Abstract: The composition consists of an aqueous solution of nitric acid and nitrous acid with a pH below 1 and an acid equivalent of from 6 to 10 mmole/ml; the amount of nitrous acid corresponds to 0.01 to 5 mg of nitrite (NO.sub.2.sup.-) per ml. Additionally, the solution preferably contains acetic acid, oxalic acid and lactic acid as well as copper and cadmium ions. For the preferred composition, the preparation takes place by mixing the components and letting them react to the end or by an oxidative method, in the course of which nitrous acid is formed. The composition is suitable for the local treatment of superficial lesions of the skin and mucous membranes in the fields of cosmetics and medicine, particularly for certain malignant tumors. Experimentally, the effectiveness can be checked by two biological tests developed for this purpose.

Abstract: The organ transplants are intended to be used as a replacement (prostheses) for organs or parts of organs, for examples arteries or veins, which have undergone pathological change or are functionally impaired. The organs, which are taken from a fish, bird or higher mammal, are subjected to crosslinking of the amino groups and of the alcoholic hydroxyl groups of the peptide chains of the intercellular matix by means of a di-, tri- or poly-carboxylic acid. It is advantageous subsequently to treat the crosslinked product with a dialdehyde, in order to bind amino groups which have not reacted, or to free the crosslinked product from material which potentially may act as an antigen, by hydrolysis with ficin, papain or a protease having a smaller action. After the hydrolysis, a comprehensive crosslinking is appropriately ensured using a dialdehyde or a di-, tri- or poly-carboxylic acid.