Abstract: The present invention provides a novel hydroxyquinoxaline carboxamide derivative that is useful for preventing and/or treating blood coagulation disorders. A compound represented by formula (i), or a pharmacologically acceptable salt thereof: wherein, each of R1 and R2 independently represents a group such as a hydrogen atom or a halogen atom; R3 represents a group such as a hydrogen atom; each of R4 and R5 independently represents a group such as a hydrogen atom, a halogen atom or a C1-4 alkyl group; each of R6 and R7 independently represents a hydrogen atom or a C1-4 alkyl group; X represents a group such as a C3-10 cycloalkyl group, C6-10 aryl group or a 5- to 10-membered heterocyclic group, which may be substituted with substituent(s) selected from substituent group ?; Y represents a group such as —CO—, —O— or —NRa—, and Ra represents a group such as a hydrogen atom or a C1-4 alkyl group.

Abstract: The thymidine kinase-lacking hybridoma of the invention has resistance to oaubain and an Ig-producing ability and is formed by fusing a chicken B lymphoblast cell with an immunized chicken spleen cell. The hybridoma can be used as parental cell line for cell fusion, and the fused cell is excellent in the production of IgG.

Abstract: A thymidine kinase-lacking hybrid cell having an Ig-producing ability in which chicken B lymphoblast with immunized chicken spleen cell, a method of obtaining the above hybrid cell which comprises mutating chicken B lymphoblast cell, isolating a thymidine kinase-lacking cell using a culture medium containing a thymidine analog, fusing it with immunized chicken spleen cell, mutating the hybrid cell, and isolating a thymidine kinase-lacking hybrid cell using a culture medium containing a thymidine analog, a hybrid cell having an IgG-producing ability in which a chicken spleen cell immunized with an antigen is further fused with the above hybrid cell, a method of producing a chicken IgG which comprises culturing the above hybrid cell having an IgG-producing ability in a culture medium. The antibody-producing cell of the invention can produce chicken IgG stably for a long period, and thereby it opens the way for the massproduction of chicken IgG.