JPH10332831A - Monitoring apparatus using cut of dna chain as index - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure effect of an ionizing radiation or an electromagnetic wave on human bodies and the environment by detecting a lag phenomenon of a DNA chain to facilitate understanding by the general public while offering an index with a higher direct correlation with the biological influence. SOLUTION: This apparatus determines the dose of an ionizing radiation or an electromagnetic wave using as unit a cut phenomenon of DNA chain which is relatively understandable appealing to intuition appearing as one of phenomena of biological effect by radiation. A number of breakage in DNA detecting section is so arranged to seal DNA molecules or cells into a gel or a porous substance and is held in a housing case. The DNA molecules are previously included in a buffer solution, the gel or a capillary tube or on a silicon substrate. For example, a individual monitoring device is made up of a lower lid 35 and an upper lid 31 both making a case and a high polymer gel 30 such as agarose or polyacrylamide gel to be housed therein and a hook 36 is mounted for wearing in individual use. A well 6 is provided to add the DNA molecules.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for quantifying biological effects of ionizing radiation or electromagnetic waves applied to a human body or a surrounding environment by direct biological indicators.

[0002]

2. Description of the Related Art In radiation exposure management of individuals, the exposure dose has been quantified by a small personal monitoring device called a film batch, a thermoluminescence dosimeter, or a pocket dosimeter. Film batches have been applied as dosimeters because photographic emulsions exhibit a blackening effect in proportion to radiation along with the sensitizing effect. When radiation is applied to the thermoluminescent material, electrons released from the crystal lattice are excited and captured in a metastable state, and remain stable for a long time at room temperature. When this is heated from the outside, the trapped electrons are thermally released according to the temperature, and the thermoluminescence dosimeter utilizes the fact that it emits luminescence and returns to the ground state. The pocket dosimeter measures the dose using an ionization chamber. Specifically, the gas enclosed in the box is ionized according to the radiation dose, and the ionizing radiation dose is measured from the current value flowing at that time. Japan Radioisotope Association, Radiation Management Practice for Chief, Revised 2
Edition, page 140 (1992).

On the other hand, environmental radiation is measured by an ionization chamber type, GM
It is done by a counter tube type, NaI (Tl scintillation type, semiconductor type survey meter. Japan Radioisotope Association, radiation control practice for chief, 2nd revised edition,
See page 124 (1992).

[0004]

The prior art such as film batch, thermoluminescence dosimeter, pocket dosimeter and various survey meters has a long history, and is capable of measuring the dose of ionizing radiation at low cost and with good reproducibility. it can. However, the unit to be measured is the amount of energy applied per unit volume, such as sievert (Sv, J / kg) or sievert per hour (Sv / h, J / kg / h). Although this physical unit is used without difficulty among experts, it is a unit that is difficult to intuitively understand for the general public, and is not widely known. The fact that the amounts of Sv and Sv / h do not coincide with biological effects, especially at low doses, has long been discussed as an important issue in radiation effects studies. For this reason, even if it measures with the above-mentioned dosimeter, it cannot be wiped out the general public's sense of danger about nuclear power and radiation.

In recent years, there has been a concern that an electromagnetic wave (electromagnetic field) near a high-voltage transmission line may adversely affect a living body. With regard to this electromagnetic wave, the correlation between the energy application and the biological effect is hardly clear.

[0006] At present, the general public is conscious of a measuring instrument using an amount that can more intuitively understand biological effects than a physical unit such as Sv or Sv / h, which is discussed only between experts. It is rare.

[0007]

A relatively well understood phenomenon of radiobiological effects is DNA strand breaks. fact,
Cells lacking the ability to repair DNA strand breaks are known to be vulnerable to radiation (International
Journal of Radiation Biology (In
tJ Radiat. Biol.), 67, pp. 7-18 (199
See 5). Therefore, the present invention provides a method for quantifying the dose of ionizing radiation or electromagnetic wave in a unit more easily intuitively understood, which is a DNA strand break, although the cost and the simplicity of the measurement are inferior to the conventional technology.

[0008] This device is used for mobile phones, personal computer CRTs, T
Environmental monitoring can be performed by integrating with V or the like, or by being fixed around a high-voltage transmission line. Also DN
When measuring A-strand breakage by gel electrophoresis, it is necessary to extract DNA from cells, drop the extract into a groove in the gel with a pipette, and apply a voltage. In order to prevent DNA molecules from being damaged in this processing step, the present apparatus is characterized in that it has a structure in which DNA molecules are included in advance in a buffer solution, a gel, a capillary, or a silicon substrate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A method for quantifying the number of DNA strand breaks will be described. First, Fig. 1 shows a short DNA of several thousand base pairs in length.
Shows how the morphology changes due to strand breakage. This short DNA is called a plasmid DNA, and a DNA extracted from Escherichia coli or the like is commercially available. Plasmid DN
A is supercoiled 1 when there is no strand break,
D, in which only one of the two strands of the DNA molecule is cleaved
The presence of NA single-strand breaks 2 results in a circular ring 3. Also D
DN where both strands of two strands of NA molecule are cleaved
The presence of A double-strand break 4 results in a linear 5. These three have the same molecular weight, but have different molecular shapes.
Differences appear in mobility within the gel. In other words, the supercoiled 1 has a small molecular shape and therefore has a high passing speed in the gel, but the annular 3 has a low tail and the passing speed in the gel is low. Utilizing this difference in passage speed, the three components of supercoiled, annular, and linear 5 can be separated and the ratio can be determined. The number of strand breaks can be calculated.

X = ln [(1-L) / S] (Equation 1) Y = L / (1-L) (Equation 2) However, the average number of single strand breaks per DNA molecule is X, The average number of double strand breaks is Y, the ratio of supercoiled 1 is S, and the ratio of linear 5 is L. The ratio is each ratio when the total amount of the supercoiled shape, the annular shape, and the linear shape is defined as 100%.

FIG. 2 shows an electrophoretic image observed when the plasmid DNA is irradiated with cobalt 60 gamma rays. Cobalt 60 emits gamma rays with energies of 1.17 MeV (mega electron volts) and 1.33 MeV. This high-energy gamma ray causes DNA
The strand is cut.

FIG. 2 shows the band structure of DNA observed after electrophoresis. Before the electric field is applied, the DNA molecule is present in the well 6 (x = x0). Thereafter, when the DNA molecules are migrated in the direction of x = xi, the migration distance of the supercoiled 1 is the longest, and subsequently the migration distances of the linear 5 and the ring 3 are different.

When this band structure is read by a scanner or the like, a peak-like pattern as shown in FIG. 9 is seen. D
(A), (b), (c), and (c) of FIG.
A peak-like pattern as shown in FIG. As the number of DNA strand breaks increases, the proportion of supercoiled 1 decreases and the proportion of circular 3 with single strand breaks and linear 5 with double strand breaks increases. Utilizing the fact that this peak area is proportional to the amount of DNA, the number of DNA strand breaks can be quantified by Formulas 1 and 2 (Journal of Radiation Research, 3
6, pp. 46-55 (1995)).

FIG. 3 shows the configuration of the apparatus when this monitor is applied to personal monitoring. The apparatus according to the present embodiment includes a lower lid 35 and an upper lid 31 serving as a case, and a polymer gel 30 housed therein. Hook 36 for individual wear
Is attached to a part of the storage case. It is desirable that the height and width of the entire apparatus be within several cm and the thickness be about several mm so as not to disturb the wearing of the device. Also,
By reducing the size, it can be integrated with a mobile phone, a personal computer CRT, or a TV, and can be used after being replaced periodically, such as every other month.

By replacing the hook 36 of the personal monitor shown in FIG. 3 with an adhesive tape, it is possible to obtain a stationary monitor fixed to the surface of the electric appliance. A well 6 to which DNA molecules are added in advance is provided in a polymer gel 30 such as agarose or polyacrylamide gel.

FIG. 4 shows a typical size of this polymer gel.
(A) and (b) show. Gels are susceptible to drying because they contain moisture. Therefore, the periphery of the polymer gel 30 is sealed in a bag (not shown) made of a polymer film in order to prevent drying and deterioration due to sunlight or the like. A thin glass window 32 that shields the polymer gel 30 from radiation and electromagnetic waves, an aluminum or iron window 33 that shields low-energy radiation and electromagnetic waves, and a metal window 34 that is excellent in shielding radiation such as lead. It is sandwiched between an upper lid 31 provided on the surface thereof and a lower lid 35 made of the same material as the upper lid provided with a clip 36 to be attached to the body. The upper lid 31 and the lower lid 35 are made of a material having a high atomic number, such as lead, which has a high ionizing radiation shielding ability, and a high metal such as copper, aluminum, etc., having a high electromagnetic shielding ability, in order to shield both ionizing radiation and electromagnetic waves. It is composed of a multilayer board with a conductor.

Since the transmission abilities of the glass window 32, the window 33 made of aluminum or iron, and the window 34 made of metal such as lead differ depending on the difference in radiation energy, the type of radiation that has been exposed can be easily evaluated. In addition, a DNA molecule for control measurement for measuring the number of strand breaks which occur naturally even without being irradiated with radiation or electromagnetic waves is arranged inside a metal window 34 having excellent radiation shielding ability such as lead.
Each time the wear is performed for a certain period, the cases 31 and 35 are opened, the gel 30 contained in the film bag is taken out, and the gel 30 is directly attached to the analysis unit. Then, the number of DNA strand breaks is quantified by the method shown in FIGS.

Next, FIG. 5 shows a conceptual diagram in a case where a microfabrication is performed on a silicon substrate and applied to the present monitor. By reducing the volume of DNA, damage to DNA molecules due to a change in external temperature is reduced, and the unit cost of the apparatus can be reduced. In each of the electrophoresis units 50, electrode terminals 51 for electrophoresis are connected to a DNA reservoir 52 before migration and a DNA reservoir 54 after migration. Those electrode terminals 51
A gel electrophoresis path 53 for DNA is formed between them.
The size of each electrophoresis unit 50 can be within several tens of mm square.

An electrophoresis gel and DNA are enclosed in a capillary (capillary), and the DNA is obtained by electrophoresis.
FIG. 6 shows a conceptual diagram in the case of measuring strand breaks. Capillary 6
By enclosing the DNA in 2, the volume of the DNA can be reduced, so that damage to the DNA molecules due to a change in the external temperature is reduced, and the unit cost of the apparatus can be reduced. Each of the electrophoresis units 60 stores the DNA pool 6 before electrophoresis.
1, a capillary gel electrophoresis path 62 and the like.

FIG. 7 shows a conceptual diagram of the stationary type monitoring apparatus. It is placed on the wall 70 of the room or the like to monitor the environment. At regular intervals, the outer case 71 and the inner case 31 are opened, the gel 30 inside is taken out, and attached to an analysis unit such as an electrophoresis apparatus as it is to connect electrodes, similarly to a personal monitor. When considering the skin tissue of the human body, the material of the outer case 71 is made of a skin equivalent material (C, N, O of skin tissue) used in a pseudo human body (called a phantom) created by imitating the composition of a human. It is made of plastic that takes into account the atomic ratio.

FIG. 8 shows the overall configuration of the analyzer. The analysis unit includes a measurement unit 80 that attaches a detection unit to a gel containing DNA molecules, connects electrodes, and measures DNA strand breaks,
A detector 81 for detecting light and fluorescence, a data processor 82,
It comprises a data display section 83 and a power supply 84 for supplying electricity to the above sections.

[0022]

According to the present invention, an apparatus for measuring the effects of ionizing radiation or electromagnetic waves on the human body and the environment with an index that is easily understood by the general public, that is, DNA strand breaks, and has a high direct correlation with biological effects. Can be provided. Compared to conventional methods such as film batches, although the measurement cost and measurement time are longer, workers at nuclear power plants can perform measurements using DNA strand breaks, a direct indicator that is considered harmful to cells. It is easy to get public understanding around the power plant. In addition, by integrating the present monitoring device on the surface of a mobile phone, a personal computer CRT, or a TV, monitoring at home can be performed. It is also possible to monitor the environment by placing the detector at a location where the effects of radiation and the like are expected.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a change in the shape of plasmid DNA due to strand breaks.

FIG. 2 is an explanatory diagram of a method for quantifying the number of DNA strand breaks by electrophoresis.

FIG. 3 is a perspective view showing a configuration of a detection unit according to an embodiment in which the present invention is applied to personal monitoring.

FIG. 4 is a dimensional view of a detection unit of an embodiment in which the present invention is applied to personal monitoring.

FIG. 5 is a plan view of a detection unit according to an embodiment to which silicon microfabrication technology is applied.

FIG. 6 is a perspective view of a detection unit of an embodiment to which capillary electrophoresis is applied.

FIG. 7 is a perspective view of a detection unit according to an embodiment in which the present invention is applied to environmental monitoring.

FIG. 8 is a block diagram showing a configuration of an analyzer of the monitor according to the present invention.

FIG. 9 is a characteristic diagram showing an optical reading result of the band structure of FIG. 2;

[Explanation of symbols]

1 ... Supercoiled plasmid DNA, 2 ... DNA
Single strand break, 3 ... circular plasmid DNA, 4 ... DN
A double-strand break, 5: linear plasmid DNA, 6: well holding DNA molecules before electrophoresis, 30: gel, 3
DESCRIPTION OF SYMBOLS 1 ... Storage case (upper lid), 32 ... Glass window, 33 ... Aluminum or iron window, 34 ... Lead window, 35 ... Storage case (lower lid), 36 ... Hook when attaching to clothes etc., 5
0: DNA electrophoresis section using silicon microfabrication technology, 51: Electrode, 52: DNA reservoir (before electrophoresis), 53: Electrophoresis path with polymer gel sealed in silicon groove, 54 ...
DNA pool (after electrophoresis), 60: DNA electrophoresis section by capillary (capillary), 61: DNA pool (before electrophoresis), 6
2 ... Electrophoresis path with polymer gel sealed in capillaries, 70 ...
Building wall, 71: outer case, 80: DNA strand break measurement unit, 81: light and fluorescence detection unit, 82: data processing unit,
83: Data display unit, 84: Power supply.

Claims (10)

[Claims] An apparatus for monitoring the biological effects of ionizing radiation and electromagnetic waves, comprising a detector for detecting a DNA strand break phenomenon and an analyzer for analyzing the number of DNA strand breaks generated in the detector. 2. The detecting unit for detecting the number of DNA strand breaks according to claim 1,
Encapsulate NA molecules or cells in gel or porous membrane,
Furthermore, a monitoring device that is housed in a storage case and has a structure in which the detection unit can be attached to a human body with a hook or the like. 3. The monitoring device according to claim 2, wherein the detection unit for detecting the number of DNA strand breaks according to claim 1 is a device in which DNA molecules or cells are added to a buffer solution and further housed in a storage case. 4. A monitoring device using Escherichia coli or yeast as the cell according to claim 2 or 3. 5. A part of the storage case of the detection part is shielded by a box-shaped structure of a multilayer plate of a metal having a large atomic number such as lead and a high conductor such as copper and aluminum. 3. The monitoring device according to claim 2, wherein the monitoring device has a structure in which a control measurement DNA molecule for measuring the number of naturally occurring strand breaks even when the inner surface is not exposed is arranged. 6. A structure in which the detecting section is enclosed in a bag made of a polymer film such as polyvinyl chloride and the entrance of the bag is sealed in order to prevent drying of the detecting section and deterioration due to sunlight. Monitoring equipment. 7. The monitoring device according to claim 2, wherein a DNA molecule or a cell such as Escherichia coli or yeast is sealed in a capillary substrate inside or on a silicon substrate whose surface is grooved, and is used as a detection unit. 8. A DNA having at least one light detecting section and a data processing section, wherein the detecting section according to claim 2 or 6 is taken out of the storage case and directly attached to a part of the analyzing section.
A monitoring device having an analysis unit capable of measuring the number of strand breaks. 9. A photodiode, a CCD (Charge Coupl)
9. The monitoring apparatus according to claim 8, further comprising a light detection unit for converting a luminescence value derived from the DNA strand break detection unit into an electric signal using an optical sensor such as an ed Device). 10. A data processing unit for calculating the number of DNA strand breaks by integrating the area of the electric signal waveform curve obtained from the light detection unit according to claim 8 and utilizing the fact that the integrated value is proportional to the DNA molecular weight. A monitoring device having a in the analysis unit.