A Novel Methodology for Detecting Variations in Cell Surface Antigens Using Cell-Tearing by Optical Tweezers.

The quantitative analysis of cell surface antigens has attracted increasing attention due to the antigenic variation recognition that can facilitate early diagnoses. This paper presents a novel methodology based on the optical "cell-tearing" and the especially proposed "dilution regulations" to detect variations in cell surface antigens. The cell attaches to the corresponding antibody-coated slide surface. Then, the cell-binding firmness between a single cell and the functionalized surface is assayed by optically tearing using gradually reduced laser powers incorporated with serial antibody dilutions. Groups B and B3 of red blood cells (RBCs) were selected as the experiment subject. The results indicate that a higher dilution called for lower power to tear off the cell binding. According to the proposed relative-quantitative analysis theory, antigenic variation can be intuitively estimated by comparing the maximum allowable dilution folds. The estimation result shows good consistency with the finding in the literature. This study suggests a novel methodology for examining the variation in cell surface antigens, expected to be widely capable with potential sensor applications not only in biochemistry and biophysics, but also in the micro-/nano- engineering field.

Frequent DNA methylation of MiR-129-2 and its potential clinical implication in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a highly malignant tumor with poor prognosis and high mortality due to a lack of effective medical treatment and apparent early stage symptoms. Understanding molecular mechanism of cancer development is crucial for HCC diagnosis, prognosis, and treatment. Recently, microRNAs have been shown to play an important role in carcinogenesis, being regulated by DNA methylation in several cases. In this study, a whole genome approach was used to identify methylation-regulated miRNAs in HCC, finally focusing on miR-129-2. MiR-129-2 methylation and reduced expression were observed in all examined HCC cell lines but not in normal liver cells and tissues. In 39 (93%) of 42 HCC, the methylation levels of miR-129-2 were significantly increased in tumor tissues compared with adjacent normal tissues. Furthermore, miR-129-2 methylation was detectable in plasma samples from HCC patients, but not in plasma samples from healthy individuals or patients with liver cirrhosis. At a cut-off value of -2.36 (log2 transformation of methylation level), it was possible to distinguish HCC from healthy and cirrhotic controls with sensitivity and specificity of 88% and 100%, respectively. This study indicates that miR-129-2 methylation is highly accurate in distinguishing HCC patients from cirrhosis patients and healthy individuals, implying its potential utility as an early diagnostic marker for HCC.

Anti-inflammatory effect of Lactobacillus casei on Shigella-infected human intestinal epithelial cells.

Shigella invades the human intestinal mucosa, thus causing bacillary dysentery, an acute recto-colitis responsible for lethal complications, mostly in infants and toddlers. Conversely, commensal bacteria live in a mutualistic relationship with the intestinal mucosa that is characterized by homeostatic control of innate responses, thereby contributing to tolerance to the flora. Cross-talk established between commensals and the intestinal epithelium mediate this active process, the mechanisms of which remain largely uncharacterized. Probiotics such as Lactobacillus casei belong to a subclass of these commensals that modulate mucosal innate responses and possibly display anti-inflammatory properties. We analyzed whether L. casei could attenuate the pro-inflammatory signaling induced by Shigella flexneri after invasion of the epithelial lining. Cultured epithelial cells were infected with L. casei, followed by a challenge with S. flexneri. Using macroarray DNA chips, we observed that L. casei down-regulated the transcription of a number of genes encoding pro-inflammatory effectors such as cytokines and chemokines and adherence molecules induced by invasive S. flexneri. This resulted in an anti-inflammatory effect that appeared mediated by the inhibition of the NF-kappaB pathway, particularly through stabilization of I-kappaBalpha. In a time-course experiment using GeneChip hybridization analysis, the expression of many genes involved in ubiquitination and proteasome processes were modulated during L. casei treatment. Thus, L. casei has developed a sophisticated means to maintain intestinal homeostasis through a process that involves manipulation of the ubiquitin/proteasome pathway upstream of I-kappaBalpha.