Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1997-11-20
2001-05-15
Alexander, Lyle A. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C427S061000, C206S204000, C073S864720, C435S307100
Reexamination Certificate
active
06231815
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a system for storing and transporting sample material on absorbent material.
BACKGROUND OF THE INVENTION
The glycation of haemoglobin and serum proteins is increased in patients with diabetes mellitus. The increase is dependent on the glucose concentration and the incubation period of the protein with glucose. In these cases the serum proteins, including haemoglobin, are not glycated enzymatically but rather by means of an uncatalysed chemical reaction of glucose with amino groups of proteins. Experts assume that the concentration of a particular protein-glucose adduct reflects the glucose concentration over a particular period as well as the turn-over rate of the protein. Glycated haemoglobin is regarded as an indicator of the average blood glucose concentration during the last two to three months before the blood collection and examination. Glycated serum protein shows the blood glucose concentration during a shorter period of time. The determination of glycated protein such as glycated haemoglobin (HbA
1c
) or glycated serum protein is therefore considerably important for the long-term glycemic control of diabetes patients.
In order to examine blood for the content of glycated protein the sample must often be transported to a far distant laboratory. The content of glycated protein in the sample should not change during this transport period and during a possible subsequent waiting period. The examination of blood samples which had been stored for a long period for glycated haemoglobin is reported in Clinical Chemistry 29, 1080-1082 (1983). This shows that whole blood can be stored up to 21 days at room temperature with essentially no change in the HbA
1c
content.
However, the transport of liquid blood samples is complicated and involves risks such as breakage of the transport vessel. In addition the puncture of a vein is necessary to collect whole blood although the small amounts obtained by withdrawing capillary blood from the finger pad would be sufficient for the analysis. Thus methods have been developed for the transport and analysis of smaller amounts of sample in which capillary blood is applied to filter paper and allowed to dry there. The filter paper is subsequently transported to the site of the examination. Here a disk containing the sample is cut out from the filter paper, eluted and the eluate is examined. The report in Clinical Chemistry 28, 386-387 (1982) refers to such a method. In this report it is stated that the content of glycated protein changes considerably compared to the original sample during blood sample storage on filter paper. After storage of whole blood on filter paper considerably increased measured values for glycated protein are found.
The impregnation of filter paper with glucose oxidase to prevent the increase in the content of glycated haemoglobin caused by storage of blood on filter paper is described in Clinical Chemistry 32, 869-871 (1986). However, impregnation with glucose oxidase was not able to completely prevent the increase of glycated protein. The false increase in the values can only be reduced by this measure. A further disadvantage of impregnating with glucose oxidase is its own instability during storage under the usual storage conditions.
Similar conclusions are reached by an article in Diabetes Care 10, 352-355 (1987). Here it is reported that the treatment of filter paper with glucose oxidase or with ethanol cannot satisfactorily prevent a false increase in the values for glycated haemoglobin when blood is stored on filter paper.
Apart from the poor stability of the sample, a further disadvantage of the methods described in the state of the art for the transport and storage of sample materials is that the liquid sample has to be completely dried before the final packaging. For this the filter paper has to be typically dried for 10 to 60 minutes in the air. Incompletely dried samples can lead to non-reproducible test results or for example contaminate the shipping packaging.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention was therefore to eliminate the disadvantages of the state of the art. In particular the content of glycated protein should be stabilized in a sample when stored on an absorbent material. After storage of the glycated protein on an absorbent material a value should be found for the glycated protein which corresponds to that found after sample collection and before storage. Furthermore it should simplify the handling of the carrier containing the sample material and make it safer.
This object is achieved by the subject matter characterized in more detail in the patent claims.
The invention concerns a system for storing and transporting sample material. The system is composed of an absorbent material for absorbing a liquid sample, a closable container in which the material can be stored and transported and a moisture absorbent medium.
An essential feature of the system according to the invention is that the system itself contains no test reagents. In particular the absorbent material which serves to absorb the sample material contains no test reagents.
In this connection test reagents are those reagents or substances which are usually contained in analytical test elements such as colorimetric test strips or electrochemical sensors and biosensors and are used to detect a target analyte. In other words test reagents are substances which interact with the target analyte and allow it to be directly or indirectly detected i.e. optionally not until after the addition of other reagents. Examples are enzymes, coenzymes, dyes, mediators, pH and redox indicators, immunological detection reagents such as antibodies or antigens, ionophores, complexing agents etc..
Test reagents do not include reagents or substances that are not used directly to detect a target analyte. Such substances must not interact with the target analyte in the sample in a manner which would allow its detection. Examples of these are stabilizers, which are also understood to include enzyme substrates and coenzymes which mainly serve to stabilize the analyte, buffer substances, spreading agents and other common substances familiar to a person skilled in the art.
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Clinical Chemistry vol. 29, pp.1080-1082 (1983).
Clinical Chemistry, vol. 28, pp. 386-387 (1982).
Clinical Chemistry, vol. 32, pp. 869-871 (1986).
DIN 53106 (May 1981) and English translation.
Bainczyk Gregor
Leininger Helmut
Lerch Rolf
Nagel Rolf
Alexander Lyle A.
Fulbright & Jaworski LLP
Roche Diagnostics GmbH
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