Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Tissue
Reexamination Certificate
2000-04-06
2003-02-04
Isabella, David J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Tissue
C623S011110
Reexamination Certificate
active
06514291
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an artificial dura mater to be used for prosthesis of dural defect in the field of neurosurgery and a process for producing the same.
BACKGROUND ART
The dura mater, occurring between the cranial bones and brain and covering the spinal cord, protects the brain and spinal cord and inhibits leakage of cerebrospinal fluid. In the field of neurosurgery, a defect or contracture of the dura mater used to be filled with lyophilized products of human dura mater.
However, the lyophilized products of human dura mater have had drawbacks such as low homogeneity and short supply. Further, a possible transmission of infection of Creutzfelt-Jacob disease through the use of the human dura mater was reported (Noshinkeigeka; 21(2), 167-170, 1993) and, eventually, the Japanese Ministry of Health and Welfare banned the use of the lyophilized product of human dura mater on Apr. 7, 1997.
To solve the above drawbacks, artificial dura mater made of silicone, for example, was developed. However, the silicone dura mater has fallen into disuse as it was reported that the silicone dura mater predisposed to meningorrhagia by remaining in vivo permanently because it was non-biodegradable, whereby being a chronic stimulant for the surrounding tissue to cause hypertrophy of the granulation tissue.
In contrast, artificial dura maters made of biodegradable and bioabsorbable materials such as collagen (Journal of Biomedical Materials Research; Vol. 25 267-276, 1991) and gelatin (No to Shinkei; 21 1089-1098, 1969) were produced, but they were not in practical use because of strength-related problems, i.e., because of the insufficiency in the suture strength to be sutured integrally with the internal dura mater.
The applicant provided, in Japanese Unexamined Patent Publication No. 8-80344, an artificial dura mater comprising a sheet made of a biodegradable and bioabsorbable polymer, for example, a copolymer of lactic acid and caprolactone and, further, an artificial dura mater comprising introducing a biodegradable and bioabsorbable polymer made of a material different from that of the sheet as a reinforcement between the sheets and integrally molding the sheets and the reinforcement.
The present invention relates to improvements in the artificial dura mater disclosed in the above publication. An object of the present invention is to provide an artificial dura mater improved in qualities such as non-leakage and suture strength, and a process for producing the same.
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“Glossary of Technical Terms in Japanese Industrial Standards, 5th Edition,” 5th Edition, p. 1296, and a translation of the definition of the term “loss factor.”.
“Japanese Industrial Standards—Testing methods for water resistance of textiles—JIS L1092,” 1998, pp. 1-4 and 11.
Noshinkeigeka; 21(2), 167-170 91993).
Journal of Biomedical Materials Research; vol. 25, pp. 267-276 (1991).
No to Shinhei; 21, pp. 1089-1098 (1969).
Takayama et al. “Creutzfeldt-Jakob Disease,” Neurological Surgery, vol. 21, No. 2 (1993).
Collins et al. “Use of collagen film as a dural substitute: Preliminary animal studies,” Jouranl of Biomedical Materials Research; vol. 25, pp. 267-276 (1991).
Mizazaki et al., “Fundamental and Clinical Studies on the Absorbable Gelatin Film as Dural Substrate,” Handbook of Clinical Neurology, No to Shinhei; 21, pp. 1089-1098 (1969).
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Yamada, K., et al., “Development of a dural substitute from synthetic bioabsorbable polymers,”Journal of Neurosurgery,vol. 86, No. 6 (1997), pp. 1012-1017.
San Galli, F., et al., “Use of a biodegradable elastin-fibrin material, Neuroplast®, as a dural substitute,”Biomaterials,Elsevier Science Publishers Bv., Barking, UK, vol. 17, No. 11 (1996), pp. 1081-1085.
Asahara Tomohiko
Ikada Yoshito
Miyamoto Susumu
Yamada Keisuke
Yamauchi Koji
Baker & Botts L.L.P.
Gunze Limited
Isabella David J.
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