Abstract: Methods and means for treating interferon-sensitive diseases are disclosed, wherein a whole blood sample is taken from a patient suffering from such disease and is incubated in vitro together with a mitogen to produce .gamma.-interferon. After incubation the whole blood sample is subjected to a separation step for producing a blood plasma product, which is free from the mitogen but contains .gamma.-interferon. This blood plasma product is used for re-administration to the patient from which the whole blood sample was taken.

Abstract: An impression tray for dental purposes has a shovel-like blade provided on its inside with layer forming attachments for a semi-liquid or plastic impression material which is put onto the tray when it is pressed against the lower or upper jaw for taking an impression. The layer is of uniformly distributed threads with closely-lying attachment points on the inside of the tray, the threads having a stiffness such that they can penetrate into the semi-liquid or plastic impression material when the tray with the material is pressed against the respective jaw for the purpose of the layer being incorporated as effective anchoring means in the bottom layer of the impression material when the material has solidified and the tray is to be jerked loose. The threads are in the form of a non-woven fabric and are bonded to each other at their contact points.