The present study investigated the effects of homocysteine on platelet activation induced by collagen and the downstream signaling pathways potentially involved in these effects.
Washed human ...platelets were incubated with homocysteine and collagen type I. The effects of homocysteine on platelet aggregation and adhesion and the tyrosine phosphorylation of total platelet proteins, Src kinase, and phospholipase-Cγ2 (PLCγ2) were studied.
Homocysteine (10 to 100 μM) increased collagen-induced aggregation of washed platelets. Upon homocysteine (50 to 100 μM) treatment, platelet deposition to collagen-coated surface was significantly augmented under the low shear rate model (100/s) but not under the high shear rate model (1600/s). Collagen-stimulated total protein tyrosine phosphorylation in platelets was further enhanced by incubation with homocysteine. This effect was almost abrogated by genistein. Homocysteine potentiated collagen-stimulated tyrosine phosphorylation of the Src kinase and PLCγ2, which was partly decreased by integrin β
1 blocking antibody.
Homocysteine (at 10 to 100 μM) potentiates collagen type I induced-platelet activation through signaling components of glycoprotein VI and integrin α
2β
1 pathway. Our results suggested that upregulation of tyrosine phosphorylation of proteins such as Src and PLCγ2 is involved in the downstream signaling events of homocysteine stimulation in human platelets.
Cantharidin, a natural toxin, is the active substance of mylabris and has antitumor effects in man. Norcantharidin, the demethylated analogue of cantharidin, has been used in the treatment of ...patients with primary hepatoma and those with leukopenia in China. The present study was designed to investigate whether norcantharidin exerts cytotoxic activity against colorectal cancer cells by inducing apoptosis and to examine the possible mechanism in the phenomenon.
Inhibition of proliferation of norcantharidin on Colo205, HT-29, and SW480 colorectal cancer cells was determined by the trypan blue dye exclusion test. Apoptosis of norcantharidin-treated cells was determined by morphological analysis, agarose gel DNA electrophoresis, and quantitated by flow cytometry after staining with propidium iodide. Cell cycle and the cell surface expression of the CD95/CD95 ligand were evaluated by flow cytometry. Caspase 8-like protease and protein phosphatase 1 and 2A activities were also analyzed.
Treatment with norcantharidin of colorectal cancer cells not only inhibited cell proliferation, but also induced apoptosis. Norcantharidin induced apoptosis mainly in two phases: rapid apoptosis in S-phase cells and delayed apoptosis in G2/M arrested cells. Treatment with norcantharidin resulted in an upregulation of the CD95 receptor and CD95 ligand on the cell surface. Furthermore, stimulation with anti-CD95 monoclonal antibody (mAb) resulted in further induction of apoptosis after treatment with norcantharidin. In addition, the apoptosis-inducing effect of norcantharidin was almost completely inhibited by anti-CD95 ligand mAb. Norcantharidin-treated cells showed the activation of caspase 8. Both zVAD-FMK (a broad range caspase inhibitor) and IETD-FMK (a caspase-8 inhibitor) showed apparent inhibition of the apoptosis-inducing effect. Norcantharidin did not show an inhibitory effect on protein phosphatase.
These results suggest that norcantharidin triggers apoptosis in colorectal cancer cell lines via the activation of the CD95 receptor/ligand system, and that this agent may be useful for developing new therapeutic regimens for the treatment of colorectal carcinoma.
Pinus massoniana (Masson's pine) is a widespread tree species in central and southern China and northern Vietnam; it is valued for rosin and paper production. Despite the significant economic value ...of Masson's pine, little work has been done on its molecular genetics. We developed 318 SSR primers from genome sequences of P. massoniana, and we identified 10 polymorphic markers. The number of alleles in the population of P. massoniana that we examined ranged from two to four, and the Shannon diversity index ranged from 0.150 to 1.133. Cross-species transferability of the 318 SSRs was also analyzed in the slash pine (Pinus elliottii), the Caribbean pine (Pinus caribaea) and the Yunnan pine (Pinus yunnanensis); 15, 10, and 10 primer pairs generated polymorphic amplification, respectively. These sets of polymorphic SSR markers will be useful for population genetics studies of P. massoniana, for genetic identification of interspecific hybridization, and for phylogeographic studies of Pinus spp.
Absract
Fresh lotus pods were treated with 1‐methylcyclopropene (1‐MCP) at a concentration of 0.5 μL L−1 for 24 h at 25°C and then stored at 25°C for 8 days. First, their quality and physiological ...changes during storage were measured in terms of visual appearance, respiration rate, firmness, and the contents of sugars, protein, total phenolics and malondialdehyde (MDA). The results showed that the 1‐MCP treatment reduced the browning of fresh lotus pods, and inhibited the respiration rate during storage. In addition, the 1‐MCP treatment alleviated changes in firmness, delayed starch and protein degradation, and the accumulation of reducing sugars and total sugars in lotus seeds, preserving the good taste of lotus seeds. Moreover, the 1‐MCP treatment alleviated the increase of MDA and effectively inhibited the decrease in total phenolics in lotus seeds during days 6 to 8 of storage. Meanwhile, the results of antioxidant capacity in lotus seeds indicated that 1‐MCP not only sustained a higher level of 1,1‐diphenyl‐2‐picrylhydrazyl free radical scavenging activity, but also increased the activities of superoxide dismutase, catalase and peroxidase throughout the storage period. However, the 1‐MCP treatment reduced polyphenol oxidase activity in seeds relative to the control. Moreover, we found that the adenosine triphosphate content and energy charge during the last 4 days of storage were higher in 1‐MCP‐treated seeds than in the control. These results indicated that the use of 0.5 μL L−1 1‐MCP provided an effective method, via multiple lines of evidence, to delay the postharvest senescence of fresh lotus pods and seeds.
Mathematical modeling for power dc-dc converters is a historical problem accompanying dc-dc conversion technology since the 1940s. The traditional mathematical modeling is not available for complex ...structure converters since the differential equation order increases very high. We have to search for other ways to establish mathematical modeling for power dc-dc converters. We have defined energy factor (EF) and new mathematical modeling for power dc-dc converters that have attracted much attention in recent years. This paper describes the small signal analysis of EF and mathematical modeling for power dc-dc converters in continuous conduction mode and discontinuous conduction mode. EF and the subsequential parameters can illustrate the unit-step response and interference recovery. This investigation may be helpful for system design and dc-dc converters characteristics. Two dc-dc converters: Buck converter and super-lift Luo-converter as the samples, are analyzed in this paper to demonstrate the applications of EF, pumping energy, stored energy (SE), capacitor/inductor SE ratio, energy losses, time constant tau, and damping time constant tau d
Osteoporosis (OP) is a prevalent physiological bone disorder that attribute to elevated bone absorption and disrupted bone formation. Accumulating evidence has reported that epigenetic modifications ...may participate in mechanisms of OP. In this work, we aimed at determining the expression pattern and effects of circular RNA GLIS2 on OP. The concentrations of circGLIS2, miR-214-3p, and Smad5 in clinical samples of OP patients and healthy donors were quantified by qRT-PCR. Human bone marrow stem cells (BMSCs) were stimulated with osteogenic medium to promote bone development. The protein expression of osteogenic biomarkers, such asosteocalcin (OCN) and osteopontin (OPN), were assessed with western blotting. The expression of circGLIS2 and Smad5 were decreased and miR-214-3p values was elevated in clinical specimens of OP patients in comparison with the healthy donors. The expression of circGLIS2 was notably elevated in BMSCs upon osteogenic differentiation. Knockdown of circGLIS2 notably suppressed the OPN and OCN levels, decreased the ALP activity and the Alizarin Red S staining. Overexpression of Smad5 and inhibition of miR-214-3p could recover the suppressed osteogenic differentiation that caused by circGLIS2 depletion. In conclusion, circGLIS2 sponges miR-214-3p to upregulate Smad5, the which enhanced osteogenic differentiation of the BMSCs. Our finding provided a potential novel target for the therapeutic strategies of OP.
Failure analysis of IEU drill pipe wash out Lu, Shuanlu; Feng, Yaorong; Luo, Faqian ...
International journal of fatigue,
10/2005, Letnik:
27, Številka:
10
Journal Article, Conference Proceeding
Recenzirano
Many 127.0×9.19
mm IEU G105 drill pipe failures of wash out occurred after 2367
h of pure drilling time and 8726
m of penetration footage. This paper gives a detailed investigation on these failures ...and a systematic analysis is carried out on service and loading conditions of the drill pipes. Measurement and inspection were performed on configuration dimensions, chemical composition, mechanical performance, metallography, macro-fractography, micro-fractography, and corrosion products. Configuration stresses at the crack positions of the drill pipe were calculated by FEA. Crack extending velocity of the drill pipe material under corrosion medium was also measured. It is thought from test and analysis results that the drill pipe wash out or fracture accidents were premature corrosion fatigue failure accident. The failure courses were as the following: corrosion pits occurred first on the internal surface at the stress concentrating area of the drill pipe, and then fatigue cracks initiated in pit bottoms, and washed out or fractured subsequently as cracks penetrated through the wall thickness of the drill pipe. The reasons of drill pipe wash out were related to configuration, material quality, and load condition of the drill pipe string.
It is well known that zirconia materials have good biocompatibility; however, little is known regarding the mechanism by which cells attach to these materials. The purpose of this study is to ...elucidate the mechanism of cell attachment.
In this study, we examined the surface characteristics of ceria-stabilized zirconia/alumina nanocomposite (NANOZR), yttria-stabilized zirconia (Y-TZP) and commercially pure titanium (CpTi), and we evaluated the initial response of osteoblast-like cells to them with different inhibitors.
Under the same polishing treatment, the three materials, NANOZR, Y-TZP and CpTi, show similar surface wettability but different surface roughness. Osteoblasts could adhere to the surface of all three materials, and spindle shapes were clearer in serum-containing media compared to PBS and serum-free culture media, suggesting that serum-contained proteins are helpful for the initial cell adhesion and spreading. Cell adhesion and proliferation were disrupted in the presence of EDTA. RGD-peptide interfered with cell proliferation by affecting cell protrusion and stress fibers. Monoclonal antibody against non-RGD type integrin α
β
enhanced proliferation in Y-TZP, CpTi and culture dish but not in NANOZR. Cell proliferation on NANOZR was specifically inhibited in the presence of heparin. Furthermore, under heparin administration, spindle shape formation was maintained but actin cytoskeleton was disrupted, resulting in loose cellular spreading.
These results suggest that RGD type integrins and heparin-sensitive protein in coordination regulate cell morphology and proliferation on NANOZR, through the regulation of cell polarity and stress fiber formation, respectively.
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