Après une stimulation antigénique, les cellules de Langerhans quittent les épithéliums de revêtement et migrent par la voie lymphatique vers les zones thymo-dépendants des ganglions proximaux où elles vont transmettre aux lymphocytes T naïfs l'information antigénique et stimuler ainsi la prolifération de clones spécifiques. Les cellules de Langerhans naissent dans la moelle osseuse et l'on connaît leurs précurseurs CD34+ dans le sang circulant ou le sang de cordon. Ces cellules sont responsables de réactions cutanées allergiques de contact et jouent un rôle essentiel dans l'atopie. Elles jouent un rôle sentinelle dans la défense anti cancer et représentent la première cible et le vecteur de diffusion dans l'infection muqueuse par le VIH. Depuis 1992, on sait produire in vitro des cellules de Langerhans, soit à partir des précurseurs hémato INSERM Unité 346, Dermatologie, Pavillon R, poïétiques CD34+ par culture en présence de GM-CSF et TNFa, soit à partir des monocytes circulants par culture en présence de GM-CSF, IL4 et TGFß. Une sous-population CDla+ circulante représente leur précurseur direct. La possibilité d'obtenir ainsi, en grand nombre, ces cellules dendritiques à partir d'éléments du sang a ouvert la voie à leur utilisation en thérapie cellulaire et, en particulier, en immuno thérapie anti-cancer. En dermatologie, c'est dans le mélanome que les essais cliniques sont les plus avan cés. Nestlé et al., en 1998, Schuler et al. en 1999 ont utilisé chez des patients porteurs de mélanome, des cellules dendritiques produites à partir des mono cytes sanguins, et chargées avec des antigènes tumo raux de mélanome. Injectées soit dans la peau, soit dans les ganglions, ces cellules ainsi chargées indui sent une forte réponse immune spécifique, une régres sion significative dans un nombre important de cas et, dans un petit nombre, une rémission complète des métastases. Ces résultats encourageants nécessitent des études complémentaires visant à mieux com prendre les mécanismes de la tolérance induite par les cellules tumorales et les mécanismes immuns induits chez les patients par vaccination au moyen des cel lules dendritiques.
Revue Française d'Allergologie et d'Immunologie Clinique, 1997
La peau est un organe tr6s riche en cellules immunitaires et en fibres nerveuses. Les neurom6diat... more La peau est un organe tr6s riche en cellules immunitaires et en fibres nerveuses. Les neurom6diateurs cutan6s semblent jouer un r61e important dans la physiologie cutan6e et l'inflammarion cutan6e. Au cours de dermatoses allergiques teltes que la dermatite atopique ou l'urticaire, de nombreuses modifications du systbme nerveux (densit6 des fibres nerveuses, concentration et r6partition des neurom6diateurs) ont 6t6 observ6es. L'implication des neurom6diateurs dans la patho-g6nie des phases vasculaire et cellulaire de l'inflammation permet de penser que de nouvelles possibilit6s th6rapeutiques vont bient6t 6merger dans les dermatoses allergiques. MOTS-CLt~S : Neurom6diateurs-Neuropeptides-Allergie-Dermatoses allergiques. SUMMARY Neurotransmitters and the skin. Perspectives for allergic dermatoses?-The skin has a high density of immune cells and nerve fibers. Cutaneous neurotransmitters are very important in skin physiology and cutaneous inflammation. In the course of allergic dermatoses, such as atopic delTmatitis or urticaria, the cutaneous nervous system is modified (density of nerve fibers, concentration and distribution of neuropeptides). Neurotransmitters are actively involved in the pathogenesis of the vascular and cellular phases of inflammation. These data suggest that agonists and antagonists of neurotransmitters may represent a new and very interesting alternative for the treatment of patients.
Uploads
Papers by Daniel Schmitt