Abstract: A prosthesis for a blood vessel, which is an expanded porous polytetrafluoroethylene tube having a fine fibrous structure with nodes connected to each other by fibrils. The average fibril length is at least 40 &mgr;m, and the tube has a porosity of at least 70%. The load required for compressing the tube by 10% in its axial direction at a strain rate of 100%/min is at least 10 gf. The resistant force per unit sectional area of the tube produced upon the 10% compression is at least 1.0 gf/mm2.

Abstract: An indole derivative represented by the general formula (I) ##STR1## wherein R is hydrogen, lower alkyl having 1 to 6 carbons, carboxymethyl, or substituted or unsubstituted aralkyl; R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may be the same with or different from each other and are hydrogen, halogen, lower alkyl having 1 to 6 carbons, lower alkoxy having 1 to 6 carbons, acyl, substituted or unsubstituted amino, nitro, hydroxy, acyloxy, substituted or unsubstituted aralkyl, substituted or unsubstituted aryloxy, or substituted or unsubstituted aralkyloxy, or a combination of R.sup.2 and R.sup.3 may be methylenedioxy;R.sup.5 is hydrogen, lower alkyl having 1 to 6 carbons, or substituted or unsubstituted aralkyl; R and R.sup.4, or R.sup.1 and R.sup.5 may form together a six-membered ring constituted of methylene chains which may contain a heteroatom;R.sup.6 and R.sup.