Publications by authors named "Efrain Siller"

Background: Palliative care aims to improve or maintain quality of life for patients with life-limiting or life-threatening diseases. Limited research shows that palliative care is associated with reduced intensive care unit length of stay and use of high-cost resources.

Methods: This was an observational, non-experimental comparison group study on all patients 18 years or older admitted to any intensive care unit (ICU) at Memorial Hermann - Texas Medical Center for 7 to 30 days from August 2013 to December 2015.

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Genetic code redundancy allows most amino acids to be encoded by multiple codons that are non-randomly distributed along coding sequences. An accepted theory explaining the biological significance of such non-uniform codon selection is that codons are translated at different speeds. Thus, varying codon placement along a message may confer variable rates of polypeptide emergence from the ribosome, which may influence the capacity to fold toward the native state.

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Alzheimer disease (AD) is associated with extracellular deposition of proteolytic fragments of amyloid precursor protein (APP). Although mutations in APP and proteases that mediate its processing are known to result in familial, early onset forms of AD, the mechanisms underlying the more common sporadic, yet genetically complex forms of the disease are still unclear. Four single-nucleotide polymorphisms within the ubiquilin-1 gene have been shown to be genetically associated with AD, implicating its gene product in the pathogenesis of late onset AD.

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Various human neurodegenerative disorders are associated with processes that involve misfolding of polypeptide chains. These so-called protein misfolding disorders include Alzheimer's and Parkinson's diseases and an increasing number of inherited syndromes that affect neurons involved in motor control circuits throughout the central nervous system. The reasons behind the particular susceptibility of neurons to misfolded proteins are currently not known.

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The great diversity of structural conformations available to proteins allows this class of molecules to carry out the vast majority of biochemical functions in the cell. In order to function adequately, proteins must be synthesized, folded/assembled and degraded with great temporal and spatial accuracy. Precise coordination of multiple processes, including ribosome assembly and movement along mRNA, charging and recycling of tRNAs, recruitment and action of molecular chaperones, and tight control of the degradation machinery is essential to create and maintain a stable proteome.

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Protein supra-domains are defined as recurring arrangements of two or three domains present adjacent to each other along a polypeptide chain. Such combinations have novel functions beyond those of the individual partner domains that compose them, which can exist in isolation. Here, we describe a new type of large supra-domain (approximately 360 residues) in which one of the component partners (approximately 200 residues) appears to be incapable of existing in a context other than immediately adjacent to the C-terminus of the well-characterized Hsp90-like ATPase domain.

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The mechanisms for de novo protein folding differ significantly between bacteria and eukaryotes, as evidenced by the often observed poor yields of native eukaryotic proteins upon recombinant production in bacterial systems. Polypeptide synthesis rates are faster in bacteria than in eukaryotes, but the effects of general variations in translation rates on protein folding efficiency have remained largely unexplored. By employing Escherichia coli cells with mutant ribosomes whose translation speed can be modulated, we show here that reducing polypeptide elongation rates leads to enhanced folding of diverse proteins of eukaryotic origin.

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