Although skeletal muscle fiber types are often defined as belonging to discrete categories, many muscles possess fibers with intermediate phenotypes. These hybrid fiber types can be identified by their expression of two or more myosin heavy chain (MHC) isoforms within the same single fiber. In mouse muscles, the most common hybrid fibers are those coexpressing the IIX and IIB MHC isoforms. In the present study, we focused on these IIX/IIB fibers from normal mouse muscles to determine the relative proportions of MHC isoforms at both the protein and mRNA levels and to examine the longitudinal distribution of isoforms within single fibers. We found that IIX/IIB hybrids represent ∼25 and 50% of the fibers in the mouse tibialis anterior and brachioradialis, respectively. The relative proportion of the IIX and IIB isoforms in these fibers spans a continuum, from predominantly IIB-like hybrids to IIX-like hybrids. Quantitative assessment of mRNA levels using real-time PCR from single fibers indicated that IIB expression dominated over IIX expression in most fibers and that a general correlation existed between mRNA isoform levels and MHC protein content. However, the match between mRNA levels and protein content was not precise. Finally, we measured MHC isoform proportions in adjacent fiber segments and discovered that ∼30% of hybrids possessed significant differences in isoform content along their length. In some instances, the muscle fiber type as defined by MHC content changed completely along the length of a fiber. This pattern of asymmetrical MHC isoform content along the length of single fibers suggests that the multiple myonuclei of a muscle fiber may express distinct myofibrillar isoforms in an uncoordinated fashion.
BackgroundThe aim of the study was to identify the incidence and the predictors of recurrence after curative resection and the clinical significance of epithelial-mesenchymal transition (EMT) and stem cell-like phenotypes in gastric cancer.MethodsIn a total of 1,463 patients that underwent curative resection for gastric cancer between January 2001 and January 2008 at Drum Tower Hospital, 402 (27.5%) experienced recurrence. They were divided into early recurrence (within two years) and late recurrence (more than two years). The clinicopathological characteristics, including five EMT-related proteins (Snail-1, ZEB-1, E-cadherin, vimentin, and β-catenin) and the gastric cancer stem cell markers CD44 and CD54, therapeutic modalities, survival time after recurrence, and recurrence patterns were compared between the two groups.ResultsLoss of E-cadherin expression and aberrant expression of vimentin and the known gastric cancer stem cell maker CD44 were significantly associated with aggressive clinicopathologic features. Multivariate analysis showed that stage III gastric cancer patients with early recurrence had larger tumors and more lymph node metastasis, coupled with aberrant expression EMT and cancer stem cell marker, than patients with late recurrence. Early recurrence was associated with more distant metastasis than late recurrence and patients tended to die within two years of recurrence.ConclusionsCombined EMT with cancer stem cell-like marker is a predictor of recurrence after radical resection for gastric cancer. Advanced TNM stage was associated with early cancer death after recurrence.
Due to its single-stage high head, compact structure, convenient maintenance, low cost and high reliability, the high-speed centrifugal pump has been widely used in refining, petrochemical, chemical industry, and aerospace engineering fields. However, as the speed increases, the increasingly high demand for stability is showing and cavitation characteristics of the high-speed centrifugal pump is emerging. Reducing the mechanical vibration, hydraulic losses and improving the pressure distribution of the high-speed pump have become one of the main research fields for high-speed pumps. Three types of splitter blades were designed in this paper. Numerical simulations of the 3D steady flow in the high-speed pump have been carried out by using the software ANSYS CFX 12.0 and the comparative analysis of the velocity, pressure distributions and fluid mechanics in the high-speed pump under three different flow conditions were also carried out,Respectively. The effects of splitter blades on the high-speed pump performance were studied by analyzing both its inner flow field and hydraulic performance. The calculated H-Q curve of the high-speed pump was compared with the test results, and they agreed well with each other. The relative error of head at design conditions was lower than that at the non-design conditions.
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