Each individual who has an ownership interest in a veterans’ small business concern that is provided a direct loan under this subchapter, or that obtains a loan guaranteed under this subchapter, shall execute a note or other document evidencing the direct or guaranteed business loan, and such individuals shall be jointly and severally liable to the United States for the amount of such direct loan or, in the case of a guaranteed loan, for any amount paid by the Secretary on account of such loan.