1,504 research outputs found

    MHC Class II haplotypes of Colombian Amerindian tribes

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    We analyzed 1041 individuals belonging to 17 Amerindian tribes of Colombia, Chimila, Bari and Tunebo (Chibcha linguistic family), Embera, Waunana (Choco linguistic family), Puinave and Nukak (Maku-Puinave linguistic families), Cubeo, Guanano, Tucano, Desano and Piratapuyo (Tukano linguistic family), Guahibo and Guayabero (Guayabero Linguistic Family), Curripaco and Piapoco (Arawak linguistic family) and Yucpa (Karib linguistic family). for MHC class II haplotypes (HLA-DRB1, DQA1, DQB1). Approximately 90% of the MHC class II haplotypes found among these tribes are haplotypes frequently encountered in other Amerindian tribes. Nonetheless, striking differences were observed among Chibcha and non-Chibcha speaking tribes. The DRB1*04:04, DRB1*04:11, DRB1*09:01 carrying haplotypes were frequently found among non-Chibcha speaking tribes, while the DRB1*04:07 haplotype showed significant frequencies among Chibcha speaking tribes, and only marginal frequencies among non-Chibcha speaking tribes. Our results suggest that the differences in MHC class II haplotype frequency found among Chibcha and non-Chibcha speaking tribes could be due to genetic differentiation in Mesoamerica of the ancestral Amerindian population into Chibcha and non-Chibcha speaking populations before they entered into South America

    STUDIES ON THYMUS FUNCTION : II. COOPERATIVE EFFECT OF NEWBORN AND EMBRYONIC HEMOPOIETIC LIVER CELLS WITH THYMUS FUNCTION

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    Significant immunological restoration of 45-day old, neonatally thymectomized C3Hf mice was obtained by the cooperation of syngeneic newborn or embryonic hemopoietic liver cells with thymic function. Thymic function or cells alone are almost ineffective or restore approximately 10% of the animals. Newborn liver cells are effective in association with thymus grafts or humoral thymic function (thymoma grafts and thymus or thymomas in diffusion chambers). Embryonic liver cells are ineffective, even in large numbers, when associated with humoral thymic function. On the other hand, embryonic liver cells are effective in the cooperative effect only in association with viable thymus grafts, preferably syngeneic, whether the grafts were placed subcutaneously, intraperitoneally, or under the kidney capsule. Dispersed viable thymic cells are ineffective in association with embryonic liver cells. Cells capable of cooperating with humoral thymic function start to appear to embryonic liver by day 19–21 of gestation and are detectable until day 5–6 postbirth. Embryonic hemopoietic liver cells from 12 to 18 days of gestation contain cells capable of cooperation only with viable free thymus grafts and not with humoral thymic function. A prethymic cell population of partially differentiated cells of hemopoietic origin, insensitive to humoral activity of the thymus but requiring thymic stroma and traffic through the thymus is postulated to explain our results. This population of prethymic cells can become postthymic through this process and eventually develop into competent cells. Postthymic cells are characterized by their sensitivity to humoral activity of the thymus and by their wide distribution in the lymphohemopoietic tissues of newborn and young adult mice

    STUDIES ON THYMUS FUNCTION : III. DURATION OF THYMIC FUNCTION

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    The immune functions of neonatally thymectomized C3Hf mice exposed only temporarily to thymus function show a progressive decay with time in the absence of the thymus. The immune responses studied at different ages in the range of 100–600 days were: first-set rejection of H-2-compatible and incompatible skin allografts, second-set rejection of skin allografts, capacity of spleen cells to produce graft-versus-host reactions in F1 hybrids, resistance to infection with mouse hepatitis virus, and response of spleen cells to phytohemagglutinin in vitro. These long-term studies had the purpose of determining the duration of the restoration induced by thymus function when the mice were exposed only temporarily to it. Different models were used but the two basic ones were: (a) mice grafted intraperitoneally at 15 days of age with a syngeneic thymus that was removed surgically at 10, 20, or 30 days after grafting, and (b) mice grafted at 15 days of age with allogeneic strain A thymoma or C57BL thymus, these representing situations in which there is spontaneous rejection of the restoring graft. In all the experimental models used, the animals were restored when tested at 100 days of age, but progressively became immunologically incapacitated at 200–300 days of age. From the more controlled experiments in which the restoring thymus graft was removed surgically, the following conclusions can be drawn. (a) A short exposure to a thymus graft can produce restoration of immune functions in neonatally thymectomized mice, but this restoration is not self-sustaining in the absence of the thymus and declines progressively with age. The decline usually starts at 200–300 days of age. (b) This was especially clear in experiments in which the same animal was tested twice in its lifetime for capacity to produce graft-versus-host reactions; these animals were competent at 100 days and became incompetent at 400 days of age. (c) The shortest period of thymic exposure studied was 10 days; if vascularization of the graft is taken into account, 2–3 days of thymic function are sufficient to produce restoration. (d) The immune decay observed in the thymectomized animals exposed temporarily to thymus was more profound than the physiological decay of immunity observed in control animals of similar age. (e) Of all the tests studied, the response of spleen cells to phytohemagglutinin was to be preserved the longest in animals exposed only temporarily to thymic function. The present results were interpreted in accordance with our previous findings indicating that a population of postthymic cells can be developed by temporary exposure of neonatally thymectomized animals to thymic function, but that this population is not self-sustaining in the absence of thymus and progressively decays by physiological attrition

    STUDIES ON THYMUS FUNCTION : I. COOPERATIVE EFFECT OF THYMIC FUNCTION AND LYMPHOHEMOPOIETIC CELLS IN RESTORATION OF NEONATALLY THYMECTOMIZED MICE

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    Immunological restoration of 45-day old, neonatally thymectomized C3Hf mice by treatment with humoral thymic function (thymoma grafts, thymus or thymoma in diffusion chambers) ranges from 0 to 12% and is difficult to acheive. When small numbers (5–20 x 106) of young adult lymphohemopoietic cells, ineffective by themselves, are given in association with humoral thymic function, a cooperative effect is observed and restoration ranges from 30 to 60%. With a particular cell dosage (20 x 106), effectivity for cooperation with thymic function was the following in decreasing order: spleen, lymph nodes, thoracic duct cells, bone marrow, blood leukocytes, thymus, and Peyer's patch cells. Comparable results were obtained using spleen, thymus, and hemopoietic liver from newborn donors in association with thymic function. For similar cell dosages, newborn thymus cells were more effective than adult thymus in their cooperative effect with thymic function. Dispersed thymus cells in association with young adult bone marrow or newborn hemopoietic liver cells showed no synergism for the cooperative effect with thymic function in the present model. Using hemiallogeneic cells (F1 hybrid into parent) it was possible to show that restoration was mediated by proliferative expansion of the injected cells. This was indicated by specific tolerance to tissues of the other parental strain and by cellular chimerism, especially of lymphoid tissues, as indicated by chromosome markers and absence of significant numbers of immunocompetent cells of host origin. A population of paritally differentiated cells of hemopoietic origin, termed postthymic, sensitive to humoral activity of the thymus and present in the lymphohemopoietic tissues of adult and newborn mice is postulated to explain our results. These cells are postthymic and thymus dependent in the sense that they already received thymic influence, probably through traffic, and are incapable of self-renewal in absence of the thymus. Sensitivity to humoral activity of the thymus is characterized by proliferative expansion and/or a differentiative process eventually leading to larger numbers of competent cells

    Origen geno-geográfico de haplotipos STR del cromosoma Y en una muestra caucásico-mestiza y afrodescendiente de Colombia

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    Introduction: Y chromosome STR haplotypes have been widely used in population studies to establish the origin of diverse populations.Objective: We analyzed Y chromosome STR haplotypes (8 loci) in 134 Caucasian-mestizo and 137 African-descent Colombian unrelated individuals to correlate the geographical origin with historical data as well as the genetic relationships and possible admixture patterns.Materials and methods: One hundred samples of African descent and 137 Caucasian-mestizo samples analyzed for Y chromosome STR haplotypes by PCR followed by acrylamide electrophoresis.Results: No evidence of population substructure was found for the African descent. Two point fiftynine per cent of the haplotypes were shared between the two groups with the possible existence of Caucasian gene flow towards Afro-descendants.Conclusion: The Caucasian-Mestizo Colombian population is grouped with other populations of the Iberian Peninsula and Europe, while the Afro-Colombian population is grouped with other African populations reported. doi: http://dx.doi.org/10.7705/biomedica.v33i3.807 Introducción. Los haplotipos STR de cromosoma Y han sido ampliamente utilizados en estudios de poblaciones para establecer el origen de diversas poblaciones.Objetivo. Se analizaron haplotipos STR del cromosoma Y (8 loci) en 134 afrodescendientes y caucásico-mestizos no relacionados de Colombia, para correlacionar el origen geográfico con los datos históricos, así como las relaciones genéticas y posibles patrones de mezcla.Materiales y métodos. Se analizaron los haplotipos STR del cromosoma Y mediante PCR seguidas de electroforesis en acrilamida, de 134 muestras de afrodescendientes y 137 muestras de caucásicos mestizos.Resultados. No se encontró evidencia de subestructuración de la población afrodescendiente. El 2,59 % de los haplotipos eran compartidos en los dos grupos analizados, con la posible existencia deflujo génico de caucásico-mestizos hacia los afrodescendientes.Conclusión. La población caucásico-mestiza colombiana se agrupa con otras poblaciones de la península Ibérica y Europa, mientras que la población afrodescendiente colombiana se agrupa conotras poblaciones africanas reportadas. doi: http://dx.doi.org/10.7705/biomedica.v33i3.80

    Women Filmmakers in the United Arab Emirates

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    This entry provides an introduction to the work of and the challenges faced by women filmmakers in the United Arab Emirates while at the same time providing an overview of the emerging film industry in the country. The fact that these women claim the power of representation and start telling their stories against the backdrop of a conservative, patriarchal society, obviously opens up space for gender redefinition. Overall, it seems that their films reveal a preference for strong, interesting women that fight for a meaningful life against the backdrop of a globalized society that has left women weaker and more fragile, with less obvious choices and possibilities for fulfillment. As their female characters claim center stage, both traditional and contemporary constructions of gender are called into question and popular stereotypes about Emirati women are challenged
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