613 research outputs found
Sleep deprivation increase the expression of inducible heat shock protein 70 in rat gastric mucosa
Aim: To investigate if sleep deprivation is able to increase the expression of inducible heat shock protein 70 in gastric mucosa and its possible role in mucosal defense. Methods: Rats for sleep disruption were placed inside a computerized rotating drum, gastric mucosa was taken from rats with 1, 3 and 7 d sleep deprivation. RT-PCR, immunohistochemistry and Western blotting were used to determine the expression of heat shock protein 70. Ethanol (500 mL.L-1, i.g.) was used to induce gastric mucosa damage. Results: RT-PCR, Western blotting and immunostaining confirmed that the sleep deprivation as a stress resulted in significantly greater expression of inducible heat shock protein 70 in gastric mucosa of rats. After the 500mL.L-1 ethanol challenge, the ulcer area found in the rats with 7 d sleep deprivation (19.15 ± 4.2) mm2 was significantly lower (P<0.01) than the corresponding control (53.7 ± 8.1) mm2. Conclusion: Sleep deprivation as a stress, in addition to lowering the gastric mucosal barrier, is able to stimulate the expression of inducible heat shock protein 70 in gastric mucosa of rats, the heat shock protein 70 may play an important role in gastric mucosal protection.published_or_final_versio
Expression and activities of three inducible enzymes in the healing of gastric ulcers in rats
Aim: To explore the roles of nitric oxide synthase (NOS), heme oxygenase (HO) and cyclooxygenase (COX) in gastric ulceration and to investigate the relationships of the expression and activities of these enzymes at different stages of gastric ulceration. Methods: Gastric ulcers (kissing ulcers) were induced by luminal application of acetic acid. Gastric tissue samples were obtained from the ulcer base, ulcer margin, and non-ulcerated area around the ulcer margin at different time intervals after ulcer induction. The mRNA expression and protein levels of inducible and constitutive isoforms of NOS, HO and COX were analyzed with RT-PCR and Western blotting methods. The activities of the total NOS, inducible NOS (iNOS), HO, and COX were also determined. Results: Differential expression of inducible iNOS, HO-1 and COX-2 and enzyme activities of NOS, HO and COX were found in the gastric ulcer base. High iNOS expression and activity were observed on day 1 to day 3 in severely inflamed ulcer tissues. Maximum expressions of HO-1 and COX-2 and enzyme activities of HO and COX lagged behind that of iNOS, and remained at high levels during the healing phase. Conclusion: The expression and activities of inducible NOS, HO-1 and COX-2 are found to be correlated to different stages of gastric ulceration. Inducible NOS may contribute to ulcer formation while HO-1 and COX-2 may promote ulcer healing.published_or_final_versio
SILAC-based phosphoproteomics reveals an inhibitory role of KSR1 in p53 transcriptional activity via modulation of DBC1
BACKGROUND
We have previously identified kinase suppressor of ras-1 (KSR1) as a potential regulatory gene in breast cancer. KSR1, originally described as a novel protein kinase, has a role in activation of mitogen-activated protein kinases. Emerging evidence has shown that KSR1 may have dual functions as an active kinase as well as a scaffold facilitating multiprotein complex assembly. Although efforts have been made to study the role of KSR1 in certain tumour types, its involvement in breast cancer remains unknown.
METHODS
A quantitative mass spectrometry analysis using stable isotope labelling of amino acids in cell culture (SILAC) was implemented to identify KSR1-regulated phosphoproteins in breast cancer. In vitro luciferase assays, co-immunoprecipitation as well as western blotting experiments were performed to further study the function of KSR1 in breast cancer.
RESULTS
Of significance, proteomic analysis reveals that KSR1 overexpression decreases deleted in breast cancer-1 (DBC1) phosphorylation. Furthermore, we show that KSR1 decreases the transcriptional activity of p53 by reducing the phosphorylation of DBC1, which leads to a reduced interaction of DBC1 with sirtuin-1 (SIRT1); this in turn enables SIRT1 to deacetylate p53.
CONCLUSION
Our findings integrate KSR1 into a network involving DBC1 and SIRT1, which results in the regulation of p53 acetylation and its transcriptional activity
Chinese green tea ameliorates lung injury in cigarette smoke-exposed rats
Background: Epigallocatechin-3-gallate (EGCG), which has been shown to have potent antioxidant effect, comprises 80% of catechins in Chinese green tea. This study was to investigate whether cigarette smoke (CS) exposure would induce lung morphological changes and oxidative stress in the CS-exposed rat model, and whether Chinese green tea (Lung Chen tea with EGCG as its main active ingredient) consumption would alter oxidative stress in sera and lung leading to protection of CS-induced lung damage. Methods: Sprague-Dawley rats were randomly divided into four groups, i.e. sham air (SA), 4% CS, 2% Lung Chen tea plus SA or 4% CS. Exposure to SA or 4% CS was performed for 1 h/day for 56 days in ventilated smoking chambers. Sera and lung tissues were collected 24 h after last CS exposure for histology and all biochemical assays. Results: Airspace enlargement and goblet cell hyperplasia were observed after 56-day CS exposure alone, which were abolished in the presence of green tea consumption. Serum 8-isoprostane level was significantly elevated (p < 0.01) as well as lung superoxide dismutase (SOD) and catalase activities in CS-exposed rats compared to SA-exposed rats (p < 0.05), which returned to the levels of SA-exposed rats after Chinese green tea consumption. Conclusion: These results indicate that increased levels of systemic oxidative stress after CS exposure play an important role in the induction of lung damage. Chinese green tea may have the ability to suppress CS-induced oxidative stress that leads to protection of lung injury. © 2009 Elsevier Ltd. All rights reserved.postprin
Radio emission from Supernova Remnants
The explosion of a supernova releases almost instantaneously about 10^51 ergs
of mechanic energy, changing irreversibly the physical and chemical properties
of large regions in the galaxies. The stellar ejecta, the nebula resulting from
the powerful shock waves, and sometimes a compact stellar remnant, constitute a
supernova remnant (SNR). They can radiate their energy across the whole
electromagnetic spectrum, but the great majority are radio sources. Almost 70
years after the first detection of radio emission coming from a SNR, great
progress has been achieved in the comprehension of their physical
characteristics and evolution. We review the present knowledge of different
aspects of radio remnants, focusing on sources of the Milky Way and the
Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief
overview of theoretical background, analyze morphology and polarization
properties, and review and critical discuss different methods applied to
determine the radio spectrum and distances. The consequences of the interaction
between the SNR shocks and the surrounding medium are examined, including the
question of whether SNRs can trigger the formation of new stars. Cases of
multispectral comparison are presented. A section is devoted to reviewing
recent results of radio SNRs in the Magellanic Clouds, with particular emphasis
on the radio properties of SN 1987A, an ideal laboratory to investigate
dynamical evolution of an SNR in near real time. The review concludes with a
summary of issues on radio SNRs that deserve further study, and analyzing the
prospects for future research with the latest generation radio telescopes.Comment: Revised version. 48 pages, 15 figure
Experimental and theoretical studies of nanofluid thermal conductivity enhancement: a review
Nanofluids, i.e., well-dispersed (metallic) nanoparticles at low- volume fractions in liquids, may enhance the mixture's thermal conductivity, knf, over the base-fluid values. Thus, they are potentially useful for advanced cooling of micro-systems. Focusing mainly on dilute suspensions of well-dispersed spherical nanoparticles in water or ethylene glycol, recent experimental observations, associated measurement techniques, and new theories as well as useful correlations have been reviewed
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