Sample records for laminac
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Strain distribution in hot rolled aluminum by photoplastic analysis
DOE Office of Scientific and Technical Information (OSTI.GOV)
Oyinlola, Adeyinka Kofoworola
1974-10-01
A previously developed photomechanic material, Larninac, which excellently simulates the behavior of aluminum in tension has been investigated intensively as a possible modeling material for hot-rolled aluminum billets. Photoplasticity techniques combined with the Moire method have been used to study the behavior of the Laminac mixture in compression. Photoplastic analysis revealed that a Laminac mixture of 60% flexible and 40% rigid resins, compressed or rolled at 40°C, showed the phenomenon of double bulging which has been observed in hot-rolled aluminum billets. The potentiality of the 60:40 Laminac mixture as a possible Simulating material at 40°C is further enhanced by themore » fact that the true stress-true strain curves of cylindrical samples compressed at 40°C correlated very well with true stresstrue strain of identical cylindrical samples of aluminum compressed. at 300°C, 425PC and 500°c.« less
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Nuclear Physics in a biological context
NASA Astrophysics Data System (ADS)
Discher, Dennis
2012-02-01
A solid tissue can be soft like fat or brain, stiff like striated muscle and heart, or rigid like bone -- and of course every cell has a nucleus that contributes in some way small or large to tissue mechanics. Indeed, nuclei generally exhibit rheology and plasticity that reflects both the chromatin and the nuclear envelope proteins called lamins, all of which change in differentiation. Profiling of tissue nuclei shows that the nuclear intermediate filament protein Lamin-A/C varies over 30-fold between adult tissues and scales strongly with micro-elasticity of tissue, while other nuclear envelope components such as Lamin-B exhibit small variations. Lamin-A/C has been implicated in aging syndromes that affect muscle and fat but not brain, and we find nuclei in brain-derived cells are indeed dominated by Lamin-B and are much softer than nuclei derived from muscle cells with predominantly Lamin-A/C. In vitro, matrix elasticity can affect expression of nuclear envelope components in adult stem cells, and major changes in Lamin-A/C are indeed shown to direct lineage with lower levels favoring soft tissue and higher levels promoting rigid tissue lineage. Further molecular studies provide evidence that the nucleus transduces physical stress. References: (1) J.D. Pajerowski, K.N. Dahl, F.L. Zhong, P.J. Sammak, and D.E. Discher. Physical plasticity of the nucleus in stem cell differentiation. PNAS 104: 15619-15624 (2007). (2) A. Buxboim, I. Ivanova, and D.E. Discher. Matrix Elasticity, Cytoskeletal Forces, and Physics of the Nucleus: how deeply do cells `feel' outside and in? Journal of Cell Science 123: 297-308 (2010).
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Cho, Sangkyun; Abbas, Amal; Ivanovska, Irena L.; Xia, Yuntao; Tewari, Manu; Discher, Dennis E.
2018-01-01
ABSTRACT Interphase phosphorylation of lamin-A,C depends dynamically on a cell's microenvironment, including the stiffness of extracellular matrix. However, phosphorylation dynamics is poorly understood for diseased forms such as progerin, a permanently farnesylated mutant of LMNA that accelerates aging of stiff and mechanically stressed tissues. Here, fine-excision alignment mass spectrometry (FEA-MS) is developed to quantify progerin and its phosphorylation levels in patient iPS cells differentiated to mesenchymal stem cells (MSCs). The stoichiometry of total A-type lamins (including progerin) versus B-type lamins measured for Progeria iPS-MSCs prove similar to that of normal MSCs, with total A-type lamins more abundant than B-type lamins. However, progerin behaves more like farnesylated B-type lamins in mechanically-induced segregation from nuclear blebs. Phosphorylation of progerin at multiple sites in iPS-MSCs cultured on rigid plastic is also lower than that of normal lamin-A and C. Reduction of nuclear tension upon i) cell rounding/detachment from plastic, ii) culture on soft gels, and iii) inhibition of actomyosin stress increases phosphorylation and degradation of lamin-C > lamin-A > progerin. Such mechano-sensitivity diminishes, however, with passage as progerin and DNA damage accumulate. Lastly, transcription-regulating retinoids exert equal effects on both diseased and normal A-type lamins, suggesting a differential mechano-responsiveness might best explain the stiff tissue defects in Progeria. PMID:29619860
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Yoshida, Kanako; Kuramitsu, Yasuhiro; Murakami, Kohei; Ryozawa, Shomei; Taba, Kumiko; Kaino, Seiji; Zhang, Xiulian; Sakaida, Isao; Nakamura, Kazuyuki
2011-06-01
TS-1 is an oral anticancer agent containing two biochemical modulators for 5-fluorouracil (5-FU) and tegafur (FT), a metabolically activated prodrug of 5-FU. TS-1 has been recognized as an effective anticancer drug using standard therapies for patients with advanced pancreatic cancer along with gemcitabine. However, a high level of inherent and acquired tumor resistance to TS-1 induces difficulty in the treatment. To identify proteins linked to the TS-1-resistance of pancreatic cancer, we profiled protein expression levels in samples of TS-1-resistant and -sensitive pancreatic cancer cell lines by using two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The cytotoxicity of a 5-FU/5-chloro-2,4-dihydroxypyridine (CDHP) combination towards pancreatic cancer cell lines was evaluated by MTS assay. Panc-1, BxPC-3, MiaPaCa-2 and PK59 showed high sensitivity to the 5-FU/CDHP combination (TS-1-sensitive), whereas PK45p and KLM-1 were much less sensitive (TS-1-resistant). Proteomic analysis showed that eleven spots, including T-complex protein 1 subunit beta, ribonuclease inhibitor, elongation factor 1-delta, peroxiredoxin-2 and superoxide dismutase (Cu-Zn), appeared to be down-regulated, and 29 spots, including hypoxia up-regulated protein 1, lamin-A/C, endoplasmin, fascin and annexin A1, appeared to be up-regulated in TS-1-resistant cells compared with -sensitive cells. These results suggest that the identified proteins showing different expression between TS-1-sensitive and -resistant pancreatic cancer cells possibly relate to TS-1-sensitivity. These findings could be useful to overcome the TS-1-resistance of pancreatic cancer cells.