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At least 667 records · Page 37Linked to original sources
PubMed1988

Estimation of lipid concentrations on thin-layer plates by densitometry of transparent copies.

A relatively simple procedure for the quantitative estimation of phospholipids resolved on thin-layer plates has been developed. After resolution in an appropriate solvent, the lipids are visualized by staining with iodine, ninhydrin, or molybdate and then photocopied onto transparent sheets with a standard office copy machine. The density of each spot on the photocopy, measured with a simple silicon cell area densitometer, is a direct function of each lipid applied to the plate over at least a six- to eightfold range in concentration. Under controlled conditions the staining and photocopying steps are quite reproducible. Known concentrations of the choline, ethanolamine, serine, and inositol derivatives of L-alpha-phosphatidic acid applied either separately or as mixtures can be determined essentially quantitatively (100 +/- 5%) by this procedure following their resolution on the thin-layer plates.

Animals↗
PubMed1989

Ultraviolet scanning densitometry for detection, quantitation, and preparative elution of protein bands from unstained gels.

Ultraviolet scanning of gel rods was used to identify and quantify protein bands in a nondestructive manner with good precision and sensitivity. This same technique, applied on a preparative scale, allowed quantitative protein elution, by reversed electrophoresis, from gel slices completely sealed in a dialysis bag. Protein recovery approached the theoretical yield (93.5 +/- 5%), with practically no interfering substances, and the entire preparative process (first electrophoresis, densitometric scanning, and reversed electrophoresis) could be performed in approximately 6 h. Its application to human growth hormone has shown no alteration in the biological activity of this protein.

Animals↗
PubMed1990

Quantitation of ultraviolet radiation-induced cyclobutyl pyrimidine dimers in DNA by video and photographic densitometry.

We have compared video and photographic methods for calculating the number of ultraviolet radiation (uv)-induced pyrimidine dimers in DNA from the bacteriophage T7 exposed to uv (0 to 800 J/m2) from an FS40 sunlamp. DNA was incubated with a pyrimidine dimer-specific Micrococcus luteus uv endonuclease, subjected to alkaline agarose gel electrophoresis, neutralized, and stained with ethidium bromide, and the DNA fluorescence was recorded either with a video camera or on photographic film. The slopes of the dose-response curves for the number of uv-endonuclease-sensitive sites per 10(3) bases (pyrimidine dimers) was 1.2 (+/- 0.1) X 10(-4) uv-endonuclease-sensitive sites per J/m2 for the video analysis and 1.3 (+/- 0.04) X 10(-4) uv-endonuclease-sensitive sites per J/m2 for the photographic analysis. Results for pyrimidine dimer determination by either method were statistically comparable.

Analog-Digital Conversion↗
PubMed1993

Analysis of charge of kappa and lambda chain-containing serum immunoglobulin A by immunoblotting and densitometry.

A novel method for studying the charge distribution of different subclasses of serum immunoglobulin A (defined by the light chains) is described. Affinity-chromatography purified immunoglobulins were focused in polyacrylamide gel and were then transferred electrophoretically onto nitrocellulose membranes. The transferred immunoglobulins were detected by rabbit antiserum to human kappa (kappa) or lambda (lambda) chain, swine antirabbit IgG, rabbit anti-peroxidase antibodies and peroxidase, together with a substrate solution comprising H2O2 and diaminobenzidine. Finally, the developed membranes were made transparent with Triton-x 114, scanned at 485 nm with a densitometer to obtain quantitation of charge distribution.

Densitometry↗
PubMed1988

Evaluation of densitometry data using interactive computer graphics: application to DNA agarose gels.

A method of analyzing DNA agarose gels using interactive computer graphics is described. After electrophoresis in an alkaline agarose gel, DNA is neutralized, stained with ethidium bromide and excited with ultraviolet radiation. The resulting fluorescent distribution on the gel is photographed, and the negative scanned by a digitizing densitometer. The data is subsequently analyzed using a computer program developed to facilitate manipulation and selection of data from the densitometer trace. The method has been applied to determine pyrimidine dimer yields in DNA from human lymphocytes exposed to UV radiation. The technique significantly reduces the time required to analyze such data, while also providing greater accuracy. The method could be easily adapted to assist in similar analyses of other macromolecules such as RNA or proteins.

Computer Graphics↗
PubMed1996

Screening for anemia in pregnancy with copper sulfate densitometry.

OBJECTIVE: The copper sulfate method of screening for anemia was evaluated to determine its accuracy in antenatal patients. METHODS: In an antenatal clinic in a tertiary referral center, which also serves a local urban black community, 100 antenatal patients were prospectively tested for anemia by Coulter hemoglobin analysis in comparison with the copper sulfate test. The respective accuracy and costs of the tests were evaluated. RESULTS: Once initial technical difficulties had been overcome, the copper sulfate test proved accurate in detecting a hemoglobin level < 10 g% in pregnancy (sensitivity 94%, specificity 95%, positive predictive value 80%, negative predictive value 99%). The cost of the copper sulfate test is estimated to be less than 0.3% that of the Coulter test. CONCLUSION: The copper sulfate test is accurate and inexpensive, and can be recommended for screening for anemia in pregnancy.

Anemia↗
PubMed1988

Application of fluorescence densitometry to the study of net albumin uptake by the rabbit aortic wall up- and downstream of intercostal ostia.

A method was developed for measuring levels of lissamine rhodamine B-labelled albumin in arterial walls with a spatial resolution of ca. 1 micron 3. The method was used to study variation in net macromolecular uptake up- and downstream of intercostal ostia in a small number of rabbit aortae. The physical and biological properties of the fluorescent tracer, including its stability, were compatible with its use in vivo. Tracer was injected into the ear vein of conscious rabbits. After 3 h the rabbits were anaesthetized and the thoracic aorta was fixed in situ at physiological pressure. The vessel was embedded in epoxy resin and longitudinal sections of the aortic wall were cut through the centre of the intercostal ostia. Photomicrographs were used to record fluorescence from these sections. The optical density across the photomicrographs was measured and related to the distribution of tracer in the wall. Mean intima-medial levels of tracer were greater downstream of ostia than upstream but were lower near the flow divider than further downstream. Higher levels of tracer were found in the adventitia than in the media and, in the latter, the distribution appeared to be related to the lamellar structure.

Animals↗