ABSTRACT
BACKGROUND: Infrared spectroscopy probes the chemical composition and molecular structure of complex systems such as tissue and cells. Infrared spectroscopic imaging combines this spectral information with lateral resolution near the single-cell level. We analyzed whether this method is competitive with classic immunohistochemical methods for immunologic tissue and cells. METHODS: We recorded infrared microspectroscopic mapping datasets with a 90- x 90-microm2 aperture from a 3- x 3-mm2 unstained tissue area of human spleen. A secondary follicle containing a germinal center and a T zone were studied in more detail by infrared microspectroscopic imaging with lateral resolution near 5 mum. The results were compared with consecutive sections stained by immunoglobulin D antibodies. T and B lymphocytes were extracted from human blood and served as independent test samples. RESULTS: Cluster analysis of infrared datasets produced images that distinguished anatomical features such as primary and secondary follicles, T zones, arteries, and spleen red pulp. The assignments could be confirmed in consecutive sections by immunohistochemical staining. Main spectral variances between T and B lymphocytes in high-resolution measurements were attributed to specific spectral contributions of DNA and cytosol. CONCLUSIONS: Sensitivity and specificity of the infrared based methods are comparable to those of standard staining procedures for identification of B and T cells. However, infrared spectroscopic imaging can offer advantages in velocity, data throughput, and standardization because of minimal sample preparation. The results emphasize the potential of infrared spectroscopy as an innovative tool for the distinction of cell types, in particular in immunologic tissue.
Subject(s)
B-Lymphocytes/cytology , Microscopy, Confocal/methods , Spectroscopy, Fourier Transform Infrared/methods , Spleen/cytology , T-Lymphocytes/cytology , Adolescent , B-Lymphocytes/immunology , Cluster Analysis , Humans , Image Processing, Computer-Assisted/methods , Immunoglobulin D/analysis , Immunomagnetic Separation , Male , Staining and Labeling , T-Lymphocytes/immunologyABSTRACT
Motivated by a recent proposal for an experimental verification of the dynamical Casimir effect, the macroscopic electromagnetic field within a perfect cavity containing a thin slab with a time-dependent dielectric permittivity is quantized in terms of the dual potentials. For the resonance case, the number of photons created out of the vacuum due to the dynamical Casimir effect is calculated for both polarizations. It turns out that only TM modes can be excited efficiently.
ABSTRACT
We investigate the asymptotic properties of higher-order binding corrections to the one-loop self-energy of excited states in atomic hydrogen. We evaluate the historically problematic A60 coefficient for all P states with principal quantum numbers n
ABSTRACT
During the germinal center (GC) reaction a characteristic morphology is developed. In the framework of a recently developed space-time model for the GC, a mechanism for the formation of dark and light zones has been proposed. There, the mechanism is based on a diffusing differentiation signal which is distinguished by follicular dendritic cells (FDC). Here, we investigate a possible influence of recently found chemoattractants on GC formation in the framework of a single cell-based stochastic and discrete three-dimensional model. This necessitates a more detailed spatial description. The model is enlarged by a detailed prescription of cell motility and it is introduced as a consistent volume concept. We consider various possible chemotactic pathways that may play a role for the development of both zones. Our results suggest that the centrocyte motility resulting from a FDC-derived chemoattractant has to exceed a lower limit to allow the separation of centroblasts and centrocytes. In contrast to light microscopy, the dark zone is ring shaped. This suggests that FDC-derived chemoattractants alone cannot explain the typical GC morphology.
Subject(s)
Cell Differentiation , Chemotaxis , Germinal Center/cytology , Models, Immunological , Antigen-Antibody Reactions , Cell Division , Chemotactic Factors/metabolism , Germinal Center/immunology , Signal Transduction , Time FactorsABSTRACT
As an alternative to the sonic black hole analogs we discuss a different scenario for modeling the Schwarzschild geometry in a laboratory--the dielectric black hole. The dielectric analog of the horizon occurs if the velocity of a medium with a finite permittivity exceeds the speed of light in that medium. The relevance for experimental tests of the Hawking effect and possible implications are addressed.
