Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cryoelectron microscopy has been performed on frozen-hydrated pyruvate dehydrogenase complexes from bovine heart and kidney and on various subcomplexes consisting of the dihydrolipoyl transacetylase-based (E2) core and substoichiometric levels of the other two major components, pyruvate dehydrogenase (E1) and dihydrolipoyl dehydrogenase (E3). The diameter of frozen-hydrated pyruvate dehydrogenase complex (PDC) is 50 nm, which is significantly larger than previously reported values. On the basis of micrographs of the subcomplexes, it is concluded that the E1 and E3 are attached to the E2-core complex by extended (4-6 nm maximally) flexible tethers. PDC constructed in this manner would probably collapse and appear smaller than its native size when dehydrated, as was the case in previous electron microscopy studies. The tether linking E1 to the core involves the hinge sequence located between the E1-binding and catalytic domains in the primary sequence of E2, whereas the tether linking E3 is probably derived from a similar hinge-type sequence in component X. Tilting of the E2-based cores and comparison with model structures confirmed that their overall shape is that of a pentagonal dodecahedron. The approximately 6 copies of protein X present in PDC do not appear to be clustered in one or two regions of the complex and are not likely to be symmetrically distributed.
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PMID:Cryoelectron microscopy of mammalian pyruvate dehydrogenase complex. 176 62

The combined orthodontic, orthognathic surgical, and prosthodontic reconstruction of the previously treated bilateral cleft lip and cleft palate of a 20-year-old white man is reviewed. Maxillary arch collapse and severe malocclusion occurred after palatal closure in early childhood with alveolar bone grafting and premaxillectomy. A modified Le Fort I osteotomy, using a jackscrew with a modified posterior hinge, was employed to achieve rapid palatal expansion. In addition, mandibular subapical osteotomy was performed, in conjunction with postoperative orthodontic realignment. Fixed prosthodontic restorations were then used to achieve stability and a more esthetic appearance.
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PMID:Treatment of maxillary arch collapse in an adult cleft palate patient: report of case. 700 12

The function of the human papillomavirus (HPV) E4 proteins is unknown. In cultured epithelial cells the proteins associate with the keratin intermediate filaments (IFs) and, for some E4 types, e.g., HPV type 16 (HPV-16), induce collapse of the keratin networks. An N-terminal leucine-rich motif (LLXLL) is a conserved feature of many E4 proteins. In a previous study we showed that deletion of this region from the HPV-1 and -16 E4 proteins abrogated the localization of the mutant proteins to the keratin cytoskeleton in a simian virus 40-transformed human keratinocyte cell line (S. Roberts, I. Ashmole, L. J. Gibson, S. M. Rookes, G. J. Barton, and P. H. Gallimore, J. Virol. 68:6432-6445, 1994). The E4 proteins of HPV-1 and -16 have little sequence homology except at the N terminus. Therefore, to establish the role of sequences other than those at the N terminus, we have performed a mutational analysis of the HPV-16 E4 protein. The results of the analysis were as follows: (i) similar to findings for the HPV-1 protein, no mutation of HPV-16 E4 sequences (other than the N-terminal leucine motif) results in a mutant protein which fails to colocalize to the keratin IFs; (ii) the C-terminal domain (residues 61 to 92) is not essential for association with the cytoskeleton; and (iii) deletion of C-terminal sequences (residues 84 to 92; LTVIVTLHP) corresponding to part of a domain conserved between mucosal E4 proteins affects the ability of the mutant protein to induce cytoskeletal collapse, despite colocalization with the keratin IFs. Further analysis of this region showed that conserved hydrophobic residues valines 86 and 88 are important. In addition, we show that the HPV-16 E4 protein is detergent insoluble and exists as several disulfide-linked, high-molecular-weight complexes which could represent homo-oligomers. The C-terminal sequences (residues 84 to 92), in particular valines 86 and 88, are important in the formation of these insoluble complexes. The results of this study support our postulate that the E4 proteins include functional domains at the N terminus and the C terminus, with the intervening sequences possibly acting as a flexible hinge.
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PMID:Mutational analysis of the human papillomavirus type 16 E1--E4 protein shows that the C terminus is dispensable for keratin cytoskeleton association but is involved in inducing disruption of the keratin filaments. 909 27

The hairpin ribozyme is a short endonucleolytic RNA motif isolated from a family of related plant virus satellite RNAs. It consists of two independently folding domains, each comprising two Watson-Crick helices flanking a conserved internal loop. The domains need to physically interact (dock) for catalysis of site-specific cleavage and ligation reactions. Using tapping-mode atomic force microscopy in aqueous buffer solution, we were able to produce high quality images of individual hairpin ribozyme molecules with extended terminal helices. Three RNA constructs with either the essential cleavage site guanosine or a detrimental adenosine substitution and with or without a 6-nt insertion to confer flexibility to the interdomain hinge show structural differences that correlate with their ability to form the active docked conformation. The observed contour lengths and shapes are consistent with previous bulk-solution measurements of the transient electric dichroism decays for the same RNA constructs. The active docked construct appears as an asymmetrically docked conformation that might be an indication of a more complicated docking event than a simple collapse around the interdomain hinge.
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PMID:Imaging of single hairpin ribozymes in solution by atomic force microscopy. 1142 63

One hundred ninety-seven patients with unilateral Legg-Calve-Perthes disease (LCPD) were followed-up to skeletal maturity. According to the lateral pillar classification, 142 hips were classified as group B and 55 hips as group C. Radiographs were evaluated for percent of collapse of the femoral head, Waldenstrom stage of disease at diagnosis, Mose sphericity, hinge abduction, lateral acetabular shape, and limb-length discrepancy. The hips were treated either by bedrest and traction in abduction (76), Petrie cast (21), abduction brace (74), or by pelvic or femoral osteotomy (26). One hundred twenty-five hips had less than a 2-mm difference in Mose sphericity at followup. According to the classification of Stulberg et al., 89 hips (45%) were class I, 57 (29%) were class II, 35 (18%) were class III, 12 (6%) were class IV, and 4 (2%) were class V. Analyses revealed statistically significant differences between group B versus group C with regard to the classifications of Stulberg et al. and Mose, lateral acetabular shape, age at onset, and limb-length discrepancy. There was no significant statistical difference with regard to the types of treatment. Containment treatment of a deformed femoral head from LCPD improves the sphericity of the hip and gives 63% satisfactory results according to the Mose classification and 74% satisfactory results according to the Stulberg et al. classification.
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PMID:Treatment of the collapsed femoral head by containment in Legg-Calve-Perthes disease. 1249 36

If you've ever built a house of cards or played a game of Jenga, you know how quickly an ill-timed move can destroy your goal of maintaining equilibrium. The consequence of upsetting one piece of the whole is a common metaphor many safety net providers use to help other healthcare organizations understand their role in the system. The fiscal and physical pressure on just one safety net provider can create a dangerous ripple effect in a community, threatening the stability of other area providers and access to care for the patients they serve. "We have created a complicated tension within our healthcare system," says Stuart H. Altman, Ph.D., HFACHE, professor, National Health Policy, at Brandeis University in Waltham, MA. "If any single major sector of the system is out of balance, the others will be affected in a very negative way." Depending (in part) on geography as well as local and state politics, the fate of "non"-safety net providers can hinge on the success of those organizations whose primary mission is to provide indigent care. "If the safety net fails, the whole healthcare system could potentially collapse because the remaining providers simply cannot handle all of the demand," says C. Duane Dauner, FACHE, president of the California Healthcare Association in Sacramento. The current situations in Washington, D.C., Dallas, and several California counties illustrate this domino effect Dauner describes.
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PMID:Strengthening the safety net. 1471 22

Tumor necrosis factor (TNF) is involved in pathologies like septic shock, inflammatory bowel disease and rheumatoid arthritis. TNF and lipopolysaccharide can incite lethal shock, in which cardiovascular collapse is centrally orchestrated by the vasodilating free radical nitric oxide (NO). However, NO synthase (NOS) inhibition causes increased morbidity and/or mortality, suggesting a dual role for NO. To investigate the potential protective role of NO during TNF shock, we treated mice with TNF with or without NOS inhibition. Experiments in endothelial- NOS- and inducible NOS-deficient mice identified inducible NOS as the source of protective NO. Distinctive TNF-induced lipid peroxidation, especially in liver and kidney, was aggravated by NOS inhibition. In addition, various antioxidant treatments and a phospholipase A2 (PLA2) inhibitor prevented sensitization by NOS inhibition. Together, these in vivo results indicate that induced NO not only causes hemodynamic collapse, but is also essential for curbing TNF-induced oxidative stress, which appears to hinge on PLA2-dependent mechanisms.
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PMID:Dual role of endogenous nitric oxide in tumor necrosis factor shock: induced NO tempers oxidative stress. 1599 Sep 56

Cation-mediated RNA folding from extended to compact, biologically active conformations relies on a temporal balance of forces. The Mg2 +-mediated folding of the Tetrahymena thermophila ribozyme is characterized by rapid nonspecific collapse followed by tertiary-contact-induced compaction. This article focuses on an autonomously folding portion of the Tetrahymena ribozyme, its P4-P6 domain, in order to probe one facet of the rapid collapse: chain flexibility. The time evolution of P4-P6 folding was followed by global and local measures as a function of Mg2 + concentration. While all concentrations of Mg2 + studied are sufficient to screen the charge on the helices, the rates of compaction and tertiary contact formation diverge as the concentration of Mg2 + increases; collapse is greatly accelerated by Mg2 +, while tertiary contact formation is not. These studies highlight the importance of chain stiffness to RNA folding; at 10 mM Mg2 +, a stiff hinge limits the rate of P4-P6 folding. At higher magnesium concentrations, the rate-limiting step shifts from hinge bending to tertiary contact formati
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PMID:Hinge stiffness is a barrier to RNA folding. 1847 29

At the first glance CK2alpha, the catalytic subunit of protein kinase CK2, is a rigid molecule: in contrast to many eukaryotic protein kinases in CK2alpha the canonical regulatory key elements like the activation segment occur exclusively in their typical active conformations. This observation fits well to the constitutive activity of the enzyme, meaning, its independence from phosphorylation or other characteristic control factors. Most CK2alpha structures are based on the enzyme from Zea mays, supplemented by an increasing number of human CK2alpha structures. In the latter a surprising plasticity of important ATP-binding elements - the interdomain hinge region and the glycine-rich loop - was discovered. In fully active CK2alpha the hinge region is open and does not anchor the ATP ribose, but alternatively it can adopt a closed conformation, form hydrogen bonds to the ribose moiety and thus retract the gamma-phospho group from its functional position. In addition to this partially inactive state human CK2alpha was recently found in a fully inactive conformation. It is incompatible with ATP-binding due to a combination of a closed hinge and a collapse of the glycine-rich loop into the ATP cavity. These conformational transitions are apparently correlated with the occupation state of a remote docking site located at the interface to the non-catalytic subunit CK2beta: if CK2beta blocks this site, the fully active conformation of CK2alpha is stabilized, while the binding of certain small molecule seems to favour the partially and fully inactive states. This observation may be exploited to design effective and selective CK2 inhibitors.
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PMID:Conformational plasticity of the catalytic subunit of protein kinase CK2 and its consequences for regulation and drug design. 1979 13

We designed a pentagonal hinge osteotomy procedure for reduction of the wide nasal base of Asians. Minimal dissection was performed on the nasal bone and frontal process of the maxilla. Following determination of the desired width of the nose, partial-thickness osteotomy was performed first, using a hand saw at the midlevel from the midline to the lateral osteotomy line. Then, using a guarded osteotome, lateral osteotomy was performed at the piriform aperture. Thus, the lateral border of the triangle was a full-thickness cut, and the medial border was a partial-thickness cut. With digital pressure, lateral parts of triangular segments were moved medially, leaving the medial hinge intact, causing a greenstick fracture. Thereafter, the nasal framework became a pentagonal structure, and the broad nasal base was narrowed. Seven patients (4 males and 3 females; mean age, 24.6 years) underwent surgery. Average follow-up period was 23.8 months. No occurrence of mucosal injury, infection, step deformity, or airway collapse was observed. It is thought that pentagonal hinge osteotomy might be useful for reduction of the wide nasal base of Asians.
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PMID:Pentagonal hinge osteotomy for reduction of the wide nasal base of Asians. 2294 28


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