Patent Grant
8092834
This application claims priority to the Japanese Patent Application 2001-200002 filed on Jun. 29, 2001 and is hereby incorporated with reference for all purposes.
1. Field of the Invention
The present invention relates to complex powder and external preparation for skin comprising the same, and in particular, powder that has function to living body.
2. Prior Art
It has been known that various kinds of medicines, external preparations for skin and cosmetics are effective for improvement and prevention of symptoms such as skin disease, rough skin and pimples. As an effective component of these medicines and cosmetics, for example, antiphlogistic agents, essences extracted from plants or animals which are effective for anti-inflammation, or those having moisture retaining or water retaining effect such as amino acids, polysaccharide, lipid and natural polymer have been used because these components are effective for prevention of dermatitis or prevention of water volatilization from a horny layer of epidermis.
On the other hand, an increasing attention is paid not only to morbid dermatitis such as atopic dermatitis or severe pimples but also to a condition which is not morbid dermatitis but hypersensitive reaction is shown to the change in the environment, i.e., so-called sensitive skin. Since such skin is associated frequently with an inflammation or a reduced barrier function, it may exhibit a hypersensitive reaction or irritation in response to various substances, therefore careful selection of effective components should be needed.
However, conventional medicines used as effective components for rough skin permeate into skin by percutaneous absorption, so in some cases it have probability to give other undesired effects to skin.
Accordingly, an effective component which is safe and free from irritation has been required.
An objective of the present invention is to provide a powder that has rough skin-improvement effect without percutaneous absorption, and an external composition for skin comprising the same.
As a result of diligent studies for achieving the object, the inventors found that a specific enzyme on the skin is related closely to rough skin and the like, and also that a certain complex powder adsorbs or inhibits said specific enzyme.
Thus, a complex powder of the present invention comprises an adsorption site and an operation site,
wherein said adsorption site attracts or adsorbs a specific enzyme,
wherein said operation site inhibits or activates said enzyme, and wherein each of the both sites are appeared on the surface of the powder.
In a complex powder described above, it is preferable that ζ-potential of the adsorption site at pH employed is a negative value,
wherein said adsorption site attracts or adsorbs the specific enzyme whose ζ-potential is positive value,
and wherein said adsorption site inhibits or activates said specific enzyme.
In a complex powder described above, it is preferable that said adsorption site has ζ-potential at pH7.5 of −10 mV or below.
In a complex powder described above, it is preferable that said adsorption site has ζ-potential at pH7.5 of −20 mV or below.
In a complex powder described above, it is preferable that said specific enzyme is a plasminogen activator, and wherein the operation site inhibits said plasminogen activator.
In a complex powder described above, it is preferable that inhibition rate of the plasminogen activator is 40% or higher.
In a complex powder described above, it is preferable that inhibition rate of the plasminogen activator is 45% or higher.
In a complex powder described above, it is preferable that inhibition rate of the plasminogen activator is 50% or higher,
wherein said inhibition rate of the plasminogen activator is determined by measuring a decomposition activity for a synthetic substrate caused by a buffer solution comprising 0.1% of sample and 300 U/ml of a double-stranded urokinase type plasminogen activator.
In a complex powder described above, the first mode is a complex powder in which the operation site is formed in the form of stripes or spots on the surface of the adsorption site.
In a complex powder of the first mode described above, it is preferable that covering quantity of the operation site based on the adsorption site is 1 to 70% by weight.
In a complex powder of the first mode described above, it is preferable that covering rate of the operation site based on the surface of the adsorption site is 1 to 90%.
In a complex powder of the first mode described above, it is preferable that covering rate of the operation site based on the surface of the adsorption site is 2 to 70%.
In a complex powder of the first mode described above, it is preferable that covering rate of the operation site based on the surface of the adsorption site is 4 to 50%.
In a complex powder described above, the second mode is a complex powder in which the adsorption site is formed in the form of stripes or spots on the surface of the operation site.
In a complex powder described above, the third mode is a complex powder in which the adsorption site is formed in the form of a network on the surface of the operation site.
In a complex powder of the second or third modes described above, it is preferable that covering quantity of the adsorption site based on the operation site is 0.1 to 75% by weight.
In a complex powder of the second or third modes described above, it is preferable that covering quantity of the adsorption site based on the operation site is 3 to 50% by weight.
In a complex powder of the second or third modes described above, it is preferable that metal ion elution level during use is 0.7 to 40 ppm.
In a complex powder of the second or third modes described above, it is preferable that metal ion elution level during use is 1.2 to 30 ppm.
In a complex powder described above, the fourth mode is a complex powder in which the operation site and the adsorption site are formed in the form of stripes or spots on the surface of a substrate particle.
In a complex powder described above, it is preferable that the operation site is made from a metal or a metal compound capable of releasing zinc ion and the adsorption site is made from silica, talc or mica.
In a complex powder described above, it is preferable that the operation site is made from a metal or a metal compound capable of releasing zinc ion and the adsorption site is made from polyamide, polymethyl methacrylate or silicone resin.
In a complex powder described above, it is preferable that zinc ion elution level during use is 40 ppm or below.
In a complex powder described above, it is preferable that the relationship between ζ-potential and zinc ion elution level is represented by Formula (I):
ζ-potential (mV)≦Zinc ion elution level (ppm)×1.5-25 (I).
An external composition for improving rough skin according to the present invention comprises one or more of the complex powders described above.
An external composition for sensitive skin according to the present invention comprises one or more of the complex powders described above.
In an external composition for improving rough skin described above, it is preferable that one or more selected from a group consisting of a zinc oxide-covering silica, zinc oxide-covering talk and zinc oxide-covering mica are contained.
In an external composition for sensitive skin described above, it is preferable that one or more selected from a group consisting of a zinc oxide-covering silica, zinc oxide-covering talk and zinc oxide-covering mica are contained.
The complex powder described above can be used as an improving agent for rough skin.
The complex powder described above can be used as a care agent for sensitive skin.
The complex powder and the external preparation for skin comprising the same according to this invention were found out by the circumstances like the following.
It has been made clear recently that an activity change of protease, especially an activity change of fibrinogenolysis type enzyme (plasminogen activating enzyme) such as plasmin or plasminogen activator, is closely related to a formation of various types of diseased skin accompanied with rough skin or abnormal cornification.
For example, it was reported that a distribution of plasmin in an epidermal cell layer of rough skin experimentally formed was changed relative to a distribution of plasmin in epidermal cell layer of normal skin, and anti-plasmin agent is effective for improvement and prevention of rough skin (Kenji Kitamura: J. Soc. Cosmet. Chem. Jpn; 29(2), 1995). Further in case of atopic dermatitis high fibrinogenolysis activity in epidermis was also reported (T. Lotti: Department of Dermatology; 28(7), 1989). On the other hand, in the case of psoriasis, representative of diseased skin accompanied with inflammation and abnormal cornification, it was reported that there exists high plasminogen activator activity at a portion of parakeratosis in an epidermis of the affected part (Haustein: Arch. Klin. Exp. Dermatol; 234, 1969), and it was also reported that a plasminogen activator was extracted from a flake of psoriasis by using a high-concentration buffer solution(Fraki, Hopsu: Arch. Dermatol. Res; 256, 1976).
A plasminogen activator is a protease which selectively acts on a plasminogen, (a precursor of plasmin) and transform plasminogen to active form. Based on the above-mentioned existing background, the present inventors paid attention to the behavior of the various kinds of enzymes on the skin on the occasion of the development of a new medicine for rough skin. Then various kinds of inorganic powder were investigated for improvement and prevention of rough skin, based on the idea that a material which adsorbs and deactivates a plasminogen activator at a surface of skin and does not have the process of percutaneous absorption would be effective for improvement and prevention of diseased skin or rough skin which accompanies an activity change for a plasminogen activating enzyme, and also would be highly safe for human body. As a result of exploring various kinds of powder, it was found that a specified complex powder adsorbs and inhibits plasminogen activator.
Structure of Complex Powder
A complex powder 10 of this invention, typically as shown in
Also as shown in
Alternatively, as shown in
Those which can also be illustrated as a complex powder 10 of this invention are;
A complex powder 10 in which an operation site 14 and an adsorption site 12 are supported on, coated on, included in, adsorbed on or mixed in a substrate particle (FIG. 1(D));
A complex powder 10 in which an operation site 14 such as zinc ion is supported between the layers of an adsorption site 12 such as laminar clay mineral (FIG. 1(E)); and
A complex powder 10 in which an operation site 14 such as zinc oxide is included in an adsorption site 12 of a porous tabular silicon oxide (
In the case of
In the case of
Also in the cases of
For example the complex powder shown in
Adsorption Site
In the complex powder of the present invention, an adsorption site is selected in relation with the target enzyme to be adsorbed. It is preferable to be evaluated on the basis of the correlation with ζ-potential of the target enzyme.
When a powder has an electric charge in liquid, an ion with the opposite electric charge is attracted to said powder by static electricity power in order to compensate the electric charge, so an electric double layer is produced. The outermost potential of the double layer is ζ-potential. Accordingly, the ζ-potential is employed preferably in evaluating the surface charge condition of an object, enabling the evaluation of an ability of adsorbing an enzyme electrically.
The ζ-potential can be obtained in accordance with the Smoluchowski's formula: ζ-potential=4πηU/∈
(in the above formula, η is the viscosity of the solvent, U is the electrophoresis mobility, ∈ is the dielectric constant of the solvent).
In order to obtain ζ-potential, an electrophoresis is employed to measure the velocity of the colloidal particle (V) and the electrophoresis mobility (U). Under the electric field (E), the charged colloidal particle moves. V is obtained by the formula: V=L/t (wherein L is the distance of the movement and t is the time), and U is obtained by the formula: U=V/E.
When the target enzyme is a plasminogen activator whose ζ-potential is positive value, ζ-potential of the substance forming an adsorption site is preferably negative value at pH employed. The ζ-potential of the substance forming an adsorption site is preferably −10 mV or below at pH 7.5, more preferably −20 mV or below.
The method for measuring ζ-potential is discussed later.
The relationship between ζ-potentials of major substances at pH 7.5 and adsorption rate of UK at 100 ppm is shown in Table 1.
The method for measuring UK adsorption rate is discussed later in detail.
As shown in Table 1, lower ζ-potential tended to result in a higher UK adsorption rate over respective organic powders and inorganic powders, indicating a correlation between ζ-potential and UK adsorption rate.
A preferable material for an adsorption site may be inorganic powders such as silica, mica, talc and the like and organic powders such as polyamide, polymethyl methacrylate, silicone resin and the like.
Operation Site
An operation site is also selected in relation with an enzyme to be targeted.
In the case that the target enzyme is plasminogen activator, metals or metal compounds that releases ions of the Groups IV, IX, X, XI and XII are raised as an operation site. A particularly preferred metal ion may for example be zinc ion.
The metal compounds releasing the metal ions may for example be inorganic compounds such as oxides, hydroxides, nitrates, chlorides, hydroxides, carbonate, bicarbonates, sulfates, borates, persulfates as they are and as being contained in molecules of inorganic compounds (complexes):
organic acid salts such as glycerophosphate, acetates, hydroxides, α-hydroxy acid salts (citrates, tartrates, lactates, malates), fruit acids, amino acid salts (aspartates, alginates, glycolates, fumarates), fatty acid salts (palmitates, oleates, caseinates, behenates) and the like. When a complex powder of this invention is used in an external composition, an especially preferred metal compound may for example be zinc oxide.
The followings are UK inhibition rates of various ions at the ion concentration of 100 ppm.
The method for measuring UK inhibition rate is detailed later.
As shown in Table 2, zinc ion exhibited the most excellent UK inhibiting effect. While an analogous UK inhibiting effect was exhibited by the zirconium ion, there were the ions not exhibiting substantially UK inhibiting effect such as sodium ion and calcium ion. Accordingly, it is admitted that there is high specificity in the operation of each ion to the enzyme.
Zinc oxide has been mainly used as an external composition like cosmetics, or ultraviolet-scattering agent and as a white pigment. However its ultraviolet-scattering effect was not sufficient, and zinc oxide decreased stability of a formulation by its catalytic activity. Based on these problems, for the purpose of improvement of stability and utility of a formulation system without decreasing the ultraviolet-scattering function, zinc oxide which has more smaller particle size than that of previously used zinc oxide (Japanese Patent Publication No. Shou 60-33766, Japanese Patent Publication No. Hei 5-77644) or a complex with various inorganic or organic compounds have been developed (Japanese Patent Laid Open No. Hei 1-190625, Japanese Patent Laid Open No. Hei 3-183620, Japanese Patent Laid Open No. Hei 7-277914, Japanese Patent Laid Open No. Hei 10-87434, Japanese Patent Laid Open No. Hei 10-87467, Japanese Patent Laid Open No. Hei 10-87468).
On the other hand, zinc oxide is registered in Japanese pharmaceutical codex, and is known to combine with protein existing on skin to form film and as a result having a pharmacological effect such as astriction, improvement of inflammation and protecting. Based on these pharmacological effects, zinc oxide has been used as a form of a mixture of zinc oxide, lanolin and white ointment or as a powder preparation mixed with those such as talc or starch for applying to diseased skin, rough skin by diaper and so on. Moreover, to add medical effect of zinc oxide to other materials, zinc oxide was applied to skin as a form of mixture with other agents such as an anti-inflammating agent, antibacterial material (Japanese Patent Publication No. Hei 4-63046, Japanese Patent Publication No. Hei 6-76330, Japanese Patent Laid Open No. Hei 2-23361, Japanese Patent Laid Open No. Hei 6-157277, Japanese Patent Laid Open No. Hei 8-217616, Japanese Patent Laid Open No. Shou 57-62220), anti-oxidation agent (Japanese Patent Laid Open No. Hei 7-304665) and protease inhibitor (Japanese Patent Laid Open No. Hei 3-169822), or as a form of a complex.
However, a report or a description rarely exists concerning the character of zinc oxide suitable for medicine. Such a description only exists in Japanese patent laid open No. Hei 6-239728 where it is described that ultra-microparticle zinc oxide is more effective on astringent than zinc oxide previously used, but a concrete example is not described in that literature.
Substrate Particle
As mentioned above, a complex powder of the present invention may have a structure in which an operation site and an absorption site are formed in stripes or spots on the surface of a substrate particle. Said substrate particle is not limited particularly as long as it does not affect the effect of the present invention, and may for example be an inorganic substrate particle, organic substrate particle, inorganic pigment substrate particle, inorganic pigment substrate particle and the like.
Complex Effect
In a complex powder of the present invention, the effect of an operation site to a specific enzyme is further improved due to the presence of an adsorption site of said enzyme.
Nevertheless, in the cases of a complex powder having the both of an operation site and an absorption site, such as the case using zinc oxide as an operation site and silica as an adsorption site where the adsorption site is formed as a network on the operation site (
Even when an absorption site and an operation site are simply mixed, the effect may sometimes be higher than those of the respective sites used independently. Nevertheless, an extremely high operation to the enzyme, such as a plasminogen activator inhibiting effect, is exhibited particularly by a complex powder which has the operation site and the adsorption site are to be a complex on the surface of said complex powder.
The present inventors tested trypsin as a reference which is classified into a serine protease as same as a plasminogen activator. In the case of the trypsin, the trypsin was adsorbed on complex powder, but its activity was maintained as same as before adsorption. So it should be obvious that it cannot be said that complex powder usually inhibits enzyme activity.
For the purpose of improvement of properties such as ultraviolet scattering effect, safety, stability and usability, a complex powder has been developed which has a particle component composed of zinc oxide and a material that covers zinc oxide or is covered by zinc oxide, such as inorganic or organic compounds such as carbonate, sulfate (Japanese Patent Laid Open No. Hei 10-87468), meta-magnesium silicate aluminate (Japanese Patent Laid Open No. Hei 1-308819), silica, alumina (Japanese Patent Laid Open No. Hei 3-183620, Japanese Patent Laid Open No. Hei 10-87467), organofluorinated modified silicone (Japanese Patent Laid Open No. Hei 7-277914), polyester, nylon and cellulose (Japanese Patent No. 2628058). However there is not the report that zinc oxide adsorbs the enzyme on the skin and operate to the activity of said enzyme, in as long as this inventor knows. Although a fluorescent zinc oxide manufactured by calcinating of zinc oxide under reduction-atmosphere with hydrogen or carbon monoxide (disclosed in Japanese Patent Laid Open No. Hei 5-117127) was tested, it showed little adsorption of a plasminogen activator and little inhibition of its activity, and also did not show any improvement of skin.
The complex powder of the present invention is employed preferably to skin having pathological dermatitis or to sensitive skin, due to the ability of reducing the irritation.
When complex powder of the present invention is used as an external preparation for skin, it can be treated with materials like silicone for giving hydrophobic property on its surface if needed.
An external preparation for skin of the present invention can comprise one or more types of complex powders mentioned above and gives excellent effect on adsorption of plasminogen activator and inhibition of its activity, improvement of skin results, and it is very safe.
Two kinds of plasminogen activator are known. One is called urokinase and exists in healthy epidermis and the other is called organized plasminogen activator and exists in morbid skin.
Complex powder of the present invention has an effect for both types of plasminogen activator mentioned above. The effect is on adsorption of plasminogen activator and on inhibition of plasminogen activity.
The preferable blending amount of complex powder in an external preparation for skin of the present invention is 0.1 to 50.0% by weight per total amount, more preferably 2.0 to 20.0% by weight per total amount, and the most preferably 5.0 to 20.0% by weight per total amount. When used with less than 0.1% by weight the effect of the present invention is not sufficient, and when used with more than 50.0% by weight it is difficult to formulate an external preparation for skin.
If the effect of the present invention is maintained, an external preparation for skin of the present invention can include components usually applicable to an external preparation for skin used as cosmetics or medicines, such as moisture retaining agents, oil ingredients, ultraviolet absorbent, emulsifiers, surfactants, thickeners, alcohols, powder components, colorants, hydrophilic components, water, skin eutrophic medicine.
Further an external preparation for skin of the present invention can comprise: a sequestering agent such as disodium EDTA, trisodium EDTA, sodium citrate, sodium polyphosphate, sodium metaphosphate, gluconic acid and malic acid: plant extracts such as glycyrrhiza extract, Chinese quince extract, ichiyakusou extract: medical components such as caffeine, tannin, verapamil, tranexamic acid and its derivatives, tocopherol acetate, glycyrrhezinic acid and its derivatives or salts: whitening agents such as vitamin C, magnesium ascorbate phosphate, glucoside ascorbate, arbutin, kojic acid: amino acids and its derivatives such as arginine, lysine: saccharides such as fructose, mannose, erythritol, trehalose, xylitol: and so on.
An external preparation for skin of the present invention can be applied in a form such as ointment, cream, lotion, pack, foundation, face powder, cheek, eye shadow, sun screen, lipstick, bath composition, paper for oil absorption, paper powder and other forms normally used for external for skin preparations. A shape of said external preparation for skin is arbitrary.
A complex powder of this invention exhibits an excellent effect especially on skin such as sensitive skin suffering from difficulty in using cosmetics of prior arts.
A sensitive skin is defined in publications as follows:
“A skin usually susceptible to a damage due to a specific response to quasi-drugs, cosmetics, plants, ultraviolet ray, metals to which most of human beings do not respond particularly.”
“A skin which is sensitive constitutionally to an allergenic substances (pollen, fragrance) or irritative substances (alcohols) due to a reduced barrier function of skin.”
“A skin susceptible to a damage by an irritating substance only temporarily when the resistance of skin or the physiological functions of skin are deteriorated due to an insufficient sleep, overwork, menstruation, seasons change, mental stress and the like.”
“A skin posing an anxiety about the use of cosmetics used routinely.”
Thus, factors for sensitive skin condition are reduced skin barrier function, reduced skin irritation threshold, skin dryness, substance causing contact dermatitis, physicochemical irritation, stress, physical condition, seasons change, ultraviolet ray, menstruation and the like. It is also possible that one's false skin care itself causes a sensitive skin and that one's obsession just causes sensitive skin.
As used herein, a subject having a sensitive skin is defined as one who experiences abnormal felling in any of the procedures (1) to (5) shown below.
(1) 100 μl of 5% aqueous solution of citric acid is applied over the cheek and allowed to stand for 10 minutes.
(2) 100 μl of 5% aqueous solution of lactic acid is applied over the cheek and allowed to stand for 10 minutes.
(3) 100 μl of 50% ethanol solution is applied over the cheek and allowed to stand for 10 minutes.
(4) An unwoven fabric (2×2 cm) is impregnated with 100 μl of 0.2% aqueous solution of methylparaben, and allowed to stand on the cheek for 10 minutes.
(5) An unwoven fabric (2×2 cm) is impregnated with 100 μl of 5% aqueous solution of SDS, and allowed to stand on the cheek for 10 minutes.
The abnormal felling means relatively painful feeling experienced on skin, such as stingy pain, irritating sensation, itching sensation, burning sensation, discomfort, pricking pain and the like.
In the following, the present invention will be explained by using specific examples. However, the present invention should not be restricted thereto. Unless otherwise stated, quantities are expressed as percent by weight.
First of all, concrete methods for testing the plasminogen activator adsorbing effect, the plasminogen activator inhibiting effect and skin improving effect are discussed below.
1. Plasminogen Activator Adsorption/Inhibition Operation Test (In Vitro)
(1) Preparation of the Samples
Talc, mica, silica, complex powder of the example, and zinc oxide of the comparative were used as samples. 0.1% of a sample was suspended in water and the adsorption/activation inhibiting effect to urokinase (UK) was evaluated.
(2) Measurement of Adsorbing Effect for Plasminogen Activator (Measuring Method of the UK Adsorption Rate)
Tris-HCl buffer (pH 7.4) was added into 20 μl of a sample suspension to give total amount of 180 μl, followed addition of 20 μl of a precursor type urokinase containing solution(10 μg/ml). The solution was left for 5 minutes at room temperature, and the sample powder was filtered and the filtrate was collected. The sample powder was washed sufficiently with a constant amount of Tris-HCl buffer, and the Tris-HCl buffer used for washing was added to the filtrate, and this solution was used as the non-adsorbent urokinase containing solution. The concentration of said non-adsorbent urokinase containing solution was determined by the ELISA method using TintElize uPA(biopool), and then the amount of the urokinase adsorbed on the sample powder was calculated.
(3) Measurement of Activation Inhibiting Effect for a Plasminogen Activator (Measuring Method of the UK Active Inhibition Rate)
Tris-HCl buffer(pH 7.5) was added in 20 μl of a sample suspension to give the total amount of 180 μl, following addition of 20 μl of an activator type urokinase containing solution (300 U/ml). The solution was left for 30 minutes at the room temperature, and 20 μl of S2444 (CHROMOGENIX), specified synthetic substrate of urokinase, was added to the solution, and the solution was left for 30 minutes at 37° C. Then the reaction was stopped by adding 20 μl of water solution containing 12% of trichloroacetic acid, then the sample powder was filtered and activity of urokinase was derived by measuring absorbance of the filtrate at 405 nm, then activation inhibition rate of a plasminogen activator was calculated.
2. Test for Evaluating the Rough Skin Preventing Effect (In Vivo)
(1) Preparation of the Samples
As same as the test procedure at the condition in vitro, talc, mica, silica, complex powder of the example, and zinc oxide of the comparative were selected as samples and a sample suspension was prepared by suspending 3% of a sample powder in water. Then the rough skin preventing effect caused by zinc oxide of the present invention was evaluated.
(2) Judgment of the Rough Skin Preventing Effect
A cotton sheet (2×2 cm) soaked by 5% of SDS solution was put on inside of each forearm of panelists composed of 54 men and left alone for 15 minutes. The forearm of a panelist was washed, and then 0.5 ml of a sample suspension selected for each panelist was applied on the portion where said cotton sheet was put, and 0.5 ml of water was also applied as a reference on the portion where said cotton sheet was put and the sample suspension was not applied (n=3). This procedure, applying the sample and water, was daily repeated for seven days. After seven days past, the tested portion was sufficiently washed, and left for 60 minutes, then a condition of rough skin caused by SDS was observed and the evaluation point was decided based on the judgment standard described below. The difference of the evaluation point between the sample applied portion and the reference portion was derived for each panelist, and the differences derived were summed for each sample, and the rough skin preventing effect of each sample was judged based on the judgment standard described below.
<The Standard Used to Decide the Evaluation Point Concerning the Condition of Rough Skin>
Evaluation Point 4:
An obvious erythema and/or scaled horny layer was observed.
Evaluation Point 3:
A medium erythema and/or a little degree of scaled horny layer was observed.
Evaluation Point 2:
A little erythema and/or a crack in horny layer was observed.
Evaluation Point 1:
<The Judgment Standard for the Rough Skin Preventing Effect>
AA (Obvious effect was recognized):
A (A little effect was recognized):
B (A trend of prevention was recognized):
C (No effect was recognized):
The difference of the evaluation point is less than 1.
3. Method for Measuring ζ-potential
A sample was dispersed in Tris-HCl buffer solution at pH 7.5, treated ultrasonically, and then measured. The ζ-potential was measured using an electrophoresis scattering photometer LEZA-600 manufactured by Otsuka Electronics Co., Ltd. Each sample was measured 3 times and the mean value of the results was represented.
Zinc Oxide Concentration and UK Active Inhibition Rate
The relationship between the concentration and the UK inhibition rate was examined about the zinc ion, which exhibits a plasminogen activator inhibiting effect. The UK inhibition rate was measured by the method described above.
As evident from Table 3, a higher zinc ion concentration gave a higher inhibition rate. An UK inhibition rate of 40% or higher required a zinc ion concentration of 45 ppm or higher, and an UK inhibition rate of 50% or higher required a zinc ion concentration of 50 ppm or higher.
However, the presence of the zinc ion at a higher concentration may not be preferable in view of the preparation of a pharmaceutical, and the zinc ion concentration is preferably 40 ppm or lower.
Zinc Ion Elution Level and UK Active Inhibition Rate
Then the zinc ion elution levels from any of various zinc oxides on the market and a silica-covering zinc oxide as an complex powder of the present invention (silica covering quantity: 20% by weight) were measured and the relationship with the UK inhibition rate were investigated.
A dispersion of each sample in a 0.01 Tris-HCl buffer (pH 7.5) was stirred, centrifuged, and the filtrate was subjected to an ICP analysis to measure the zinc ion elution level of each sample. In accordance with the method for measuring the UK inhibition rate described above, the UK inhibition rate of each sample suspension was calculated.
As evident from Table 4, there was almost no difference in the zinc ion elution level among various zinc oxides on the market, whose levels were around 45 ppm.
Accordingly, there was almost no difference in the UK inhibition rate among the zinc oxides on the market, whose values were around 40%. These results were in agreement with the relationship between the zinc ion concentration and the UK inhibition rate shown in Table 3. Accordingly, the inhibition of the activity by the ion oxide alone may be attributable to the eluted zinc ion.
Nevertheless, the dispersion of the silica-covering zinc oxide (complex powder of the present invention) exhibited 45% UK inhibition in spite of its low zinc ion elution level 8.9 ppm, and this fact is not in agreement with the relationship between the zinc ion concentration and the UK inhibition rate shown in Table 3. Thus, it was suggested that the UK activity inhibition by the silica-covering zinc oxide is not attributable only to the eluted zinc ion.
Accordingly, the zinc ion elution level and the UK inhibition rate of a zinc oxide, silica-covering zinc oxide and alumina-covering zinc oxide were measured by the method described above, and the relationship between the zinc ion elution level and the UK inhibition rate was investigated. The results are shown in
Silica (ζ-potential: −20.0 mV, UK adsorption rate: 82%)
Alumina (ζ-potential: +17.3 mV, UK adsorption rate: 0%)
The alumina-covering zinc oxide using an alumina(ζ-potential: +17.3 mV) exhibited a lower UK inhibition rate compared with the zinc oxide, while the silica-covering zinc oxide using a silica(ζ-potential: −20 mV) exhibited a higher UK inhibition rate compared with the zinc oxide even at a lower zinc elution level.
These findings may be due to an efficient inhibition of the UK activity by the zinc ion as a result of the zinc ion and the UK were adsorbed onto the surface of the silica, since the ζ-potential of the silica is negative.
The fact that the silica-covering zinc oxide exhibited a high UK inhibition rate in spite of a low zinc ion concentration of the solution may possibly be due to the UK activity inhibition by the silica-covering zinc oxide which is attributable not only to the eluted zinc ion but also to the UK absorption effect of the silica. The presence of the zinc ion at a high concentration may not be preferable in view of the preparation of a pharmaceutical such as an external composition. A complex powder of this invention is preferred since it exhibits a UK inhibiting effect even at a low concentration of the zinc ion.
(A) Complex Powder Having Operation Site on Absorption Site (Zinc Oxide-Covering Powder)
A 3 L separable reaction vessel was charged with 1000 mL of ion exchange water and 100 g of a talc (ζ-potential: −26.5 mV, average particle size: 16 μm), and fitted with a pH controller connected to two microtube pump and a stirrer. One microtube pump was connected to zinc chloride solution prepared by dissolving 16.75 g of zinc chloride and 2.4 ml of 5M aqueous solution of hydrochloric acid in 150 ml of ion exchange water and the other microtube pump was connected to alkaline solution prepared by dissolving 12 g of sodium hydroxide in 150 ml of ion exchange water, and the tubes were fixed to enable dropwise addition to the reaction vessel while controlling pH.
With stirring at room temperature, the reaction was conducted while adjusting the quantity of the two aqueous solution added dropwise so that pH was kept at 10. The time period of the dropwise addition was about 30 minutes. The resultant precipitation was washed with water and filtered 5 times repetitively, dried in an oven at 120° C. for 15 hours and then ground using a personal mill. The powder obtained was sieved through a 100 mesh sieve to obtain the intended material.
The intended material was obtained similarly to Embodiment 1 except for using mica (ζ-potential: −36.1 mV, average particle size: 18 μm) instead of talc.
The intended material was obtained similarly to Embodiment 1 except for using spherical silica (ζ-potential: −25.1 mV, average particle size: 5 μm) instead of talc.
The intended material was obtained similarly to Embodiment 1 except for using tabular silica (ζ-potential: −24.7 mV, average particle size: 4.5 μm) instead of talc.
A 3 L separable reaction vessel was charged with 1000 mL of ion exchange water and 100 g of talc (ζ-potential: −26.5 mV, average particle size: 16 μm), and fitted with a pH controller connected to two microtube pump and a stirrer. One microtube pump was connected to zinc chloride solution prepared by dissolving 16.75 g of zinc chloride and 2.4 ml of 5M aqueous solution of hydrochloric acid in 150 ml of ion exchange water and the other microtube pump was connected to alkaline solution prepared by dissolving 6.52 g of sodium and 7.95 g of sodium hydroxide in 150 ml of ion exchange water, and the tubes were fixed to enable dropwise addition to the reaction vessel while controlling pH.
With stirring at room temperature, the reaction was conducted while adjusting the quantity of the two aqueous solution added dropwise so that pH was kept at 8. The time period of the dropwise addition was about 30 minutes. The resultant precipitation was washed with water and filtered 5 times repetitively, dried in an oven at 80° C. for 15 hours and then ground using a personal mill. The powder obtained was baked for 1 hour at 300° C. and sieved through a 100 mesh sieve to obtain the intended material.
The intended material was obtained similarly to Embodiment 5 except for using mica (ζ-potential: −36.1 mV, average particle size: 18 μm) instead of talc.
The intended material was obtained similarly to Embodiment 5 except for elevating covering quantity of zinc oxide from 10% to 50% by increasing the amount of each mixture solution added dropwise.
Comparative 1 Talc on the market
Comparative 2 Mica on the market
Comparative 3 Silica on the market
Comparative 4 Zinc oxide (spot state synthesis method)
A 1 L separable reaction vessel was charged with 300 mL of ion exchange water, and fitted with a pH controller connected to two microtube pump and a stirrer. One microtube pump was connected to zinc chloride solution prepared by dissolving 16.75 g of zinc chloride and 2.4 ml of a 5M aqueous solution of hydrochloric acid in 150 ml of ion exchange water and the other microtube pump was connected to an alkaline solution prepared by dissolving 12 g of sodium hydroxide in 150 ml of ion exchange water, and the tubes were fixed to enable dropwise addition to the reaction vessel while controlling pH.
With stirring at room temperature, the reaction was conducted while adjusting the quantity of the two aqueous solution added dropwise so that pH was kept at 10. The time period of the dropwise addition was about 30 minutes. The resultant precipitation was washed with water and filtered 5 times repetitively, dried in an oven at 120° C. for 15 hours and then ground using a personal mill. The powder obtained was sieved through a 100 mesh sieve to obtain the intended material.
As evident from Table 5, the effect of a rough skin was almost proportionated to inhibition rate of the plasminogen activator. One with a inhibition rate of 40% or higher had a high rough skin-preventing effect, and one with a inhibition rate of 50% or higher had a marked effect.
Any of complex powders of this invention exhibited relatively high adsorption rate and inhibition rate, and had a high effect on the rough skin,
While the talc, silica and mica exhibited excellent UK adsorption rates since their ζ-potentials were not higher than −10 mV, any of them exhibited almost no UK inhibiting effect when employed alone and showed no rough skin-preventing effect (Comparatives 1 to 3).
The rough skin-preventing effect was more excellent at zinc oxide-covering quantity of 50% by weight (Embodiment 7) than zinc oxide-covering quantity of 10% by weight (Embodiment 1). This may be attributable to the tendency of a reduction in the UK activity inhibiting effect due to the difficulty in adsorbing the UK resulting from the coverage of absorption sites of talc due to an excessive amount of covering of zinc oxide.
While ζ-potential of the overall complex powder in each of Embodiments 5 to 7 was positive, a rough skin-protecting effect was exhibited. Since ζ-potential at the adsorption site where is not covered with the zinc oxide was negative, UK could still be adsorbed.
Zinc Oxide Covering Quantity and UK Activity Inhibition Rate
The relationship between zinc oxide covering quantity and UK activity inhibition rate was investigated using a zinc oxide-covering talc.
Similarly to Embodiment 1, zinc oxide-covering talcs having various zinc oxide-covering quantity were obtained (
In zinc oxide-covering talc, UK is adsorbed onto the surface of the talc, and zinc ion inhibits UK activity.
At covering quantity up to 10% by weight, increased covering quantity of zinc oxide resulted in increased UK inhibition rate, while at 30% covering quantity the UK inhibition rate was rather reduced.
These findings may be attributable to the difficulty in allowing zinc ion to inhibit UK activity due to the difficulty in adsorbing UK as a result of too high ζ-potential because of an excessive amount of the covering of the zinc oxide. As a result of a further investigation, it was revealed that the UK inhibiting effect (UK inhibition rate: 40% or higher) was obtained with a covering rate of 1 to 70% weight.
Accordingly, it is preferable that in a complex powder having an operation site formed on an adsorption site the covering quantity of the operation site is 1 to 70% by weight.
Zinc Oxide Covering Rate and UK Activity Inhibition Rate
The relationship between zinc oxide covering rate (surface area) and the UK activity inhibition rate was investigated.
Similarly to Embodiment 1, zinc oxide-covering talcs having various coverings rate of zinc oxide were obtained. The results are shown in Table 7 and
At covering rate up to 20% by weight, an increased zinc oxide covering rate resulted in increased UK inhibition rate, but once exceeding 20% covering an increased zinc oxide covering rate rather resulted in reduced UK inhibition rate. These findings may be due to the difficulty in allowing the zinc ion to inhibit the UK activity resulting from the coverage of the silica's absorption sites due to an excessive amount of the covering of the zinc oxide and also resulting from reduced UK absorption ability due to elevated ζ-potential because of the covering of the zinc oxide. As evident from
Accordingly, it is preferable that in a complex powder having an operation site formed on the surface of an adsorption site, the covering rate of the operation site is 1 to 90% by weight, typically 2 to 70%, especially 4 to 50%.
While the ζ-potential of the overall complex powder was positive at zinc oxide covering rate of 25% or higher, the UK could still be adsorbed since the ζ-potential at the adsorption site not covered with the zinc oxide was negative, whereby exhibiting UK activity inhibiting effect.
ζ-Potential and Zinc Ion Elution Level
In zinc oxide-covering organic powder, UK is adsorbed onto the surface of the organic powder and the zinc ion inhibits UK activity.
The level of zinc ion eluted from various zinc oxide-covering organic powders was measured, and the relationship with UK activity inhibition rate was investigated.
Zinc Oxide/Organic Powder Complex Formation
Organic powders and zinc oxide (Zinc white SEIDO) were mixed preliminary, and said organic powders were covered with said zinc oxide by a mechanofusion processing, whereby producing complex powders shown in Table 8. The mechanofusion processing is a procedure in which mixed powders are agitated at a high rotation speed and the powders hit against each other during the passage through narrow gaps whereby forming a complex powder.
Organic Powders
Polyamide (Nylon SP500™: ζ-potential: −32 mV)
Polymethyl methacrylate (Ganzpearl™: ζ-potential: −18 mV)
Silicone resin microparticle (Tospearl 145A™: ζ-potential: −14 mV)
The relationship between zinc ion elution level and UK inhibition rate is shown in
As evident from
It was also revealed that the complex powder of the Nylon SP 500™ and the zinc oxide exhibited a rough skin-preventing effect.
The microscopic photograph of the polyamide covered with 30% by weight of the zinc oxide is shown in
A powder of talc covered with each of amino acids shown below was further covered (by the mechanofusion treatment) with zinc oxide (Zinc white manufactured by SEIDO) to produce a complex powder (covering at 30% by weight). Any of the powders had UK activity inhibition rate of about 40% and proven to have a sufficient inhibiting effect.
Ne-lauroyl-L-lysine (amphoteric)
di-Sodium N-stearoyl-L-glutamate (anion)
Poly sodium aspartate (anion)
(B) Complex Powder Having Adsorption Site Formed on Operation Site (Silica-covering Zinc Oxide)
20 Kg of a zinc oxide powder is filled in a reaction device, which is then subjected to a reduced pressure and purged with nitrogen, and then the internal temperature is raised to 60° C. 1,3,5,7-Tetramethylcyclotetrasiloxane is fed at a rate of 40 to 50 g/hr into the device, where it is reacted with the surface of the zinc oxide. Once the silicon deposition rate reached an optimum value of 0.5% to 10%, the internal temperature is raised to 105° C. to sinter for 2 hours. After replacing with nitrogen, the system is allowed to stand to cool to room temperature. The sample thus synthesized is taken out, ground and disintegrated, sieved through a 100 mesh sieve, sintered for several hours at an optimum temperature of 400 to 700° C. at which the silicone is converted into a silica using an electric furnace, disintegrated, whereby obtaining the intended material.
20 kg of a zinc oxide powder is filled in a Henschel mixer, to which 200 to 600 g of methyl hydrogen polysiloxane (Shin-Etsu Chemical Co., Ltd.) or a silane coupling agent (octyl trimethoxysilane, octyl triethoxysilane, methyl trimethoxysilane, methyl triethoxysilane, dimethyl diethoxysilane, hexamethyl disilazane: Shin-Etsu Chemical Co., Ltd.) dissolved in 400 g of hexane is added with stirring. A powder in which the silicone is dispersed uniformly is subjected to the reaction of the silicone with the surface of the powder at 150° C. whereby evaporating the solvent. The powder is taken out, sintered for several hours at an optimum temperature of 400 to 700° C. at which the silicone is converted into a silica using an electric furnace, disintegrated, whereby obtaining the intended material.
As evident from Table 9, silica-covering entire surface of zinc oxide (Comparative 5) showed the effect which was lower than that of silica network-covering zinc oxide (Embodiments 9 and 10). This may be due to the disability of inhibiting UK activity when the entire surface of zinc oxide was covered with silica.
Silica Covering Quantity and UK Activity Inhibition Rate Zinc Ion Elution Level
Then a silica-covering zinc oxide was employed to investigate the relationship between the silica covering quantity and UK activity inhibition rate or zinc ion elution level.
Similarly to Embodiment 9, silica-covering zinc oxides with various silica covering quantities were obtained.
The results are shown in Table 10 and
In silica-covering zinc oxide, zinc ion and UK are adsorbed onto the surface silica, and zinc ion inhibits UK activity.
At covering quantity up to 20% by weight, an increased silica covering quantity resulted in increased UK inhibition rate, but once exceeding 20% covering quantity increased silica covering quantity rather resulted in reduced UK inhibition rate. These findings may be due to the difficulty in allowing zinc ion to be eluted at an excessive silica covering quantity, which leads to the difficulty in exerting UK activity inhibition. As evident from
Accordingly, it is preferable that in complex powder of this invention having an adsorption site formed on the surface of an operation site, covering rate of the absorption site is preferably 0.1 to 75% by weight, especially 3 to 50% by weight.
Also as evident from
A zinc oxide was covered with each of anionic polymers shown in Table 11 to form complex powder, whose UK inhibition rate was investigated. The results are shown in Table 12.
Method for Producing Anionic Polymer-covering Zinc Oxide
Each of various anionic polymers is dissolved in a good solvent, to which a zinc oxide is added. After mixing sufficiently, the sample is filtered and washed, and dried sufficiently.
It was confirmed that all complex powders above have sufficient inhibition ability.
A complex powder according to the present invention exhibits not only a promotive effect on a rough skin-improving effect but also a irritation-reducing effect on a sensitive skin having a pathological dermal inflammations.
On the other hand, a complex powder having a marked effect was imparted with a water-repelling ability by the treatment with 3% silicone to obtain a sample, which was, however, not dispersed in the assay system because of its hydrophobicity and was not able to be examined for the inhibition rate (N.D.), but it still exhibited a sufficient rough skin-preventing effect when used actually, although the effect was lower than that of a non-treated complex powder.
The effect of a complex powder of the present invention was examined for the rough skin-improving effect and the skin irritating effect on the skin condition of a sensitive skin. As samples, a powdery foundation blended with 10% by weight of the zinc oxide-covering talc (Embodiment 12) and a non-blended powdery foundation (Comparative 7) having the compositions (% by weight) shown in Table 13 were employed.
The Embodiment 12 was applied to one cheek of each of the 50 female panelists having the sensitive skins described above once a day or more for 8 weeks while applying the Comparative 7 to the other cheek, and the subsequent skin condition was evaluated on the basis of the following criteria.
[1] Criterion of Skin Condition-improving Effect
Very good: The skin condition became markedly improved.
Good: The skin condition became improved.
Slightly good: The skin condition became slightly improved.
Poor: The skin condition was unchanged or rather exacerbated.
<Evaluation of Improving Effect on Skin Condition>
AA: The efficacy rate (The ratio of the panelists answering “Very good”, “Good” and “Slightly good”) is 80% or higher.
A: The efficacy rate is 50% or higher and less than 80%.
B: The efficacy rate is 30% or higher and less than 50%.
C: The efficacy rate is less than 30%.
[2] Skin Irritating Feel
<Evaluation of Skin Irritating Feel>
AA: The ratio of the panelists experiencing irritating feel on the skin is 0%.
A: The ratio of the panelists experiencing irritating feel on the skin is less than 5%.
B: The ratio of the panelists experiencing irritating feel on the skin is 5% or more and less than 10%.
C: The ratio of the panelists experiencing a stingy feel on the skin is 10% or more.
[3] Criterion by Replica Method
Simultaneously with the visual examination of the skin condition, a skin replica was obtained by subjecting the skin surface morphology to a replica method using a myricin resin, and observed microscopically (×17) and evaluated.
<Replica Method Evaluation>
1: Skin groove and skin convex were lost and horny layer was peeled over a wide area.
2: Skin groove and skin convex were unclear and horny layer was peeled.
3: Skin groove and skin convex were observed but rather flat.
4: Skin groove and skin convex were clear.
5: Skin groove and skin convex were clear and well-regulated.
As evidence from Table 13, the sample of Embodiment 12 supplemented with oxide-covering talc of the present invention exhibited a more excellent improving effect on the sensitive skin than the sample of the Comparative 7, without exhibiting any skin irritating effect.
Preferred formulations of the present invention are shown below. Any of these formulations exhibited excellent preventing ability and improving ability against a rough skin as well as improving effect on an atopic dermatitis, pimples and the like while showing an extremely low irritation to a sensitive skin or allergic skin.
(The Process)
The Components 1) to 7) and 9) are heated and kept at 75° C. (oil phase). The Components 10) and 11) are dissolved in the Component 12), to which then the Component 8) is added, dispersed and warmed at 75° C. (water phase). The water phase is added to the oil phase, emulsified uniformly using a homomixer, and cooled to 30° C. with stirring thoroughly.
(The Process)
The Components 1) and 2) are stirred and mixed thoroughly using a blender while spraying the Component 3) uniformly.
(The Process)
The Components 1) to 6) are stirred and mixed thoroughly using a blender
(The Process)
The Components 1) to 4) are heated and dissolved at 85° C., combined with the Components 5) to 9), stirred and mixed and then combined with the Component 10) with stirring, charged into a container and cooled.
(The Process)
The Components 1) to 11) are heated and dissolved/dispersed at 85° C., and then combined with the Component 12), which is dispersed uniformly. To this mixture, the Components 13), 14) and 16) which was dissolved and mixed with heating at 85° C. is added in portions to give an emulsion. The emulsifying temperature is kept for 10 minutes with stirring, the mixture is cooled to 45° C. with stirring. To this mixture, the Component 15) was added, cooled to 35° C. with stirring, and then charged into a container.
(The Process)
To the Component 8), the Components 2), 3) and 6) are added and dissolved. Then, the Component 1) is added and dissolved with heating, and then the Component 5) was dispersed. To this mixture, the Components 4) and 7) are added and dissolved with stirring.
(The Process)
The Components 7) to 9) are mixed at 80° C., combined with the Components 1) to 6), mixed using a disper and subjected to a TK milling. To this mixture, the Components 10) and 11) which have been heated and dissolved are added, mixed and degassed. The Component 12) is mixed gently, and the mixture is charged at 80° C. into a container and then cooled.
(The Process)
The Components 1) to 17) are stirred and mixed thoroughly using a blender
(The Process)
The Components 1) to 9), 12), 16) to 18) are dissolved with heating at 85° C., combined with the Components 10) and 11), and dispersed (oil phase). To the Component 13), the Components 14) and 15) are added and dispersed uniformly (water phase). The oil phase is added to the water phase, kept at 85° C. for 100 minutes with stirring, cooled with stirring to 45° C.
(The Process)
The Components 1) to 14) are dissolved with heating at 85° C. (oil phase). To the Component 16), the Component 15) is added and dispersed uniformly (water phase). The oil phase is added to the water phase, kept at 85° C. for 100 minutes with stirring, combined with the Components 17) to 19), and cooled with stirring to 45° C.
(The Process)
The Components 1) to 6) are stirred and mixed thoroughly using a blender while spraying the Component 7) uniformly.
(The Process)
The Components 1) to 12) are dissolved with heating at 85° C. (oil phase). To the Component 17), the Components 13) to 15) are added and dispersed uniformly (water phase). The oil phase is added to the water phase, kept at 85° C. for 100 minutes with stirring, combined with the Component 16), and cooled with stirring to 45° C.
(The Process)
The Components 5) to 14) are dissolved with heating at 85° C. (oil phase). To the Component 1), the Components 2) to 4) are added and dispersed uniformly (water phase). The oil phase is added to the water phase, kept at 85° C. for 100 minutes with stirring, combined with the Component 15), and cooled with stirring to 45° C.
(The Process)
The Components 1) to 7) are dissolved with heating at 85° C., combined with the Components 8) to 12), mixed with stirring, and then combined with the Components 13] and 14] with stirring, charged into a container, and then cooled.
(The Process)
The Components 1) to 7) are heated and dissolved at 85° C., combined with the Components 8) to 15), stirred and mixed and then combined with the Components 16) and 17) with stirring, charged into a container and cooled.
(The Process)
The Components 1) to 22) are heated and dissolved at 85° C., and then spraying the Component 23) uniformly.
(The Process)
The Components 1) to 18) are heated and dissolved at 85° C., and then spraying the Component 19) uniformly.
(The Process)
The Components 2) to 8) are dissolved and dispersed in the Compound 1) with stirring thoroughly, and an unwoven fabric is impregnated with this mixture.
(The Process)
The coating solution that mixed the Components 1) to 7) in the Components 8) is coated on the paper, and dried.
Any of the external compositions of the Blending examples 1 to 19 had a plasminogen activator adsorbing effect and inhibiting effect, and exhibits excellent improving effect and preventing effects against rough skin or pimples experienced by a normal human as well as contact dermatitis, psoriasis, atopic dermatitis.
As described above, a complex powder of the present invention has abilities of adsorbing and operating on a specific enzyme, and said complex powder is highly safe and exhibits excellent effect to the skin.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001-200002 | Jun 2001 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP02/06561 | 6/28/2002 | WO | 00 | 12/22/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO03/002076 | 1/9/2003 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4524787 | Khalil et al. | Jun 1985 | A |
| 5073272 | O'Neill et al. | Dec 1991 | A |
| 5122418 | Nakane et al. | Jun 1992 | A |
| 5439935 | Rawlings et al. | Aug 1995 | A |
| 5545428 | Crimp et al. | Aug 1996 | A |
| 5616872 | O'Brien | Apr 1997 | A |
| 5786137 | Diamond et al. | Jul 1998 | A |
| 5876758 | Meybeck et al. | Mar 1999 | A |
| 5902569 | Oshima et al. | May 1999 | A |
| 5925350 | Verheijen | Jul 1999 | A |
| 5968531 | Miyoshi et al. | Oct 1999 | A |
| 6572693 | Wu et al. | Jun 2003 | B1 |
| 6642252 | Bisacchi et al. | Nov 2003 | B2 |
| 6649179 | Yoshida et al. | Nov 2003 | B2 |
| 7381415 | Yokoyama et al. | Jun 2008 | B2 |
| 20010014356 | Yoshida et al. | Aug 2001 | A1 |
| Number | Date | Country |
|---|---|---|
| 0824086 | Feb 1998 | EP |
| 1112744 | Jul 2001 | EP |
| Number | Date | Country | |
|---|---|---|---|
| 20040175386 A1 | Sep 2004 | US |
