2,823 research outputs found
School-based Decision-making: What Is Necessary for a Successful Implementation in the Public Schools of Tennessee
The Tennessee State Board of Education was moving to establish school-based decision making, with little or no apparent attention to what may be needed by educators. This study has been conceived based on the lack of an advertised plan of skill instruction, the lack of a supplied knowledge base from which educators can pull resources, and the lack of an obvious high level of understanding on the part of educators in general. A developmental inquiry and a survey were conducted to determine what principals and supervisors know about school-based decision making and what will be needed to increase the chances for a successful implementation. Descriptive and inferential statistics and a review of the research were used to answer five research questions that directed the study. Statistical analyses revealed the following: (1) Almost one-fourth of the administrators think they are currently implementing formal school-based decision making. (2) Those administrators reporting experience with school-based decision making tend to have more positive and closely aligned opinions to the literature than those reporting no experience. (3) While there was little reported difference in the survey results among the four sample groups, elementary principals were slightly more concerned about implementing the process. Principals and supervisors\u27 ideas and perceptions of what school-based decision making is and how it should work were helpful in planning a model for implementation. The goal was to provide information to administrators concerning school-based decision making in a way that will strengthen and foster school programming and improve the quality of education for all students. Seven phases were projected to effect a successful transition from current practice to where school-based decision making becomes the rule rather than an exception in Tennessee schools: initial decision phase, preliminary plans, staff development, implementation, monitoring, adjusting, and evaluation
The cellular and molecular mechanisms of glucocorticoid-induced growth retardation
Since the introduction of glucocorticoids (GCs) in the treatment of rheumatoid arthritis in 1949, GC therapy has been associated with a number of adverse effects. Long-term use of GCs can result in growth retardation during childhood due to their actions on growth plate chondrocytes, although the exact mechanisms involved are unclear. The work of this thesis has investigated the cellular and molecular mechanisms involved in mediating GC effects at the growth plate.
Affymetrix microarray has been used to identify and characterise the expression of lipocalin 2, a novel GC-responsive chondrocyte gene which may contribute to GC-induced growth retardation in the growth plate. In vitro and in vivo studies have also been used to examine the role of the cell cycle regulator, p21WAF1/CIP1 in GC-induced growth retardation. Finally, the growth plate sparing effects of a novel GC receptor modulator, AL-438, have also been identified. AL438, has reduced effects on bone growth compared to Dex, but maintains similar anti-inflammatory efficacy.
This work has not only determined novel mechanisms of GC-induced growth retardation, but has also advanced the search for novel GC receptor modulators with reduced adverse effects
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Structures of Ras superfamily effector complexes: What have we learnt in two decades?
The Ras superfamily small G proteins are master regulators of a diverse range of cellular processes and act via downstream effector molecules. The first structure of a small G protein-effector complex, that of Rap1A with c-Raf1, was published 20 years ago. Since then, the structures of more than 60 small G proteins in complex with their effectors have been published. These effectors utilize a diverse array of structural motifs to interact with the G protein fold, which we have divided into four structural classes: intermolecular Ξ²-sheets, helical pairs, other interactions, and pleckstrin homology (PH) domains. These classes and their representative structures are discussed and a contact analysis of the interactions is presented, which highlights the common effector-binding regions between and within the small G protein families.This is the accepted manuscript. The final version is available at http://informahealthcare.com/doi/abs/10.3109/10409238.2014.999191
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Allostery and dynamics in small G proteins.
The Ras family of small guanine nucleotide-binding proteins behave as molecular switches: they are switched off and inactive when bound to GDP but can be activated by GTP binding in response to signal transduction pathways. Early structural analysis showed that two regions of the protein, which change conformation depending on the nucleotide present, mediate this switch. A large number of X-ray, NMR and simulation studies have shown that this is an over-simplification. The switch regions themselves are highly dynamic and can exist in distinct sub-states in the GTP-bound form that have different affinities for other proteins. Furthermore, regions outside the switches have been found to be sensitive to the nucleotide state of the protein, indicating that allosteric change is more widespread than previously thought. Taken together, the accrued knowledge about small G protein structures, allostery and dynamics will be essential for the design and testing of the next generation of inhibitors, both orthosteric and allosteric, as well as for understanding their mode of action
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CRIB effector disorder: exquisite function from chaos.
The CRIB (Cdc42/Rac interactive binding) family of small G-protein effectors contain significant regions with intrinsic disorder. The G-protein-binding regions are contained within these intrinsically disordered regions. Most CRIB proteins also contain stretches of basic residues associated with their G-protein-binding regions. The basic region (BR) and G-protein-binding region together allow the CRIB effectors to bind to their cognate G-protein via a dock- and coalesce-binding mechanism. The BRs of these proteins take on multiple roles: steering G-protein binding, interacting with elements of the membrane and regulating intramolecular regulatory interactions. The ability of these regions of the CRIBs to undergo multivalent interactions and mediate charge neutralizations equips them with all the properties required to drive liquid-liquid phase separation and therefore to initiate and drive signalosome formation. It is only recently that the structural plasticity in these proteins is being appreciated as the driving force for these vital cellular processes.MRC CASE studentship MR/K017101/
Successful Use of Alternative Anticoagulants in the Management of Heparin-induced Thrombocytopenia with Thrombotic Complications : Report of 5 cases and review of literature
Heparin is one of the most frequently used anticoagulants. It is easy to use, but can be associated with life-threatening side effects. One of these is heparin-induced thrombocytopenia syndrome (HITS), which develops in about 3β5% of patients exposed to heparin and is associated with thrombosis in 1% of cases. We report here the successful treatment of five patients with HITS who were treated with alternative anticoagulants namely danaparoid or hirudin. The median time between their exposure to heparin and onset of symptoms and or signs was 10.2 days (range 7β14 days). Platelet counts decreased to a mean of 38.4 x 109 /l (12β82 x 109/l). All five patients had evidence of thrombosis; four patients had clinical and radiological evidence of pulmonary emboli, one patient had confirmed deep vein thrombosis (DVT) and one patient had extensive skin necrosis of the thighs and abdomen. Platelet aggregation test were positive in two patients, inconclusive in one patient and negative in two patients. Two patients were anticoagulated with danaparoid and three with hirudin until their platelet counts returned to normal between 4 and 14 days (average 6 days) following the recognition of the syndrome. Our patients had significant morbidity, but no mortality. Immediate withdrawal of heparin is of paramount importance and introduction of alternative anticoagulant is necessary in the presence of thrombosis
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RLIP76: A Structural and Functional Triumvirate.
RLIP76/RalBP1 is an ATP-dependent transporter of glutathione conjugates, which is overexpressed in various human cancers, but its diverse functions in normal cells, which include endocytosis, stress response and mitochondrial dynamics, are still not fully understood. The protein can be divided into three distinct regions, each with its own structural properties. At the centre of the protein are two well-defined domains, a GTPase activating protein domain targeting Rho family small G proteins and a small coiled-coil that binds to the Ras family small GTPases RalA and RalB. In engaging with Rho and Ral proteins, RLIP76 bridges these two distinct G protein families. The N-terminal region is predicted to be disordered and is rich in basic amino acids, which may mediate membrane association, consistent with its role in transport. RLIP76 is an ATP-dependent transporter with ATP-binding sites within the N-terminus and the Ral binding domain. Furthermore, RLIP76 is subject to extensive phosphorylation, particularly in the N-terminal region. In contrast, the C-terminal region is thought to form an extensive coiled-coil that could mediate dimerization. Here, we review the structural features of RLIP76, including experimental data and computational predictions, and discuss the implications of its various post-translational modifications
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Class IA PI3K regulatory subunits: p110-independent roles and structures.
The phosphatidylinositol 3-kinase (PI3K) pathway is a critical regulator of many cellular processes including cell survival, growth, proliferation and motility. Not surprisingly therefore, the PI3K pathway is one of the most frequently mutated pathways in human cancers. In addition to their canonical role as part of the PI3K holoenzyme, the class IA PI3K regulatory subunits undertake critical functions independent of PI3K. The PI3K regulatory subunits exist in excess over the p110 catalytic subunits and therefore free in the cell. p110-independent p85 is unstable and exists in a monomer-dimer equilibrium. Two conformations of dimeric p85 have been reported that are mediated by N-terminal and C-terminal protein domain interactions, respectively. The role of p110-independent p85 is under investigation and it has been found to perform critical adaptor functions, sequestering or influencing compartmentalisation of key signalling proteins. Free p85 has roles in glucose homeostasis, cellular stress pathways, receptor trafficking and cell migration. As a regulator of fundamental pathways, the amount of p110-independent p85 in the cell is critical. Factors that influence the monomer-dimer equilibrium of p110-independent p85 offer additional control over this system, disruption to which likely results in disease. Here we review the current knowledge of the structure and functions of p110-independent class IA PI3K regulatory subunits
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