Except as otherwise provided, no board member nor employee of the board shall have any personal interest in the gains or profits of any investment made by the board; nor shall any board member or employee of the board, directly or indirectly, for the member or employee or as an agent, in any manner for the member or employee or as an agent, in any manner use the gains or profits except to make the current and necessary payments authorized by the board; nor shall any member or employee of the board become an endorser or surety, or in any manner an obligor, for money loaned to or borrowed from the board.