JPH0647030B2 - Pseudo-biological structure for physical therapy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a pseudo anatomical structure, and more particularly to a pseudo anatomical structure necessary for performing medical treatment using electromagnetic waves or ultrasonic waves.

<Prior art and problems> Conventionally, as a pseudo-biological structure necessary for performing electromagnetic wave (warming) therapy, radiation therapy, ultrasonic therapy, etc., a fresh fault of an animal or a konjac that imitates this, gelatin ( Jelly), agar, rubber, starch paste, etc. have been proposed and some have already been put into practical use, but many problems have been pointed out.

First, the necessity of the pseudo anatomy in the treatment using these electromagnetic waves or ultrasonic waves is summarized below.

In reaching the lesion, the normal (healthy) tissue between the irradiation source and the lesion cannot be ignored. When the intervening tissue is flat and has a uniform thickness, the attenuation of radiation due to the intervening tissue can be taken into consideration in advance, and the desired dose can be made to reach the lesion area as predicted. However, since the body surface is generally not flat, the intervening tissue cannot be approximated as a uniform attenuation band (a flat plate having a constant thickness), which causes a difficulty in performing irradiation treatment. In order to overcome this difficulty, the body surface (surface of intervening tissue) is flattened. A flattening method of compressing and deforming the vicinity of the body surface can be considered for this purpose, but there is a limit to the deformation shaping of the body surface tissue (non-invasive flattening) (the effect is poor), rather the body surface (skin surface) A method is adopted in which a pseudo living tissue is supplemented to the top, and this is freely molded and constructed to form a vertical plane with respect to the direction connecting the lesion and the radiation source. Therefore, in this case, as the pseudo biological tissue, a material that can be arbitrarily molded, can be closely attached to the body surface, and exhibits a radiation attenuation effect equivalent to that of the biological tissue is desired.

Further, in this case, since the pseudo living tissue is pasted on the body surface (skin surface), it is desired that it is a transparent material. That is, in order to immediately determine whether or not the pseudo living tissue is properly applied to a predetermined (irradiated) site on the skin surface, it is desirable that the material has excellent visible light transmittance. Further, since it is applied to the opposite surface, it is required to have adhesiveness to a living tissue and also to be non-fluid.

In the hyperthermia of cancer which is irradiated with ultrasonic waves, radio waves, microwaves, etc., the body lesion temperature at the time of irradiation is 41.5 to 4
Although it is necessary to maintain the temperature at 3 ° C for a predetermined time, a biological model is desired because it is necessary to know in advance the relationship between the irradiation conditions (frequency, irradiation time) and the temperature rise at various parts of the body. Materials that exhibit thermal properties are eagerly awaited.

Thus, the need for pseudo-anatomy in treatment with ultrasound or electromagnetic waves is well known. As the material for the pseudo-biological structure, there is animal tissue immediately after slaughter, but it is difficult to obtain such fresh tissue by engraving each time when desired, and after obtaining it, store it in a cool place. However, its electromagnetic wave properties or ultrasonic wave properties change drastically (HF Bowma
n; Ann. Rev. Biophys. Bioeng., 4 , 43 (1975), FKStormet a
l.; Int.J.Radiation Oncology Biol.Phys., 8 , 865 (198
2), Sekiya Tomio et al. (Jun Egawa), “Cancer / Heat Therapy” p.39 (1)
982) Shinohara Publishing, Kunio Tanaka et al., Hokkaido University Research Report, 29 , (3) 174.
(1977), Yoshifumi Yamada et al., Hokkaido University Research Report, 29 (3) 184 (197)
7), RVDamadian; US 3,789,832 (1974)). Therefore,
Natural products or artificial products having properties similar to biological tissues have been searched for.

In general, biological tissues have electromagnetic and ultrasonic properties similar to water (Masao Saito; “Eco-engineering” p.19,20,21,24,
25 (1985) Corona Publishing Co., Ltd. Yoshimitsu Kikuchi; “Ultrasonic Medicine” p.7, p.69
(1980) Medical School), water or high water content gel was proposed as a material for simulated ecological structure. For example, in radiation irradiation, a water bag (water-filled bag) is placed on the skin surface for the purpose of flattening the irradiation surface.
In addition, for the purpose of air elimination (reflection / scattering prevention, impedance matching), also in electromagnetic wave heating, ultrasonic heating, etc., a water bladder is also placed on the skin surface, but in this case, the water bladder deforms and moves. Easy and difficult to operate stably. To overcome this drawback, highly hydrous gels such as jelly, konjac and agar have been proposed. Although they have physical properties similar to those of living tissue and have some shape-retaining property, jelly (gelatin) is soft and easily loses its shape (Shinichi Chikada (Electronic Machinery Industries Association of Japan), “Medical Sonic Equipment Handbook ”p.2
42 (1985) Corona). Agar is also fragile and easily damaged, and konjac is severely deformed (contracted), which is troublesome for syneresis after production. Further, all of them have an excessively high water content as compared with the biological tissue (soft tissue / water content of 70 to 80 wt%), and this point is not always satisfactory. For the purpose of further enhancing the biosimilarity, there is an attempt to replace a part of these waters with n-propyl alcohol, glycerin, polyethylene glycol, sodium carbonate, graphite powder, etc. It has also been pointed out that the quality of natural products such as konjac is unstable, and that the stable supply of standardized products is soft (Shinichi Chikada (The Japan Electronic Machinery Manufacturers Association), "Handbook for Medical Ultrasonic Equipment").
p.242 (1985)).

There are also attempts to crosslink with formalin, glutaraldehyde, etc. in order to prevent the gelatin from losing its shape (EL
Madsen et al.; Ultrasound in Med.Biol., 8 , (4) 381 (198
2), ELMadsen et al .; Mag. Res. Imag. 1 , 135 (1982), E.
L. Madsen et al .; Am.Assoc.Phys.Med., 5 , 591 (1978)),
In this case, inhomogeneous gelation (crosslinking) is caused, and it is difficult to obtain a molded product of constant quality. High water-containing gels of polysaccharides such as galagenan and alginic acid also have poor mechanical strength like agar.

Polyacrylamide as a well-known synthetic high water content gel has the advantage that the water content can be adjusted to bioequivalent (70-85%) (Tatsuo Yamazaki et al .; Radiation Research, 13 , 92 (198)
3)), gelation (radical cross-linking) is difficult to proceed uniformly, and a homogeneous molded product cannot be obtained. Also, the gel itself is brittle,
It is easily damaged when handled with tweezers.

As described above, since it is difficult to obtain an appropriate structural material for both water sac, natural gel, and synthetic gel, the water immersion method of immersing the affected part in water is rather adopted. By immersing the drooping breast in a water tank in the lying position, air bubbles are surely removed from the vicinity of the breast (surface), and an ultrasonic wave or the like is radiated there. This water immersion method
Although it can be applied to the abdomen, chest, and neck, it is inconvenient for actual operation because it requires a large-scale water tank, and it is difficult to apply it to the face (head), eyeballs, intraoperative organs, and the like.

In this way, the conventionally proposed pseudo-biological structure has ultrasonic and electromagnetic properties similar to those of living tissue (water),
No material is found that is flexible and hard to break, has adhesiveness and non-fluidity suitable for application to living tissue, is harmless to the living body, and is preferably transparent.

<Objects of the Invention> The present invention comprises a transparent highly water-containing gel which has ultrasonic properties and electromagnetic properties equivalent to those of living tissues, is flexible, is non-fluidic, is hard to break, is adhesive, and is harmless to living organisms. Provided is a pseudo-biological material for physical treatment (treatment using electromagnetic waves or ultrasonic waves).

<Means for Solving Problems> According to the present invention, the degree of saponification is less than 95 mol% and 70 mol%
As described above, after pouring an aqueous solution in which the concentration of polyvinyl alcohol having an average degree of polymerization of 1,000 or more exceeds 7 wt% and 50 wt% or less into a molding mold of an arbitrary shape, it is cooled to a temperature of -10 ° C or less and solidified. A pseudo-biological structure for physical therapy is proposed, which comprises a highly water-containing gel obtained by repeating a series of connecting and thawing operations of molding and then thawing it to obtain a cumulative freezing number of 3 to 10.

Hereinafter, the present invention will be described in more detail.

In the present invention, a pseudo-biological structure material for physical therapy is manufactured using a highly hydrous gel having a specific formulation described below.

The polyvinyl alcohol used in the present invention has a saponification degree of less than 95 mol%, 70 mol% or more, preferably 80 mol% or less.
~ 93 mol% is required. Further, the degree of polymerization of polyvinyl alcohol needs to be 1,000 or more.

In the present invention, first, an aqueous solution containing the above-mentioned polyvinyl alcohol is prepared. The concentration of polyvinyl alcohol is more than 7 wt% and 50 wt% or less.

In the present invention, the polyvinyl alcohol aqueous solution is poured into a mold suitable for desired molding that can be adapted to the shape of the human body model or the human body local body surface, and after cooling and freezing, a series of freeze / thaw operations for thawing this is performed. And the cumulative number of freezes is 3
By setting the ratio to 10, it is possible to obtain a flexible and tacky highly water-containing gel that can be used in the present invention. As the cumulative freezing number is increased, the fluidity of the obtained high hydrous rubber is decreased and the hardness is improved, but after the cumulative freezing number 11, the effect is almost disappeared. Therefore, the above 3 to 10 are economical. is there.

As the molding mold, as described above, such as compatible with the shape of the biological model or the local body surface, other than that the desired shape is obtained, there is no particular limitation, microwave,
The thickness (uniformity or thickness distribution), size, shape, etc. can be appropriately selected according to the actual conditions of treatment using radio waves, γ waves, X waves, neutrons, laser beams, ultrasonic waves, and the like.

In the present invention, various gels can be obtained according to the water content of various biological tissues. The gel water content depends on the initial composition of the polyvinyl alcohol aqueous solution (or suspension), and since the initial polyvinyl alcohol aqueous solution gels as it is, the gel water content can be easily calculated.

Therefore, in the present invention, the water content of various biological tissues, that is, skin (51-69%), ureter (58%), nucha (58%), Achilles tendon (63%), tongue (60-68).
%), Prostate (69-76%), lens (67-70%)
%), Liver (70-77%), stomach (80%), pancreas (7
5%), small intestine (80%), skeletal muscle (79-80%), uterus (80%), thymus (82%), bladder (82%), kidney (78-81%), etc. Pseudo biological structures are manufactured, and their electromagnetic properties (relative permittivity (electrical conductivity),
The electrical conductivity, thermal conductivity, specific heat, hardness) and ultrasonic physical properties (density, speed of sound) also have the characteristics that they substantially match each living tissue. Although the importance of the physical properties listed above is well known, the density (living tissue soft tissue 0.98 × 10 ³ to 1.
1 × 10 ³ [kgm ^-3 ]) is an important factor that influences X-ray permeability and is inversely proportional to the thermal diffusion coefficient, and also controls ultrasonic velocity, ultrasonic transmission, reflection, and attenuation ( Sekiya Tomio et al. (Harakawa Jun); “Cancer / Heat Therapy” p.32 (1982) Shinohara Publishing, HSHo et al .; Trans. Microwava Theory.Tech.MTT1
9,224 (1971), JBLeonard et al,; IEE Trans.Biomed.En
g., BME-31,533 (1984), FWKremkau (translated by Toshiji Kobayashi);
"Principles and practice of ultrasonic diagnosis" (1981, Kinhodo). Hardness (bulk elastic modulus, biological soft tissue 2.6 × 10 ⁹ Nm ⁻² ) still controls the reflection, transmission, and attenuation of ultrasonic waves, and the ultrasonic velocity is proportional to the 1/2 power of the bulk elastic modulus. Is well known.

Relative permittivity (64 to 200 in 10 MHz region of biological soft tissue,
In the 1 GHz region, 30 to 80) dominates the attenuation, reflection, and impedance of electromagnetic waves, and for example, it is well known that it is proportional to the amount of heat loss and that the electromagnetic wave penetration depth is proportional to the 1/2 power of the relative permittivity. (Harakawa Jun, “Cancer / Hyperthermia” p.
21, p.63 (1983)).

Conductivity (0.5-0.9 in 10 MHz region of biological soft tissue,
1-2 in 1 GHz range, 10 [ohm ^-1 m in 10 GHz range
^-1 ]) still controls the attenuation, permeability, and impedance of electromagnetic waves, and, for example, the penetration depth is proportional to the -1/2 power of conductivity.

Thermal conductivity (0.5-1.3 in 1MHz region of biological soft tissue)
[Jm ^-1 s ^-1 K ^-1 ] 0.48 to 0.66 in the 1 GHz region
[Jm ^-1 s ^-1 K ^-1 ]) governs the heat generation and thermal diffusion of the living body during electromagnetic wave irradiation, and the temperature of the living tissue in this case is 1/1 of the thermal conductivity.
It is proportional to the square.

Specific heat (biological soft tissue 3.2 to 3.7 [Jg ^-1 K ^-1 ]) also governs heat generation and thermal diffusion, and the biological tissue temperature has a specific heat of −
Proportional to 1/2 power.

It is well known that the physical property values of the above-mentioned various items of the biological soft tissue are necessarily determined by the water content in the biological tissue (the physical properties of the biological tissue are roughly similar to water) ( Masao Saito; “Biotechnology” p.19, p, 20, p27 (1985) Corona Publishing Co., Ltd., Yoshimitsu Kikuchi; “Ultrasonic Medicine” p.7, p.69 (1980) Medical Institute). The material for the pseudo-biological structure used in the present invention also contains a large amount of water, so that it substantially satisfies the above-mentioned physical properties.
%, Usually 70 to 80 wt%), so that it is more excellent in biosimilarity than pure water. However, it is well known that fat-rich tissue exists in the living body. In order to imitate a tissue rich in fat, it is sufficient to mix lipids into the initial aqueous solution of polyvinyl alcohol and disperse them evenly. For example, in order to imitate a fatty tissue having a water content of 40%, polyvinyl alcohol with a water content of 80% is used. Disperse an equal amount of lecithin or tristearin in an aqueous alcohol solution. In order to further mimic a fat-rich tissue, from the viewpoint of avoiding deterioration of shape retention of the pseudo-biological structure (gel) due to fat, after heating and liquefying solid fat such as monostearin and tristearin,
It is added to a polyvinyl alcohol aqueous solution heated to 70 ° C. or higher to uniformly suspend it, and then the freezing operation of the present invention is performed. As a result, a pseudo-biological structure corresponding to adipose tissue having a water content of 15 to 30% can be obtained, and the physical properties of electromagnetic waves and harmonics thereof substantially match those of adipose tissue.

In the present invention, the pseudostructures of various human body tissues having different water contents thus obtained are bonded (joined) to each other.
You can In this case, although a cyanoacrylate-based adhesive can be used as the adhesive, it is preferable to apply an aqueous polyvinyl alcohol solution having a desired water content to the adhesive surface and bond the adhesive surface, followed by freezing and thawing.

In the present invention, by producing a molding mold in advance as desired, a gel having an appropriate shape can be obtained, and after obtaining a gel having an arbitrary shape, it is cut with scissors or a sharp blade to obtain a desired shape. It does not matter to say. In addition, human bones or the like can be imbedded in the mold in advance, or human bones or the like can be inserted into the cavity obtained by inserting a burning iron round bar into the generated gel to simulate a tissue containing a bio-skeleton. In addition, it is possible to provide a space in the gel imitating the trachea, esophagus, stomach, bladder, lungs, nasal cavity, oral cavity, blood vessels, ureter, urethra or a water storage cavity, and electromagnetic waves due to air, storage fluid, blood flow, etc. It also satisfies the requirements as a bioequivalent model for studying the reflection, scattering, absorption, transmission, and multiple reflection of ultrasonic waves.

In the present invention, a single component of polyvinyl alcohol is used as a gel material (gelling component). However, coexistence of a component that does not inhibit gelation of polyvinyl alcohol, if necessary, is not limited to the present invention, as shown in the above-mentioned fat and oil addition example, and the coexisting amount thereof is, for example, 1/2 amount of polyvinyl alcohol. It can be:

Examples of the components that do not inhibit gelation of polyvinyl alcohol include alcohols such as isopropyl alcohol, glycerin, propylene glycol and ethyl alcohol, proteins such as casein, gelatin and albumin, lipids such as lecithin, monostearin and tristearin. , Sugars or polysaccharides such as glucose, agar and carrageenan, organic compounds such as urea, butyl p-hydroxybenzoate, phthalocyanine blue, flavanthron, nickel salts, copper salts, manganese salts, iron salts, graphite, activated carbon,
In addition to silica, alumina, zeolite, inorganic compounds such as calcium silicate, inorganic salts, organic acid salts, etc., polyethylene powder, aluminum powder, acetylene black, sodium carbonate, sodium chloride, etc. (AWGuy ; IEEE Trans.Microwave Theory Tech., MTT-1
9,205 (1971), JB Leonard et al .; IEEE Trans.Biomed.
Eng., BME-31,533 (1984), FKStorm et al .; Int.J.Radi
ation Oncology Biol. Phys. 8 , 865 (1982), ELMdsen et
al.; Med.Phys. 5 , 391 (1978), M. Michele et al .; Radiol
ogyh, 134 , 517 (1980), PESchuwert; Ultrasonics, 275 (1
982), Japan Electronic Machinery Manufacturers Association; “Medical Ultrasonic Equipment Handbook” (1985) Corona Publishing Co., Ltd.).

To incorporate these into the pseudo-biological material of the present invention,
These may be added as they are or as an aqueous solution or suspension to a polyvinyl alcohol aqueous solution in advance, and then stirred to be uniformly dispersed, after which the above-mentioned freezing and the subsequent treatment may be performed.

<Effects of the Invention> The material for the pseudo-biological structure of the present invention contains water in an amount of 50 to 93 wt%, and the skin, nucha (water 58 to 61%), the liver, the bladder (water 78 to 82%). The water content of various biological tissues up to

As described above, the pseudo-biological structure material of the present invention has shape retention even at 37 ° C. even though it contains a large amount of water, and can be molded into a desired shape and stored.

The pseudo biological structure material of the present invention can contain a large amount of fat, and can imitate biological adipose tissue having a low water content.

Since the pseudo-biological structure material of the present invention exhibits physical properties (relative permittivity, conductivity, density, thermal conductivity, specific heat, hardness) that almost match biological tissues having the same water content, electromagnetic waves, ultrasonic waves, etc. Satisfies the requirements as a biomimetic structure material in the physical therapy used (X-ray irradiation, γ-ray irradiation, ultrasonic irradiation, neutron irradiation, laser light irradiation, radio frequency irradiation, microwave irradiation).

Since the pseudo-biological structure material of the present invention is highly flexible, it can be adhered without damaging these surfaces as long as it is molded according to a complicatedly shaped body surface or intraoperative organ surface, and it is adhesive Since it is abundant, it does not come off or move after being applied to the above-mentioned living tissue unless it is intentionally peeled off. Further, since the pseudo-biological structure material of the present invention is colorless and transparent, after being applied to the skin surface or an organ,
Since the pasting surface can be seen through, it is convenient to correctly determine the pasting site of the pseudo anatomical structure element, that is, the planned site of irradiation of electromagnetic waves, ultrasonic waves, and the like.

The pseudo-biological structure material of the present invention is sterilized by an antiseptic solution such as chlorhexidine, osvan or γ-ray irradiation, and the material is not destroyed or deteriorated by this, so that it can be applied not only to the skin surface but also to various intraoperative organs. Can be pasted.

The pseudo-biological structure material of the present invention is easily obtained by simply giving an aqueous polyvinyl alcohol solution a heat history in a low temperature region, or by subjecting it to freeze / decompression treatment, and acid, alkali, and other chemicals harmful to living tissues. No reagents or crosslinking reagents are used. Therefore, it does not require a great deal of labor to remove harmful substances from the product, is inert to living tissues, and even if it is implanted in the living body for a long time, foreign body reaction, cell infiltration, Since no inflammation is observed, it can be applied not only to the skin surface but also to various organs during surgery.

The pseudo biological structure material of the present invention can be provided with a cavity of any shape inside, human bones, animal bones, plastic cylinders,
Since it is possible to embed a tube or the like, it is possible to imitate a skeletal tissue or a luminal tissue.

<Examples> Examples of the present invention will be described below. The percentages are based on weight.

Example 1 A 29% aqueous solution of polyvinyl alcohol (NaCl 0.9%) having an average degree of polymerization of 2,000 and a degree of saponification of 89 mol% was poured into a cylindrical mold having a diameter of 15 cm and a height of 12 cm, and then frozen 9 times. Moisture content of the transparent adhesive gel obtained by thawing (7
It was confirmed that 0 to 71%) is close to human liver (water 70 to 77%), lens (67 to 70%), and prostate (69 to 76%).

Electromagnetic properties of this sample were measured, and the conductivity (ohm) was measured when it was compared with the values of dog liver immediately after slaughter (within 1 hour) (in []) and pure water (in ()).
^-1 m ^-1 , 10MHz) 0.7 [0.6] (1.5), dielectric constant
(10MHz) 70 [64] (79), Density [kgm ^-3 ] 1,040 [1,
030] (1,000), thermal conductivity [Jm ^-1 s ^-1 K ^-1 ] 0.
8 [0.7] (0.6), constant pressure specific heat [Jg ^-1 K ^-1 ] 3.7
[3.5] (4.2), bulk modulus [dyne cm ^-2 ] 2.
It was 5 × 10 ¹⁰ [2.6 × 10 ¹⁰ ] (2.0 × 10 ¹⁰ ), which was in good agreement with the soft tissue of the living body.

This was subjected to 2.8 Mrad γ-ray irradiation sterilization, but the above-mentioned various characteristics were not changed, and the transparency of the gel (visible light transmittance 9
7% (1 mm), non-fluidity and flexibility were not affected.

The non-fluid gel fragments were applied to the chest in the sitting position, the back in the anterior position, the apex in the anterior cervical position, and the throat in the overextended cervical position for at least 30 minutes or more. It did not fall off or peel off.

Example 2 314 g of a 20% aqueous solution of polyvinyl alcohol having an average degree of polymerization of 1,000 and a degree of saponification of 88 mol% was poured into a disk molding mold having a thickness of 1 cm and a diameter of 20 cm, and after cooling (freezing) to -30 ° C. A series of operations for thawing was repeated 7 times to obtain an adhesive transparent gel having a water content of 80%, which was stored in a sealed container. This water content substantially matches the water content (78 to 81%) of human skeletal muscle, small intestine, stomach, uterus, kidney and the like.

Next, the disc was placed in a polyethylene film bag, sealed, sterilized with 3 Mrad of γ-ray, and then opened, and a part of the fragment (10 g) was transferred to a broth medium and kept at 37 ° C. for 7 days. The culture was tried, but no microorganism was detected.
The density of another partially cut piece (40 × 40 × 10 mm) was measured to obtain 1.03 × 10 ³ [kgm ⁻³ ] at 37 ° C. This is slightly higher than that of pure water, and
3 × 10 ³ kgm ⁻³ ). Next, the sound propagation velocity during this test was determined by an underwater ultrasonic total reflection angle detection method, and was found to be slightly higher than the sound velocity in pure water (1,500 [ms ^-1 ]) (1,600 [ms] ^-1 ]), biological soft tissue (liver 1,
600, skeletal muscle 1,600, kidney 1,560, skin 1,6
It was in good agreement with the case of 00 [ms ^-1 ]). Therefore,
Acoustic impedance (density x sound velocity) is 1,648 x 1
0 ³ [kgm ^-2 s ^-1 ], and the soft tissue (1,600 ~
It is a bioequivalent material that matches well with 1,700 × 10 ³ [kgm ⁻² s ⁻¹ ]). Silicone rubber (1,100 x 1
0 ³ ), polystyrene (2,460 × 10 ³ ), butadiene-acrylonitrile rubber (2,000 × 10 ³ [kgm ^-2
While the impedance such as s ⁻¹ ]) is significantly different from the value of the living tissue, the advantages of the above-described pseudo living body material of the present invention are obvious.

Next, the ultrasonic output on the basis of radiation pressure was measured for the above-mentioned cut pieces, and an attenuation (absorption) coefficient of 3 dBcm ^-1 (5 MHz) was obtained. Compared with pure water (0.3 dBcm ^-1 ), this value is much higher than that of living soft tissue (liver 3 dBcm ^-1 , kidney 4.5 dBcm).
^-1 ), natural rubber (155), silicone rubber (0.8), butadiene-acrylonitrile rubber (70)
The advantage of the pseudo-biological material of the present invention was clear even when compared with dB cm ⁻¹ ).

Example 3 A 25% aqueous solution of polyvinylalurol having an average degree of polymerization of 2,600 and a degree of saponification of 82 mol% was treated with a diameter of 30 cm and a height of 30.
It is poured into a cm casting mold, frozen at -40 ° C, and thawed. By repeating this freezing / thawing operation 9 times, a transparent adhesive gel was obtained. Its elastic modulus (10 ⁵ N
m ^-2 ) is 0.3, showing flexibility similar to smooth muscle, and despite being reversibly deformable, it does not lose its shape even when kept under a pressure of 10 kgcm ^-2 for 30 minutes. Its tensile strength was 4 kgcm ^-2 .

Example 4 According to Example 3, a highly water-containing gel film (30
× 30mm) 10 pieces were produced.

These were sterilized with chlorhexidine, and then aseptically washed with physiological saline.
After implanting for 6 months, no foreign body reaction such as inflammation or cell infiltration was observed in the living tissue, and no excessive proliferation of connective tissue was observed.

A 3 cm incision is made longitudinally on the medial side of the knee joint of a rabbit (weight 2.5 kg), the quadriceps femoris inner surface is longitudinally dissected, the patella is dislocated to the outside, and the knee joint is bent to anterior joint fat. After excising the tissue and cutting the crossed ligaments, the joint capsule and meniscus other than the posterior joint capsule are removed. Next, the femoral articular cartilage is removed and replaced with this cartilage, and the sterilized test piece is inserted into the femoral joint surface.
After fixation, a cast was applied from the upper part of the thigh to the foot at a flexion of the knee joint of 150 degrees, and this was removed 4 weeks later. At this point, slight swelling was noted in the joint, but redness and
There is no local heat sensation, good primary fusion, no secretions are seen, and the knee joint is flexed at about 120 degrees, showing protective lameness. The passive dynamic range was 150 to 90 °. For tissue specimens, fixed with formalin, embedded in paraffin, stained with hematoxylin and eosin, and stained with Mallory Azan,
As a result of microscopic examination, the articular surface of the femur was covered with connective tissue, and neither reactive bone growth nor intramedullary inflammation was observed by the insertion test. From these findings,
It was confirmed that the highly hydrous gel of the present invention has good biocompatibility.

Example 5 A 15% aqueous solution of polyvinyl alcohol having an average polymerization degree of 1,200 and a saponification degree of 79% was used, and the radius of curvature was 8 mm and the thickness (0.2
mm uniform), injection marks into a curved film molding mold with a diameter of 13 mm, 10
The molded product obtained by freezing and thawing twice was attached to the cornea of the eyeball of a volunteer for 10 hours, and after detachment, the cornea was stained with fluorestin, and then observed with a slit lamp microscope. There wasn't. That is, it is clear that the pseudo-biological structure material of the present invention is inert to the cornea of the eyeball and has excellent biocompatibility, and together with the findings of Example 4, it is suitable for use by contacting with biological tissue, if necessary. It is clear that

Claims (1)

[Claims] 1. An aqueous solution containing polyvinyl alcohol having a saponification degree of less than 95 mol%, 70 mol% or more and an average degree of polymerization of 1,000 or more, and having a polyvinyl alcohol concentration of more than 7 wt% and not more than 50 wt% in an arbitrary shape. After it is poured into the molding mold of No. 3, it is cooled, solidified, and molded at a temperature of -10 ° C or lower, and then a series of freezing and thawing operations for thawing it are repeated to make the cumulative number of freezing 3 to 10 A pseudo-biological structure for physical therapy, which is a transparent / adhesive, non-fluidic gel obtained by the above.