[Spectrophotometry of nucleic acids in turbid media].
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Methods↗
Biomedical subjects
O L Hörer
Publications and source records attributed to O L Hörer.
Ultraviolet inactivation of MM virus RNA in terms of sodium chloride concentrations.
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Encephalomyocarditis virus↗
The spectrophotometric microdetermination of substances on paper disks.
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Microchemistry↗
The distribution of nucleic acid chromophores at cellulose-water interfaces. 1. Photometric parameters.
A computer-assisted calculus of the chromophores distribution in the contiguous layer around the scattering centers of a multiple scattering medium, using bichromate photometric data and an extended Kubelka-Munk expression, was developed. Explanatory examples of nucleic acid impregnated chromatography paper disks show the efficiency of the method proposed for the study of macromolecular structures and the dependence upon the physico-chemical peculiarities of the solutions used.
Cellulose↗
Fluorescence anisotropy of viruses treated with formaldehyde and dimethyl-sulfoxide.
The fluorescence anisotropy changes observed in A-1 (H1N1) influenza and Sendai parainfluenza viruses in aqueous suspensions when formaldehyde (0.1 to 1.0 p.c.) and dimethyl-sulfoxide (0.3 to 5.0 p.c.) were added, using both intrinsic fluorescence of viral proteins and that of the membrane fluorescent probe--DPH, showed significant differences with regard to the virus and the history of the suspensions used, allowing under rigorous standardized conditions the use of fluorescence anisotropy measurements for viral antigen and vaccine control.
Dimethyl Sulfoxide↗
Fluorescence anisotropy of UV-irradiated viruses.
The steady-state fluorescence anisotropy measurements on influenza and parainfluenza viruses, showed no changes in the microviscosity of the viral membranes after exposure to UV-irradiation, when a fluorescent probe was used, but the intrinsic fluorescence of viral proteins presented, under the same experimental conditions, a significant difference of anisotropy behaviour in the two viruses used.
Fluorescence Polarization↗
Development of scientific tools: an innovative activity of the "Stefan S. Nicolau" Institute of Virology.
The innovative activity of the research team of the "Stefan S. Nicolau" Institute of Virology in the field of scientific tool design is presented, in a brief description of the devices, apparatuses and systems claimed in 32 patents registered not only in Romania, but also in the United States of America, United Kingdom, West Germany, France and Belgium, applied in usual virology diagnosis, research and production, for analytical purposes of computer assisted absorption and fluorescence spectrophotometry and for bichromatic ultramicroanalysis.
Academies and Institutes↗
Anti-influenza antibody assay by light scattering.
A physical method based on light scattering at 90 degrees was used to make evident the specific interaction between influenza virus and influenza antiserum. Purified virus put in contact with different dilutions of normal chicken serum exhibited a dose-effect dependence, which was significantly different from that corresponding to the virus-antiserum interaction. The maximum dilution of anti-influenza rabbit serum allowing the detection of the specific interaction between serum and infected allantoic fluid was then established. This value was considered to represent the "light scattering titer" of the antiserum.
Allantois↗
Computer-assisted photometric microplate analysis.
The main algorithm of computer-assisted absorption and emission photometry of samples on a microplate is presented. The software can be used for the enzyme immunoassay (EIA) and other virological tests. The performances of an SPF-500 (Aminco) spectrofluorometer/Felix M18 microcomputer system are discussed on the ground of some results obtained by using the implemented programs.
Algorithms↗
RNase activity in the capillary blood of children.
A bichromatic ultramicromethod on paper disks was used to determine the age-dependence of capillary blood RNase activity in healthy infants and young children.
Capillaries↗
Menu software for the processing of spectrofluorometry analysis.
Menu software is presented for the computer-assisted spectrofluorometric analysis of the 3,4-benzopyrene contents of different samples, determined by a method implying the addition of fluorescent substances in the presence of other fluorochromes. A system consisting of an SPF-500 spectrofluorometer interfaced to a Felix-M18 microcomputer was used for this purpose. The advantages of the computer-assisted processing of spectrofluorometric analyses are discussed.
Benzo(a)pyrene↗
A theoretical approach to the spectrophotometry of nucleic acids on paper disks.
A linear approximated model is presented that takes into account a local anisotropic distribution of scattered light within a turbid medium. Light intensity depends upon the distance from the boundary surface of the scattering centers, so that the probability of photon-chromophore interaction is a function of the distance. For the sake of simplicity it is assumed that there are only two main zones, corresponding to two probabilities of photon-chromophore interaction. In this form, the Kubelka-Munk theory fits the experimental data supplied by bichromatic photometry of nucleic acids on paper disks.
Chromatography, Paper↗
Automation of laboratory instrumentation--recent achievements in the Stefan S. Nicolau Institute of Virology.
An automated system consisting of an SPF-500 spectrofluorometer interfaced to a Felix-M18 microcomputer was provided with a series of additional accessories benefitting from the inputs and outputs through the interface. An adequate set of programs for computer-controlled operations was developed. The system has allowed the performance of more than 15,000 absorption, emission and light scattering determinations. The role of interfacing to low cost computers in the automation of presently available laboratory instrumentation is discussed.
Academies and Institutes↗
Algorithms for automated ultramicroanalysis by bichromatic paper disk spectrophotometry.
Three types of methods for bichromatic paper disk spectrophotometry are described and illustrated by the detailed presentation of procedures for the dosage of hemoglobin and protein (with some applications in virology), as well as for glucose determination. The general algorithms that would make possible the automation of these methods by means of programmable systems are presented.
Autoanalysis↗
Densitometry of aflatoxin thin-layer chromatograms performed by computer-assisted spectrofluorometry.
A system consisting of an SPF-500 (Aminco) spectrofluorometer interfaced to a Felix-M18 microcomputer was used for the fluorescence densitometry analysis of aflatoxin fractions separated by silica gel thin-layer chromatography. The efficiency of fluorescence densiotmetry ultramicroanalysis was dependent on the type of aflatoxin (B1, B2, G1, G2 or M1) and on the nature of the contaminated sample.
Aflatoxins↗
Light scattering from polycation--virus--oligocation mixtures.
The effect of a polycation (histone H2A) and of oligocations (spermine, spermidine and putrescine) on Sendai and influenza virus particles was investigated by light scattering measurements at 90 degrees and at various wavelengths. The method allows the study of the changes in the size and shape of virus particles in suspension.
Cations↗
RNA--streptomycin interaction on cellulose.
Bichromatic paper disk spectrophotometry allowed the demonstration of an analogy between the increase in the solubility of highly polymerized RNA complexed with streptomycin cations (which accounts for the preservation in vivo of the infectivity of a viral RNA--streptomycin complex) and the effect of a cellulose/solution interface on the distribution of the highly polymerized RNA.
Cellulose↗