WO2007142402A1

WO2007142402A1 - A liver function tester and liver function testing system

Info

Publication number: WO2007142402A1
Application number: PCT/KR2007/001442
Authority: WO
Inventors: Bong Hyun Chung; Joong Jin Lee; Sang Kyu Kim; Hye Jung Park
Original assignee: Korea Research Institute Of Bioscience And Biotechnology
Priority date: 2006-06-09
Filing date: 2007-03-23
Publication date: 2007-12-13

Abstract

Disclosed are a liver function tester and a liver function testing system. The tester comprises a sensor strip for converting density of GPT and GOP in blood into current values, a current detection/amplification unit for detecting the current flowing in the sensor strip, and a control unit for converting the current into a digital signal and outputting the level of GPT and GOP from the digital signal. The sensor strip comprises a reaction unit, in which amino acids, reacting with GPT and GOT in the blood, and enzymes, involved in the generation of electrons from the amino acids, are fixed, and an electrode unit consisting of a plurality of working electrodes and a reference electrode, one end of each of said electrodes being connected to the reaction unit.

Description

A LIVER FUNCTION TESTER AND LIVER FUNCTION

TESTING SYSTEM

Technical Field

[1] The present invention relates, in general, to a liver function tester and liver function testing system and, in particular, to a liver function tester constituted as a portable module which simply makes liver measurements and displays the value through a mobile communication terminal or a computer connected to the tester, and a system comprising the same. Background Art

[2] According to the cause of the disease, liver diseases are classified as viral liver diseases, alcoholic liver diseases caused by excessive drinking, toxic liver diseases caused by drugs, autoimmune liver diseases caused by improper functioning of the human body immune system, metabolic liver diseases, caused by excessive accumulation of toxic material, and liver diseases having unknown causes. "Liver disease" means all diseases affecting the liver, and thus comprises hepatitis, cirrhosis and liver cancer. Hepatitis is classified as acute hepatitis, in which inflammation forms suddenly and usually disappears after 3 or 4 months, and chronic hepatitis, which lasts for longer than 6 months.

[3] In Korea, 60-70% of chronic liver disease and liver cancer is related to hepatitis B, about 15-20% to hepatitis C, and the remaining 10-20% to alcoholic hepatitis, hepatitis due to obesity, and autoimmune hepatitis. In other words, in Korea, almost all chronic liver disease and liver cancer is caused by hepatitis B and C. Hepatitis B is the more important of the two. 5-8% of the entire population has been reported to carry hepatitis B, and although the number has decreased recently, the number of carriers is still high. 1% of the entire Korean population is reported to carry hepatitis C, and moreover, the number is increasing according to age, and 5-6% of all people over age 70 are hepatitis C carriers. Hepatitis A and E viruses cause only acute hepatitis, while hepatitis B, C and D viruses cause acute hepatitis as well as the advancement of the acute disease to chronic forms such as liver cirrhosis and liver cancer.

[4] In Korea, so many people have liver disease that liver disease is the number 5 cause of death, and the number 1 cause among those in their 40s. According to 'National Health Nutrition Research' in 1998, 17 people out of every 1,000 were reported to suffer from chronic hepatitis or cirrhosis. Chronic liver disease (cirrhosis and liver cancer) is one of the most important causes of death, and the incidence of liver cancer patients among middle aged (40-65 years old) people is 74.8 in 100,000 for men and 15.6 in 100,000 for women, which is the highest in the world. Deaths attributable to liver cancer totaled 32.3 in 100,000 for men and 10.0 in 100,000 for women, which is the highest among 21 OECD countries that were compared, as reported in International Health Statistics Annual.

[5] Even though the death rate attributable to liver disease is increasing, methods for preventing and treating liver disease are not effective. This is at least partly attributable to shortcomings in methods for making liver measurements in hospitals.

[6] Typical factors for diagnosing liver disease are the enzymes Glutamate Pyruvic

Transaminase (GPT) and Glutamate Oxaloacetic Transaminase (GOT). These hepatic enzymes flow into the blood when liver cells are damaged. Accordingly, liver condition can be determined according to increases and decreases in the levels of GPT and GOT in the blood.

[7] The basic principle behind the conventional method for measuring liver parameters is the oxidizing enzyme-mediated oxidation of pyruvate and oxaloacetate, which are the products resulting from the enzymatic reaction of GPT and GOT with of L-alanine, L- aspartate, and L-ketoglutarate. This method typically involves observing changes in the pigment of TMB as an indicator chromogen to measure the density of GPT and GOT.

[8] This liver test method for GPT and GOP, based on color change and comprising measuring the extent of color change, has a disadvantage in that it cannot use blood as it is in a quick manner, and requires blood serum. Furthermore, the apparatus for measuring the color change is too big to carry. Accordingly, people must travel to hospitals having the apparatus in order to obtain diagnoses, and therefore, they are reluctant to seek treatment. Disclosure of Invention Technical Problem

[9] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a liver function tester which is constructed as a portable module so as to promptly and simply measure the level of GPT and GOT in the blood on the basis of electrochemical reactions.

[10] Another object of the present invention is to provide a liver function testing system for measuring the level of GPT and GOT in which the tester can be connected to a mobile communication terminal or to a computer for display purposes, whereby it can measure level of GPT and GOT in real time to thus realize ubiquitous health care. Technical Solution

[11] In order to achieve these objects, there is provided a liver function tester comprising; a sensor strip for converting density of GPT and GOP in the blood into current values; a current detection/amplification unit for detecting the current flowing in the sensor strip; and a control unit for converting the current into a digital signal and outputting the level of GPT and GOT from the digital signal.

[12] The sensor strip comprises a reaction unit, in which amino acids reacting with GPT and GOT in blood and enzymes involved in the generation of electrons from the amino acids are fixed, and an electrode unit consisting of a plurality of working electrodes and a reference electrode, one end of each of the electrodes being connected to the reaction unit.

[13] In the tester, the amino acids fixed to the reaction unit may comprise L-alanine reacting with GPT and L-aspartate reacting with GOT. Preferably, the enzymes fixed on the reaction unit comprise L-glutamate oxidase, α-ketoglutaric acid and peroxidase.

[14] Optionally, the reaction unit of the sensor strip may further comprise glucose oxidase, reacting with glucose, fixed thereon, whereby the tester can measure blood glucose levels.

[15] Preferably, the tester may further comprise a power supply unit for providing electric power to the electrode unit, the current detection/amplification unit and the control unit from an external mobile communication terminal or a computer connected thereto. In a preferred modification, this tester may further comprise a transmitting/receiving unit for exchanging information on level of GPT and GOT with an external mobile communication terminal or a computer.

[16] The sensor strip is detachably mounted on the tester so as to form one module with the other units of the tester.

[17] In order to accomplish the above objects, there is provided a liver function testing system comprising; a tester for measuring the level of GPT and GOT in the blood; and a mobile communication terminal or computer which is connected to the tester so as to exchange signals therewith and has a display unit for displaying the measured levels of GPT and GOT thereon.

[18] In this system, the tester comprises a sensor strip for converting the density of GPT and GOP in the blood into current values; a current detection/amplification unit for detecting current flowing in the sensor strip; a control unit, comprising an analog- digital converter for converting the detected current into a digital signal, adapted to outputting the digital signal; a power supply unit for providing electric power to the electrode unit, the current detection/amplification unit and the control unit from an external mobile communication terminal or a computer connected thereto; and a transmitting/receiving unit for receiving the digital signal from the control unit and transmitting it to the external mobile communication terminal or computer.

[19] In the system, the sensor strip comprises: a reaction unit, in which amino acids reacting with GPT and GOT in blood and enzymes involved in the generation of electrons from the amino acids are fixed, and an electrode unit consisting of a plurality of working electrodes and a reference electrode, each of the electrodes being connected to the reaction unit at one end thereof and to the current detection/amplification unit at the other end thereof.

[20] Preferably, the reaction unit in the sensor strip further comprises glucose oxidase, which reacts with glucose, additionally fixed thereon, so that the system can also be used to measure blood glucose levels. Brief Description of the Drawings

[21] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[22] FlG. 1 is a structural view of an tester in accordance with an embodiment of the present invention;

[23] FlG. 2 is an enlarged plan view of the sensor strip of FlG. 1 ;

[24] FIGS. 3 to 5 are graphs showing the relationship between the current values detected by the tester 10 of the present invention and the concentrations(densities) of GPT, GOT and glucose in the blood, detected using a conventional electrochemical reaction measuring instrument;

[25] FlG. 6 is an outlined structural view of a system in accordance with the embodiment of the present invention;

[26] FlG. 7 is a block diagram showing the system of FlG. 6; and

[27] FlG. 8 is a view explaining the use of the system in accordance with the embodiment of the present invention. Best Mode for Carrying Out the Invention

[28] The object, characteristic and advantages of the present invention will be more readily comprehensible with reference to the detailed description and the attached drawings, which explain a preferred embodiment thereof. Hereunder, the liver function tester in accordance with a recommended embodiment of the present invention will be described in detail in conjunction with the attached drawings.

[29] With reference to FlG. 1, a tester 10 is provided for measuring level of GPT and

GOT in accordance with an aspect of the present invention. As seen in this figure, the tester 10 comprises a sensor strip 20, a power supply unit 40, a current detection/ amplification unit 30, a control unit 50, and a transmitting/receiving unit 60. The tester 10 is in the form of a portable module in which the sensor strip 20 is detachably mounted on the tester 10 for measuring levels of GPT and GOT. The sensor strip 20 converts the density of GPT and GOT in the blood into electronic current values through an electrochemical method, and the tester 10 displays levels of GPT and GOT using the detected current value. The present invention confers the advantage of enabling levels of GPT and GOT to be conveniently measured.

[30] With reference to FlG. 2, the structure of the sensor strip 20 is described in detail. As seen in this figure, it comprises a non-conductive substrate 21, a reaction unit 22, and an electrode unit 23 comprising a working electrode 24 and a reference electrode 25.

[31] In the reaction unit 22, amino acids reacting with GPT and GOT in the blood and enzymes including L-glutamate oxidase are fixed. When a blood sample is introduced into the reaction unit 22, a series of consecutive electrochemical reactions occurs, for which GPT and GOT in the blood and the enzymes fixed on the reaction unit 22 are responsible, with the concomitant production of electrons. Accordingly, because the level of GPT and GOT in the blood sample is proportional to the quantity of current generated in the reaction process, the current can indicate the blood level of GPT and GOT.

[32] Optionally, the tester 10 can also be adapted to measure blood sugar level. In this regard, in addition to the amino acids and L-glutamate oxidase, glucose oxidase, which reacts with glucose, is fixed in the reaction unit 22 of the sensor strip 20. When introduced into the reaction unit, glucose in the blood is oxidized while glucose oxidase is reduced. Then, an electron carrier transfers electrons from the reduced glucose oxidase to the working electrode 24, to which a predetermined potential is applied. In detail, the electron carrier receives electrons from the reduced glucose oxidase so that a redox reaction occurs to reduce the electron carrier while the reduced glucose oxidase reverts to neutral. Then, the electron carrier loses the electrons at the working electrode 24. During the electron transfer, current is therefore generated in proportion with the level of blood sugar.

[33] As mentioned above, the electrode unit 23 comprises the working electrode 24 and the reference electrode 25. The working electrode 24 and the reference electrode 25 are separately connected to the reaction unit 22 at their respective ends, so that the current (electrons) generated as a result of the reaction of GPT and GOT in the blood sample interacting with the amino acids in association with the fixed enzymes in the reaction unit 22 flows through the electrode unit 23. In an embodiment, three working electrodes are provided to measure GPT, GOT and glucose. Hereunder, the procedure for measuring GPT and GOT is described in detail using reaction formulas. As for the measurement of glucose, its description is omitted because it is commonly known.

[34] Three working electrodes 24a, 24b and 24c of the electrode unit 23 are adapted to measure levels of GPT, GOT and glucose in the blood, respectively. Corresponding to the targets, proper reaction materials are fixed to the working electrodes of the reaction unit 22. In the reaction unit 22, L-alanine, for example, is fixed to the first working electrode 24a for measuring GPT, L-aspartate to the second working electrode 24b for measuring GOT, and glucose oxidase to the third working electrode 24c for measuring glucose. In the reaction unit 22, a mixture fluid of α-ketoglutaric acid, L-glutamate oxidase and peroxidase is fixed, along with the amino acid substrates, to both the first and the second working electrodes 24a, 24b.

[35] When a blood sample is introduced into the working electrode 24a, 24b to which the amino acids are fixed, GPT and GOT in the blood react with each amino acid (L-alanine, L-aspartate) fixed to the reaction unit 22 to generate L-glutamate, as in the following reaction formulas 1-1 and 1-2.

[36] Ξenun GPT i L - Alanine + a - ketoglutar ate → pyruvate + L - glutarate GPT Rxn (1 - 1)

[37] Serum GOT i

L - Aspartate + oc -ketoglutar ate -> oxaloacetate + L -glutarate G0T Rxn (l - 2)

[38]

[39] The L-glutamate is re-oxidized to α-ketoglutarate in the presence of L-glutamate oxidase, with the concomitant production of hydrogen peroxide (H O ). H O is degraded by peroxidase to generate electrons, as in the following reaction formulas 2 and 3. [40]

[41] L -glutamate oxidase i

L - Glutarnate + O₂ → a - ketoglutar ate + NH₃ + H₂O₂ (2)

[42]

[43] Peroxidase

I

H₂O₂ → 2H⁺ + O₂ + 2e^" (3)

[44]

[45] The glucose in the blood is oxidized by glucose oxidase while the glucose oxidase is reduced. [46] Thus, the current generated during the transport of the electrons to a final electron acceptor through each working electrode 24 is displayed as the level of GPT, GOT and blood sugar. [47] Returning to FlG. 1, the power supply unit 40 provides electricity to the electrode unit 23, the current detection/amplification unit 30, and the control unit 50. Electric power may be supplied to the power supply unit 40 from a mobile communication terminal 110 or a computer 120 (F1G.6), as will be described later, when the tester 10 is connected to them. The power supply unit 40 can employ a direct current voltage source when connected to a mobile communication terminal 110, or either a direct current or alternating current voltage source when connected to a computer 120.

[48] The current detection/amplification unit 30 functions to detect the quantity of current flowing between the working electrode 24 and the reference electrode 25 of the electrode unit 23. To accomplish this, the current detection/amplification unit 30 is connected to the other end of the working electrode 24 and the reference electrode 25. In the current detection/amplification unit 30, three switches SWl, SW2 and SW3 are provided, which connect the three working electrodes to three resistors Rl, R2 and R3, respectively. The three switches SWl, SW2 and SW3 are successively operated in such a way that one is in an ON state while the others are in an OFF state. For example, when SWl is on, SW2 and SW3 are both off. Current flowing through the working electrodes is converted to voltage by the resistors Rl, R2 and R3 in association with respective operational amplifiers OPl, OP2 and OP3. The converted voltage is input into the control unit 50.

[49] The control unit 50 converts the voltages input from the current detection/amplification unit 30 into digital signals using analog-digital converters ADCl, ADC2 and ADC3. These digital signals are used to output level of GPT , GOT and blood sugar information. The control unit 50 can output level information by converting the quantity of current flowing in each working electrode 24 into a voltage value.

[50] The transmitting/receiving unit 60 receives the converted level information from the control unit 50 and transmits it to the mobile communication terminal 110 or the computer 120 in which the information is read. The information exchange of the transmitting/receiving unit 60 may be performed in a wireless manner.

[51] The most important characteristic of the present invention is that an electrochemical method, currently used to measure blood sugar level, is also used to make liver function measurements. Therefore, the tester according to the present invention can be manufactured as a portable module which makes it convenient for users to simply and promptly test liver function. In addition, the tester according to the present invention confers the advantage of measuring blood glucose level at the same time.

[52] FIGS. 3 to 5 are graphs showing the relationship between the current values detected by the tester 10 and the concentrations(densities) of GPT, GOT and glucose in the blood, detected using a conventional electrochemical reaction measuring instrument.

[53] First, sera and serial dilutions of GPT, GOT and glucose are measured for current values according to concentrations of GPT, GOT and glucose using a conventional electrochemical reaction measuring instrument (Potentiostat, Wonatech Inc., Model WPG 100) (curved and straight lines). Separately, the same sera and serial dilutions of GPT, GOT and glucose as used above are dropped on the reaction unit 22 of the sensor strip 20. To make liver funbtion measurements, current values for the different densities were measured with the tester 10 and graphically shown (dots), along with those obtained with the electrochemical reaction measuring instrument, in FIGS. 3 to 5. Each density measurement was repeated 5 times.

[54] As shown in the graphs, the results obtained by the tester of the present invention are almost coincident with those obtained by the currently used instrument, particularly in the clinically important range of GPT and GOT (10 to 1000 units/L) and glucose (100-600 mg/dL).

[55] Referring to FIGS. 6 and 7, a system 100 is provided for testing liver functions. The system 100, as shown, comprises the tester 10 and a mobile communication terminal 110, such as a cellular phone or a PDA, or a computer 120, whether a laptop or desktop.

[56] The mobile communication terminal 110 or the computer 120 has a transmitting/ receiving unit 111 or 121 provided to receive the information from the tester 10 through an interface (not shown) such as a USB or RS-232C port, or in a wireless manner, such as such as IrDA or Blue Tooth.

[57] After converting level information transmitted from the tester 10 into a digital signal, the control unit 112 of the mobile communication terminal/control unit 122 of the computer displays said information on each display unit 113, 123. They also perform control to drive sound process unit 114, 124 to audibly inform the blind or the old of the liver measurements. Preferably, the sound process unit 114, 124 generates a warning sound when the levels are dangerously high, that is, exceeding a certain level.

[58] Each key operation unit 115, 125 can store information about liver measurement diagnoses, transmitted from the tester 10, in a database. Each data base 116, 126 stores a list of users for whom liver function test have been taken and the levels in a table form, or sequentially according to date. Thus, liver function measurements are stored in an orderly manner according to user or date, and can be searched systemically.

[59] As described above, the tester 10, based on an electrochemical method, in accordance with the present invention is composed of a portable module so that it allows the user to promptly and simply measure the level of GPT and GOT in the blood and can display the levels in real time when connected to a mobile communication terminal or to a computer in the system 100 of the present invention.

[60] The tester and the system have the advantage of realizing ubiquitous health care.

According to Fig. 8, the mobile communication terminal 110 or computer 120 provides the liver function information via wired or wireless communication after connecting with a web server of management service provider 130 or a server of a competent hospital 140, as set by the user. [61] In response to the management information provided, accordingly, the service provider 130 or the competent hospital 140 can provide prescription information, dietetic therapy information and exercise therapy information in order to manage liver function. They also can store and receive a patient's medical examination information and can inform the patient of the process via an SMS sent to the patient's cellular ph one. The web server of management service provider 130 or the competent hospital 140, in which liver measurements of each patient are stored in a database, may provide the user with information on liver function or abnormal changes in order to promptly manage liver functionss, thereby preventing unexpected problems in advance.

[62] According to the present invention, a patient can be continuously provided with liver function management in real time. There is an advantage in that the patient does not need to frequently go to the hospital in order to undergo liver examination. Industrial Applicability

[63] As can be seen from the foregoing, the tester and system according to the present invention can promptly and simply measure the level of GPT and GOT in the blood on the basis of an electrochemical method. Thanks to the constitution as a portable module, the tester of the present invention makes it possible for the user to measure levels of GPT and GPT quickly and readily. The tester is also convenient because the liver measurements can be displayed on a mobile communication terminal or a computer via wired or wireless communication therewith.

[64] According to the present invention, a user can be continuously provided with management of liver function in remote places, and the inconvenience of having to go to the hospital to examine and treat the liver is minimized.

[65] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings thereof, but, on the contrary, is intended to cover various modifications and variations within the spirit and scope of the appended claims.

[66]

Claims

[ 1 ] A liver function tester, comprising ; a sensor strip for converting density of GPT and GOT in blood into current values; a current detection/amplification unit for detecting the current flowing in the sensor strip; and a control unit for converting the current into a digital signal and outputting the level of GPT and GOT from the digital signal, wherein said sensor strip comprises; a reaction unit, in which amino acids reacting with GPT and GOT in blood and enzymes involved in the generation of electrons from the amino acids are fixed, and an electrode unit consisting of a plurality of working electrodes and a reference electrode, one end of each of said electrodes being connected to the reaction unit.

[2] The tester according to claim 1, further comprising a power supply unit for providing electric power to the electrode unit, the current detection/amplification unit and the control unit from an external mobile communication terminal or a computer connected thereto.

[3] The tester according to claim 1, wherein the amino acids fixed to the reaction unit comprise L-alanine reacting with GPT and L-aspartate reacting with GOT.

[4] The tester according to claim 1, wherein the enzymes fixed on the reaction unit comprise L-glutamate oxidase, α-ketoglutaric acid and peroxidase.

[5] The tester according to claim 1, wherein the reaction unit of the sensor strip further comprises glucose oxidase, reacting with glucose, fixed thereon, so that the tester can measure blood sugar level.

[6] The tester according to claim 1 or claim 5, further comprising a transmitting/ receiving unit for exchanging information on levels with an external mobile communication terminal or a computer.

[7] The tester according to claim 1, wherein the sensor strip is detachably mounted on the tester so as to form one module with the other units of the tester.

[8] A liver function testing system, comprising; a tester for measuring levels of GPT and GOT in blood; and a mobile communication terminal or computer which is connected to the tester so as to exchange signals therewith and has a display unit for displaying the measured levels of GPT and GOP thereon, said tester comprising: a sensor strip for converting the density of GPT and GOT in blood into current values; a current detection/amplification unit for detecting current flowing in the sensor strip; a control unit, comprising an analog-digital converter for converting the detected current into a digital signal, adapted to outputting the digital signal; a power supply unit for providing electric power to the electrode unit, the current detection/amplification unit and the control unit from the external mobile communication terminal or the computer connected thereto; and a transmitting/receiving unit for receiving the digital signal from the control unit and transmitting it to the mobile communication terminal or computer.

[9] The system according to claim 8, wherein the sensor strip comprises: a reaction unit, in which amino acids, which react with GPT and GOT in blood, and enzymes, which are involved in the generation of electrons from the amino acids, are fixed, and an electrode unit consisting of a plurality of working electrodes and a reference electrode, each of said electrodes being connected to the reaction unit at one end thereof and to the current detection/amplification unit at the other end thereof.

[10] The system according to claim 8, wherein the reaction unit in the sensor strip further comprises glucose oxidase, which reacts with glucose, fixed thereon, whereby the system can measure blood sugar level.