Abstract: A simple and efficient method of preparing active recombinant human neutrophil chemotactic factor. The human neutrophil chemotactic factor (NCF) is solubilized from a transformant cell homogenate using urea or guanidine hydrochloride. The polypeptide is further purified from the solution using conventional protocols such as CM-Sepharose CL-6B, HW-55 column, etc.. By using this method, large amounts of active human NCF can be recovered and purified.

Abstract: An expression vector in which a DNA encoding a human neutrophil chemotactic factor polypeptide is inserted, a transformant (a host cell transformed with the expression vector), and a process for production of the said polypeptide by using the said transformant.

Abstract: A cordless telephone communication system having a handset unit and base unit connected by a radio transmission channel, the base unit being connected to a remote telephone through a public telephone line, of the base unit and handset unit, at least the base unit having provided therein a detection unit and semi-mute unit, the detection unit sending out a detection output when the handset unit is positioned outside a service area, the semi-mute unit reducing the level of the received signals when the detection output is given, the remote party being expected to take the natural action of waiting without hanging up the telephone while this reduction in level continues.