Amyloid-beta peptide induces time dependent biphasic change of membrane phase properties in DITNC cells [abstract]

Abstract only availableAmyloid-beta peptide (Aβ) has been widely implicated in the pathogenesis of Alzheimer's disease (AD). In AD patients amyloid plaques accumulate extensively in the brain, a pathological archetype of the disease. To elucidate one pathway that contributes to AD dysfunction, we demonstrate that oligomeric Aβ1-42 alters the membrane phase properties of DITNC cells time-dependently, with the phase change made quantifiable through fluorescence microscopy and GP analysis. Initially, after oligomeric Aβ1-42 treatment the phase properties became more liquid-crystalline, and subsequently, after 2-3 hours the phase became more gel-like. However, in lipid vesicles the change in membrane phase properties wasn't biphasic; the phase became only more liquid-crystalline, indicating the role of cell signaling in the phenomenon. Western blot analysis demonstrated the ability of oligomeric Aβ1-42 to increase levels of phosphorylated cPLA2 on a time scale corresponding to the observed change in membrane phase, implicating cPLA2 as a likely contributor to the liquid-crystalline to gel transition, with its activation and translocation to the membrane likely the cause of the specific time frame associated with the liquid-crystalline to gel transition. Co-treatment of oligomeric Aβ1-42 with MAFP, an inhibitor of iPLA2 and cPLA2 caused the membrane to become only more liquid crystalline, while oligomeric Aβ1-42 + BEL, a specific inhibitor of iPLA2, resulted in the previously observed biphasic transition, eliminating iPLA2 as a contributor to the phenomenon. Additionally, Aβ1-42 + Apocynine, an antioxidant, caused the membrane to become only more liquid crystalline, which more specifically revealed oligomeric Aβ1-42 triggers the activation of cPLA2 through ROS generation, likely through NADPH oxidase, activating the MAPK cascade. Evaluating the effect of oligomeric Aβ1-42 on membrane phase properties provides a different view of a widely implicated pathogen in AD, revealing that it acts both to immediately cause the membrane to become more liquid-crystalline, while triggering cPLA2 to change the membrane phase to gel-like over time.College of Engineering Undergraduate Research Optio

Neural Cell 3D Microtissue Formation Is Marked by Cytokines' Up-Regulation

Cells cultured in three dimensional (3D) scaffolds as opposed to traditional two-dimensional (2D) substrates have been considered more physiologically relevant based on their superior ability to emulate the in vivo environment. Combined with stem cell technology, 3D cell cultures can provide a promising alternative for use in cell-based assays or biosensors in non-clinical drug discovery studies. To advance 3D culture technology, a case has been made for identifying and validating three-dimensionality biomarkers. With this goal in mind, we conducted a transcriptomic expression comparison among neural progenitor cells cultured on 2D substrates, 3D porous polystyrene scaffolds, and as 3D neurospheres (in vivo surrogate). Up-regulation of cytokines as a group in 3D and neurospheres was observed. A group of 13 cytokines were commonly up-regulated in cells cultured in polystyrene scaffolds and neurospheres, suggesting potential for any or a combination from this list to serve as three-dimensionality biomarkers. These results are supportive of further cytokine identification and validation studies with cells from non-neural tissue

Postoperative hyperphosphatemia significantly associates with adverse survival in colorectal cancer patients

BACKGROUND: Hyperphosphatemia has been implicated in the development and treatment of various cancers. However, whether it can be used as a direct prognostic marker of colorectal cancer (CRC) has remained unexplored. Given new insights into the importance of hyperphosphatemia in CRC, we sought to evaluate the association of hyperphosphatemia with the clinical outcomes of this disease. METHODS: In a retrospective analysis of a well-characterized clinic-based cohort with 1,241 CRC patients, we assessed the association of postoperative hyperphosphatemia with patient overall survival. RESULTS: Postoperative hyperphosphatemia measured within the first month after surgery was significantly associated with CRC survival. Compared to patients with a normal phosphate level, those with hyperphosphatemia exhibited a significant unfavorable overall survival with a hazard ratio (HR) of 1.84 (95% confidence interval [CI] 1.49–2.29, P=2.6×10(−8), (log-rank P=1.2×10(−7)). Stratified analyses indicated the association was more pronounced in patients with colon (HR=2.00, 95% CI 1.57–2.56, P=3.17×10(−8)) but not rectal cancer (HR=0.96, 95% CI 0.58–1.59, P=0.889) (P interaction=0.023), as well as in those not receiving chemotherapy (HR=2.15, 95% CI 1.59–2.90, P=6.2×10(−7)) but not in those receiving chemotherapy (HR=1.30, 95% CI 0.92–1.82, P=0.136) (P interaction=0.012). Flexible parametric survival model demonstrated that the increased risk for death conferred by postoperative hyperphosphatemia persisted over 150 months after surgery. CONCLUSION: Our data indicated that postoperative hyperphosphatemia might be used as a prognostic marker of CRC patients after surgery. Since phosphate level is routinely tested in clinics, it may be incorporated into clinical models to predict CRC survival

Cell-free circulating mitochondrial DNA content and risk of hepatocellular carcinoma in patients with chronic HBV infection.

Recent studies have demonstrated a potential link between circulating cell-free mitochondrial DNA (mtDNA) content and cancers. However, there is no study evaluating the association between circulating mtDNA as a non-invasive marker of hepatocellular carcinoma (HCC) risk. We conducted a nested case-control study to determine circulating mtDNA content in serum samples from 116 HBV-related HCC cases and 232 frequency-matched cancer-free HBV controls, and evaluate the retrospective association between mtDNA content and HCC risk using logistic regression and their temporal relationship using a mixed effects model. HCC cases had significantly lower circulating mtDNA content than controls (1.06 versus 2.47, P = 1.7 × 10(-5)). Compared to HBV patients with higher mtDNA content, those with lower mtDNA content had a significantly increased risk of HCC with an odds ratio (OR) of 2.19 (95% confidence interval [CI] 1.28-3.72, P = 0.004). Quartile analyses revealed a significant dose-dependent effect (Ptrend = 0.001) for this association. In a pilot longitudinal sub-cohort of 14 matched cases-control pairs, we observed a trend of dramatically decreased mtDNA content in cases and slightly decreased mtDNA content in controls, with a significant interaction of case-control status with time (Pinteraction = 0.049). Our findings suggest that circulating mtDNA is a potential novel non-invasive biomarker of HCC risk in HBV patients

CPLA2: key enzyme for astroctytic cell membrane phase property change induced by abeta

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on April 14, 2008)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2007.Dissertations, Academic -- University of Missouri--Columbia -- Biological engineering.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The interaction of amyloid beta peptide (A[beta]) and cell membrane is believed to be the basis of its biological function including its toxicity to neurons, thus it is important to understand how A[beta] affects cell membrane properties. Contradictory observations have been reported on A [beta]'s effect on membrane fluidity, possibly resulted from different target samples, distinct A[beta] types, A[beta] preparation procedure, various incubation time length and diverse testing techniques applied. Among all these variables, we suspect A[beta] treatment time length to be one of the most important factors that will affect the effect of A [beta] on cell membrane. Here, we reported an interesting time-dependent biphasic change pattern of DITNC cell membrane phase properties induced by oligomeric A[beta][subscript 1-42]. A novel membrane phase property marker - Laurdan was applied in our study to reveal not only the overall membrane phase changes but also specific local membrane phase properties. The role of phospholipase A[subscript 2] (PLA[subscript 2]) in the membrane phase property changes induced by oligomeric A[beta][subscript 1-42] has also been tested. Based on our experimental results, a model was proposed to explain the time dependent biphasic membrane phase property change phenomenon and how A[beta] affects cell membrane phase properties

Three dimensional neuronal cell cultures more accurately model voltage gated calcium channel functionality in freshly dissected nerve tissue.

It has been demonstrated that neuronal cells cultured on traditional flat surfaces may exhibit exaggerated voltage gated calcium channel (VGCC) functionality. To gain a better understanding of this phenomenon, primary neuronal cells harvested from mice superior cervical ganglion (SCG) were cultured on two dimensional (2D) flat surfaces and in three dimensional (3D) synthetic poly-L-lactic acid (PLLA) and polystyrene (PS) polymer scaffolds. These 2D- and 3D-cultured cells were compared to cells in freshly dissected SCG tissues, with respect to intracellular calcium increase in response to high K(+) depolarization. The calcium increases were identical for 3D-cultured and freshly dissected, but significantly higher for 2D-cultured cells. This finding established the physiological relevance of 3D-cultured cells. To shed light on the mechanism behind the exaggerated 2D-cultured cells' functionality, transcriptase expression and related membrane protein distributions (caveolin-1) were obtained. Our results support the view that exaggerated VGCC functionality from 2D cultured SCG cells is possibly due to differences in membrane architecture, characterized by uniquely organized caveolar lipid rafts. The practical implication of use of 3D-cultured cells in preclinical drug discovery studies is that such platforms would be more effective in eliminating false positive hits and as such improve the overall yield from screening campaigns

Cell morphology on 2D substrates.

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