Comparison of seven bio- and chemiluminescent reagents for in situ detection of antigens and nucleic acids

Protein microchips in biomedicine and biomarker discovery

Protein microarray technology is of high recent interest, especially for generating confirmatory and complementary information for transcriptomic studies. In this paper, the advantages, technical limitations, main application fields, and some early results of protein microarrays are reviewed. Today protein microchip technology is mostly available in the form of printed glass slides, bioaffinity surfaces, and tissue microarray (TMA)-based techniques. The advantages of glass slide-based microchips are the simplicity of their application and their relatively low cost. Affinity surface-based protein chip techniques are applicable to minute amounts of starting material (< 1 microg), but interrogation of these chips requires expensive instrumentation, such as mass spectrometers. TMAs are useful for parallel testing of antibody specificities on a broad range of histological specimens in a single slide. Protein microarrays have been successfully implemented for serum tumor marker profiling, cell physiology studies, and mRNA expression study verification. Some of the bottlenecks of the technology are protein instability, problems with nonspecific interactions, and the lack of amplification techniques to generate sufficient amounts of the lower abundance proteins. In spite of the current difficulties, protein microchips are envisioned to be available for routine biomedical and diagnostic applications provided that the ongoing technological developments are successful in improving sensitivity, specificity, and reducing costs.

An in vitro system to evaluate the effects of ischemia on survival of cells used for cell therapy

Maintaining cell viability is a major challenge associated with transplanting cells into ischemic myocardium to restore function. A likely contributor to significant cell death during cardiac cell therapy is hypoxia/anoxia. We developed a system that enabled quantification and association of cell survival with oxygen and nutrient values within in vitro constructs. Myoblasts were suspended in 2% collagen gels in 1 cm diameter x 1 cm deep constructs. At 48 +/- 3 h post-seeding, oxygen levels were measured using microelectrodes and gels were snap-frozen. Bioluminescence metabolite imaging and TUNEL staining were performed on cryosections. Oxygen and glucose consumption and lactate production rates were calculated by fitting data to Fick's second law of diffusion with Michaelis-Menten kinetics. Oxygen levels dropped to 0 mmHg and glucose levels dropped from 4.28 to 3.18 mM within the first 2000 mum of construct depth. Cell viability dropped to approximately 40% over that same distance and continued to drop further into the construct. We believe this system provides a reproducible and controllable test bed to compare survival, proliferation, and phenotype of various cell inputs (e.g., myoblasts, mesenchymal stem cells, and cardiac stem cells) and the impact of different treatment regimens on the likelihood of survival of transplanted cells.

Studies on PVP hydrogel-supported luminol chemiluminescence: 1. Kinetic and mechanistic aspects using multivariate factorial analysis

The chemiluminescent oxidation of luminol by hydrogen peroxide in the presence of hemin is revisited in an UV-C cross-linked PVP hydrogel. Chemiluminescence properties such as initial light intensity (I(0)), area of emission (S) and observed rate constants (k(obs)) are studied, varying the concentration of all reactants using a multivariate factorial approach.

Applications of immunogold and lectin-gold labeling in tumor research and diagnosis

Immunohistochemistry and carbohydrate histochemistry have had an enormous impact on both tumor research and diagnosis. In particular, immunogold labeling has provided significant advantages over classical fluorescence and enzyme-based techniques. In light microscopy, the silver-intensified gold labeling has proven highly sensitive and precise in localization. In electron microscopy, the gold particle marker was a prerequisite for successful and unequivocal antigen detection in electron-dense cellular structures such as secretory granules. In this review we demonstrate the usefulness of light and electron microscopical gold labeling techniques as applied in tumor research and diagnosis. The examples include expression of beta-1,6 branches and specific sialoglycoconjugates in colon carcinoma, b-12 carbohydrate epitope in breast carcinoma, polysialic acid in neuroendocrine tumors of lung, adrenal and thyroid, as well as studies on proinsulin to insulin conversion in insulinomas. In addition, practical hints for prevention of background staining, tissue fixation, and silver intensification of gold labeling are given.