Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Patent
1998-02-09
1999-07-13
Campbell, Eggerton A.
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
435 912, C12Q 168, C12P 1934
Patent
active
059225440
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of detecting cells appearing in biological samples. A variety of cells are observed in the feces in cases of diseases of the digestive tract such as ulcers and tumors. For example, when there is bleeding into the feces, an observation of the blood cells in the feces can be an indicator of diseases in the digestive system. To be concrete, bleeding into the feces is often detected in cases of ulcers in the stomach and duodenum, or cancers in the digestive tract such as the esophagus, stomach, and colon. Except for regular bleeding, when diseases such as ulcerous colitis and tumorous necrosis cause a diapedesis, blood cells are observed in the feces.
It is especially important to detect occult blood in the feces when screening for colon cancer. To a certain degree, colon cancer can be detected in its early stages by taking a sample of the feces collected noninvasively. The diagnostic technology using bleeding into the feces as an indicator can also be applied to other animal species besides human beings.
In addition to feces, urine is commonly used as a biological sample. Detecting cells in urine is an important marker of disease. For example, urinary tract infection is suspected when white blood cells are detected in urine. Thus, the detection of cells in biological samples from a living organism, in which no cells can be detected under normal conditions, will provide valuable information for diagnosing many kinds of diseases.
BACKGROUND ART
Currently, a widely used method for detection of bleeding into feces is indexing hemoglobin derived from blood. Accordingly, a method of biochemical coloring reaction using hemoglobin's peroxidase-like activity, and a method of immunological detection using an antibody against hemoglobin (Songstar et al., Cancer. 45, pp. 1099-1102, 1980) are known. Even though the former biochemical method can detect blood from the digestive tract, there is always the possibility of a false-positive because a similar reaction may be caused by other substances with peroxidase-like activity or animal hemoglobin originating from diet. On the other hand, the latter immunological method will not be influenced by animal hemoglobin or substances with peroxidase-like activity originating from diet. The immunological method with those characteristics is widely used because testing can be done at any time without restricting meals.
Even though the immunological method of detecting fecal occult blood has been successful in terms of specificity and sensitivity, even now there are several problems raised about that method. The biggest problem is the hemoglobin's stability while it is in the digestive tract, and its stability at the time of preservation or transportation of the fecal samples. Feces contain several factors which will significantly affect the hemoglobin's immunological activity. In the case of bleeding in an upper part of the digestive tract, hemoglobin's detection sensitivity will be strongly influenced by digestion by digestive enzymes, the biological dissolution by microorganisms, or chemical transformation under acidic conditions. There are cases in which no hemoglobin is detected in spite of bleeding because the hemoglobin's immunological activity was weakened or lost due to a non-specific adhesion of various kinds of solid substances. Thus, bleeding detection techniques using hemoglobin as an indicator can detect bleeding in a lower part of the digestive tract. However, there is a stability problem when used as an indicator of bleeding in the upper part of the digestive tract. Furthermore, there is also a possibility of false negative detection due to unknown factors that cannot be explained simply by the above causes. The solutions to these problems are in great demand.
Another problem with the immunological method is to maintain specificity. The immunological method accomplishes a higher specificity, compared with the classical method using hemoglobin's chemical activity as an indicator. It also demands strict conditions of
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Miyai Kiyoshi
Naitoh Tsutomu
Yonekawa Toshihiro
Campbell Eggerton A.
Eiken Kagaku Kabushiki Kaish
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