Optical density, gels

A TLC method was developed for the estimation of nieotinie aeid and nicotinamide (Fignre 10.7) in phatmacentical preparations containing other vitamins, enzymes, herbs, and drugs, etc. [16]. The percentage recoveries for nicotinic acid and nicotinamide were 100.1 + 1.9 and 100.2 1.5, respectively, with this system. Each alcohol extract of samples or standard was pnt on sihca gel TLC plates, which were developed with distilled water. Each silica gel spot visualized under UV lamp was collected and extracted with 0.1 mol/1 HCl. The optical density of each clear extract was measured at 262 run. 

The data can be visualized in several formats. In a gel image, the optical density at each point is related to the fluorescence intensity false color images can be used to improve the dynamic range of visualization. We usually employ a logarithmic compression to help visualize the wide dynamic range of the data the image can be processed to saturate the most intense components, allowing observation of less intense components. 

Figure 15.6 presents the data of Fig. 15.4 in the form of a gel image. The optical density in the image is proportional to the logarithm of the fluorescent intensity this... 

In order to quantitatively analyze the protein patterns, the gels were scanned, and the relative optical density of the bands was plotted against the distance from the start of the gel. 

Results of electrophoretic analysis of proteins in the allantoic fluid and blood serum before and after photodynamic treatment are presented in Figs. 5.5 and 5.6. Visually, we did not detect any changes in the position and intensity of protein bands. In order to quantitatively analyze these parameters we scanned the gels and measured the relative optical density of the bands (Figs. 5.7 and 5.8). 

Quantification of radioactivity is possible by densitometry (scanning) of the developed film. It should be taken into consideration that the optical density of the film is not linear proportional to the amount of radioactivity, especially at lower radioactivity. Dot defined amounts of radioactivity onto a part of the gel or membrane and use the obtained darkening to construct a calibration curve. 

Densitometric scanning of the dried gels with integration of the optical density of the peaks allows then the semi-quantitative analysis of the different lipoproteins. 

Remove the solution from the gel by careful filtration on a glass sinter, followed by washing of the gel with a small volume of bicarbonate buffer. Measure the optical density of the pooled filtrate at 280 nm to determine the amount of protein that has not coupled to the gel (see Note 7). 

Fig. 12. Diagram of elution pattern of red cell acid phosphatase and various markers on Biogel P 60. The position of the various protein markers was determined both by optical density determination and by starch gel electrophoresis of the individual fractions (83). The experiment was carried out using a polyacrylamide gel (Biogel P 60, 50-150 mesh exclusion limit >60,000 Bio-Rad Laboratories, California) in 0.05 M tris buffer, pH 8.0, containing 0.08% (v/v) Tween 80 and 0.1% (v/v) 2-mercaptoethanol to stabilize the enzyme. Column 60 X 4 cm. Flow rate 20 ml/hr, 4 ml fractions. (A) OD at 280 nm, ( ) OD at 540 nm, ( ) LDH assay with p-nitrophenyl phosphate for AcP. From Hopkinson and Harris (85).

Fig. 16. The gel formation of pseudo-isocyanine-chloride in water (7,5 g/1) determined by the optical density Fmax of the association band at 570 mp. The gel formation in D20 changes about 3.8 °C, the melting point difference D20 H20 D = 0.02 cm94)...

On irradiation the t-t-t-dye is isomerized to its c-t-c-isomer this conformational change causes a decrease of dye-polymer interactions resulting in a gel contraction of 1.2%, i.e. a change in volume of about 3.6%. In the dark the gel recovers its original dimensions the rate of recovery is a function of temperature and parallels the increase of optical density of chrysophenine at 400 nm. 

Our approach for quantitating MDR-1 mRNA by PCR begins with reverse transcription of the mRNA to cDNA. Customarily, 1 pg total RNA is subjected to the reverse transcription reaction following gel electrophoresis that verifies the quality and quantity of the RNA measurements see Note 1). The resulting cDNA is serially diluted and separate PCR reactions are performed on each of the serial dilutions (Fig. 1). This will allow determination of the exponential range of amplification. By convention, the quantity of cDNA in each serial dilution is referred to by either the dilution factor or the calculated input RNA for that dilution. When the PCR products are in the exponential range, the difference in the optical density of the PCR products from a two-fold dilution of... 

At the end of focusing, the electrofocusing tube is removed and the optical density in the gel is read with an ISCO gel scanner. 

After 20 hours of focusing the gel tube is removed, equilibrated at room temperature, and immediately placed in an ISCO gel scanner (slits 0.25 mm) equipped with a UA 5 detector. The scan is shown in Fig. 47 as well as the temperature and paH gradients. From an 8-cm gel containing the protein, a zone of 0.6-0.7 cm (measured in the scanner densitogram at half optical density) is obtained after isoelectric focusing. 

Figure 4. Anticoagulant activity of individual heparin chains of beef-lung heparin. Chains were separated by electrophoresis of Upjohn beef-lung heparin Lot 517-042 with LKB carrier ampholine batch 18. The apparent molecular weights were obtained from electrophoresis in acrylamide by the technique of Hilborn and Anastassiadis (10). The anticoagulant activity was determined by the USP procedure comparing the individual fraction with the original heparin. The quantity was estimated by optical density of toluidine blue-stained band on gel. (2)...

DNA sequencing techniques have relied heavily on electrophoresis to separate the DNA fragments. Autoradiography and optical density measurements have been used to help interpret the resulting bands in the electrophoresis gel. 

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