Macromolecular weight and size of deoxypentose nucleic acids

Instrumentation for Multi-modal Spectroscopic Diagnosis of Epithelial Dysplasia

Reflectance and fluorescence spectroscopies have shown great promise for early detection of epithelial dysplasia. We have developed a clinical reflectance spectrofluorimeter for multimodal spectroscopic diagnosis of epithelial dysplasia. This clinical instrument, the FastEEM, collects white light reflectance and fluorescence excitation-emission matrices (EEM's) within a fraction of a second. In this paper we describe the FastEEM instrumentation, designed for collection of multi-modal spectroscopic data. We illustrate its performance using tissue phantoms with well defined optical properties and biochemicals of known fluorescence properties. In addition, we discuss our plans to develop a system that combines a multi-spectral imaging device for wide area surveillance with this contact probe device.

Live-cell mass profiling: an emerging approach in quantitative biophysics

Cell mass, volume and growth rate are tightly controlled biophysical parameters in cellular development and homeostasis, and pathological cell growth defines cancer in metazoans. The first measurements of cell mass were made in the 1950s, but only recently have advances in computer science and microfabrication spurred the rapid development of precision mass-quantifying approaches. Here we discuss available techniques for quantifying the mass of single live cells with an emphasis on relative features, capabilities and drawbacks for different applications.

Imaging human epithelial properties with polarized light-scattering spectroscopy

Biomedical imaging with light-scattering spectroscopy (LSS) is a novel optical technology developed to probe the structure of living epithelial cells in situ without need for tissue removal. LSS makes it possible to distinguish between single backscattering from epithelial-cell nuclei and multiply scattered light. The spectrum of the single backscattering component is further analyzed to provide quantitative information about the epithelial-cell nuclei such as nuclear size, degree of pleomorphism, degree of hyperchromasia and amount of chromatin. LSS imaging allows mapping these histological properties over wide areas of epithelial lining. Because nuclear enlargement, pleomorphism and hyperchromasia are principal features of nuclear atypia associated with precancerous and cancerous changes in virtually all epithelia, LSS imaging can be used to detect precancerous lesions in optically accessible organs.

The absence of histone in the bacterium Escherichia coli. I. Preparation and analysis of nucleoprotein extract

The deoxyribonucleic acid (DNA) from Escherichia coli has been isolated as an extract containing about 50 per cent by weight protein. The protein component differs both in composition and chemical behaviour from histone which occurs in combination with the DNA in most cells of higher organisms. Although this result suggests the absence of histone-like protein, it is not clear whether the bacterial protein found is naturally bound to the bacterial DNA in the cell or becomes attached to the DNA during the course of isolation.

The response of motor neurones to intramuscular injection of botulinum toxin

1. The dry mass and nucleic acid content of both nerve cell bodies and their nucleoli were measured by interference microscopy and ultra-violet absorption microspectrography respectively: succinoxidase and acetylcholine hydrolase activities were also determined. Autoradiography was used to follow synthesis of deoxyribonucleic acid (DNA) by glial cells, and to follow nucleic acid and protein metabolism in muscle fibres.2. After injection of botulinum toxin the synthesis of ribosomal RNA by the neurone followed closely the pattern found after axotomy.3. After injection of toxin neuronal dry mass increased before the rate of ribosomal RNA synthesis was raised. This early increase, which was not due to increased protein synthesis, probably represents a ;damming back' of proteins within the nerve cell body.4. After injection of toxin no local accumulation of microglial cells synthesizing DNA was found around the affected neurones: it is suggested that this reflects the intact system for intra-axonal transport under these conditions.5. The affected muscles show increased nucleic acid and protein synthesis.6. It is suggested that the results obtained indicate that membrane expansion or synthesis which occurs both in muscle and in neurone under these circumstances is the factor responsible for inducing directly or indirectly the changes found in nucleic acid metabolism after injection of botulinum toxin and after axotomy.