JP3402650B2 - Processing method of densitogram of electrophoresis image - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a densitogram of an electrophoretic image.

[0002]

2. Description of the Related Art A serum protein fraction obtained by electrophoresis is widely used as an item for primary screening because it can obtain a lot of information on pathological conditions obtained by a single analysis.

In an electrophoretic device, a sample is applied to a support by an applicator and allowed to migrate in a migration tank for a predetermined time,
After sequentially performing dyeing, decolorizing and drying treatments in a dyeing tank, the obtained partial image is measured with a densitometer to obtain an absorbance curve. This absorbance curve is called a densitogram. FIG. 7 shows an example of a densitogram of human serum protein. The densitogram in FIG. 7 has four fractional points m, and albumin (A1b) and α ₁ -globulin (α
₁ -G), α ₂ - globulins (α ₂ -G), it is fractionated into β- globulin (beta-G) and γ- globulin (γ-G).

In the conventional electrophoretic apparatus, the minimum value in such a densitogram is defined as the fraction point m, and the area (integral value) of the densitogram in the section sandwiched between the adjacent fraction points m.
Is calculated as the absolute value of each fraction and is reported together with the densitogram.

[0005]

However, the information obtained from the densitogram of serum protein is sufficient if only the concentration value of each fraction is sufficient for a sample having no particular abnormality, but the densitogram has various pathological conditions. It contains information, and it requires considerable experience and skill to interpret this information only from the densitogram and the concentration value of each fraction.

In particular, a peak due to a specific component called a minor band may appear in the serum protein fraction. The minor band includes, for example, M protein (monoclonal protein), complement, fibrinogen and β-lipoprotein. Among such minor bands, the peak due to a component called M protein is particularly important, and its increase or decrease needs to be monitored. FIG. 8 shows an example of a densitogram of human serum protein containing M protein.

Conventionally, the increase / decrease of the peak due to M protein has been grasped by visually observing the peak due to M protein in the densitogram, and cannot be quantified. On the other hand, it may be possible to grasp the increase / decrease in the peak due to M protein from the increase / decrease in the concentration value of the fraction containing the peak due to M protein. However, it is difficult to distinguish between the increase and decrease of the fractional component and the increase and decrease of the peak due to M protein. Such a problem is a common obstacle in reading the pathological condition information from the above-mentioned minor band.

The present invention has been made in view of the above points, and provides a method for processing a densitogram of an electrophoretic image capable of digitizing a peak due to a specific component appearing in the densitogram.

[0009]

The present invention comprises a step of determining a starting point P and an ending point Q of a peak due to a specific component in a densitogram obtained by photometrically measuring an electrophoretic image of a serum protein, and the starting point P and X corresponding to each of the end points Q
Two points P _X on the _shaft, a step of calculating the area S ₁ of the region surrounded by the densitograms and the X-axis between the Q _X, two points P _X on the _X-axis, between the Q _X A method for processing a densitogram of an electrophoretic image, comprising a step of calculating an area S _{2 of} a region surrounded by a straight line connecting the start point P and the end point Q and the X axis, Normalize the densitogram obtained by photometric analysis of the electrophoretic image, and normalize the densitogram obtained by photometric analysis of the electrophoretic image of serum protein in the normal sample. A curve corresponding to the difference between the normalized densitograms of the sample is obtained, and the point corresponding to the minimum point of the curve is set to the starting point P of the peak due to the specific component in the densitogram of the measured sample.
And an end point Q are provided. A method for processing a densitogram of an electrophoretic image is provided.

Here, the start point P and the end point Q of the peak due to the specific components in the densitogram obtained by measuring the electrophoretic image of the serum protein are determined by calculating the convex value of the densitogram of the serum protein, This can be performed by setting the points corresponding to the obtained minimum points of the convex values as the starting point P and the ending point Q of the peak due to the specific component in the serum protein densitogram.

Further, the densitogram obtained by photometrically measuring the electrophoretic image of the serum protein in the measurement sample is subjected to a normalization process, and the densitogram obtained by photometrically measuring the electrophoretic image of the serum protein in the normal sample. After normalizing, the curve corresponding to the difference between the normalized densitograms of the measurement sample and the normal sample is obtained, and the point corresponding to the minimum point of the obtained curve is the specific component in the densitogram of the measurement sample. It is also possible to set the start point P and the end point Q of the peak due to.

[0012]

According to the method for processing the densitogram of the electrophoretic image of the present invention, the starting point P and the end point Q of the peak due to the specific component appearing in the densitogram obtained by photometrically measuring the electrophoretic image of the serum protein are determined. To do. This starting point P and starting point Q
Based on, the area S _{1 of the} region surrounded by the densitogram and the X axis between the two points P _x and Q _x on the X axis corresponding to the start point P and the end point Q, respectively, and the two points P on the X axis. _x ,
A straight line connecting the start point P and the end point Q between Q _x and X
The area S ₂ of the area surrounded by and on the axis is calculated. The difference ΔS between these areas S ₁ and S ₂ corresponds to the area of the peak due to the specific component extracted from the densitogram. Based on the obtained area difference ΔS, the fractional% value of the peak due to the specific component can be obtained from the ratio of the whole densitogram and the area surrounded by the X axis to the area.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

First, a densitogram I is obtained by photometrically measuring an electrophoretic image of serum protein according to a conventional method. Β-containing a peak due to M protein of this densitogram I (indicated by M in the figure)
The portion corresponding to the globulin-γ-globulin fraction is shown in FIG.
Shown in. The degree of the convex portion of the densitogram I, that is, the convex value is calculated. The convex value can be calculated according to the calculation method described in JP-A-62-47534. For example, centering on an arbitrary data point i on the densitogram, a detection width 2k having respective data numbers k is set on both sides of the densitogram, and as shown in FIG. 2, data values Di-k at ik points are set.
And the amount of protrusion of the densitogram with respect to the straight line connecting the data value Di + K at the point i + k are evaluated by the area S of the portion surrounded by the straight line and the densitogram. This area S is a convex value at the data point i.

When the convex value at each data point of the densitogram I is obtained as described above and plotted with the data point on the X axis and the convex value on the Y axis, the waveform II shown in FIG. 1 is obtained.
This waveform II is the second derivative of densitogram I-
It is close to the sum of 1. In the obtained waveform II, the peak P ₁ corresponding to the peak due to M protein remarkably appears. Two local minimum values m ₁ and m ₂ sandwiching this peak P ₁
The two points on the densitogram I corresponding to are determined as the starting point P and the ending point Q of the peak due to the M protein.

Next, as shown in FIG. 1, the densitogram I between the two points P _x and Q _x on the X axis corresponding to the start point P and the end point Q, and the two points between the two points P _x and Q _x , respectively. The area S ₁ of the region surrounded by the X axis and the straight line connecting the start point P and the point P _{x and the} end point Q and the point Q _x is calculated. Next, the area S ₂ of the trapezoid PQP _x Q _x surrounded by the start point P, the end point Q, and the two points P _x and Q _x on the X axis is calculated.

The area S ₁ and the area S thus obtained are
The area difference ΔS from ₂ is calculated. This area difference ΔS corresponds to the area of the peak due to only M protein, and the area S _{0 of the} region surrounded by the area difference ΔS between the albumin fraction of the densitogram I and the X-axis from the γ-globulin fraction. The fractional% value of the peak due to M protein can be obtained by dividing by.

As described above, according to the method for processing the densitogram of the electrophoretic image of this embodiment, the peak due to the M protein can be extracted from the densitogram I and digitized as a fractional% value. it can. This makes it possible to easily and accurately grasp the increase / decrease in M protein in the sample by the increase / decrease in the fractional% value of the peak due to M protein.

[0019]

In this way, the protein concentration (unit: g / dl) of the peak due to M protein can be obtained from the area difference ΔS obtained from the densitogram I subjected to the concentration normalization process. For example, the standard total area of densitogram is 100,0
Densitogram I subjected to concentration normalization processing so that the total protein concentration of the specimen sample becomes 7 g / dl when it is 00.
Then, the area difference ΔS obtained as described above is 10,
In the case of 000, the ratio of the reference total area to the area difference ΔS is 100,000: 10,000, so the protein concentration of M protein is 0.7 g / dl. In this method, since the M protein can be expressed by an absolute concentration, the increase / decrease in the M protein can be confirmed more easily and accurately.

Start point P and end point Q of the peak due to M protein
The determination of is not limited to the method of determining based on the convex value of the densitogram I described above. For example, as shown in FIG. 3, the peak due to the M protein is clearly a fraction point m ₃ ,
When m ₄ is formed, the fraction points m ₃ and m ₄ can be set as the start point P and the end point Q, respectively.

Further, the densitogram obtained by fractionating the electrophoretic image of the measurement sample is subjected to normalization processing, and the electrophoretic image of the normal sample which is already known not to contain M protein is fractionated. It is also possible to determine the start point P and the end point Q of the peak due to the M protein by taking the difference between these densitograms after normalizing the densitogram obtained in this way. That is, the densitogram I obtained by fractionating the electrophoretic image of the measurement sample is subjected to X-axis normalization processing and Y
The axis normalization processing is sequentially performed. Here, the normalization process is described in JP-A-62-42034, and the X-axis normalization process detects at least two reference points associated with a predetermined migration length in the densitogram. Then, normalize the densitogram so that these reference points respectively correspond to the predetermined data positions related to the predetermined migration length, and the data numbers of the two reference points and the predetermined data positions related to the predetermined migration length. It means to normalize the value of densitogram based on the number of data between.

The Y-axis normalization processing is the normalized X
The number of data between the reference points of the densitogram and the distance between these reference points are located on the X axis so that the area of the reference points on the axis is approximately equal to the area between the corresponding data positions. It means that the Y axis is normalized based on the ratio with the number of data.

The fractional point position and the peak position of the densitogram normalized in this way can eliminate the influence of the difference in migration length or migration position. That is, by subjecting the densitogram of the measurement sample and the densitogram of the normal sample to the X-axis normalization process, as shown in FIG. Densitogram IV is obtained. Further, by subjecting the densitograms III and IV to the Y-axis normalization treatment, the densitogram III ′ of the measurement sample and the densitogram of the normal sample in which the concentration values of the γ-globulin fractions are equal to each other as shown in FIG. IV 'is obtained.

By taking the difference between the densitogram III 'of the measured sample and the densitogram IV' of the normal sample, a waveform V obtained by extracting the peak due to M protein as shown in FIG. 6 can be obtained. The points on the densitogram I corresponding to the minimum points m ₅ and m ₆ of the waveform V are determined as the start point P and the end point Q of the peak due to the M protein.

The densitogram obtained by fractionating an electrophoretic image of a normal sample is, for example, an electrophoretic image obtained by electrophoresing a commercially available control serum or a normal sample obtained by electrophoresing a sample to be measured. Densitograms obtained from the ones shown can be used.

[0027]

As described above, according to the method for processing a densitogram of an electrophoretic image of the present invention, it is possible to quantify the peak due to the specific component appearing in the densitogram. As a result, it is possible to easily and accurately grasp the increase / decrease of the minor band, and thus it is possible to obtain remarkable effects such as facilitating the interpretation of the pathological condition information from the minor band.

[Brief description of drawings]

FIG. 1 β containing a peak due to M protein in densitogram
-Characteristic diagram showing a portion corresponding to a globulin-γ-globulin fraction.

FIG. 2 is an explanatory diagram for explaining a method of calculating a convex value of a densitogram.

FIG. 3 is an explanatory diagram for explaining a calculation method for obtaining an area difference ΔS corresponding to the area of a peak due to M protein in a densitogram.

FIG. 4 is a characteristic diagram showing a densitogram of a measurement sample and a normal sample subjected to X normalization processing.

5 is a characteristic diagram showing a densitogram of a measurement sample and a densitogram of a normal sample in which the densitogram shown in FIG. 4 is further Y-normalized.

6 is a characteristic diagram showing a waveform obtained by taking the difference between the densitogram shown in FIG. 5 and the densitogram of a normal sample.

FIG. 7 is a characteristic diagram showing a densitogram obtained by photometry of an electrophoretic image of serum protein.

FIG. 8 is a characteristic diagram showing a densitogram including a peak due to M protein.

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (3)

(57) [Claims] 1. A step of determining a starting point P and an ending point Q of a peak due to a specific component in a densitogram obtained by measuring an electrophoretic image of a serum protein, and X corresponding to the starting point P and the ending point Q, respectively. two points P _X on the _shaft, a step of calculating the area S ₁ of the region surrounded by the densitograms and the X-axis between the Q _X, two points P _X on the _X-axis, between the Q _X A method for processing a densitogram of an electrophoretic image, which comprises a step of calculating an area S _{2 of} a region surrounded by a straight line connecting the start point P and the end point Q and the X axis, Normalize the densitogram obtained by photometric analysis of the electrophoretic image, and normalize the densitogram obtained by photometric analysis of the electrophoretic image of serum protein in the normal sample. A curve corresponding to the difference in the normalized densitogram of the normal sample is obtained, and the points corresponding to the minimum points of the curve are set as the starting point P and the ending point Q of the peak due to the specific component in the densitogram of the measured sample. A method for processing a densitogram of an electrophoretic image, which is characterized in that 2. After calculating a convex value of a densitogram obtained by photometrically measuring an electrophoretic image of a serum protein, a point corresponding to a minimum point of the obtained convex value is a peak due to a specific component in the densitogram. 2. The method for processing a densitogram of an electrophoretic image according to claim 1, wherein the starting point P and the ending point Q are. 3. A difference ΔS between the obtained area S ₁ and area S _2.
The method for processing a densitogram of an electrophoretic image according to claim 1, further comprising the step of: