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T M Chou

Publications and source records attributed to T M Chou.

76 records · Page 5Linked to original sources
PubMed1985

Tropomyosin lysine reactivities and relationship to coiled-coil structure.

We have carried out a detailed analysis of tropomyosin structure using lysines as specific probes for the protein surface in regions of the molecule that have not been investigated by other methods. We have measured the relative reactivities of lysines in rabbit skeletal muscle alpha, alpha-tropomyosin with acetic anhydride using a competitive labeling procedure. We have identified 37 of 39 lysines and find that they range 20-fold in reactivity. The observed reactivities are related to the coiled-coil model of the tropomyosin molecule [Crick, F.H.C. (1953) Acta Crystallogr. 6, 689-697; McLachlan, A.D., Stewart, M., & Smillie, L.B. (1975) J. Mol. Biol. 98, 281-291] and other available chemical and physical information about the structure. In most cases, the observed lysine reactivities can be explained by allowable interactions with neighboring amino acid side chains on the same or facing alpha-helix. However, we found no correlation between reactivity and helical position of a given lysine. For example, lysines in the outer helical positions included lysines of low as well as high reactivity, indicating that they vary widely in their accessibility to solvent and that the coiled coil is heterogeneous along its length. Furthermore, the middle of the molecule (residues 126-182) that is susceptible to proteolysis and known to be the least stable region of the protein also contains some of the least and most reactive lysines. We have discussed the implications of our results on our understanding the structures of tropomyosin and other coiled-coil proteins as well as globular proteins containing helical regions.

Acetates↗
PubMedDate not supplied

Cardiogenic shock: thrombolysis or angioplasty?

Cardiogenic shock (CGS) occurs in 3 to 20% of patients presenting with acute myocardial infarction (MI), and it generally involves dysfunction of at least 40% of the total myocardial mass. Prior to the advent of balloon angioplasty and thrombolysis, in-hospital mortality was greater than 75%. This mortality rate has been consistent in reported series despite the advent of cardiac intensive care units, vasopressor, inotropic, and vasodilator therapy. Intra-aortic balloon counterpulsation therapy provides hemodynamic improvement, and it may provide some mortality benefit when used in conjunction with appropriate revascularization. Survival studies have shown that patency of the infarct-related artery is a strong predictor of survival. No randomized trials have been completed to examine which reperfusion therapy best treats this emergent situation. Subgroup analysis of large scale, multicenter trials, although underpowered, has shown no improvement in mortality with use of thrombolytic agents, leading many to advise use of mechanical intervention. In patients who present with acute MI with contraindications to thrombolysis, primary angioplasty is the treatment of choice. At selected centers, primary angioplasty is comparable to or better than thrombolytic therapy for patients presenting with acute MI, with or without CGS. Studies examining angioplasty in patients with CGS have shown high procedural success rates (75%) and reduced in-hospital mortality (44%), particularly in those patients with successful revascularization. Emergency bypass surgery may improve survival, but it is costly, unavailable to many, and often leads to excessive delays in therapy. If available, we believe that primary angioplasty is the treatment of choice for patients with CGS.

Angioplasty, Balloon↗
PubMedDate not supplied

Tuberous sclerosis in the premature infant: a report of a case with immunohistochemistry on the CNS.

Numerous hard cortical nodules, a large subependymal giant-cell astrocytoma and a massive rhabdomyoma were described in a hydropic infant of 31 weeks gestation who lived only four hours. With six other documented cases, tuberous sclerosis in premature infants was reviewed in the hope to pinpoint the early lesions in the CNS and heart. Three premature infants including the present case with tuberous sclerosis presented as hydrops fetalis, and all three had a massive rhabdomyoma. Immunohistochemistry on the CNS lesions disclosed aggregates of bizarre giant cells, which concomitantly expressed epitopes for astroglial, oligodendroglial and neuronal phenotypes in the subpial, cortical, subcortical and subependymal zones. The findings strongly indicate that hamartomatous differentiation of pluripotential germinal neuroglia in the subependymal layer establishes early in the gestational stage and causes aberrant and/or arrested migration towards the cortical surfaces.

Brain↗