JPH1087512A - Method for real-time inspection of helicobacter pylori infection through urea reagent labeled with 13c - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid errors in measurement, as well as to make packs, etc., unnecessary, steeply shorten the testing time, and increase the number of cases tested, by continuously analyzing expired gas with a fast response gasometric analyzer for expiration and calculating the isotope ratio before and after the dosage of a urea labeled with<13> C. SOLUTION: Before and after oral dosage of a urea labeled with<13> C, a subject is made to hold a tube 1 (e.g. mouthpiece) in his/her mouth and is made to breathe out. Concentrations of<12> CO2 and<13> CO2 (where<13> C is a stable isotope of<12> C) in expired gas are continuously measured at the same time, and the values of the concentrations for a few seconds ending the end of exhaling are known. Then the ratios of<13> CO2 /<12> CO2 for a few seconds ending the end of exhaling are calculated and the mean value of these ratios is calculated at the end of exhaling. Moreover, the rate of change of<13> CO2 /<12> CO2 before and after dosage of urea labeled with<13> C is calculated and the presence or absence of Helicobacter pylori infection is judged from whether the rate of change is over a set point or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a test method based on the principle of " ^13C- labeled urea breath gas test" as a method for examining the presence or absence of infection for prevention of Helicobacter pylori infection on the stomach wall.

[0002]

2. Description of the Related Art When Helicobacter pylori is exposed to urea, it is hydrolyzed to generate carbon dioxide and ammonia. Carbonic acid (C) which is a constituent element of the carbon dioxide gas is derived from carbonic acid (C) which is a constituent element of urea. Therefore, if a mark is made with carbonic acid ¹³ C, which is a constituent element of urea, it is possible to determine whether or not urea has been decomposed by measuring the carbon dioxide gas in the breath. This makes it possible to know the presence of Helicobacter pylori. Conventionally, this test method uses ¹³ C-labeled urea labeled with ¹³ C, which is a stable isotope of carbonic acid, a constituent element of urea, and exhales the bag before and after oral administration. After storing, this gas is analyzed with a gas analyzer,
Calculating the isotope ratio of carbon dioxide _{^{(13 CO 2/12 CO 2}} ), we examined the ¹³ C-labeled urea administered before and after the change rate of the isotope ratio, the infection to determine exceeds the rate of change set The presence or absence was determined.

[0003]

In the conventional test method,
Once the expiration gas is stored in a pack etc., one pack is required before and after the administration of labeled urea, which is costly. If this pack is to be reused, sterilization must be performed, which is troublesome. Had occurred. In addition, it takes time to derive test results, and the number of test processes is limited. In addition, when inhaling the pack, when exhaling, the exhaled air reaches the lungs at first and contributes to gas exchange. In this test method for analyzing a change in gas isotope ratio, an error was caused by mixing with carbon dioxide in air.

The present invention uses a breath gas analyzer having a high response speed without using a pack or the like, and continuously analyzes the carbon dioxide gas concentration for several seconds until the end of the breath by using a breath gas analyzer having a high response speed and isotope. By calculating the ratio, there is provided a test method that does not require a pack, greatly reduces test time, increases the number of test processes, and further eliminates measurement errors.

[0005]

Real-time Helicobacter pylori infection inspection method according to ¹³ C-labeled urea reagent according to the present invention, in order to solve the problems] examines the infection of Helicobacter pylori ^"13
In the “C-labeled urea breath gas test”, the subject was given a tube such as a mouthpiece before and after oral administration of ¹³ C-labeled urea.
(1) is added to the mouth, breath is exhaled, and the concentration of carbon dioxide ( ¹² CO ₂ ) and its stable isotope ( ¹³ CO ₂ ) in the breath is simultaneously and continuously measured by a gas analyzer with high-speed response performance. Measurement, recognizing each gas concentration value for several seconds until the end of the call, and carbon dioxide isotope ratio (
¹³ CO _^2/12 CO ₂₎ that calculates a, and calculating the average value of the carbon dioxide gas isotope several seconds until the call terminated at the call termination _{^{(13 CO 2/12 CO 2}} ), 13 C and calculating the rate of change of the carbon dioxide gas isotope ratio across labeled urea administered _{^{(13 CO 2/12 CO 2}} ), by determining whether or not exceed the value of this rate of change set, infection of Helicobacter pylori Is a method of determining the presence or absence of the

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention in conjunction with the accompanying drawings ¹³
A preferred embodiment of a real-time Helicobacter pylori infection test method using a C-labeled urea reagent will be described.
As shown in FIG. 1, before and after the administration of the reagent, the subject holds the tube 1 such as a mouthpiece and slowly calls it once. The change in the carbon dioxide concentration at this time is analyzed by a gas analyzer having a high-speed response such as a mass spectrometer. Analyze in total. During exhalation at this time
¹³ CO ₂ and ¹² CO ₂ component change and the ratio of _{^{(13 CO 2/12 CO 2}} )
Is as shown in FIG. That is, in FIG. 2, the first phase is a phase in which the last air inhaled before exhalation is inhaled only to the oral cavity and the trachea and does not contribute to gas exchange in the lungs, but is exhaled again by exhalation. There is no change in carbon dioxide gas, and the concentration changes at the same level as air. The second phase is a mixed phase of gas that has contributed to gas exchange in the lungs and gas that has not contributed to gas exchange in the oral cavity and trachea. When exhalation gas is collected in the pack, the first phase and the second phase are mixed, so that the gas concentration value due to gas exchange is mixed with the gas concentration value of air, which causes a measurement error. The third phase, a phase gas contributing to gas exchange in the lungs is exhaled carbon dioxide isotope ratio when the _{^{(13 CO 2/12 CO 2}} ) indicates a constant value as shown in FIG. The presence or absence of Helicobacter pylori infection is determined based on whether or not the value after the administration of the reagent at which the isotope ratio of the third phase becomes constant exceeds a predetermined threshold value as compared with the value before and after the administration of the reagent.

[0007]

According to the present invention, the test time can be shortened, and parts (packs and the like) required for the test are not required, so that the number of test processes can be greatly increased.
Further, the presence or absence of air mixing can be monitored during the exhalation process, and the isotope ratio of only alveolar carbon dioxide can be analyzed purely, so that the test accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-drawing diagram illustrating the method of measurement of the present invention.

FIG. 2 is a characteristic diagram showing a state of a change in concentrations of carbon dioxide ¹² CO ₂ and ¹³ CO ₂ and a change in carbon dioxide isotope ratio obtained by measurement.

[Explanation of symbols]

 1 cylinder

Claims (1)

[Claims] 1. A " ^13C- labeled urea breath gas test" for examining Helicobacter pylori infection, in which a mouthpiece or other tube (1) is added to a subject before and after oral administration of ^13C- labeled urea. Simultaneously and continuously measure the concentration of carbon dioxide ( ¹² CO ₂ ) and its stable isotope ( ¹³ CO ₂ ) in the exhaled breath using a gas analyzer with high-speed response and possible to recognize each gas concentration value of a few seconds up to the end, and that the calculating few seconds CO isotope to at call ends _{^{(13 CO 2/12 CO 2}} ), call termination at call termination carbon dioxide isotope several seconds until _{^{(13 CO 2/12 CO 2}} ) of the possible to calculate the mean value, ¹³ C-labeled urea carbon dioxide isotope before and after administration _{^{(13 CO 2/12 CO 2}} ) By calculating the rate of change of the helicopter and determining whether the rate of change exceeds a set value. Real-time Helicobacter pylori infection inspection method according to ¹³ C-labeled urea reagent and determining the presence or absence of infection of H..