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Editor's Note: This is the first installment of a three-part MODERN CASTING series highlighting concepts and methods for foundries to consider in increasing their marketing effectiveness. It's been said that [...]

The year 2008 was absolutely booming until the fourth quarter, when the wheels fell off. To review: August, September and October had Purchasing Managers Indexes (PMIs) of 49.9,43.9 and 38.9. [...]

You offer a great product and have several loyal customers. If you want to grow your business, however, you'll have to find new markets with new customer lists. And as [...]

Quadruplex structures are higher order structures formed by guanine-rich oligonucleotides. In the present study, temperature-induced conformational changes in the quadruplex structures of aptamers and other guanine-rich oligonucleotides are probed by Raman spectroscopy. In particular, dramatic changes in the fingerprint region are observed in the spectra of thrombin binding aptamer at higher temperatures. These changes are accompanied by a decrease in the intensity of the 1480 cm^−1 peak (attributed to C8 = N7-H2), which is diagnostic of the quadruplex structure. We also show that these changes can be reversed (to a certain extent) by addition of K^+ ions.

ABSTRACTLaser tweezers Raman spectroscopy was used to detect the cellular response of Escherichia colicells to penicillin G-streptomycin and cefazolin. Time-dependent intensity changes of several Raman peaks at 729, 1,245, and 1,660 cm-1enabled untreated cells and cells treated with the different antibiotic drugs to be distinguished.

Current methods for identifying neoplastic cells and discerning them from their normal counterparts are often nonspecific, slow, biologically perturbing, or a combination thereof. Here, we show that single-cell micro-Raman spectroscopy averts these shortcomings and can be used to discriminate between unfixed normal human lymphocytes and transformed Jurkat and Raji lymphocyte cell lines based on their biomolecular Raman signatures. We demonstrate that single-cell Raman spectra provide a highly reproducible biomolecular fingerprint of each cell type. Characteristic peaks, mostly due to different DNA and protein concentrations, allow for discerning normal lymphocytes from transformed lymphocytes with high confidence (p ≪ 0.05). Spectra are also compared and analyzed by principal component analysis to demonstrate that normal and transformed cells form distinct clusters that can be defined using just two principal components. The method is shown to have a sensitivity of 98.3% for cancer detection, with 97.2% of the cells being correctly classified as belonging to the normal or transformed type. These results demonstrate the potential application of confocal micro-Raman spectroscopy as a clinical tool for single cancer cell detection based on intrinsic biomolecular signatures, therefore eliminating the need for exogenous fluorescent labeling.

Current methods for identifying neoplastic cells and discerning them from normal counterparts are often non-specific, slow, biologically perturbing, or a combination, thereof. Here, we show that single-cell, laser-tweezers Raman spectroscopy (LTRS) averts these shortcomings and also permits mechanical manipulation of the single cell under investigation. LTRS is used to characterize the biomolecular Raman signature of both normal human lymphocytes and transformed Jurkat and Raji lymphocyte cell lines from single, unfixed cells in suspension. We demonstrate that single-cell Raman spectra provide a highly reproducible biomolecular fingerprint. Characteristic peaks, mostly due to different DNA and protein concentrations, allow for discerning normal lymphocytes from transformed lymphocytes with high confidence (p << 0.05). Spectra are also compared and analyzed by principal component analysis (PCA) to demonstrate that normal and transformed cells form distinct clusters that can be defined using just two principal components. The method is shown to have a sensitivity of 98.3% for cancer detection, with 97.2% of the cells being correctly classified as being normal or transformed. These results demonstrate the potential application of LTRS as a clinical tool, research instrument, and for cell sorting based on its intrinsic biomolecular signature, therefore eliminating the need for exogenous fluorescent labeling.

Raman spectroscopy is a laser-based analytical technique that enables chemical characterization of molecules in a sample. It is based on the inelastic scattering of photons by molecular bond vibrations. A Raman spectrum obtained from single cells is an intrinsic molecular fingerprint of the sample, revealing detailed information about DNA, RNA, protein, lipid, and carbohydrate content as well as macromolecular conformations. This technique is rapid, non-invasive and non-destructive. We have demonstrated that single-cell laser tweezers Raman spectroscopy (LTRS) reliably discriminates between normal human T- and B-lymphocytes and their transformed, Jurkat-T and Raji-B, counterparts. Herein the same technique is used to discern normal human T- and B-cells from T- and preB-leukemia cells. Also, demonstrated are Raman spectra changes that result from the activation of normal T-cells with a combination of TPA and ionomycin, and normal B-cells by cross linkage of surface immunoglobulin. T- and B-cells were isolated from healthy volunteers. T- and preB-leukemia cells were isolated from patient samples. Spectra are both compared directly and analyzed by principal component analysis. Significant Raman spectra differences in characteristic DNA and protein signals discriminate between normal cells and their leukemia counterparts. Human leukemia cells were indistinguishable from Jurkat-T and Raji-B cells. Changes in spectra that result from cell activation and proliferation only partially account for the spectra changes of leukemia cells. These data demonstrate the utility of LTRS to discern normal lymphocytes from both transformed cells and leukemia cells.