3 resultados para In-row spacing

em DigitalCommons@The Texas Medical Center


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This participatory action-research project addressed the hypothesis that strengthened community and women's capacity for self-development will lead to action to address maternal health problems and the prevention of maternal morbidity and mortality in Mali. Research objectives were: (1) to undertake a comparative cross-sectional study of the association of community capacity with improved maternal health in rural areas of Sanando, Mali, where capacity building interventions have taken place in some villages but not in others. (2) to describe women's maternal health status, access to and use of maternal health services given their residence in program or comparison communities.^ The participatory action research project was an integrated qualitative and quantitative study using participatory rural appraisal exercises, semi-structured group interviews and a cross-sectional survey.^ Factors related to community capacity for self-development were identified: community harmony; an understanding of the benefits of self-development; dynamic leadership; and a structure to implement collective activities.^ A distinct difference between the program and comparison villages was the commitment to train and support traditional birth attendants (TBAs). The TBAs in the program villages work in the context of the wider, integrated self-development program and, 10 years after their initial training, the TBAs continue to practice.^ Many women experience labor and childbirth alone or are attended by an untrained relative in both program and comparison villages. Nevertheless a significant change is apparent, with more women in program villages than in comparison villages being assisted by the TBAs. The delivery practices of the TBAs reveal the positive impact of their training in the "three cleans" (clean hands of the assistant, clean delivery surface and clean cord-cutting). The findings of this study indicate a significant level of unmet need for child spacing methods in all villages.^ The training and support of TBAs in the program villages yielded significant improvements in their delivery practices, and resulting outcomes for women and infants. However, potential exists for further community action. Capacities for self-development have not yet been directed toward an action plan encompassing other Safe Motherhood interventions, including access to family planning services and emergency obstetric care services. ^

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Neuronal outgrowth has been proposed in many systems as a mechanism underlying memory storage. For example, sensory neuron outgrowth is widely accepted as an underlying mechanism of long-term sensitization of defensive withdrawal reflexes in Aplysia. The hypothesis is that learning leads to outgrowth and consequently to the formation of new synapses, which in turn strengthen the neural circuit underlying the behavior. However, key experiments to test this hypothesis have never been performed. ^ Four days of sensitization training leads to outgrowth of siphon sensory neurons mediating the siphon-gill withdrawal response in Aplysia . We found that a similar training protocol produced robust outgrowth in tail sensory neurons mediating the tail siphon withdrawal reflex. In contrast, 1 day of training, which effectively induces long-term behavioral sensitization and synaptic facilitation, was not associated with neuronal outgrowth. Further examination of the effect of behavioral training protocols on sensory neuron outgrowth indicated that this structural modification is associated only with the most persistent forms of sensitization, and that the induction of these changes is dependent on the spacing of the training trials over multiple days. Therefore, we suggest that neuronal outgrowth is not a universal mechanism underlying long-term sensitization, but is involved only in the most persistent forms of the memory. ^ Sensory neuron outgrowth presumably contributes to long-term sensitization through formation of new synapses with follower motor neurons, but this hypothesis has never been directly tested. The contribution of outgrowth to long-term sensitization was assessed using confocal microscopy to examine sites of contact between physiologically connected pairs of sensory and motor neurons. Following 4 days of training, the strength of both the behavior and sensorimotor synapse and the number of appositions with follower neurons was enhanced only on the trained side of the animal. In contrast, outgrowth was induced on both sides of the animal, indicating that although sensory neuron outgrowth does appear to contribute to sensitization through the formation of new synapses, outgrowth alone is not sufficient to account for the effects of sensitization. This indicates that key regulatory steps are downstream from outgrowth, possibly in the targeting of new processes and activation of new synapses. ^

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Transcription factors often determine cell fate and tissue development. Chondrogenesis is the developmental process by which cartilages form. Recently, gene targeting studies have shown that two transcription factors, L-Sox5 and Sox6, play essential and redundant roles in chondrogenesis in vivo by converting precartilaginous cell condensations into cartilages. Both are highly similar High-Mobility-Group (HMG)-domain proteins that bind and subsequently bend DNA containing the 7bp HMG site (A/T)(A/T)CAA(A/T)G. They have no transactivation domain, but homo- and hetero-dimerize and preferentially bind DNA containing two HMG sites. They are thought to play an architectural role in transactivation by facilitating long-range DNA and protein interactions. To understand their molecular mechanism of action, we investigated how phasing, orientation, and spacing between HMG sites affect L-Sox5 and Sox6 DNA-binding. We determined that L-Sox5 and Sox6 dimers bind with high affinity to paired HMG sites in DNA rather than a single HMG site. Binding of paired sites is independent of DNA helical phasing, orientation of paired HMG sites and independent of distance up to 255 base pairs between sites. Mutational analysis demonstrated that binding of L-Sox5 and Sox6, independent of orientation of the sites, is critically dependent on the presence of paired HMG sites rather than one HMG site alone. Our data support a unique and novel model whereby L-Sox5 and Sox6 dimerize and bind DNA with pronounced spatial flexibility, possibly by a flexible hinge, and act as architectural transcription factors that bring distant DNA sites and proteins together to form higher order transcriptional complexes that are essential for the activation of their target genes in chondrogenesis. ^