Quantitative intracellular molecular profiling using a one-dimensional flow system

Multifunctional Microspheres Encoded with Upconverting Nanocrystals and Magnetic Nanoparticles for Rapid Separation and Immunoassays

Immunoassays based on the downconversion target materials (organic dyes or quantum dots) lead to fairly strong spectral interference between the coded signal and reporter signal, which seriously affects the detection accuracy and hampers their applications. In this work, a new kind of upconverting nanocrystals encoded magnetic microspheres (UCNMMs) were designed and prepared successfully to solve the problem mentioned above. The UCNMMs were obtained by incorporating magnetic Fe3O4 nanoparticles and upconverting nanocrystals with polystyrene microspheres. Due to that upconverting nanocrystals (UCNs) and reporter signals are excitated by near-infrared and UV/visible light separately, immunoassays based on UCNMMs do not occur optical spectral interferences. Furthermore, these new functionalized UCNMMs have excellent properties in binding biomolecules and fast separating, which would have large potential applications in multiplexed assays.

Original article. Potential risk of dihydroergotamine causing medicationoveruse headache: preclinical evidence

Background: Overuse of abortive medication is a common factor contributing to an increase in headache frequency in patients with migraine. Whether or not chronic exposure to dihydroergotamine (DHE) can lead to this transformation remains uncertain.

Objective: To determine the effect of acute and chronic DHE exposure on development of cortical spreading depression (CSD) and trigeminal nociception.

Methods: The study comprised two experiments, namely acute and chronic exposure. In the acute experiment, a single dose of DHE (100 μg/kg) was given to male Wistar rats after successful induction of CSD. In the chronic experiment, DHE was given daily for the period of 0, 7, 14, and 28 days. CSD was induced 30 minutes after the final injection and the cortical field potential was recorded. Expression of c-Fos in caudal brainstem was used as an indicator of trigeminal nociception.

Results: Acute exposure to DHE attenuated the expression of c-Fos in the caudal brainstem without change in CSD response. By contrast, chronic exposure (14 and 28 days) to DHE increased the area under the curve of CSD waveforms. In parallel with the change in the CSD, there was significant increase of c-Fos expression within 14 days exposure to DHE and the expression remained significantly elevated for up to the 28 days examined.

Conclusion: Our study demonstrated that chronic DHE administration can increase cortical excitability and increase c-Fos expression in caudal brainstem. Our preclinical evidence suggests the possible adverse effect of chronic DHE use in causing chronification of headache.

An integrated electrochemical device based on immunochromatographic test strip and enzyme labels for sensitive detection of disease-related biomarkers

A novel electrochemical biosensing device that integrates an immunochromatographic test strip and a screen-printed electrode (SPE) connected to a portable electrochemical analyzer was presented for rapid, sensitive, and quantitative detection of disease-related biomarker in human blood samples. The principle of the sensor is based on sandwich immunoreactions between a biomarker and a pair of its antibodies on the test strip, followed by highly sensitive square-wave voltammetry (SWV) detection. Horseradish peroxidase (HRP) was used as a signal reporter for electrochemical readout. Hepatitis B surface antigen (HBsAg) was employed as a model protein biomarker to demonstrate the analytical performance of the sensor in this study. Some critical parameters governing the performance of the sensor were investigated in detail. Under optimal conditions, this sensor was capable of detecting a minimum of 0.3 ng mL(-1) (S/N=3) HBsAg with a wide linear concentration range from 1 to 500 ng mL(-1). The sensor was further utilized to detect HBsAg spiked in human plasma with an average recovery of 91.3%. In comparison, a colorimetric immunochromatographic test strip assay (ITSA) was also conducted. The result shows that the SWV detection in the electrochemical sensor is much more sensitive for the quantitative determination of HBsAg than the colorimetric detection, indicating that such a sensor is a promising platform for rapid and sensitive point-of-care testing/screening of disease-related biomarkers in a large population.

Immunoassays in microfluidic systems

Immunoassays have greatly benefited from miniaturization in microfluidic systems. This review, which summarizes developments in microfluidics-based immunoassays since 2000, includes four sections, focusing on the configurations of immunoassays that have been implemented in microfluidics, the main fluid handling modalities that have been used for microfluidic immunoassays, multiplexed immunoassays in microfluidic platforms, and the emergence of label-free detection techniques. The field of microfluidic immunoassays is continuously improving and has great promise for the future.

Detection of circulating tumor cells in peripheral blood of patients with renal cell carcinoma correlates with prognosis

PURPOSE

The aim of this study was to evaluate the clinical relevance of the presence of disseminated tumor cells in peripheral blood (so-called circulating tumor cells) for renal cell carcinoma patients.

METHODS

Two hundred thirty-three peripheral blood samples from 154 renal cell carcinoma patients were investigated for the presence of disseminated tumor cells by autoMACS technique and immunocytochemical staining of cytokeratin. The frequency of circulating tumor cells was analyzed statistically for correlation with relevant clinical data.

RESULTS

Two kinds of tumor cells were detected: those with expression of cytokeratin 8/18 (CK+) and cells without a detectable cytokeratin expression, which we called large blue-stained cells with a tumorlike morphology. After following the CD45 autoMACS depletion protocol, we identified circulating tumor cells in 96 (41%) of 233 peripheral blood samples, which originated from 81 (53%) of 154 renal cell carcinoma patients. A significant correlation between the detection of circulating tumor cells and positive lymph node status (P < 0.001; chi(2) test) and the presence of synchronous metastases at the time of primary tumor resection (P = 0.014; chi(2) test) was found. In a multivariate Cox's regression hazard model, presence of CK+ circulating tumor cells was significantly correlated with poor overall survival for renal cell carcinoma patients (relative risk, 2.3; P = 0.048).

CONCLUSIONS

The presence of circulating tumor cells correlated to lymph node status and presence of synchronous metastases in renal cell carcinoma. It is important to evaluate CK+ and blue-stained tumor cells together to determine the role of circulating tumor cells in tumor behavior and disease progression. Detection of CK+ circulating tumor cells in peripheral blood is a significant and independent prognostic factor for renal cell carcinoma.

Fiber-optic microsphere-based antibody array for the analysis of inflammatory cytokines in saliva

Antibody microarrays have emerged as useful tools for high-throughput protein analysis and candidate biomarker screening. We describe here the development of a multiplexed microsphere-based antibody array capable of simultaneously measuring 10 inflammatory protein mediators. Cytokine-capture microspheres were fabricated by covalently coupling monoclonal antibodies specific for cytokines of interest to fluorescently encoded 3.1 microm polymer microspheres. An optical fiber bundle containing approximately 50,000 individual 3.1 microm diameter fibers was chemically etched to create microwells in which cytokine-capture microspheres could be deposited. Microspheres were randomly distributed in the wells to produce an antibody array for performing a multiplexed sandwich immunoassay. The array responded specifically to recombinant cytokine solutions in a concentration-dependent fashion. The array was also used to examine endogenous mediator patterns in saliva supernatants from patients with pulmonary inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD). This array technology may prove useful as a laboratory-based platform for inflammatory disease research and diagnostics, and its small footprint could also enable integration into a microfluidic cassette for use in point-of-care testing.

HER2 status predicts the presence of circulating tumor cells in patients with operable breast cancer

INTRODUCTION

Circulating tumor cells (CTCs) correlate with worse prognosis in patients with metastatic breast cancer, but there are little data on CTCs in operable patients. We hypothesized that primary tumor characteristics would predict the likelihood of identifying CTCs in patients with operable breast cancer.

METHODS

Clinical and pathological data from 92 patients with operable breast cancer were collected. The CellSearch system was used to detect CTCs in 30 ml of peripheral blood. CTCs were defined as nucleated cells lacking CD45 but expressing cytokeratins 8, 18, or 19. Univariate analysis was performed to determine if the presence of any primary tumor characteristic was predictive of CTCs. As a secondary objective we evaluated if nodal or bone marrow status was predictive of CTCs.

RESULTS

Thirty-eight percent of patients (35/92) had evidence of CTCs, with a median number of 1.0 CTC per CTC positive patient (range 1-22). HER2 status was the sole primary tumor characteristic that reliably predicted the presence of CTCs (P = 0.01, risk ratio = 3.66). No significant association was found between the presence of CTCs and tumor size (T), estrogen receptor (ER) status, progesterone receptor (PR) status, grade, histologic type, degree of nodal involvement (N), lymphovascular invasion (LVI) or Ki-67 proliferation. Bone marrow micrometastases were found in 17/64 (26.6%) of the patients but did not correlate with the presence of CTCs.

CONCLUSION

HER2 status was the only primary tumor characteristic that correlated with the presence of CTCs. Long-term follow-up will be required to determine the significance of CTCs in operable breast cancer.

Detection of single-base mutations using 1-D microfluidic beads array

The application of a 1-D microfluidic beads array that is composed of individually addressable functionalized SiO2 beads has been demonstrated for detection of single-base mutations based on "sandwich" hybridization assay without additional sample labeling and PCR amplification. We concentrated on detection of mutations in the human p53 tumor suppressor gene with more than 50% mutation frequency in the known human cancers. Using a microinjection system, functionalized beads could be selectively and linearly arrayed in a single microfluidic channel comprising many periodic chambers. This 1-D microfluidic beads array was sufficiently sensitive to identify single-nucleotide mutations in 40 pM quantities of DNA targets and could discriminate the mutated alleles in an excess of nonmutated alleles at a level of one mutant in 100 wild-type sequences. The surface of beads was regenerated and rehybridized up to six times without obvious loss of signal. The entire reaction process was done at room temperature within minutes, and only 2-10 microL sample solution was needed to complete the whole detection process. The p53 genotypes of A549, CNE2, and SKBr-3 cell lines were also correctly evaluated by using mRNA extracts as target without need for sample labeling and amplification. Thus, this platform enabled rapid and exact discrimination of gene mutations with the advantages of reusability, simple handling of liquid, low cost, and little reagent consumption.

A novel sandwich assay with molecular beacon as report probe for nucleic acids detection on one-dimensional microfluidic beads array

A novel sandwich assay with molecular beacons as report probes has been developed and integrated into one-dimensional microfluidic beads array (1-D chip) to pursue a label-free and elution-free detection of DNA/mRNA targets. In contrast with the immobilized molecular beacons, this sandwich assay can offer lower fluorescence background and correspondingly higher sensitivity. Furthermore, this sandwich assay on 1-D chip operating in conjunction with molecular beacon technique allows multiple targets detection without the need of laborious and time-consuming elution, which makes the experiment process simple, easy to handle, and reproducible results. In the experiment, the synthesized DNA targets with different concentrations were detected with a detection limit of approximately 0.05 nM. Moreover, the mRNA expression changes in A549 cells before and after anticancer drug 5-flouorouracil treatments were detected and the results were validated by the conventional RT-PCR method.