High-Bonding-Strength Polyimide Films Achieved via Thermal Management and Surface Activation.

In this study, thermal and argon (Ar) plasma/wetting treatments were combined to enhance the bonding strength of polyimide (PI) films. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was used to analyze the changes in the PI imidization degrees. The contact angles of the PI films were also measured. The results show that the contact angles of the fully cured PI films markedly decreased from 78.54° to 26.05° after the Ar plasma treatments. X-ray photoelectron spectroscopy (XPS) analysis was also conducted on the PI surfaces. We found that the intensities of the C-OH and C-N-H bonds increased from 0% to 13% and 29% to 57%, respectively, after Ar plasma activation. Such increases in the C-OH and C-N-H intensities could be attributed to the generation of dangling bonds and the breakage of the imide ring or polymer long chains. Shear tests were also conducted to characterize the bonding strength of the PI films, which, after being treated with the appropriate parameters of temperature, plasma power, and wetting droplets, was found to be excellent at greater than 35.3 MPa.

Expression of the class II tumor suppressor gene RIG1 is directly regulated by p53 tumor suppressor in cancer cell lines.

Recent studies indicated that the RIG1 (RARRES3/TIG3) plays an important role in cell proliferation, differentiation, and apoptosis. However, the regulatory mechanism of RIG1 gene expression has not been clearly elucidated. In this study, we identified a functional p53 response element (p53RE) in the RIG1 gene promoter. Transfection studies revealed that the RIG1 promoter activity was greatly enhanced by wild type but not mutated p53 protein. Sequence specific mutation of the p53RE abolished p53-mediated transactivation. Specific binding of p53 protein to the rig-p53RE was demonstrated using electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay. Further studies confirmed that the expression of RIG1 mRNA and protein is enhanced through increased p53 protein in HepG2 or in H24-H1299 cells. In conclusion, our results indicated that RIG1 gene is a downstream target of p53 in cancer cell lines.

Distinct and shared cerebral activations in processing innocuous versus noxious contact heat revealed by functional magnetic resonance imaging.

Whether innocuous heat (IH)-exclusive brain regions exist and whether patterns of cerebral responses to IH and noxious heat (NH) stimulations are similar remain elusive. We hypothesized that distinct and shared cerebral networks were evoked by each type of stimulus. Twelve normal subjects participated in a functional MRI study with rapidly ramped IH (38 degrees C) and NH (44 degrees C) applied to the foot. Group activation maps demonstrated three patterns of cerebral activation: (1) IH-responsive only in the inferior parietal lobule (IPL); (2) NH-responsive only in the primary somatosensory cortex (S1), secondary somatosensory cortex (S2), posterior insular cortex (IC), and premotor area (PMA); and (3) both IH- and NH-responsive in the middle frontal gyrus, inferior frontal gyrus (IFG), anterior IC, cerebellum, superior frontal gyrus, supplementary motor area, thalamus, anterior cingulate cortex (ACC), lentiform nucleus (LN), and midbrain. According to the temporal analysis of regions of interest, the IPL exclusively responded to IH, and the S2, posterior IC, and PMA were exclusively activated by NH throughout the entire period of stimulation. The IFG, thalamus, ACC, and LN responded differently during different phases of IH versus NH stimulation, and the NH-responsive-only S1 responded transiently during the early phase of IH stimulation. BOLD signals in bilateral IPLs were specifically correlated with the ratings of IH sensation, while responses in the contralateral S1 and S2 were correlated with pain intensity. These results suggest that distinct and shared spatial and temporal patterns of cerebral networks are responsible for the perception of IH and NH.

Identification and characterization of the retinoic acid response elements in the human RIG1 gene promoter.

The expression of retinoic acid-induced gene 1 (RIG1), a class II tumor suppressor gene, is induced in cells treated with retinoids. RIG1 has been shown to express ubiquitously and the increased expression of this gene appears to suppress cell proliferation. Recent studies also demonstrated that this gene may play an important role in cell differentiation and the progression of cancer. In spite of the remarkable regulatory role of this protein, the molecular mechanism of RIG1 expression induced by retinoids remains to be clarified. The present study was designed to study the molecular mechanism underlying the all-trans retinoic acid (atRA)-mediated induction of RIG1 gene expression. Polymerase chain reaction was used to generate a total of 10 luciferase constructs that contain various fragments of the RIG1 5'-genomic region. These constructs were then transfected into human gastric cancer SC-M1 and breast cancer T47D cells for transactivation analysis. atRA exhibited a significant induction in luciferase activity only through the -4910/-5509 fragment of the 5'-genomic region of RIG1 gene relative to the translation initiation site. Further analysis of this promoter fragment indicated that the primary atRA response region is located in between -5048 and -5403 of the RIG1 gene. Within this region, a direct repeat sequence with five nucleotide spacing, 5'-TGACCTctattTGCCCT-3' (DR5, -5243/-5259), and an inverted repeat sequence with six nucleotide spacing, 5'-AGGCCAtggtaaTGGCCT-3' (IR6, -5323/-5340), were identified. Deletion and mutation of the DR5, but not the IR6 element, abolished the atRA-mediated activity. Electrophoretic mobility shift assays with nuclear extract from atRA-treated cells indicated the binding of retinoic acid receptor (RAR) and retinoid X receptor (RXR) heterodimers specifically to this response element. In addition to the functional DR5, the region contains many other potential sequence elements that are required to maximize the atRA-mediated induction. Taken together, we have identified and characterized the functional atRA response element that is responsible for the atRA-mediated induction of RIG1 gene.